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Biomedical subjects

L Wolff

Publications and source records attributed to L Wolff.

At least 73 records · Page 4Linked to original sources
PubMed1987

Sequences responsible for the altered erythropoietin responsiveness in spleen focus-forming virus strain SFFVP-infected cells are localized to a 678-base-pair region at the 3' end of the envelope gene.

Two different strains of Friend spleen focus-forming virus, SFFVP and SFFVA, are known to cause a rapid erythroleukemia. The SFFVP-infected cells can proliferate and differentiate maximally without the addition of the erythroid-specific hormone erythropoietin, whereas the SFFVA-infected cells require erythropoietin for differentiation and for maximum proliferation. We previously reported that a recombinant virus containing sequences from the 3' half of the SFFVP envelope gene and the SFFVP long terminal repeat on an SFFVA background has all of the biological and biochemical characteristics of SFFVP. We are now presenting data on a new recombinant virus to show that only the 3' half of the SFFVP envelope gene is responsible for the differences observed between the two strains.

Animals↗
PubMed1986

Induction of the autonomous stage of transformation in erythroid cells infected with SFFV: helper virus is not required.

The erythroleukemia induced by the Friend spleen focus-forming virus (SFFV) in mice exemplifies a multistep oncogenic process. Its sequential steps include a rapid polyclonal hyperplastic stage and a more slowly developing malignant stage characterized by autonomous erythroid cells. We report here that the helper virus normally present in mice infected by SFFV is not required for development of the second stage of transformation. In this study, mice were infected with a polycythemia-inducing variant of SFFV which was prepared as a helper-free stock (L. Wolff and S. Ruscetti, 1985, Science 228, 1549). Highly malignant cells could be detected in helper-free SFFV-infected mice by their transplantability into the omentum of sublethally irradiated mice, and erythroleukemia cell lines, typical of previously isolated Friend murine erythroleukemia cell lines, could be established from diseased spleens. Like their helper virus-containing counterparts, the lines established with helper-free SFFV are inducible for hemoglobin synthesis with a variety of chemicals, but not erythropoietin, and express p53, a marker of malignant transformation. Although the cells expressed SFFV encoded proteins, none expressed gene products of replication competent murine leukemia viruses.

Animals↗
PubMed1986

Tissue tropism of a leukemogenic murine retrovirus is determined by sequences outside of the long terminal repeats.

Although it has been previously determined that the long terminal repeat (LTR) sequences of several murine retroviruses specify the major tissue tropism of leukemias they induce, data reported here show that the LTR is not responsible for tissue tropism in the case of all leukemogenic viruses. In an effort to determine whether LTR sequences of the acute erythroleukemia-inducing spleen focus-forming virus (SFFV), like those of the other murine leukemia viruses, are uniquely required to confer tissue specificity to the virus, we prepared recombinant SFFVs in which the LTR region containing promoter and enhancer functions was replaced with analogous LTR regions from Friend and Moloney ecotropic and mink cell focus-inducing viruses. It was found that all of the SFFV constructs, even those with a LTR derived from lymphoma-inducing viruses such as Moloney murine leukemia virus, transformed erythroid cells in vitro and induced exclusively an erythroid disease. These results demonstrate that sequences in SFFV that determine the tissue-specific nature of the disease reside outside the LTR.

Animals↗
PubMed1986

Expression of normal myeloid-associated antigens by acute leukemia cells.

Monoclonal antibodies that react with hematopoietic cells and their precursors in a stage and lineage restricted fashion were used in indirect immunofluorescence assays to examine leukemic cells from 105 pediatric age patients. The differentiative states of blasts from 42 patients with acute nonlymphocytic leukemia (ANLL) were defined by these antibodies. When these were compared to their morphologic and histochemical levels of differentiation as defined by the French-American-British (FAB) classification, no direct relationship was found. The reactivity of these antibodies with leukemic cells from 63 patients with acute lymphocytic leukemiA (ALL) was also investigated, and the usefulness of these antibodies in distinguishing leukemias of myeloid from those of lymphoid origin was demonstrated.

