| a specific effect of external atp on the permeability of transformed 3t3 cells. | | 1975 | 1039 |
| structural proteins of polyoma virus: proteolytic degradation of virion proteins by exogenous and by virion-associated proteases. | a model has previously been proposed for the genetic relatedness of the structural proteins of polyoma virus, based upon similarities in the peptide maps of the major capsid protein vp1 with the virion proteins vp2 and vp3. newer evidence suggests that this model is incorrect, and that protein vp1 is a product of one viral gene and that the multiple components of vp2 and vp3 are products of a second viral gene. two-dimensional peptide maps of several preparations of polyoma purified separately f ... | 1976 | 10452 |
| polynucleotide kinase exchange reaction: quantitave assay for restriction endonuclease-generated 5'-phosphoroyl termini in dna. | | 1977 | 16886 |
| overmethylation of dnas by the ecori methylase. | ecori methylase is able to catalyze methy incorporation into dna at sequences other than the canonical ecori site. at high enzyme concentrations and over a wide range of ph and ionic strengths, ecori methylase modifies polyoma dna (which contains one ecori site) at a number of sites. this modification prevents ecori endonuclease activity, and thus is presumably at or near the ecori sequences (5') naattn. | 1978 | 24833 |
| effect of 5-bromo-2'-deoxyuridine on the in vitro dna synthesizing activity of polyoma virus-infected cells. | the in vitro synthesizing activity of uninfected and polyoma virus-infected mouse embryo (me) cells was investigated by measuring the incorporation of 3h-thymidine (dtr) into acidinsoluble material in cell-free extracts. the character of the enzyme reaction was described in uninfected cells and an activating effect of 0.01 m dithiothreitol (dtt) was observed. a variation of the enzyme activity in the course of cultivation of me cells in primary culture was demonstrated. the induction of the dna ... | 1978 | 25003 |
| minichromosome from bk virus as a template for transcription in vitro. | bk virus dna can be extracted from virions as a nucleoprotein complex containing about 20 nucleosomes. transcription of this "minichromosome" with escherichia coli rna polymerase indicates that both initiation and elongation of rna chains are reduced by the presence of nucleosomes. hybridization analysis of rna made on the complex shows preferential transcription of one region of bk virus genome. no increase in strand selection is observed with respect to transcription of purified superhelical b ... | 1978 | 26051 |
| increased trypsin sensitivity of cell surface macromolecules after malignant transformation. | the effect of treatment with 0.04% (w/v) trypsin (ec 3.4.4.4) for 3 h on the electrophoretic mobility (epm) of polyoma-virus malignantly transformed bhk21 cells (py6) and their normal counterparts has been investigated. these particular conditions were chosen because an earlier study had shown that such treatment released material from the py6 cells which was not obtained from the bhk21 cells. the negative epm of the py6 cells at ph 7.5 was greatly increased by this treatment; whereas the epm of ... | 1978 | 27399 |
| hemagglutination with simian papovavirus sa12. | simian papovavirus sa12 agglutinated human, guinea pig, and chicken erythrocytes. sa12 hemagglutinin was most effectively released from debris of infected tissue culture cells at an alkaline ph. | 1978 | 29051 |
| bk papovavirus in urine of a patient with systemic lupus erythematosus. | | 1978 | 35953 |
| b.k. virus haemagglutinin. | among the widely applied buffered media, the hsag (hepes-salt-albumin-gelatin) medium at ph 5.75--6.25 was found to be the most favourable for b.k. virus haemagglutinin titration. the optimum temperature was at 4 degrees c. the haemagglutinin was not affected by temperatures up to 37 degrees c, phs between 5.5 and 9.5, and nacl concentrations between 0.063 m and 2.56 m. when incubated at 56 degrees c, the haemagglutinin shows a time and ph dependent decline in titre. no significant time dependen ... | 1979 | 44428 |
| letter: the pineal and neoplasia. | | 1975 | 46489 |
| changes in chromatin morphology after infection of mouse embryo fibroblasts with polyoma virus, detected by image analysis. | nuclear chromatin properties in control, sv40-infected and polyoma-infected cultures of mouse embryo fibroblasts were studied using quantitative image analysis. distribution of feulgen-dna-content per nucleus was found to be similar in all three groups of cultures. no differences in nuclear area, mean optical density of chromatin and area of chromatin at different optical density thresholds were measurable between control and sv40-infected fibroblasts. polyoma-infected fibroblasts were found to ... | 1975 | 47678 |
| tumor viruses: 1974. | | 1975 | 50896 |
| specificity and distribution of antigenic determinants on the polyoma virus capsid and nature of the reaction of immunoglobulin g antibody with the capsid surface. | | 1975 | 52714 |
| letter: polyoma virus in urine in aplastic anaemia. | | 1976 | 55578 |
