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R Bases

Publications and source records attributed to R Bases.

At least 37 records · Page 2Linked to original sources
PubMed1982

Diagnostic ultrasound time-lapse and transmission electron microscopic studies of cells insonated in vitro.

A fibroblast cell line (3T3) and normal rat peritoneal fluid cells were exposed in vitro to pulsed ultrasound from a diagnostic instrument (Smith-Kline "Ekoline 20"). We report here on ultrastructural changes in both cell types and on altered motility patterns in 3T3 fibroblasts. Abnormal motility was detectable 10 generations after exposure. X-irradiation and ultraviolet light elicited similar effects on cell motion. It is suggested that the cellular effects of diagnostic levels of ultrasound be further examined both in vitro and in vivo.

Animals↗
PubMed1982

Morphological transformation, DNA strand separation, and antinucleoside immunoreactivity following exposure of cells to intercalating drugs.

The intercalating drugs quinacrine and proflavine induced increases in single-stranded DNA detected in the nuclei of mouse BALB/c 3T3 1--13 cells. The denatured DNA was detected by fluorescein-labeled antinucleoside antibodies, which bind to single-stranded but not double-stranded DNA. Exposure of cells to the potent mutagen proflavine increased the fraction of immunoreactive nuclei from 0.65 to 0.8. With the weaker mutagen quinacrine, higher concentrations were needed to induce increases in immunoreactivity. Both intercalating drugs rapidly induced morphological transformation in mouse 3T3 cells. Treatment with proflavine resulted in higher transformation frequencies than were found with quinacrine. Significant increases in cell transformation frequency were observed at the concentrations which induced high levels of immunoreactivity. These results suggest that DNA strand separation is itself, or at least accompanies, an early step in cell transformation by intercalating drugs.

Animals↗
PubMed1981

Immunocytological detection of AAF-DNA adducts in HeLa cell nuclei.

Acetylaminofluorene-DNA adducts (AAF-DNA) were detected in the nuclei of HeLa cells exposed to N-acetoxy-2-acetylaminofluorene (N-Ac-AAF), using an immunocytological technique and specific antibodies directed against AAF modified DNA. The proportion of cells exhibiting specific nuclear immunoreactivity was dose-dependent. The time course of disappearance of adduct specific nuclear immunoreactivity was compared with removal of N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-C8-AAF) and other adducts.

2-Acetylaminofluorene↗
PubMed1981

Morphological changes in the surface characteristics of cultured cells after exposure to diagnostic ultrasound.

Morphological changes in the surface membranes of cultured Balb/c 3T3, clone 1-13 cells were studied by scanning electron microscopy after the cells were exposed to diagnostic ultrasound. Abundant irregular, dense microvilli appeared in transformed clones as well as in cells that had been exposed to ultrasound, but had not been morphologically transformed. This increased density of microvilli was detected as early as three days after ultrasound and was still present 37 days later. In comparison, unexposed control cells were smooth with occasional microvilli. Further studies are needed of the effects of diagnostic ultrasound.

Animals↗
PubMed1980

The percentage of cells in DNA synthesis in epidermoid carcinomas of the head and neck: a preliminary report.

The in vivo study of cell kinetics of squamous carcinomas of the head and neck is in its infancy. One cell kinetic parameter, the labelling index (LI), the percentage of cells actively replicating DNA, was estimated in carcinomas of the oral cavity (10), larynx (6) and pharynx(5) by an histochemical immunoglobulin technique developed recently in our laboratory: the antinucleoside antibody technique (ANIP-LI). Data from earlier experiments using autoradiography (3H-thymidine) have established that the enzyme-antibody and isotopic techniques are equivalent. The LI ranged from 1 to 30 with a mean of 13 in this group of tumors. The LI could not be evaluated for 14% (3/21) of the specimens. The 3 patients with tumors not suitable for ANIP-LI had received a full course of radiotherapy and/or chemotherapy before they had entered our study. The higher the LI of the tumor, the greater the likelihood that the surgical stage would be higher than the clinical stage, most often as a result of clinically unrecognized lymph node metastasis. However, the number of tumors sampled was inadequate for a statistical trend to be identified. The potential for the LI to be useful in the formulation of improved therapeutic strategies awaits the accumulation of more data from studies currently in progress.

Carcinoma, Squamous Cell↗
PubMed1980

DNA of HeLa cells during caffeine-promoted recovery from X-ray induced G2 arrest.

Progression of X-irradiated HeLa cells from G2 arrest through mitosis was promoted by 1mM caffeine. Caffeine promoted the return from abnormally high levels of radiation-induced immunoreactivity to antinucleoside antibodies, which indicates persistent DNA strand separation, to the low levels normally found in G2. With caffeine, the irradiated cells progressed through mitosis, producing daughter cells with the normal G1 content of DNA. Without caffeine, the DNA content of individual radiation-arrested cells retained G2 values and the abnormally high levels of immunoreactivity to antinucleoside antibodies.

Antibodies, Neoplasm↗
PubMed1979

Diagnostic ultrasound: effects on the DNA and growth patterns of animal cells.

The effects of diagnostic levels of ultrasound on DNA of HeLa cells included: increased immunoreactivity to antinucleoside antibodies in G1 cells, strongly suggestive of unwinding of the helix or single-strand break induction, and low levels of non-semiconservative synthesis in logarithmically growing cells treated with hydroxyurea, indicating repair synthesis. In the C3H mouse cell line 10T-1/2, Cl 8, loss of contact inhibition with a criss-crossed growth pattern was seen. In one experiment, tumors developed in syngeneic mice at the site of injection of ultrasonically treated cells. Ultrasound in the diagnostic range appears to cause detectable effects on DNA and growth patterns of animal cells.

