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Biomedical subjects

A Bernstein

Publications and source records attributed to A Bernstein.

At least 163 records · Page 9Linked to original sources
PubMed1987

Deletion of 5'-coding sequences of the cellular p53 gene in mouse erythroleukemia: a novel mechanism of oncogene regulation.

The p53 gene is rearranged in an erythroleukemic cell line (DP15-2) transformed by Friend retrovirus. Here, we characterize the mutation and identify a deletion of approximately equal to 3.0 kilobases that removes exon 2 coding sequences. The gene is expressed in DP15-2 cells and results in synthesis of a 44,000-dalton protein that is missing the N-terminal amino acid residues of p53. The truncated protein is unusually stable and accumulates to high levels intracellularly. Moreover, it appears to have undergone a change in conformation as revealed by epitope mapping studies. This study represents the first description of an altered p53 gene product arising by mutation during neoplastic progression and identifies a region in the p53 protein molecule that plays a role in determining p53 stability in vivo.

Animals↗
PubMed1985

Evaluation of a new tampon device for cytologic autocollection and mass screening of cervical cancer and its precursors.

A new autocollection tampon device for obtaining material for cervical cytologic testing was compared with cervical scraping and endocervical aspiration in order to evaluate the cytodiagnostic results. In 1428 cases there proved to be a 94% correlation between these methods. In addition, both smears were compared in a group of patients known to have neoplastic disease of the cervix. In evaluating cervical cancer both techniques detected 100% of the cases. However, the smears, both regular and tampon, were able to diagnose only 96.5% and 89% of grade 3 lesions and 86% and 81% of grades 1 and 2 lesions, respectively. False negative results occurred in 8.2% of the regular smears and 15% of the tampon smear group. These preliminary data, if confirmed by more broad and in-depth studies, suggest the new autocollection tampon may be a useful tool for mass cervical screening.

Adult↗
PubMed1985

Induction of clonogenic and erythroleukemic cells by different helper virus pseudotypes of Friend spleen focus-forming virus.

The properties of clonogenic and leukemic cells, derived from mice infected with different helper virus pseudotypes of the polycythemic strain of Friend spleen focus-forming virus (SFFVp), have been analyzed. Four different replication-competent murine leukemia viruses (MuLVs) were used as helpers for the defective SFFVp genome: the Friend MuLVs, Moloney MuLV, and an amphotropic MuLV. Three different biological parameters were measured: (i) the kinetics of emergence of clonogenic cells characteristic of the late stages of Friend erythroleukemia; (ii) the ability of cells in these colonies to give rise to secondary colonies (self-renewal capacity); and (iii) the capacity of cell lines derived from these colonies to respond to inducers of erythroid differentiation. The properties of these cells was found to be independent of the helper virus used, suggesting that it is the SFFVp genome, not the helper virus, that plays a determinant role in the late stages of erythroleukemia.

Animals↗
PubMed1985

Introduction of a selectable gene into primitive stem cells capable of long-term reconstitution of the hemopoietic system of W/Wv mice.

We have used the random chromosomal integration sites of retrovirus vectors as unique clonal markers to analyze cell lineage relationships within the hemopoietic stem cell hierarchy. Using a high efficiency protocol for retrovirus-mediated gene transfer, anemic W/Wv mutant mice were reconstituted with bone marrow cells infected with a NEO vector. Analysis of the DNA from bone marrow, thymus, and spleen of these reconstituted W/Wv mice indicated insertion of the vector into primitive pluripotent stem cells capable of producing both myeloid and lymphoid progeny as well as into more committed stem cells apparently restricted to either the myeloid or lymphoid lineages. The neo gene was also expressed in these mice, as they contained a variety of G418 resistant in vitro colony-forming cells. These results demonstrate high-efficiency gene transfer and expression in primitive hemopoietic stem cells and provide a direct approach for analyzing the hemopoietic stem cell hierarchy.

Animals↗
PubMed1985

Induction of the early stages of Friend erythroleukemia with helper-free Friend spleen focus-forming virus.

The polycythemia-inducing strain of Friend virus (FV-P) causes a multistage erythroleukemia in susceptible mice. FV-P is a complex of two viruses, a replication-competent virus [Friend murine leukemia virus (F-MuLV)] and a replication-defective spleen focus-forming virus (SFFVp). We have addressed directly the role of SFFVp in the induction of the early stages of Friend disease by constructing stocks of SFFVp free of detectable F-MuLV, using a recently described retroviral helper-cell line. These preparations are capable of inducing erythroid bursts (vBFU-E) whose inducibility, kinetics, and responsiveness to erythropoietin suggest that they are very similar, if not identical, to the vBFU-E induced by FV-P. Single injections of helper-free SFFVp had no apparent effects in vivo, although the addition of exogenous helper virus to the inoculum resulted in the induction of classic Friend disease. Increasing the effective titer by giving mice five daily virus injections resulted in the induction of splenomegaly and a large increase in the number of erythroid colony-forming units that were independent of erythropoietin. When the injections were discontinued, the spleens regressed and all the mice survived. When the injections were continued, all the mice died within 25 days of the first injection. These results demonstrate that SFFVp alone can alter the growth characteristics of erythroid progenitors and is directly responsible for the induction of vBFU-E in vitro and the erythroid hyperplasia in vivo. They also demonstrate that the initial polyclonal stage of Friend disease is reversible and can be reproduced by using preparations of SFFVp free of detectable F-MuLV.

