| 1. |
- Blad, Börje, et al.
(author)
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Impedance spectra of tumour tissue in comparison with normal tissue; a possible clinical application for electrical impedance tomography
- 1996
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In: Physiological Measurement. - 0967-3334. ; 17, s. 105-115
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Journal article (peer-reviewed)abstract
- Electrical characteristics of living tissues have been investigated for a long time in the search for further methods to complement the traditional investigations of pathology and physiology. Tumour tissue has been shown to exhibit a larger permittivity and conductivity than normal tissues. This might be associated with the fact that tumour cells have a higher water content and sodium concentration than normal cells, as well as different electrochemical properties of their cell membranes. To our knowledge only a few contributions on this subject have been published. This study describes an additional application on measurements of the complex impedance of tumour and normal tissues, in order to compare the impedance features of the two tissue types. The tissue sample is placed in a measuring cell in which the temperature is controlled. The measuring cell is connected to an impedance meter able to measure the complex impedance in terms of real and imaginary part curves for frequencies from 1.5 kHz to 700 kHz. The four-electrode principle is used with the current injected by the outer electrodes and the voltage difference measured between the inner electrodes. The current can be altered up to 1 mA. The instrument can be calibrated with known resistance and capacitance networks connected to the input of the instrument in order to minimize the measurement errors. The calibration routine uses a polynomial adaptation and can be applied interactively. Measurements performed by the instrument show promising results. Preliminary results show that this method can be extended to a new application for detection of tumour tissue by electrical impedance tomography (EIT).
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| 2. |
- Wennerberg, Johan, et al.
(author)
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Flow cytometry analysis of malignant tumors of the head and neck--differences between two methods in the recognition of aneuploidy
- 1996
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In: Analytical Cellular Pathology. - 0921-8912. ; 12:3, s. 125-136
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Journal article (peer-reviewed)abstract
- DNA aneuploidy, which reflects changes in nuclear DNA-content, as determined cytometrically is a candidate prognostic factor in squamous cell carcinoma of the head and neck. The aim of this study was to compare two different preparation methods with respect to their use in detecting aneuploid tumor cell populations in malignant tumors of the head and neck. Fresh frozen tumor material was used. The methods compared were a multistep procedure (A) including fixation of cells and enzymatic treatment, and a one step procedure (B). Both include RNAse and the use of propidium iodide for DNA staining. Forty-seven percent of the tumors were non-diploid according to method A, and 29% according to method B, discordant findings being made in 15 tumors, only two of which were non-SCC. Defining a 'true non-diploid tumor' in this series as a tumor with a DNA index outside the range of diploidy detected either by method A or B, 59% (29/49) of the tumors were non-diploid. The sensitivity was 0.48 (14/29) for method B and 0.79 (23/29) for method A. The striking differences in accuracy between methods A and B emphasize the need of caution when new methods are introduced, and when results obtained with different methods are compared.
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| 3. |
- Bergqvist, A, et al.
(author)
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Uterus and endometrium: Flow cytometric DNA analysis in endometriotic tissue compared to normal uterine endometrium
- 1996
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In: Human Reproduction. - : Oxford University Press (OUP). - 0268-1161 .- 1460-2350. ; 11:8, s. 1731-1735
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Journal article (peer-reviewed)abstract
- Endometriotic tissue sometimes shows an invasive pattern. but the growth regulation of the tissue is insufficiently characterized. In a research programme on factors regulating endometriotic growth, the DNA ploidy status and S-phase fraction (SPF) were studied. Fresh-frozen endometriotic tissue from 14 women and endometrium from 11 of them were studied using flow cytometry. A clear diploid pattern was seen in most cases of endometriotic (8/14) and endometrial (8/11) samples. In the remaining cases the G0/G1 peak was broad and skewed, which might indicate a near-diploid cell population. To clarify this, a second group was studied, consisting of 29 formalin-fixed endometriotic samples from 22 women and endometrium from five of them. All these samples were diploid, with one having a broad G0/G1 peak. No convincing difference in SPF between endometrium and endometriotic tissue was found, as the calculations had to be handled with caution because of debris in many samples. Although the study of fresh-frozen samples gave some indications of differences in DNA ploidy status, flow of cytometric DNA analysis of formalin fixed samples of endometriosis showed a diploid DNA pattern in all samples. In conclusion, DNA flow cytometry did not show a convincing aneuploid DNA pattern in endometriotic tissue.
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| 4. |
- Fernö, Mårten, et al.