Animals↗
PubMed1979

Mutagen-induced disturbances in the DNA of human lymphocytes detected by antinucleoside antibodies.

The alkylating mutagens N-methyl-N'-nitro-N-nitrosoguanidine, methyl methanesulfonate, and N-nitroso-methylurea induced immunoreactivity to antinucleoside antibodies in human peripheral blood lymphocytes in vitro. This could also be detected in lymphocytes taken from a patient soon after i.v. administration of cyclophosphamide. The immunoreactivity response, which indicates denatured DNA or DNA single-strand breaks, was scored by immunofluorescent or immunoperoxidase techniques. Examination of blood from 10 normal subjects showed that 32 +/- 4% (S.E.) of resting peripheral blood lymphocytes were immunoreactive to antinucleoside antibodies. We have shown that these naturally occurring immunoreactive lymphocytes are largely accounted for by a subpopulation of thymus-derived lymphocytes bearing the Fc receptor for immunoglobulin M. The presence of these cells did not interfere with the use of peripheral blood lymphocytes for in vitro measurement of additional immunoreactivity caused by alkylating mutagens. The response proved to be dose dependent; up to 90% of lymphocytes could be rendered immunoreactive. Parallel studies with HeLa cells showed a similar dose-response relationship between mutagen action and immunoreactivity. With some agents, the immunoreactivity technique detected effects at lower concentrations than could be detected by HeLa cell survival studies. With N-nitrosomethylurea, measurement of DNA repair synthesis by [3H]thymidine autoradiography showed that in HeLa cells these two parameters of response to DNA damage increased in parallel. Our results provide a new basis for detecting the action of alkylating mutagens on human lymphocytes in vitro or in vivo.

Alkylating Agents↗
PubMed1978

Early steps in mutagenesis by hycanthone.

Hycanthone, the most potent mutagen in a series of nine thiaxanthenones, is a potent inducer of nuclear immunoreactivity to antinucleoside antibodies in HeLa cells. This response indicates exposure of single-stranded DNA regions. All classes of mutagens thus far tested share this property with hycanthone. Immunoreactivity to antinucleoside antibodies was also induced by brief exposure to hycanthone, 3 microgram/ml, in human fibroblasts from three normal subjects and in fibroblasts from seven patients with DNA repair deficiencies. Unlike those of many other mutagens, the metabolic effects and immunoreactivity induction of hycanthone were readily reversible. No evidence for covalent attachment of [3H]hycanthone to HeLa macromolecules could be found. Induction of DNA repair synthesis could not be detected by autoradiography after exposure of cells to hycanthone. Exposure of single-stranded DNA regions appears to be an important feature of the mechanism of action of hycanthone as a mutagen. Both hycanthone and lucanthone intercalate with DNA, but hycanthone was much less active than was lucanthone in reducing the rapid sedimentation of cell lysate DNA in alkaline sucrose gradients. Similarities and differences, therefore, have been found in the way the potent and the weak mutagen affect DNA of HeLa cells. This may provide clues to understanding the mechanism of mutagenesis by thiaxanthenones and other mutagens.

Antibodies↗
PubMed1977

Novel method for estimating the labeling index in clinical specimens with the use of immunoperoxidase-labeled.

The labeling index determined by [3H]thymidine autoradiography in cells from clinical specimens was compared with the percentage of the cells showing nuclear reactivity to immunoperoxidase-labeled antinucleoside antibodies. This nuclear immunoreactivity is specific for denatured or single-stranded DNA's and is detectable almost exclusively during DNA synthesis. Results with the two methods showed excellent agreement. The new method allowed rapid accurate assessment of S phase in the tumor cells from freshly isolated aspirated specimens as well as frozen sections, suggesting general applicability to estimation of the labeling index without autoradiography.

Adenocarcinoma↗
PubMed1977

Effects of lucanthone on the sedimentation properties of DNA from HeLa cells.

Exposure of HeLa cells to lucanthone (3 microgram/ml) caused dissociation of a fast-sedimenting duplex DNA complex, as judged by lysis and sedimentation in alkaline sucrose gradients. The effect of lucanthone on the DNA complex resembled that of actinomycin D and ionizing radiation. Protein synthesis inhibitors such as cycloheximide or inhibitors of DNA synthesis such as hydroxyurea did not lead to dissociation of the complex. Lucanthone was more active than were hycanthone and five other closely related thiaxanthenones tested. Lucanthone promoted X-ray-induced denaturation of DNA in intact cells, as judged by their nuclear immunoreactivity to antinucleoside antibodies. Lucanthone did not inhibit repair of X-ray-induced DNA single-strand breaks.

Centrifugation, Density Gradient↗
PubMed1976

Deficit in DNA content relative to histones in X-irradiated HeLa cells.

The DNA and histone content of HeLa S-3 cell cultures was measured by direct mass assays 21 hours after 1000 rad of X-irradiation, when the cells were arrested in G2 phase. The nuclear DNA content of such cultures was found to be deficient (73% of control values). In contrast, the synthesis of nuclear histones persisted, and the total histone content was close to 100% of control values. When synchronously-growing cultures were irradiated in mid-S phase and examined 3-5 hours later in G2 phase, both DNA and histone content were equal to control values.

DNA↗