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Biomedical subjects

R D Cardiff

Publications and source records attributed to R D Cardiff.

At least 127 records · Page 7Linked to original sources
PubMed1979

Mouse mammary tumor virus infections: viral expression and tumor risk.

Concentrations of murine mammary tumor virus (MuMTV) antigen in the milk of individual naturally infected BALB/cfC3H and BALB/c mice given injections of MuMTV were related to their risk of developing a mammary tumor. Two distinct groups of MuMTV-infected mice were identified. One group exhibited high viral antigen levels in their milk (greater than or equal to 100 micrograms/ml), whereas the other group exhibited low viral antigen levels in their milk (less than or equal to 3 micrograms/ml). Mice that exhibited high levels developed tumors by 17 months of age, whereas those with low levels did not. Viral expression levels in mice having high risks of tumor development were also related to the length of the latency period preceding overt tumor development. The tumor risk potential of naturally infected mice was frequently that of their mothers. Various doses of MuMTV were injected into BALB/c mice, and the resulting infections differed in latency period, level of viral expression, and potential for neoplastic transformation.

Animals↗
PubMed1977

Biology of breast preneoplasia.

The literature dealing with mammary cancer and the presence of the identifiable preneoplastic lesions in the mammary gland of several species has been reviewed. A discrete morphologically identifiable lesion with a high malignant potential is considered preneoplastic. Lobuloalveolar lesions have been identified in the human mammary gland which fit most of the criteria for preneoplasia. The lesions, hyperplastic atypical lobules, are multicentric, have a high statistical association with breast cancer and demonstrate a morphological progression through dysplasia to frank carcinoma. Other breast lesions have a high statistical association but no morphological progression can be seen and their neoplastic potential remains unknown. The significance of these correlations is enhanced by the occurrence of homologous breast lesions in outbred and inbred animal models. Statistical correlation with breast cancer and aberrant morphology has been accepted as presumptive evidence of preneoplasia in some animals. Definitive proof of the neoplastic potential has been obtained in rodent models by transplantation of the suspected lesions and their subsequent development into cancers. Although a strong morphological and statistical analogy exists between the human and animal models, the causes and biological potential of the human lesions await experimental proof.

Adenocarcinoma↗
PubMed1977

Infection of cultured rat hepatoma cells by mouse mammary tumor virus.

A continuous line of buffalo rat hepatoma (HTC) cells has been successfully infected with mouse mammary tumor virus (MMTV) produced by the GR mammary tumor cell line. Uniform infection required initial exposure of the HTC cells to greater than 10(5) MMTV particles per cell. The resultant chronically infected cell population was found to have stably acquired 20-30 copies of MMTV DNA. The infected cells contain viral RNA and express viral antigens; however, very few MMTV particles are released into the culture medium. In spite of the biochemical evidence for infection, we have not detected any alterations in the morphology or growth properties of the infected HTC cells. As is the case in mammary tumor cells, the intracellular concentration of viral RNA is strongly stimulated (50-150 fold) by the synthetic glucorcorticoid, dexamethasone. Thus it appears that the mechanisms by which glucorticoids regulate MMTV gene expression in mouse cells are maintained when this virus infects nonmurine cells.

Antigens, Viral↗
PubMed1976

Distribution of dengue-2 antigens by electron immunocytochemistry.

The distribution of dengue-2 antigens was studied in infected monkey kidney cells (LLC MK2) using an indirect, horseradish peroxidase-conjugated immunoglobulin technique. This procedure allowed both light and electron microscopic examination of serial-step sections of individual cells cut in a plane perpendicular to the monolayer. Both virion and nonvirion antigens were identified on the plasma membrane with this technique. A diffuse cytoplasmic reaction product was also present. The intensity and distribution of the cytoplasmic reaction product was related to disruption of the plasma membrane.

Animals↗
PubMed1976

Hormone synergism in the in vitro production of the mouse mammary tumor virus.

The production of mouse mammary tumor virus (MMTV) in primary cell cultures of BALB/cfC3H mammary tumor cells was measured by radioimmune assay and RNA=dependent DNA polymerase activity. Maximum virus production was dependent on cell density, nutritional milieu, and hormone supplementation. The addition of insulin (u), estradiol-17 beta (E2), progesterone (P), prolactin (PRL), or thyroxine (T3) alone had little or no effect on MMTV production. Hydrocortisone (F) had a primary stimulatory effect. The combination of I, F, and T3 increased MMTV levels. The combinations containing I, F, and E2 had the greatest stimulatory effect. The stimulation of MMTV production was dose dependent. These experiments demonstrate that a variety of hormones act in a synergistic manner to stimulate MMTV production.

Animals↗
PubMed1976

Human antibodies binding to the mouse mammary tumor virus: a nonspecific reaction?