| identification of the stumptailed macaque virus as a new papovavirus. | a new viral agent, stumptailed macaque virus (stmv), isolated from uninoculated stumptailed macaque kidney cultures was identified. the virions had the size and morphology of papovaviruses of the simian virus 40 (sv40)-polyoma subgroup, but many of them appeared to have an additional outer envelope. the deoxyribonucleic acid of stmv was a superhelical circular molecule, with a mean length 91% of that of sv40. the antigenic relationship of this virus with other members of the group was examined b ... | 1976 | 59705 |
| serologically detectable specific and cross-reactive antigens on the membrane of a polyoma virus-induced murine tumor. | with the aid of an assay measuring complement-dependent cytotoxocity mediated by syngeneic antibodies, we performed a serological analysis of surface antigens of a polyoma-virus-induced murine tumor (seyf-a). in vivo propagated seyf-a ascites tumor cells expressed a specific membrane antigen in addition to various other cross-reacting antigens. among these we could identify at least four separate specificities. two of these were present on mulv-induced lymphoma cells, the first on moloney-virus- ... | 1976 | 60289 |
| development of a new human polyoma virus strain (mg). | a polyoma virus isolated from the urine of a renal transplant patient has been grown on primary human foetal fibroblasts and its pattern of replication studied by thin section electron microscopy. virus replication is characterized by the appearance of spherical, crystalline arrays in the nucleoplasm which differ from the nuclear virus crystals found in cells infected by the human polyoma virus prototypes jc and bk. a serological study has substantiated differences between the prototypes and the ... | 1976 | 61748 |
| [artificial heterogenization of tumors]. | | 1976 | 63180 |
| common tumor rejection antigens in methylcholanthrene-induced squamous cell carcinomas of mice detected by tumor protection and a radioisotopic footpad assay. | seven transplantable lines of squamous cell carcinoma of the skin initiated in balb/c mice by skin painting with methycholanthrene were systematically tested for cross-reactivity of their tumor rejection antigens in a 7 x 7 matrix. as determined by decreased tumor frequency after tumor cell challenge, each line was immunogenic against and/or immunosensitive to at least one and usually more than one of the other lines. a radioisotopic footpad assay for delayed hypersensitivity against viable tumo ... | 1977 | 63329 |
| common structural antigen of papovaviruses of the simian virus 40-polyoma subgroup. | an antigenic determinant common to the major capsid polypeptide (vp1) of simian virus 40 (sv40) and polyoma virus is described. antisera prepared against intact viral particles reacted only with cells infected with the homologous virus by immunofluorescence tests (if). however, antisera prepared against disrupted sv40 particles reacted in if with both polyoma- and sv40-infected permissive cells. the cross-reaction with polyoma was localized to vp1 by the following evidence. (i) the if cross-reac ... | 1977 | 64625 |
| cancer-associated serum galactosyltransferase activity. demonstration in an animal model system. | two different lines of solid tumors were produced in outbred hamsters by subcutaneous injection of polyoma transformed bhk cells. growth of the tumors correlated with the appearance in serum of an electrophoretically distinct peak of galactosyltransferase: neuac-, gal-free fetuin acceptor activity on polyacrylamide gels. this slow moving peak of enzyme activity (gt-hh) was detected before solid tumors could be grossly observed and the amount of activity in this peak was also found to be linearly ... | 1977 | 65353 |
| aplastic anaemia, bone-marrow transplantation, and polyoma and other virus infections. | | 1977 | 66488 |
| specificity of the tumor-specific transplantation antigen induced by jc virus, a human polyomavirus. | the specificity of the tumor-specific transplantation antigen (tsta) induced by jc virus was investigated by cross protection tests in weanling hamsters. hamsters immunized with jc virus, bk virus, or sv40 were challenged 5 weeks later with known numbers of jc virus- or sv40-induced hamster tumor cells. both the jc virus-immune and the sv40-immune hamsters showed resistance to challenge with homologous but not heterologous tumor cells, and the bk virus-immune hamsters were not resistant to eithe ... | 1977 | 67106 |
| characterization of human papovavirus rfv: comparison with sv40 and bkv. | human papovavirus, rfv, isolated from urine of a renal transplant patient was compared with two strains of sv40 and with the prototype human papovavirus, bkv. neutralization tests showed that rfv and bkv are indistinguishable, while large-plaque (lp) and small-plaque(sp) isolates of sv40 gave a low but significant level of cross-reaction with rabbit or human antisera against rfv. dna reassociation saturation tests using 125i-labelled rfv dna show that bkv has 88% homology, and sp-sv40 has 29% ho ... | 1977 | 67183 |
| polyomavirus in urine in pernicious anaemia. | | 1977 | 69234 |
| how does t antigen transform cells? | | 1977 | 70276 |
| absence of papovavirus t antibody in patients with malignancies. | | 1977 | 71512 |