Animals↗
PubMed1985

Insertion of a bacterial gene into the mouse germ line using an infectious retrovirus vector.

Using a Moloney leukemia virus vector containing the bacterial neo gene, we demonstrate that retrovirus vectors can be used to introduce genes into the mouse germ line. Infection of preimplantation embryos with the vector MLV-NEO.1 resulted in integration of neo sequences in approximately equal to 10% of the progeny mice. One of these animals, mouse F.2, contained approximately six MLV-NEO.1 proviruses at independent integration sites, each present at less than a single copy per cell. This mosaic mouse transmitted one of these proviruses to her offspring, producing a line of transgenic mice carrying a full-length, unrearranged MLV.NEO.1 provirus at a single chromosomal integration site. Mice homozygous at this MLV-NEO.1 locus have also been produced. No expression of the neo gene has been detected in the transgenic mice, either by screening of primary bone marrow or lung cells for resistance to G418 or by RNA transfer blot analysis of RNA from several tissues. In addition, the neo gene was found to be extensively methylated in the transgenic mice; however, treatment of primary cells with 5-azacytidine did not induce G418 resistance. The inactivity of the MLV-NEO.1 provirus in transgenic mice and potential means of eliciting neo expression under these conditions are discussed.

Animals↗
PubMed1985

Tissue-specific expression of the newly acquired ecotropic Emv-18 provirus in Fv-2 congenic mice.

Expression of endogenous retroviral sequences in Fv-2 congenic mouse strains was examined by Northern blot analysis. Endogenous ecotropic virus transcripts were observed in total spleen RNA of B6.S (Fv-2ss) mice. Endogenous ecotropic transcripts were not detected in spleen RNA of C57BL/6, the Fv-2rr congenic partner of B6.S, nor in spleens of the C57BL/10 (Fv-2rr) and B10.C (Fv-2ss) congenic strains. Mendelian segregation analysis revealed that only backcross mice segregating the newly acquired Fv-2-linked endogenous ecotropic provirus had endogenous ecotropic transcripts in spleen RNA. Examination of different tissues of B6.S mice showed that Emv-18 transcription was highest in spleen and bone marrow, tissues in which Fv-2 has been shown to function. These results support the conclusion that chromosomal location is an important factor controlling Emv-18 expression in B6.S mice. We also report the presence in the spleen of a novel xenotropic virus transcript detectable only in B6.S mice.

Animals↗
PubMed1985

Characterization of a retrovirus shuttle vector capable of either proviral integration or extrachromosomal replication in mouse cells.

A retrovirus shuttle vector is described that contains the dominant selectable neo gene which confers resistance to kanamycin in bacteria and to the drug G418 in animal cells. The bacterial supF gene and the origins of DNA replication from polyomavirus and the ColE1 replicon also have been included in this vector. Infection of normal rodent cells results in single-copy proviral integration, whereas infection of mouse (MOP) cells expressing polyoma large T antigen results in extrachromosomal replication of the DNA form of the virus. The copy number of the extrachromosomal circles in MOP cells varies from 0 to 100 copies per cell. G418-resistant MOP cells lose their drug-resistant phenotype after passage under nonselective conditions, suggesting that maintenance of the extrachromosomal circles is unstable. The extrachromosomal form of the virus can be recovered as plasmids in Escherichia coli. Two-thirds of the circles analyzed were found to be structurally intact. The others have undergone rearrangements including deletions and insertions. The bacterial supF gene was found to be intact in the majority of recovered plasmids. The data presented here suggest that these retroviruses should be useful as gene transfer vectors for animal cells in culture or in vivo.

Animals↗
PubMed1985

Molecular cloning and chromosomal localization of DNA sequences associated with a human DNA repair gene.

The genes and gene products involved in the mammalian DNA repair processes have yet to be identified. Toward this end we made use of a number of DNA repair-proficient transformants that were generated after transfection of DNA from repair-proficient human cells into a mutant hamster line that is defective in the initial incision step of the excision repair process. In this report, biochemical evidence is presented that demonstrates that these transformants are repair proficient. In addition, we describe the molecular identification and cloning of unique DNA sequences closely associated with the transfected human DNA repair gene and demonstrate the presence of homologous DNA sequences in human cells and in the repair-proficient DNA transformants. The chromosomal location of these sequences was determined by using a panel of rodent-human somatic cell hybrids. Both unique DNA sequences were found to be on human chromosome 19.

Animals↗
PubMed1985

Use of home health services: some findings from the National Medical Care Expenditure Survey.