Acute Disease↗
PubMed1985

[Primary chemotherapy of advanced squamous epithelial carcinomas of the head and neck].

Advanced stage squamous cell carcinomas of the head and neck have a particularly poor prognosis despite surgical and irradiation treatment. Over the last few years attempts have been made to improve the local control rate using primary chemotherapy. 70 patients with advanced carcinomas were treated with methotrexate, cisplatin and bleomycin using double the dose of cisplatin as in the EORTC-study. The remission rate for patients undergoing two treatment courses was 83%. Toxicity was moderate to low with additional intensive anti-emetic treatment. The combination is well suited for chemotherapy of advanced tumours of the head and neck in combined treatment programmes.

Adult↗
PubMed1985

Malignant transformation of erythroid cells in vivo by introduction of a nonreplicating retrovirus vector.

DNA from a replication-defective spleen focus-forming virus (SFFV) was reconstructed and transfected into psi-2 cells containing a packaging-defective mutant of Moloney murine leukemia virus. Replication-incompetent retrovirus particles (helper virus-free containing genomes that express the transforming envelope gene of SFFV (gp52) transformed bone marrow cells in vitro and, after direct intravenous introduction of the vector, induced malignant erythroid disease in vivo. Disease induction was dependent on prior treatment of mice with phenylhydrazine, which probably increased the availability of erythroid target cells. Since there was no evidence of virus particle expression in mice with malignant disease, this study demonstrates the acute oncogenic potential of a limited number of erythroid cells expressing SFFV gp52. Direct inoculation of animals with nonreplicating retroviral vectors containing transforming genes may be useful in study the oncogenic effects of such genes.

Animals↗
PubMed1985

Sequence comparisons of the anemia- and polycythemia-inducing strains of Friend spleen focus-forming virus.

A nucleotide sequence analysis carried out on the envelope gene of the anemia-inducing strain of the Friend spleen focus-forming virus (F-SFFVA) reveals that its product has some unique features in common with previously described polycythemia-inducing strains of F-SFFV (F-SFFVP). (i) It contains an amino terminus that is highly related to the gp70 of mink cell focus-inducing viruses, (ii) it is a fusion protein containing the amino terminus of gp70 and the carboxy terminus of p15E, and (iii) it lacks the R-peptide normally found at the carboxy end of the p15E region. Although the envelope genes of F-SFFVA and F-SFFVP are quite similar overall, they do show sequence variation, particularly at the 3' end in the p15E-related region. These variations may contribute to previously observed differences in the response of F-SFFVP- and F-SFFVA-infected erythroid cells to regulatory hormone or to differences in the way the envelope glycoproteins are processed. The long terminal repeat regions of F-SFFVA and the Lilly-Steeves strain of F-SFFVP were also sequenced and compared with each other and with a previously published sequence of another F-SFFVP long terminal repeat. The sequences were found to be reasonably similar to each other but different from their ecotropic parent, Friend murine leukemia virus, as a result of a deletion of one copy of the direct tandem repeat in the enhancer regions. The observation that all SFFVS have this common change in the long terminal repeat enhancer region raises the possibility that it is required for pathogenicity.

Amino Acid Sequence↗
PubMed1985

Biological and biochemical differences between variants of spleen focus-forming virus can be localized to a region containing the 3' end of the envelope gene.

Two variants of the spleen focus-forming virus (SFFV), SFFVP and SFFVA, induce acute erythroleukemia in mice but differ in their effects on erythroid cells as well as in the posttranslational modification of the product of their envelope genes. To localize the region of the SFFV envelope gene responsible for these differences, we utilized a recombinant virus containing the 3' half of the SFFVP env gene, where the vast majority of the differences between SFFVP and SFFVA reside, and the SFFVP long terminal repeat (LTR) on an SFFVA background. Analysis of the recombinant virus indicates that it is capable of inducing all of the biological effects previously associated with SFFVP, including the ability to proliferate and differentiate without the need for erythropoietin. In addition, the env gene product of the recombinant virus can be detected on the cell surface, a property previously associated only with SFFVP. Although the recombinant virus also contains LTR sequences from SFFVP, we do not believe it is likely that the four LTR nucleotides that are unique to SFFVP are responsible for the biological or biochemical differences observed. These results strengthen the argument that the SFFVP env gene product acts at the cell surface to alter the hormonal requirements for erythroid cell growth and differentiation.