| polyoma virus in urine during pregnancy. | | 1977 | 71513 |
| interspecies-, species- and type-specific t antigenic determinants of human papovaviruses (jc and bk) and of simian virus 40. | immunofluorescence tests, absorption studies and quantitative analysis by a very sensitive 51cr microcomplement fixation (cf) technique were used to define the degree of relatedness between the tumor (t) antigens induced by human papovaviruses, strain jc and bk, with simian virus 40(sv40) and mouse polyoma virus (pyv). antisera against jcv, bkv, sv40 and pyv t were raised in tumor-bearing hamsters. the data obtained indicate that t antigens of jcv, bkv and sv40 possess various subspecificities w ... | 1977 | 72046 |
| virus-specific proteins in the plasma membrane of cells lytically infected or transformed by pol-oma virus. | antisera, raised in rats, containing specificities directed against tumor antigen of polyoma virus also react with several proteins present in the plasma membrane of mouse cells infected with the virus. the main component has an apparent molecular weight of 55,000. the appearance of this protein after infection with early temperature-sensitive a mutants was temperature-dependent like tumor antigen itself. pulse and chase isotope experiments suggest that this protein originates from a precursor, ... | 1977 | 73183 |
| comparisons of the chemical and biologic properties of triaziquone and triaziquone-protein conjugates. | prepared with nonimmunospecific proteins were covalent conjugates of triaziquone [2,3,4-tris(1-aziridinyl)-p-benzoquinone] (hereafter referred to by the tradename, trenimon). the bound trenimon that absorbs maximally at 350 nm (epsilon = 8,200) was assayed by titration of the acid uptake during alkylation of thiosulfate ion and by the color produced during alkylation of 4-(p-nitrobenzyl)pyridine. conjugates of trenimon with nonimmune igg were toxic to cells in culture, although no firm binding o ... | 1978 | 74416 |
| an immunochemical investigation of sv40 t antigens. 1. production properties and specificity of rabbit antibody to purified simian virus 40 large-t antigen. | | 1978 | 78572 |
| somatic cell hybrids producing antibodies specific for the tumor antigen of simian virus 40. | we have produced somatic cell hybrids between mouse myeloma cells deficient in hypoxanthine phosphoribosyltransferase imp: pyrophosphate phosphoribosyltransferase; ec 2.4.2.8) and spleen cells derived from mice primed with either syngeneic or allogeneic cells transformed by simian virus 40. such hybrids produced antibodies specific for simian virus 40 tumor (t) antigen. only four of twelve independent hybrid cell cultures produced antibodies against simian virus 40 t antigen that crossreacted wi ... | 1978 | 79181 |
| virus-like particles in pregnancy urine. | | 1978 | 79800 |
| characterization of k virus and its comparison with polyoma virus. | the antigenic relationship between the two murine papovaviruses, k virus and polyoma virus, was examined by serological techniques to determine whether they shared any antigenic components. no cross-reactivity was found associated with the viral (v) antigens by the indirect immunofluorescence, neutralization, or hemagglutination-inhibition tests. the tumor (t) antigens expressed in transformed cells or cells productively infected by either k or polyoma virus did not cross-react by indirect immun ... | 1978 | 81318 |
| has bk virus found a disease? | | 1978 | 81417 |
| serological detection of a polyoma-tumor-associated membrane antigen. | syngeneic antisera raised against three polyoma tumors, seyf-a seso and sewe, of strain aby, a and asw origin, respectively, contain antibodies directed against multiple specificities. one specificity is cross-reactive for the three polyoma tumors, but appears to be absent from a large variety of other tumors tested. other, more "public" antigens are shared with a variety of other tumors of viral or non-viral origin. five different public specificities of this type have been demonstrated and to ... | 1979 | 88422 |
| tumorigenicity and karyotype of rat embryo cell lines transformed by bk virus. | a rat embryo cell line transformed by bk virus was used to induce tumors in rats. cell lines were established from these tumors. other sublines were obtained by in vitro cloning of the parental line. growth characteristics and karyotypes were compared to the tumorigenicity of these cell lines. the in vitro cloned sublines had a low tumorigenicity. tumorigenicity of the tumor cell lines varied from high to undetectable. the tumor cell line with the highest tumorigenicity also had the highest satu ... | 1979 | 89780 |
| identification of the primate papovavirus hd as the stump-tailed macaque virus. | the recently isolated primate papovavirus hd is shown to be indistinguishable from the stump-tailed macaque virus by immunofluorescent reactivity, by restriction endonuclease analysis, and by nucleic acid hybridization assay. | 1979 | 90163 |