Data from the National Medical Care Expenditure Survey (NMCES) are used to produce national estimates of the use and sources of payment for home health care services for various demographic groups. The findings indicate that age and health status are strongly associated with home health care use and the vast majority of home health care services are delivered to this population. Nevertheless, there are a large number of younger, relatively healthy people who also use home health care services. Such use is generally non-intensive, often involving only a single visit. In addition it was found that private insurance is only rarely mentioned as a source of payment for home health care.

Age Factors↗
PubMed1985

Complement activation after myocardial infarction.

Complement activation as reflected by C3, C4, and C3d levels was studied in 56 patients following myocardial infarction, 13 with the postmyocardial infarction syndrome (PMIS); 12 with prolonged postinfarction pyrexia; six with clinical evidence of pulmonary embolism; and 25 control patients without apparent complications. In most patients, C3d levels were elevated during the first ten postinfarction days and at the time of any pulmonary embolism; this probably represented local nonimmunologic complement utilization. The PMIS patients had much higher C3d levels associated with significantly lower concentrations of C3 at the time of disease activity. It is suggested that heart reactive antibodies combine with circulating cardiac antigens to form soluble immune complexes, and in the PMIS, these may become deposited in various sites resulting in complement-mediated tissue damage. The high C3d levels associated with the PMIS may also be of value in differentiating this condition from pulmonary embolism, as both problems may have similar clinical and roentgenographic features.

Antigen-Antibody Complex↗
PubMed1984

The relationship of dietary and serum vitamin A to the occurrence of cervical intraepithelial neoplasia in sexually active women.

Sexually active women with colposcopically directed, biopsy-proved cervical intraepithelial neoplasia were matched with normal control subjects with regard to age, race, and socioeconomic status, in order to determine if dietary and serum vitamin A (retinol) levels can be considered one of the contributing risk factors for the development of this disease process. An evaluation of women in the group with cervical intraepithelial neoplasia statistically showed lower levels of serum vitamin A (p = 0.1), although, dietary profiles of both groups did not yield a statistically significant difference (p = 0.7). These results suggest that low serum levels of vitamin A may be associated with the development of cervical intraepithelial neoplasia.

Adolescent↗
PubMed1983

Linkage of the Fv-2 gene to a newly reinserted ecotropic retrovirus in Fv-2 congenic mice.

Restriction enzyme and Southern gel analyses were used to determine the number and location of endogenous ecotropic retroviruses in the germ line of several mouse strains congenic at the Fv-2 gene locus. A new endogenous ecotropic provirus was observed in the germ line of B6.S (Fv-2ss) mice, in addition to the resident provirus found in its congenic partner C57BL/6 (Fv-2rr). This new provirus was similar in structure to the C57BL provirus. The SIM strain of mice, the donors of the Fv-2s allele in B6.S mice, does not contain ecotropic proviruses, suggesting that the new provirus in the B6.S mouse strain arose by germ-line reintegration during the construction of this strain. Mendelian segregation analysis indicated that this new provirus was linked to the Fv-2 gene locus on chromosome 9. In three other Fv-2s congenic mouse strains--B10.C (47N), B6.C (H-7b), and C57BL/6J Trfa, Bgsd--no additional ecotropic endogenous viruses were detected, suggesting that the reinsertion event that occurred during the construction of B6.S is not essential for the acquisition of the Fv-2s phenotype in the C57BL genetic background. Although numerous reports of germ-line reinsertions of ecotropic virus in high-virus mouse strains have been received, the present results provide definitive evidence that similar germ-line amplifications of endogenous ecotropic virus can occur in a low-virus mouse strain.

Animals↗
PubMed1983

Retrovirus transduction: generation of infectious retroviruses expressing dominant and selectable genes is associated with in vivo recombination and deletion events.

We describe the generation of infectious retroviruses containing foreign genes by an in vivo recombination-deletion mechanism. Cotransfection into mouse cells of chimeric plasmids carrying a murine retrovirus 5' long terminal repeat and either the thymidine kinase (tk) gene of herpesvirus or the dominant selectable bacterial gene for neomycin resistance (neo), along with a clone of Moloney murine leukemia virus, results in the generation of infectious thymidine kinase or neomycin-resistant viruses. Expression of the selectable marker in these viruses can be regulated by the homologous transcriptional promoter of the gene, by the promoter contained within the Friend spleen focus-forming virus long terminal repeat, or by the simian virus 40 early region promoter. In all cases, the rescued viruses appeared to arise by recombination in vivo with Moloney murine leukemia virus sequences, resulting in the acquisition of the Moloney 3' long terminal repeat and variable amounts of the 3' adjacent Moloney genome. In two of the thymidine kinase constructs where tk was inserted 200 base pairs downstream from the long terminal repeat, the rescued viruses acquired a large part of the murine leukemia virus genome, including the region involved in packaging genomic RNA into virions. The generation of infectious neomycin-resistant virus is associated with deletions of simian virus 40 splicing and polyadenylation sequences. These results demonstrate that nonhomologous recombination and deletion events can take place in animal cells, resulting in the acquisition or removal of cis-acting sequences required for, or inhibitory to, retrovirus infectivity.

Adenine Phosphoribosyltransferase↗