(author)
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Preoperative fine needle aspiration from human breast cancer is a valuable sampling material for progesterone receptor and cytometric DNA analysis
- 1996
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In: Acta Oncologica. - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 35:S8, s. 19-25
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Journal article (peer-reviewed)abstract
- In a breast cancer series (n = 54), preoperative fine needle aspiration (FNA) was compared with biopsy at primary surgery as a source of material for the determination of progesterone receptor (PgR) content by enzyme immuno assay. The respective results manifested a strong correlation (r(s) = 0.82). The fact that PgR content was usually higher in FNA samples than in the corresponding biopsy samples and the finding that 11% of the tumours were PgR positive in FNA but PgR negative in the corresponding biopsy samples suggest a greater proportion of malignant cells to be obtained with FNA than in surgical biopsy. In another breast cancer series (n = 50), corresponding comparisons for DNA flow cytometry showed concordance in ploidy status (diploid vs. non-diploid) in 84% of cases and a strong correlation in S-phase fraction values (r(s) = 0.70). At DNA image cytometry, concordant results (Auer I + II vs. Auer III + IV) were obtained in 87% of the cases. To sum up, FNA seems to be a useful sampling technique for PgR determination and DNA cytometry.
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| 5. |
- Gudmundsson, Thorkell E., et al.
(author)
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Methodological aspects of flow cytometry DNA analysis in endometrial carcinoma, with special reference to sampling and reproducibility
- 1996
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In: Acta Oncologica. - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 35:8, s. 999-1006
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Journal article (peer-reviewed)abstract
- Two adjacent paraffin-embedded sections manifested concordance in ploidy status in 96% of cases (45/47), and the standard deviation (SD) for SPF was 2.7%. Analysis of 'micro-heterogeneity', within a distance of < or = 700 microm, yielded results for concordant ploidy status in 94% of cases, and the SD for SPF was 1.9% (n = 17). Frozen and paraffin-embedded material yielded concordant results for ploidy status in 87% (39/45) of cases, and SPF values were significantly lower (mean difference 1.5%) in the frozen samples. Diagnostic and repeat curettage material yielded concordant results for DNA ploidy status in 85% (40/47) of cases, and no significant difference in mean SPF (12% vs. 11%) was found. Discordant DNA ploidy results were attributable to small differences in the DNA histograms influencing the interpretation of near-diploid, near-tetraploid and small non-diploid cell populations, and the influence of debris on SPF estimation. On the basis of our findings and the practical advantage we recommend paraffin-embedded material from diagnostic curettage for FCM DNA analysis; the results are available sooner and the handling and transportation of tumor samples is more convenient.
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| 6. |
- Johansson, Maria C, et al.
(author)
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Comparison of mathematical formulas used for estimation of DNA synthesis time of bromodeoxyuridine-labelled cell populations with different proliferative characteristics
- 1996
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In: Cell Proliferation. - : Wiley. - 1365-2184 .- 0960-7722. ; 29:10, s. 525-538
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Journal article (peer-reviewed)abstract
- Growth kinetic data of human tumours, obtained by flow cytometric analysis of cells labelled with bromodeoxyuridine (BrdUrd) might provide prognostic information and allow prediction of response to radio- and chemotherapy. However, the theoretical models applied for calculation of growth kinetic data are not fully evaluated. The purpose of this study was to investigate the dependence of the estimation of DNA synthesis time (Ts) on sampling time after BrdUrd labelling, using four different mathematical formulas (Begg et al., White & Meistrich, White et al. and Johansson et al.) which have been developed for the evaluation of flow cytometry-derived data of BrdUrd-labelled cells. In addition, we have investigated the influence of the growth kinetic properties of the cell populations using two cultured cell lines (one slow and one fast growing), and two hetero-transplanted human tumours. The dependence of the estimation of Ts on sampling time was more or less pronounced, depending on the cell population examined and on the formula used. In the fast growing cell line, the estimates of Ts did not vary significantly with sampling time when using the formulas by White et al., whereas in the slow growing cell line, the estimates of Ts did not show any significant dependence on sampling time when using the formula by Johansson et al. In the tumours, the estimation of Ts depended on sampling time with all formulas used, although to different degrees. In one of the tumours, this was mainly caused by the influence of mouse cells, as we demonstrate. Our results indicate that the proliferative characteristics of a cell population should be taken into consideration when choosing a mathematical formula in order to attain Ts values that are independent of sampling time.
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