| isolation of polyomavirus-induced surface antigens of mouse cells: affinity chromatography and biologic activities. | tumor-specific transplantation antigen (tsta) and polyomavirus-induced tumor-associated surface antigen (tasa) were isolated from polyomavirus-transformed balb/c mouse cells with the use of 3-m kcl solubilization and affinity chromatography on antibody-coated sepharose 4b. particular conditions were chosen for removal of the nonspecifically bound proteins from the gel. under these conditions, the ratio between the amounts of crude extract and specifically bound proteins giving the same tasa acti ... | 1979 | 92587 |
| induction of sv40-related transplantation immunity in mice by bk virus-transformed cells. | the reactivity of tumor-specific transplantation antigens (tstas) induced by sv40 and bk virus (bkv) was studied in balb/ccr mice with sv40-transformed tumor cells (mksa-4ac). the mice, which had received bkv-transformed mouse or hamster cells, were highly resistant to the challenge with mksa-4ac. the mksa-rejected animals, however, were as susceptible as non-immunized ones to the subsequent challenge with moloney sarcoma virus (kirsten)-transformed cells. the result shows that bkv-transformed c ... | 1979 | 94612 |
| the importance of pre-treatment of human sera for the titration of hemagglutination-inhibiting antibodies towards bk virus. | | 1979 | 95157 |
| virus infections in renal transplant recipients. | 534 serum samples from 73 renal transplant recipients, 41 haemodialysis patients, and 99 blood and organ donors were examined serologically for antibodies against cytomegalo, h. simplex (types 1 and 2), varicella-zoster, epstein-barr, adeno, influenza, parainfluenza, respiratory syncytial, measles, picorna- and human polyoma- viruses. serum specimens were stored in the lyophilized state until examined thus enabling a simultaneous testing of all samples belonging to one patient. all antigens, com ... | 1975 | 126545 |
| qualitative and quantitative interactions of lectins with untreated and neuraminidase-treated normal, wild-type, and temperature-sensitive polyoma-transformed fibroblasts. | the lectin receptors of confluently grown hamster bhk, wild type polyoma virus transformed pybhk, and temperature-sensitive polyoma transformed ts3-pybhk fibroblasts were investigated using cell agglutination, quantitative (125i)lectin binding, and ferritin-lectin labeling. pybhk and permissively grown ts3-pybhk cells agglutinated more strongly with ricinus communis i agglutinin (rca-i)compared to bhk and nonpermissively grown ts3-pybhk, although saturation binding of (125i)rca-i to these cells ... | 1975 | 162828 |
| effect of interferon on induction of s antigen by polyoma virus in bhk 21 cells. | a new surface antigen (s antigen) can be detected by immunofluorescence during the abortive transformation of hamster cells by polyoma virus. it was found that addition of interferon greatly reduces the percentage of cells positive for s antigen. | 1975 | 163290 |
| evaluation of dye exclusion and colony inhibition techniques for detection of polyoma-specific, cell-mediated immunity. | cellular immunity directed against polyoma virus-induced antigen was observed with c3h/hej splenic lymphoid cells from mice sensitized by a short-term immunization schedule with syngeneic polyoma 4198 and 4198v tumor cells. polyoma specificity of the response was shown by demonstration that splenic cells from dba/2j animals with polyoma virus-induced tumors were cytotoxic for the c3h 4198 and 4198v cells, but not for the l-m cell, another cell line of c3h origin. the polyoma-specific response in ... | 1975 | 163318 |
| characterization of human papovavirus bk dna. | the dna of the bk virus (bkv) human papovavirus was found to be heterogeneous, consisting of at least four discrete species of dna. only the largest of these four species, bkv dna (i), which has a molecular weight calculated to be 96% that of simian virus 40 (sv40) dna, was infectious. homogeneous preparations of bkv dna were obtained, however, from virions purified after low multiplicity infections of human embryonic kidney cells. bkv dna (i) was shown to contain a single r-eco ri and four r-hi ... | 1975 | 163342 |
| studies of polyoma virus dna: cleavage map of the polyoma virus genome. | a small-plaque polyoma virus, mpc-1, was isolated from a mouse plasmacytoma. the dna of this polyoma virus was cleaved with a restriction enzyme from haemophilus influenzae (hin d), and the molecular weights of the limit products were analyzed by electrophoresis and electron microscopy. the fragments produced by this enzyme have been ordered by analysis of partial digest products. a physical map of the polyoma virus genome was then constructed. | 1975 | 163343 |
| in vitro polyoma dna synthesis: requirement for cytoplasmic factors. | purified nuclei from polyoma-infected mouse (3t3) cells were found to be greatly reduced in their ability to synthesize viral dna in vitro when compared with a crude system consisting of an unfractionated hypotonic lysate of the infected cells. the synthetic capacity of the nuclei could be fully reconstituted when a high-speed cytoplasmic supernatant was added back to them. cytosols from uninfected mouse, monkey, and hamster cells were equally as effective in stimulating purified nuclei as that ... | 1975 | 163350 |