Animals↗
PubMed1984

Recurrent sepsis with deficiencies of C2 and galactokinase.

A 4-year-old girl with recurrent, severe bacterial infections and absence of both the second component of complement and galactokinase was investigated for immunodeficiency. The C2 deficiency (C2D) was diagnosed after four major pyogenic infections. Results of studies of cellular and humoral immunity were normal, as were polymorphonuclear leukocyte chemotaxis and bactericidal activities and alternative-pathway hemolytic activity. Serum chemotactic and opsonic activities were deficient in this patient and in an older, asymptomatic sibling with C2D. Fresh-frozen plasma, administered during an episode of Streptococcus pneumoniae meningitis, enhanced serum opsonic activity at 12 hours after infusion. To our knowledge, this is the first description of C2D in a patient with a documented second, unusual genetic defect.

Antibody Formation↗
PubMed1984

Structural analysis of the spleen focus-forming virus envelope gene product.

The structure of the envelope gene product (gp52) of the spleen focus-forming virus was analyzed and compared to that of envelope proteins (gp70 and p15E) of another pathogenic Friend virus recombinant, Friend mink cell focus-inducing virus (F-MCF). This has enabled us to confirm and extend previous nucleotide sequence data regarding the make up of specific domains of the SFFV glycoprotein. Amino-terminal 23,000-Da V8 protease fragments from gp52 of the Lilly-Steeves strain of SFFV and from gp70 of a pathogenic F-MCF isolate produced tryptic peptide fingerprints in which the mobilities of the trypsin-generated peptides were identical. The carboxyl-terminal, 21,000 Da, V8 protease fragment of gp52, however, has a unique fingerprint that contained a single highly charged trypsin-generated peptide. This peptide migrated to the same position as a peptide in F-MCF p15E, thus indicating that the p15E-related nucleotide sequences, that follow the large envelope deletion, are translated in the same reading frame as those in the standard p15E. Although R peptide determinants can be detected in F-MCF Pr15E, they could not be detected in gp52. The amino-terminal 23K domain of gp52, like that of MCF gp70, contains two oligosaccharide attachment sites. The other two attachment sites are located within the 21K carboxyl-terminal domain.

Animals↗
PubMed1983

Envelope gene of the Friend spleen focus-forming virus: deletion and insertions in 3' gp70/p15E-encoding region have resulted in unique features in the primary structure of its protein product.

A nucleotide sequence was determined for the envelope (env) gene of the polycythemia-inducing strain of the acute leukemia-inducing Friend spleen focus-forming virus (SFFV) and from this the amino acid sequence of its gene product, gp52, was deduced. All major elements of the gene were found to be related to genes of other retroviruses that code for functional glycoproteins. Although the carboxyl terminus of gp52 is encoded by sequences highly related to sequences in its putative parent, ecotropic Friend murine leukemia virus, the majority of the protein (69%), including the amino terminus, is encoded by dualtropic virus-like sequences. Nucleotide sequence comparisons suggest that the nonecotropic region may be more closely related to the 5' substitution in dualtropic mink cell focus-inducing viruses that it is to the 5' end of xenotropic virus env genes. A large deletion and two unique insertions have been located in the env gene of polycythemia-inducing SFFV and may account for some of the unusual structural characteristics, aberrant processing, and pathogenic properties of gp52. As a consequence of the deletion, amino-terminal gp70 and carboxyl-terminal p15E-encoding sequences are juxtaposed and it appears that translation from the p15E region, 3' to the deletion, continues in the standard reading frame used by other retroviruses. Insertions of six base pairs and one base pair at the very 3' end of the gp52-encoding region results in a SFFV-unique amino acid sequence and a premature termination codon.

