Sister chromatid exchanges in human lymphocytes after exposure to diagnostic ultrasound.

The frequency of sister chromatid exchanges increased in freshly isolated human lymphocytes as well as in a continuously growing lymphoblast line by exposure to diagnostic levels of ultrasound for 30 minutes. The results confirm previous findings indicating that ultrasound of diagnostic intensities can affect the DNA of animal cells.

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.

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.

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.

Comparison of needle aspiration and solid biopsy technics in the flow cytometric study of DNA distributions of surgically resected tumors.

Flow cytometric analysis (FCM) of DNA content of nuclei was performed on simultaneously obtained tissue samples and needle aspirates from 37 primary colorectal cancers and from 21 other tumors. There was a marked increase in the proportion of the nondiploid cell population in 18 of 58 aspirates when compared with the corresponding tissue samples, presumably because of selective aspiration of tumor cells. The difference was significant at level alpha much less than 0.01 by a paired t-test and was most pronounced in tumors wherein a nondiploid population constituted more than 20% of the sample. The difference did not correlate with the grade or stage of the tumor. These observations suggest that the sampling of surgically resected tissue specimens for DNA analysis by FCM is performed best by needle aspiration, which may increase the yield of nondiploid cells, does not interfere with histologic diagnosis, and may prove especially useful in the analysis of small surgical specimens.

A quick method for concentrating and processing cancer cells from serous fluids and fine-needle nodule aspirates.

A quick method of concentrating cancer cells and the preparation of cytological slides from body fluids and aspirates is described, using a single Ficoll gradient and cytocentrifuge. The method eliminates the disadvantages of conventional techniques, i.e., excess contamination by red (erythrocytes) or white (leukocytes) blood cells and a scarcity of cancer cells. Because the technique is simple and requires only standard cytotechnological equipment, it can be easily adopted as an aid to diagnostic routine in cancer cytology.

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.

The diagnostic value of flow cytometric DNA measurements in follicular tumors of the thyroid gland.

Flow cytometric analysis of DNA content was performed on single or multiple samples from 34 thyroidectomy specimens. There were 29 thyroids with diploid DNA content, comprising 15 nonneoplastic lesions, 5 follicular adenomas, 1 medullary carcinoma, and 8 papillary carcinomas. Aneuploid DNA pattern was observed in five cases, including one metastatic mammary carcinoma. The initial histologic diagnoses in the remaining four aneuploid thyroid lesions were follicular carcinoma in one and follicular adenoma in three. The abnormal DNA pattern in the three follicular "adenomas" prompted a review of their aspiration cytologic and histologic features. The fine-needle aspiration biopsy was performed in two of the three cases and showed evidence of a follicular neoplasm with significant nuclear atypia in both. Histologic review of the three lesions led to a modified diagnosis of noninvasive low grade follicular carcinoma in all three. Flow cytometric analysis of DNA content may prove to be a highly useful adjunct in the evaluation of follicular thyroid tumors. Long-term clinical follow-up is warranted to document the clinical significance of these observations.

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.

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.

Flow cytometry and Feulgen cytophotometry in evaluation of effusions.

Fifty-eight effusions (42 pleural and 16 ascitic fluids) from patients with and without cancer were analyzed by conventional cytology and the results compared with DNA patterns generated by flow cytometry of 10(4) nuclei and several modes of Feulgen cytophotometry. In 31 patients (24 without evidence of cancer and seven with history of cancer and cytologically negative fluids), the fluids were diploid by flow cytometry. One fluid with atypical cells from a lymphoma suspect was also diploid. Flow cytometry of 26 cytologically cancerous fluids disclosed aneuploid DNA patterns in 16 and diploid patterns in ten. Feulgen cytophotometry of 11 of these fluids (three aneuploid, eight diploid) was performed on nuclear preparations identical to those used in flow cytometry and on restrained smears used for visual analysis. The analysis was performed in two modes: as a study of 500 sequential nuclei in an automated system, mimicking flow cytometry, and visually selected large, presumably malignant nuclei. In nine of the 11 cases, the DNA content of visually selected cancer cells was aneuploid, even though this DNA pattern was not evident in the analysis of 500 sequential cells. In two cases, both diploid by flow cytometry, the Feulgen analysis confirmed the presence of cancer cells in the diploid range. In samples of 10(4) nuclei representing a mixed population of cells occurring in effusions, the presence of aneuploid cancer cells may not be disclosed by conventional flow cytometry. A larger sample of cells, a detailed analysis of DNA histograms, and perhaps sorting of select cells in the hypertetraploid range, may prove essential before flow cytometry can be accepted as a diagnostic tool in the laboratory in the assessment of effusions.