| replication of polyoma dna in isolated nuclei. v. complementation of in vitro dna replication. | nuclei from polyoma-infected 3t6 fibroblasts elongate in vitro the progeny strands of the replicative intermediates of polyoma dna. when high concentrations of such nuclei were incubated, short dna fragments were formed and subsequently added onto growing progeny strands. when nuclei were repeatedly washed with buffer containing detergent and then incubated at low concentrations. dna synthesis was decreased. in particular, the joining process was reduced, resulting in an accumulation of short dn ... | 1975 | 163354 |
| polyoma virus t antigen. i. synthesis of modified heat-labile t angiten in cells transformed with the ts-a mutant. | in mouse cells transformed with the ts-a mutant of polyoma virus (ts-a-3t3), only low amounts of the virus-specific t antigen were synthesized at high temperature (39 c). after a shift-down to the permissive temperature (31 c), these cells exhibited the same level of t-antigen production as wild-type polyoma transformants. the t antigen produced by ts-a-transformed cells was inactivated at 39 c in vitro at a faster rate than that produced by wild-type-transformed cells. these observations indica ... | 1975 | 163363 |
| malignant transformation of hamster kidney cells by bk virus. | primary hamster kidney cells were transformed by bk virus, a new human papovavirus. transformed (hkbk) cell produced bk virus t antigen and induced tumors in hamsters that developed antibodies to bk virus t antigen. bk virus was rescued from hkbk cells by sendai virus-assisted fusion with permissive cells. one out of six cell lines derived from hkbk cell-induced tumors showed the same characteristics as hkbk cells. | 1975 | 163364 |
| formation of nucleoprotein complexes between polyoma empty capsides and dna. | purified polyoma empty capsids and polyoma type i dna interact in a cell-free system to form nucleoprotein complexes. complexes that consist of one, two, three, and four empty capsids per dna molecule have been detected. polyoma virions or capsomers do not react with added dna to form such complexes. | 1975 | 163378 |
| temperature-sensitive growth of cells transformed by ts-a mutant of polyoma virus. | | 1975 | 163442 |
| induced agglutinability of 3t3 mouse fibroblasts. | | 1975 | 163446 |
| structural proteins of a human papovavirus (bk virus): a comparison with the structural proteins of simian virus 40. | | 1975 | 163541 |
| sites in the polyoma genome cleaved by restriction endonuclease hindii. | | 1975 | 163542 |
| tumor development after polyoma infection in athymic nude mice. | nude (nu/nu) mice in a cba/h background show an age-dependent ssuceptibility to tumor development after polyoma virus infection (strain lid-1) when compared with nu/ + or cba/h mice, which is apparent when 15- or 30-day-old mice are used: tumor incidence was 83 to 90% in nudes and 0 to 10% in controls. latent perids for tumor development were also shortened in nudes. however, with increasing age nude mice become partially resistant and only 25% develop tumors when infected at 120 days of age. th ... | 1975 | 163861 |
| in vitro polyoma dna synthesis: inhibition by 1-beta-d-arabinofuranosyl ctp. | the effects of 1-beta-d-arabinofuranosyl ctp (ara-ctp) on dna replication were studied in an in vitro system from polyoma-infected balb/3t3 cells. ara-ctp concentrations of larger than or equal to 150 mum were found to block in vitro dna synthesis completely, and concentrations of smaller than or equal to 0.3 mum had no inhibitory effect. intermediate concentrations resulted in a concentration-dependent reduction of the in vitro synthesis rate. long-term labeling with [alpha-32-p]ara-ctp demons ... | 1975 | 163918 |
| virion polypeptide composition of the human papovavirus bk: comparison with simian virus 40 and polyoma virus. | the polypeptide composition of labeled bk virus was compared with that of simian virus 40 (sv40) and polyoma virus by co-electrophoresis of disrupted virions in polyacrylamide gels containing approximately 73% of the capsid protein and had a molecular weight of 39,000. it was smaller than vp1 of sv40 and polyoma virus. the other polypeptides of bk virus were similar in molecular weight to those of sv40. a comparison of the proteins of bk virus and sv40 iodinated with chloramine t before and aft ... | 1975 | 163921 |
| physical map of polyoma viral dna fragments produced by cleavage with a restriction enzyme from haemophilus aegyptius, endonuclease r-haeiii. | digestion of polyoma viral dna with a restriction enzyme from haemophilus aegyptius generates at least 22 unique fragments. the fragments have been characterized with respect to size and physical order on the polyoma genome, and the 5' to 3' orientation of the (+) and (-) strands has been determined. a method for specific radiolabeling of adjacent fragments was employed to establish the fragment order. this technique may be useful for ordering the fragments produced by digestion of complex dnas. | 1975 | 163927 |
| non-repetitive dna transcripts in nuclei and polysomes of polyomatransformed and non-transformed mouse cells. | | 1975 | 163984 |
| virus neutralization and virus-induced immune complex disease. virus-antibody union resulting in immunoprotection or immunologic injury--two sides of the same coin. | | 1975 | 164055 |
