Biomedical subjects

L D Blackburn

Publications and source records attributed to L D Blackburn.

4 recordsLinked to original sources

PubMed1994

Radiation dose-dependent variations of micronuclei production in cytochalasin B-blocked human lymphocytes.

Using the cytokinesis-block technique, lymphocytes from healthy volunteers (n = 9) were evaluated for 1) the radiation dose-response curve for micronuclei (MN) expression; 2) technique variables on the yield of MN; and 3) the shortest lymphocyte incubation time required for the MN assay. We found that the best fitting of relationships between increasing MN production and increasing irradiation dose (0-4.0 Gy) was the linear-quadratic model as expressed by the yield equation Y = C+alpha D+beta D2 (P = 0.0003). When lymphocytes were irradiated in vitro with 2.0 Gy and harvested at various time intervals, MN increased during the entire 84 hr culture time. The radiation caused a division delay in lymphocyte as indicated by an increased frequency of mononucleated cells and a decreased number of mitotic indices. The data showed that a shortened culture time (60 hr) for the MN assay is possible and that binucleated cells with > or = 3 MN were found only in cells irradiated at > or = 2.0 Gy. These findings suggest that scoring of MN in lymphocytes may be a practical biological dosimeter for the rapid screening of accidental radiation exposure victims, especially when their clinical manifestations are not obvious.

Adult↗

PubMed1993

Variations associated with disaggregation methods in DNA flow cytometry.

We investigated the variations in DNA ploidy by flow cytometry (FC) among cell suspensions acquired by different disaggregation methods from the same tumor specimens. Cell suspensions (n = 121) of 40 solid tumors were obtained by mechanical mincing (n = 33), enzymatic digestion (n = 19), in vitro fine needle aspiration (FNA) (n = 34) or scraping (n = 35) of the tumor tissues. Mechanical disaggregation gave the highest cell yield, whereas enzymatic digestion provided the best cell viability. The mean values for the G0/G1 coefficient of variation, DNA indices and percent S phase were not significantly different in cell suspensions obtained with the four methods. However, the yield of malignant cells ranged from 60.4 +/- 5.3% (SEM) (enzymatic) to 82.3 +/- 3.1% (scraping). Tissue aliquots of 32 tumors were disaggregated by three to four methods, and the combined results of DNA ploidy obtained from different cell preparations showed that 22 tumors were nondiploid, but concordance with an abnormal DNA peak was found in only 27.3% (6/22) of the DNA nondiploid tumors. Our results indicate that scraping tumor tissue appears to be the best method for DNA FC since it has the highest percentage (61.3) of DNA nondiploid clones. Also, we believe the multiple samplings may provide comprehensive information on the DNA ploidy of solid tumors.

Biopsy, Needle↗

PubMed1992

The size of small cell lung carcinoma cells. Ratio to lymphocytes and correlation with specimen size and crush artifact.

The size of small cell lung carcinoma (SCLC) cells has often been ambiguously defined as one and a half to four times that of a lymphocyte. The purpose of this study was to determine the ratio of nuclear diameter (ND) of SCLC cells to that of lymphocytes in the same tissue sections and to assess whether the size of SCLC cells correlates with the size of tumor specimens and crush artifact. The overall mean ND (microns +/- SD) of SCLC cells was 9.2 +/- 2.1, found in 36 oat cell carcinomas (OAT, 1,800 nuclei) and 16 intermediate cell carcinomas (INT, 800 nuclei). The mean ND of OAT and INT cells was 8.1 +/- 1.3 and 11.6 +/- 1.5, respectively. The mean ND of lymphocytes (2,600 nuclei) was 5.2 +/- 0.3. The overall mean of ND ratios (+/- SD) between SCLC cells and lymphocytes was 1.8 +/- 0.4 (median, 1.7), 1.6 +/- 0.2 for OAT and 2.2 +/- 0.3 for INT. The mean size of the 52 SCLC biopsy specimens was 0.6 +/- 0.9 cm. Of all the biopsies, 84.6% (n = 44) showed various degrees of tissue crushing. The ND of SCLC cells was associated with specimen size (P = .004) and the degree of tissue crushing (P = .001). Therefore, our findings further support the hypothesis that OAT should be considered the effect of artifact rather than a true variant of SCLC and that the ND of SCLC cells is approximately two times that of lymphocytes.

Analysis of Variance↗

PubMed1992

The effect of tissue disaggregation methods on the clonogenicity of solid human tumor cells.

The effect of mechanical, enzymatic and combined disaggregations on the same tumor tissue (n = 154) to define variables related to clonogenic efficiency (CE) of human tumor clonogenic assay (HTCA) was examined. Overall, CE was highly associated with the percentage of malignant cells in the inoculative suspensions (P less than 0.001) and the total cell concentration plated (P = 0.03). However, there was no significant correlation between CE and the disaggregation method, type of tumor, cell viability, proportion of macrophages in the inoculum, or length of incubation (10 or 20 days). In addition, a higher CE was found in some nonadherent fractions when comparing the CE of the original plating suspensions to that of their nonadherent fractions. It is concluded that mechanical disaggregation is the simplest technique for obtaining the highest yield of malignant cells, which is a decisive factor for colony growth, and that an incubation time of 10 days and 1 x 10(6) cells per plate is the best condition for the human tumor clonogenic assay.

Gastrointestinal Neoplasms↗