Amino Acid Sequence↗
PubMed1983

Mutation by [5-3H]cytosine decay in DNA of Escherichia coli lacking uracil-DNA glycosylase activity.

The mutagenic local effect of tritium decay at the 5 position of cytosine in DNA of Escherichia coli was determined in wild-type and in ung strains defective in uracil-DNA glycosylase. In the absence of this in vivo activity any genetic consequences of uracil residues formed in DNA should be enhanced. However, the mutation frequency response was no greater in the mutant strain than in the wild type. This finding is inconsistent with the earlier suggestion that efficient production of C to T transitions by the local effect of [5-3H]cytosine decay results from the formation of uracil in cellular DNA. Some other intermediate should be considered, one that is not a substrate for uracil-DNA glycosylase.

Cytosine↗
PubMed1982

Preparation of rat monoclonal antibodies to epitopes encoded by the viral oncogene (v-fms) of McDonough feline sarcoma virus.

The McDonough strain of feline sarcoma virus (SM-FeSV) contains a viral oncogene, v-fms, transduced from cat cellular genetic sequences designated c-fms. Monoclonal antibodies reactive to antigenic determinants encoded by v-fms were prepared by immunizing rats with live, syngeneic SM-FeSV-transformed cells, and fusing splenic lymphocytes from a tumor-bearing animal with cultured rat myeloma cells. Culture supernatants from hybrids producing antibodies to epitopes encoded by v-fms were identified by immunoprecipitation of radiolabeled polypeptides from SM-FeSV-transformed mink cells. Four positive hybrids were cloned twice in soft agar, established as stable lines, and grown in defined serum-free medium to facilitate purification of homogeneous antibodies. The monoclonal antibodies were used to assay SM-FeSV-specific products by "immunoblotting" of electrophoretically separated proteins, and by fixed-cell immunofluorescence.

Animals↗
PubMed1982

Monoclonal antibody to spleen focus-forming virus-encoded gp52 provides a probe for the amino-terminal region of retroviral envelope proteins that confers dual tropism and xenotropism.

Monoclonal antibodies which recognize a region common to Friend spleen focus-forming virus encoded gp52 and Friend mink cell focus-inducing viral gp70 were isolated. One such antibody from hybridoma 7C10 was tested extensively in immune precipitation and was found to react with a determinant on envelope gp70s of all mink cell focus-inducing, xenotropic, and amphotropic mouse retroviruses tested, but not with envelope gp70s of ecotropic viruses, including Friend, Moloney, and AKR murine leukemia viruses. Monoclonal antibody from hybridoma 7C10 precipitated a 23,000-molecular-weight fragment, derived by V8 protease digestion of Friend mink cell focus-inducing gp70. This 23,000-molecular-weight peptide was determined to derive from the amino terminus of the molecule. These results correlate well with other genetic data which indicate that endogenously acquired sequences of mink cell focus-inducing viruses are found at the 5' end of the envelope gene.

Antibodies, Monoclonal↗
PubMed1982

Monoclonal antibodies to the transformation-specific glycoprotein encoded by the feline retroviral oncogene v-fms.

Monoclonal antibodies prepared to epitopes encoded by the transforming gene (v-fms) of the McDonough strain of feline sarcoma virus were used to study v-fms-coded antigens in feline sarcoma virus-transformed rat and mink cells. These antibodies reacted with three different polypeptides (gP180gag-fms, gp140fms, and gp120fms), all of which were shown to be glycosylated. Protein blotting with [125I]-labeled monoclonal immunoglobulin G's was used to determine the relative steady-state levels of these glycoproteins in transformed cells and showed that gp120 and gp140 were the predominant products. Immunofluorescence assays and subcellular fractionation experiments localized these molecules to the cytoplasm of transformed cells in quantitative association with sedimentable organelles. Thus, v-fms-coded glycoproteins differ both chemically and topologically from the partially characterized products of other known oncogenes and presumably transform cells by a different mechanism.

Animals↗