| the synthesis and turnover of virus-specific polyadenylated rna in polyoma-infected cells. | | 1975 | 164192 |
| surface carbohydrates of hamster fibroblasts. i. chemical characterization of surface-labeled glycosphingolipids and aspecific ceramide tetrasaccharide for transformants. | 1. neutral glycosphingolipids of hamster fibroblast nil cells have been characterized as follows: glucosylceramide, lactosylceramide (betagall yields 4glc yields cer), a digalactosylceramide (alphagall yields 4betagal yields cer), a trihexosylceramide (alphagall yields 4betagall yields 4glc yields cer), two kinds of ceramide tetrasaccharides (a: alphaga1nacl yields 3betagalnacl yields 3alphagall yields 4betagall yields 1cer, a new type of forssman active glycolipid; b: globoside, betagalnacl yie ... | 1975 | 164440 |
| cyclic amp, membrane transport and cell division. i. effects of various chemicals on cyclic amp levels and rate of transport of neucleosides, hypoxanthine and deoxyglucose in several lines of cultured cells. | nutrient transport rates and cyclic amp levels have been implicated in the regulation of cell proliferation. in the present study, however, changes in intracellular cyclic amp level in several lines of cultured cells (normal 3t3 and sv40 and polyomavirus-transformed 3t3 cells; 3t6, c6 glioma, mouse l, and novikoff rat hepatoma cells) by treatment with papaverine, prostaglandine e1 or isoproterenol did not correlate with the inhibition of the uridine, hypoxanthine or deoxyglucose transport rates ... | 1975 | 164472 |
| neoplastic differentiation: interaction of simian virus 40 and polyoma virus with murine teratocarcinoma cells in vitro. | the host-virus interactions of simian virus 40 (sv40) and polyoma virus (py) with cell lines established from a teratocarcinoma were studied. the cells utilized in this study were the multipotential stem cell of the teratocarcinoma, embryonal carcinoma, and differentiated cells derived from embryonal carcinoma. several lines of differentiated cells were established in vitro which included parietal yolk sac, epithelial, and spindle cell types. embryonal carcinoma cells are not susceptible to infe ... | 1975 | 164473 |
| unidirectional replication of a minority of polyoma virus and sv40 dnas. | poyoma dna replication is initiated predominatly at a site which is 29% from the ecori cleavage site. molecules replicating from this site, after digestion with ecori appear as linear structures with a double stranded loop centered at the origin of replication. these forms constitute 90% of all replicating intermediates. approx. 10% of the replicating intermediates of polyoma and svp40 dnas occur as y-forms after treatment with ecori. these structures have probably resulted from unidirectional r ... | 1975 | 164519 |
| hamster alpha-amanitine-resistant rna polymerase ii able to transcribe polyoma virus genome in somatic cell hybrids. | a hamster cell line resistant to alpha-amanitine has been isolated (alpha-am-r, bhk-t6-g-1). cell extracts of this mutant have an alpha-amanitine-resistant rna polymerase ii (nucleosidetriphosphate: rna nucleotidyl-transferase, ec 2.7.7.6) activity as shown by deae-cellulose column chromatography. this mutation is dominant in interspecific hybrids with 3t3 mouse cells. in such hybrids polyoma virus can grow with equal efficiency in the presence or absence of the drug, thus indicating that the rn ... | 1975 | 164668 |
| somatic hybridization and oncogenesis; (mechanism of formation of malignant tumors and metastases by the action of antilymphocytic serum). | the results of experiments carried out to test some of the consequences of the earlier general theory of oncogenesis, according to which the malignant tumor cell can arise as a result of somatic hybridization of cells of different organ- and tissue-specificity, are described. in the first series a tumor induced by cellophane film, was grafted into syngeneic and allogeneic mice, and antilymphocytic serum (als) was then injected. metastases occurred only in allogeneic recipients receiving als. it ... | 1975 | 164699 |
| the cytodiagnosis of human polyomavirus infection. | | 1975 | 164753 |
| uptake patterns and transport enhancements in cultures of hamster cells deprived of carbohydrates. | | 1975 | 164828 |
| [antigenic characteristics of hamster cells transformed by polyoma virus]. | a hamster cell line derived from a polyoma virus induced tumour (g-py) was found positive for tsta and s antigen detected by the surface immunofluorescence technique. lung metastases were observed in some hamster able to reject a g-py cell challenge dose injected by intradermal route. | 1975 | 164877 |
| the uptake of actinomycin d by normal and virus transformed bhk 21 hamster cells. | | 1975 | 165084 |
| activation of carcinogenic polycyclic hydrocarbons in polyoma-virus-transformed cells as a prerequisite for polyoma virus induction. | polyoma-virus (pv)-transformed cell clones, which are inducible for virus synthesis by various physical and chemical agents, metabolize the chemically non-reactive carcinogen benzo(a)pyrene (bp) into water soluble products. in cultures of such clones, which metabolize bp to a level of 30-6-% of that of normal cells, up to 10.4% of the cells were induced for pv synthesis by bp, 20-methylcholanthrene (mca) and 7,12-dimethylbenz(a)anthracene (cmba). no pv induction was observed with the non-carcino ... | 1975 | 165151 |