Specific rabbit antisera and over 100 human sera were found to precipitate iodinated mouse mammary tumor virus (MTV). The specificity of these reactions was tested in competitive inhibition studies. Three classes of reaction could be distinguished. The Class 1 reaction was the most specific; it could be inhibited only by MTV and was observed exclusively with rabbit anti-MTV. The Class 2 reaction was apparently against mouse cell determinants; it could be inhibited not only by MTV but also by mouse lactating mammary gland and was characteristic of rabbit anti-mouse lactating mammary gland. The Class 3 reaction was the least specific; it could be inhibited not only by MTV and mouse lactating mammary gland but also by dog milk. All of the human sera tested exhibited Class 3 reactivities.

Antibodies, Viral↗
PubMed1975

Long-term primary culture of mouse mammary tumor cells: production of virus.

Long-term primary cultures of mouse mammary tumor cells proved an excellent source of mouse mammary tumor virus (MMTV). Virus purified from these primary cultures had the same morphologic biochemical, immunologic, and biologic characteristics as MMTV. Quantitation of MMTV-protein equivalents released into the medium was measured by the radioimmunoassay for MMTV. Peak production levels were 20-40 mug MMTV protien equivalents/75-cm-2 flask/24 hours. These cultures produced MMTV for as long as 90 days. MMTV cultivation depended on the initial cell-plating density and hormones. Maximal MMTV release was obtained at a plating density of 1 times 10-6 cells/cm-2 in the presence of insulin and hydrocortisone. Insulin alone gave basal levels of MMTV, and hydrocortisone alone increased MMTV release only three-fold, but insulin and hydrocortisone together effected an eightfold increase in MMTV release. This suggested that hydrocortisone had a primary effect on MMTV release and insulin acted synergistically with hydrocortisone to maximize MMTV release.

Animals↗
PubMed1974

Structure of the mouse mammary tumor virus: polypeptides and glycoproteins.

The polypeptide and glycoprotein compositions of the mouse mammary tumor virus virion from primary monolayer cultures of BALB/cfC3H mouse mammary tumor cells were studied by polyacrylamide gel electrophoresis by using internal and external labeling and Coomassie blue and periodic acid Schiff (PAS) staining. Twelve polypeptides were reproducibly resolved by the combined methods. Five major polypeptides were demonstrable with estimated molecular weights of 52,000, 36,000, 28,000, 14,000, and 10,000. Seven minor polypeptides were also consistently detected and had estimated molecular weights of 70,000, 60,000, 46,000, 38,000, 30,000, 22,000, and 17,000. Carbohydrate was associated with five of these polypeptides as measured by PAS stain or [(3)H] glucosamine labeling, or both. These glycoproteins had estimated molecular weights of 70,000, 60,000, 52,000, 36,000 and 10,000. The majority of the PAS stain and glucosamine was found in the 52,000 and 36,000 dalton peaks.

Amino Acids↗
PubMed1974

Structure of the mouse mammary tumor virus: characterization of bald particles.

The polypeptide, antigenic, and morphological structure of the mouse mammary tumor virus was studied following protease digestion of intact virions. Intact, untreated virions (rho = 1.17 g/ml) had characteristic envelope spikes, five major polypeptides, and were precipitated by antisera against gp52. Two of the major polypeptides, with molecular weights of 52,000 (gp52) and 36,000 (gp36), had carbohydrate moieties. Protease treatment resulted in spikeless, "bald" particles (rho = 1.14 g/ml), which had altered surface antigenicity and which contained neither gp52 nor gp36. These data indicated that gp52 and gp36 were on the viral envelope. Bald particles retained a 28,000 dalton polypeptide (p28) which was proposed as the major internal polypeptide.

Amino Acids↗
PubMed1973

Cytological localization of Dengue-2 antigens: an immunological study with ultrastructural correlation.

Immunofluorescence and electron microscopy were used to study the development and cytological distribution of dengue-2 virion and nonvirion antigens in monkey kidney cells. The type and combination of fixatives were found to affect the intensity of fluorescence. Paraformaldehyde fixation alone resulted in a low level of fluorescence, but an additional fixation step with ethanol or acetone resulted in maximum staining. No fluorescence was obtained after fixation with glutaraldehyde alone or in combination with other solvents. Methanol caused selective ablation of fluorescence by antibody to purified virions. Dengue-specific fluorescence that was most intense in the perinuclear area radiated in a granular pattern of decreasing intensity into the cytoplasm. The perinuclear fluorescence was associated with nonvirion antigens and the cytoplasmic fluorescence was associated with virion antigens. Electron micrographs of infected cells revealed vesicular bodies with reticular electron-dense centers, clusters of structurally complete virions deep within the endoplasmic reticulum, and single virus particles in vacuoles near the periphery of the cell.

Animals↗