Search PubMed⌕ Search

Biomedical subjects

D DiMaio

Publications and source records attributed to D DiMaio.

65 records · Page 4Linked to original sources
PubMed1986

Nonsense mutation in open reading frame E2 of bovine papillomavirus DNA.

Oligonucleotide-directed mutagenesis was used to construct a nonsense mutation in open reading frame (ORF) E2 of bovine papillomavirus DNA. A single base substitution mutation was constructed which converted a TAC codon into a TAG amber stop codon at a position in the ORF that did not overlap with any other viral ORFs. Full-length viral DNA containing the mutation induced only approximately 2% of the transformed foci of mouse C127 cells that were induced by wild-type DNA. In a different transformation assay, approximately one-half of the C127 cells which had acquired the mutant DNA gave rise to colonies containing at least some cells with transformed morphology. The constructed mutation was maintained in cell lines derived from cells which had acquired the mutant viral DNA, but the viral DNA appeared to be integrated into the host cell genome. Genetic mapping experiments proved that the constructed amber mutation caused the decrease in focus-forming activity and the integration of the mutant viral DNA. These results suggest that ORF E2 encodes a protein which is involved either directly or indirectly in some aspects of oncogenic transformation by bovine papillomavirus and in maintaining the viral DNA as a plasmid in transformed cells.

Animals↗
PubMed1984

High-level expression of a cloned HLA heavy chain gene introduced into mouse cells on a bovine papillomavirus vector.

A gene encoding the heavy chain of an HLA human histocompatibility antigen was isolated from a library of human DNA by recombination and selection in vivo. After insertion into a bovine papillomavirus (BPV) DNA expression vector, the gene was introduced into cultured mouse cells. Cells transformed with the HLA-BPV plasmids did not appear to contain extrachromosomal viral DNA, whereas BPV recombinants usually replicated as plasmids in transformed cell lines. Large amounts of HLA RNA were produced by the transformed cells, and the rate of synthesis of human heavy chain was several-fold higher than in the JY cell line, a well-characterized human lymphoblastoid cell line which expresses high levels of surface HLA antigen. Substantial amounts of human heavy chain accumulated in the transformed cells, and HLA antigen was present at the cell surface. These observations establish the feasibility of using BPV vectors to study the structure and function of HLA antigens and the expression of cloned HLA genes.

Animals↗
PubMed1983

Identification of two distinct regulatory regions adjacent to the human beta-interferon gene.

To study the regulation of the human beta-interferon (beta-IFN) gene by poly(I)-poly(C), we analyzed the expression of deletion mutants of the cloned gene introduced into mouse cells on a new bovine papilloma virus (BPV) vector. In stable cell lines transformed by a BPV-IFN plasmid containing the beta-IFN structural gene with 210 bp of DNA to the 5' side of its mRNA cap site (denoted -210), human beta-IFN mRNA is induced approximately 400-fold by poly(I)-poly(C), and reproducible levels of expression are observed for independent cell lines. Our studies indicate that there are two distinct regulatory regions adjacent to the gene, located between -77 and -19, and between -210 and -107. The -77 to -19 region is required for constitutive and induced IFN gene expression, and both are drastically reduced by deletion to -73. When sequences between -210 and -107 are deleted, the constitutive level of IFN gene expression is increased 5- to 10-fold, while induced expression is essentially unaffected. Deletion of the -210 to -107 region also alters the kinetics of induction of the gene.

Base Sequence↗
PubMed1982

Bovine papillomavirus vector that propagates as a plasmid in both mouse and bacterial cells.