| a histochemical study of acid phosphatase in normal and virus-transformed cultured fibroblasts. | the distribution of acid phosphatase has been investigated in normal and virus-transformed cultured hamster and mouse fibroblasts. the enzyme was found to be present in lysosomes, autophagic vacuoles and elements of the golgi apparatus. it was also found to be associated with a surface coat in some virus-transformed mouse cells and in the cytoplasm of both normal and transformed hamster cells. | 1975 | 165164 |
| deoxyribinucleic acid-binding proteins in virus-transformed cell lines. | the synthesis of proteins with affinity for dna has been studied in clones of a syrian hamster cell line (nil) and subclones of this line transformed by polyoma virus (nil-py) or hamster sarcoma virus (nil-hsv). the results show that the synthesis of dna-binding proteins in nil and in its virus-transformed derivatives nil-py and nil-hsv is very similar in exponentially growing cells, but in dense culture there is a very significant difference in the level of a protein (p8), which is much higher ... | 1975 | 165180 |
| sarcoma in a hamster inoculated with bk virus, a human papovavirus. | an undifferentiated sarcoma occurred in 1 of 52 hamsters inoculated when newborn with bk virus (bkv), a simian virus 40 (sv40)-related human papovavirus. it was transplantable and grew in tissue culture. sera of tumor-bearing hamsters were without antibodies reactive to bkv virion antigens in hemagglutination-inhibition and neutralizationtexts, but contained antibodies reactive in immunofluorescence (if) tests to sv40 t antigen in sv40-transformed cells and to antigens in cells acutely infected ... | 1975 | 165302 |
| modification of surface membrane antigens by trypsin. | cultured 3t3 and py-3t3 mouse fibroblasts were subjected to mild treatment with twice crystallized trypsin and their immunogenicity tested in icr/cd-1 mice. surface antigenic modifications were observed using the foot pad swelling assay for detection of delayed hypersensitive responses. mice immunized with trypsin-treated 3t3 cells showed cell-mediated immune reactions following challenge with either homologous antigen or untreated py-3t3 fibroblasts. in contrast, treatment of the virus-transfor ... | 1975 | 165549 |
| polyoma virus-transformed rat cell lines inducible for viral capsid antigen synthesis. | | 1975 | 165623 |
| composition of membranes of cells transformed by tumorigenic dna and rna viruses. | continuous cell lines obtained from mouse and hamster embryonic tissue and human lung contain a homologous series of acidic glycolipids known as gangliosides. these complex lipids are highly concentrated in plasma cell membranes. the ganglioside pattern becomes greatly simplified when cells are transformed by tumorigenic dna and rna viruses. non-transforming viruses and lytic infection of cells by tumorigenic viruses without neoplastic tranformation do not cause changes in gangliosides. the alte ... | 1975 | 165709 |
| transcription of the repetitive dna sequences in polyoma-transformed and nontransformed mouse cells in culture. | rna-dna saturation hybridization experiments were used to estimate the extent of transcription of repetitive dna sequences in polyoma-transformed and nontransformed mouse cells in culture. measurements were made with rna from nontransformed cells in both the subconfluent and confluent stages of growth, transformed cells in normal growth medium, and transformed cells grown in medium containing 5-bromodeoxyuridine, 3 mu-g/ml, a treatment which reduces their tumorigenic potential. no differences we ... | 1975 | 165880 |
| differential cytotoxic acitivity of anticollagen serum on rat osteoblasts and fibroblasts in tissue culture. | rat skin fibroblasts grown in tissue culture were lysed by anti-rat-tail collagen serum and antibodies to the ordered collagen-like synthetic polymer (pro-gly-pro)-n. this cytotoxic effect is complement-dependent and occurs only if the fibroblasts were pretreated with trypsin. these anti-sera have very little cytotoxicity on cultured rat osteoblasts. this differential cytotoxicity is not due to differential binding of anticollagen serum to the cells. both osteoblasts and skin fibroblasts bind th ... | 1975 | 165902 |
| proliferation kinetics of a virus-induced sarcoma in the rat kidney. | | 1975 | 165938 |
| production of macrophage migration inhbitory factor(s) (mif) by virus-transformed cells. | | 1975 | 165954 |
| polyoma virus strain with enhanced synthesis of capsid protein. | a study of the immunochemical characteristics and the synthesis of the capsid proteins of two polyoma virus strains (3049 and 1ps) was carried out to determine the mechanism responsible for the unique accumulation of those structural polypeptides in the cytoplasm of cells infected with the 3049 strain. antisera prepared against disaggregated virus peptides and whole virus were used to measure the quantity of virus-specific antigens in cells infected by the two strains by using an indirect radioi ... | 1975 | 166199 |