We report the construction of a bovine papillomavirus (BPV)-derived recombinant plasmid that propagates as an extrachromosomal element in both mouse and bacterial cells. Plasmids composed of a subgenomic transforming fragment of BPV DNA, a deletion derivative of pBR322, and a 7.6-kilobase fragment of DNA from the human beta-globin gene cluster efficiently induce focus formation on mouse C127 cells. BPV-beta-globin hybrids are maintained in the transformed cells as plasmids with a copy number of about 10-30 per cell. Plasmids indistinguishable from the input DNA have been recovered by transformation of bacteria with low molecular weight DNA from transformed mouse cells. The human beta-globin gene linked to BPV DNA is transcribed from its own promoter at a high level in these cells. The expression of BPV-linked cellular genes in conjunction with the ability to shuttle DNA between bacteria and mammalian cells may provide a rapid means of analyzing and recovering genes that confer an identifiable phenotype upon mammalian cells.

Animals↗
PubMed1981

Binding of an SV40 T antigen-related protein to the DNA of SV40 regulatory mutants.

When simian virus 40 (SV40) infects host cells, the viral genes are expressed in two phases. Early in infection, the virus genome is transcribed and translated to yield two related proteins, 'large T' and 'small t' antigens. Later the rate of synthesis of the early messenger RNA falls and the viral genes coding for the coat proteins are transcribed and translated. Early gene transcription is inhibited only when an active large T antigen is present in the cell (for review see ref. 1). These and other observations have led to the hypothesis that T antigen acts as a negative feedback repressor of its own RNA transcript. The properties of SV40 tsA mutants, which produce temperature-sensitive T antigen, provide evidence for another role of T antigen--in the initiation of viral DNA replication. Mutations around the origin of DNA replication in SV40 lead to a cis-acting defect in DNA replication. These mutations fall outside the region of the A gene which codes for T antigen but within the region known to bind T antigen and the closely related and more easily prepared D2T protein which is synthesized by an adeno-SV40 hybrid virus Ad2D2 and seems to differ from SV40 T antigen only in its amino-terminal segment. Revertants of origin-defective mutants have been isolated with second site mutations within the DNA A gene coding sequence. These data support the view that T antigen modulates transcription and replication of SV40 DNA by binding to one or more sites in and around the viral origin of replication. We present here evidence to show that mutants of SV40 carrying constructed mutations in the regulatory region show reduced binding of D2T protein in vitro. This is the first demonstration in a eukaryote that a mutation in a regulatory DNA sequence alters the binding of a controlling protein in vitro.

Antigens, Neoplasm↗
PubMed1977

Traumatic death in urban children.

Trauma has remained one of the leading causes of death in children in spite of improved medical care. A review of 911 pediatric trauma deaths which occurred over a 5 yr period in an urban setting revealed that almost 50% of these children died before receiving medical care. A significant improvement of the trauma mortality can thus only be accomplished by reducing the number of "DOAs". We therefore analyzed the cause and type of injury and its relationship to age, sex, race, seasonal occurrence, and sociological circumstances. The following four categories are merely part of the overall material developed in this review. Even with improved medical care of trauma patients the overall pediatric trauma mortality cannot be significantly reduced unless the number of DOAs is decreased through prevention. Educational and family assistance programs can be designed for specific problem areas to reach identified susceptible groups through existing channels such as day care centers, schools, or welfare agencies. Statistical data, such as presented here (but not previously available) are essential to analyze the particular problems of specific geographic and sociologic areas. Since the vast majority of pediatric trauma deaths fall within the interest sphere of the pediatric surgeon, our active participation in accident prevention is essential to achieve a significant reduction of pediatric trauma mortalities.

Accidents↗
PubMedDate not supplied

Minocycline pigmentation of heart valves.

Minocycline, a derivative of tetracycline, is a broad spectrum antibiotic used in the treatment of gram-positive and gram-negative infections. Benitz et al. (1) were the first to report black discoloration of the thyroid gland in rats, dogs, and monkeys given minocycline. Since that time, there have been numerous reports in the literature describing minocycline related black pigmentation of the skin, thyroid gland, and other sites. We report an unusual case of minocycline induced pigmentation of the cardiac valves and coronary vessels. The pigment stained with Fontana-Masson and was reduced with bleaching. The exact nature of the pigment is unclear; however, various theories have been advocated. Ochronosis is another cause of black pigmentation of the heart valves; the clinical history should allow distinction between the two.

Aged↗