| fate of polyoma form idna during replication. | the fate of polyoma form idna generated during replication was investigated in resting balb-3t3 cells. the experiments showed that there was extensive re-entry of such molecules into replication. this process took place over a period of several hours and appeared to be random. progeny form i molecules must, therefore, spend some time in a nonreplicating pool before reinitiating replication. we propose that two factors affect the fate of progeny form idna. (i) the rate of reinitiation of progeny ... | 1975 | 166209 |
| [rna involvement in dna replication (author's transl)]. | | 1975 | 166414 |
| cell rigidity: effect on concanavalin a-mediated agglutinability of fibroblasts after fixation. | a quantitative hemadsorption assay distinguishes the effects of membrane fixation on concanavalin a-mediated agglutinability of fixed cells with unfixed cells. we observed undiminished adherence of unfixed erythrocytes to glutaraldehyde-fixed normal and virus-transformed hamster fibroblasts coated with concanavalin a. fixation of the erythrocytes abolished agglutination with fixed fibroblasts. the agglutinability of fixed cells is more likely related to increased cell rigidity than to decreased ... | 1975 | 166434 |
| tandem repetition of the origin of dna replication in defective polyoma virus dna's. | | 1975 | 166489 |
| a comparative study of bk and polyoma viruses. | | 1975 | 166499 |
| a study on the influence of papovavirus upon encephalitis caused by sspe agent. | to investigate a possible interaction between the sspe agent and papovaviruses, histopathological and statistical evaluations were made of encephalitis induced in hamsters by intracerberal inoculation with isolates from sspe and pml patients, and with bk virus, alone or in combination. with sspe virus alone, hamster brains showed a reduction of susceptibility to encephalitis with increasing age. a modification of the pathology of sspe encephalitis was observed after administration of the pml iso ... | 1975 | 166547 |
| excretion of morphological variants of human polyoma virus. | | 1975 | 166629 |
| in vitro polyoma dna synthesis: self-annealing properties of short dna chains. | short dna chains, isolated from in vitro pulse-labeled replicating polyoma dna, exhibit some degree of self-complementarity (28% resistance to s1 nuclease after self-annealing to plateau levels). this level of self-annealing is not increased if short dna chains present as free single-stranded dna after extraction are included in the hybridization, excluding a selective loss of chains from one side of the growing fork and supporting a semi-discontinuous mode of chain growth. this mode also applie ... | 1975 | 166760 |
| stimulation of the proliferation of normal bhk21 cultured fibroblasts by plant lectins. | | 1975 | 166854 |
| occurrence of bk virus and bk virus-specific antibodies in the urine of patients receiving chemotherapy for malignancy. | urine specimens from 23 children and 9 adults who were undergoing treatment for malignancy as well as urines from 40 normal individuals were concentrated and examined for evidence of papovavirus infection. papovavirus particles were detected in 6 of 64 urines examined by electron microscopy. three of the particle-positive urines induced bk virus-specific immunofluorescence after inoculation of wi38 cells, and three isolations of bk virus were made by inoculation of urines from virus-excreting pa ... | 1975 | 166919 |
| rat cell line 3y1 and its virogenic polyoma- and sv40- transformed derivatives. | cell lines were established from cultures derived from fischer rat embryos according to the transfer schedule described by todaro and green (1963) for mouse 3t3 cells where cell crowding and serum exhaustion were kept to a minimum. cell growth rate did not decline greatly during the course of successive 3-day transfers. like 3t3 cells the rat cell lines possess very low saturation desities under standard culture conditions. a clonal cell line with a relatively high plating efficiency as obtained ... | 1975 | 166944 |
| difference in transport of leucine in attached and suspended 3t3 cells. | 3t3 cells in subconfluent culture take up leucine through a transport system which has a relatively high affinity for leucine (m system). when the culture becomes confluent, the m system is turned off and leucine is transported by another system which has a low affinity for leucine (s system). the m system is reactivated by transferring the cells into subconfluent cultures. in suspension cultures 3t3 cells, initiated from confluent cultures, the m system is not activated and leucine is transport ... | 1975 | 167039 |
| the binding of the mucoprotein from gastric mucus to cells in tissue culture and the inhibition of cell adhesion. | the mucoprotein, which is responsible for the formation of gastric mucous gel in pig, has been shown to bind equally well to suspensions of baby hamster kidney cells, polyoma-virus-transformed baby hamster kidney cells and hela cells. the binding of the mucoprotein to the cells is dependent on ca 2 | 1975 | 167041 |