Biomedical subjects

O Pauwels

Publications and source records attributed to O Pauwels.

27 records · Page 2Linked to original sources

PubMed1993

The application of computerized analysis of nuclear images and multivariate analysis to the understanding of the effects of antineoplastic agents and their mechanism of action.

The present work involves the creation of a model that makes the rapid study of anticancer drugs possible. In order to make possible the multilevel study of antineoplastic derivatives (their effects on cell proliferation, their cell kinetics, their chromatin texture and the study of their potential operating mechanisms), the computerized analysis of nuclear images linked to multivariate analysis was chosen, and, in so doing, took into account 15 computer-calculated morphonuclear parameters for Feulgen-stained cell nuclei. In order to validate the method it was subjected to a series of well-known cancer drugs. The present results are in agreement with those obtained by conventional methods similar to those used for the study of the cytotoxicity of anticancer molecules or their effect on cell kinetics. Multivariate analysis applied to the parameters described by image analysis should make possible the rapid study of new anticancer drugs together with the rapid orientation of studies undertaken to ascertain their operating mechanisms.

Animals↗

PubMed1992

Spontaneous evolution of nuclear size and DNA content of non-small-cell-lung cancers grafted onto nude mice.

We monitored the biological evolution of four human non-small-cell lung cancers labeled KLX6, KLX7, KLX9, and KLX14 that had been grafted onto nude mice. This monitoring was carried out by means of digital cell image analysis which assessed morphometric (nuclear area, NA) and densitometric (nuclear DNA content, DI) features on Feulgen-stained nuclei from imprint smears. In each of the four models, the biological evolution of the NA and DI was characterized through their progression during serial passaging onto nude mice. The results show that of the four lung cancer models analyzed, one (KLX6) remained definitively stable with respect to its DNA content (DI assessments), while the other three, i.e., KLX7, KLX9, and KLX14, varied significantly. As assessed by the morphometric parameter, i.e., the NA, the four xenografted lines also varied significantly over serial passaging. In conclusion, we show that digital cell image analyses of Feulgen-stained cell nuclei including morphometric and densitometric parameters are a powerful tool for monitoring the biological evolution of human lung cancers grafted onto nude mice. We think therefore that the ploidy level of a tumor might be dependent upon its age and/or its related clinical stage.

Animals↗

PubMed1992

Monitoring of radiotherapy-induced morphonuclear modifications in the MXT mouse mammary carcinoma by means of digital cell image analysis.

The present work deals with the characterization of the morphological changes induced by ionizing radiation on MXT mouse mammary cancer cell nuclei. The monitoring of the radiotherapy-induced morphonuclear modifications was carried out by means of digital cell image analysis, which made it possible to compute morphometric (nuclear area), densitometric (nuclear DNA content) and textural (chromatin pattern characteristics) parameters assessed on Feulgen-stained nuclei. The biological material was obtained from serial fine needle-aspirations performed on control tumors and 2Gy and 8Gy irradiated tumors. Digital cell image analyses were assessed at the 7th, 18th, and 28th days-post irradiation. We showed that radiotherapy induced specific morphonuclear modifications that appeared in a dose-dependent and time-dependent manner. The 2Gy and 8Gy radiotherapy doses led to an increase in the mean nuclear area value, this feature being observed at both the 1st and the 4th week post-irradiation. The resultant effect on the chromatin pattern characteristics corresponded to a decrease in overall condensation level as compared to the control cell nuclei. Finally, the mean nuclear DNA content increased at the 1st week post-irradiation, but decreased at the 4th week post-irradiation as compared to the MXT control tumor. Computerized cell image analysis, therefore, appears to be a useful tool in helping to monitor the radiotherapy-induced effects that occur in neoplastic cell nuclei and which can be observed by means of optical microscopy.

Animals↗

PubMed1991

Digital morphonuclear analyses of sensitive versus resistant neoplastic cells to vinca-alkaloid, alkylating, and intercalating drugs.

We tested 12 resistant cell lines in vitro in order to evaluate common morphonuclear characteristics induced by various cytotoxic drugs on cell lines of different origins. We used the MXT mouse mammary cancer and the neoplastic J82 and T24 human bladder cell lines, whose variants are either sensitive or resistant to a vinca alkaloid derivative (Navelbine, NVB), to an investigational alkylating agent (PE1001), and to Adriamycin (ADR). We tested cell population variants resistant to NVB + PE1001 + ADR. The level of chemoresistance was evaluated by a colorimetric assay assessing the 50% concentration-induced inhibition of cellular growth (IC50) brought about by each drug on the growth of each cell variant under study. We show that resistant neoplastic cell nuclei present common morphonuclear characteristics, independent of cell origin (neoplastic mouse mammary versus human bladder cells) and the drug used (vinca alkaloid, alkylating, and intercalating derivatives). Our results further indicate that the phenotype of resistant versus sensitive cells corresponds to cell nuclei populations with smaller nuclei and less nuclear DNA content and, as a consequence, a chromatin texture showing large pale areas with some hyperchromatic clumps.

Alkylating Agents↗

PubMed1991

Influence of fetal bovine serum and hormones on primary vs. long-term cultures of human breast cancers.

We investigated the influence of fetal bovine serum, complemented or otherwise with estradiol or insulin or both, on the proliferation of mammary cancer cells from long-term and primary cultures. The long-term culture corresponded to mouse MXT and MCF-7 cell lines whereas the primary culture corresponded to primitive breast cancers squashed onto histologic slides and maintained in cultures for between 12 and 48 h. Cell proliferation was evaluated by means of digital cell image analysis of Feulgen-stained nuclei. Our results show that the addition of estradiol and insulin slightly but nevertheless significantly increases the proportion of cells still living at Hour 48 of culture. Fetal bovine serum, necessary for the growth of MXT and MCF-7 mammary cells, was highly cytotoxic with respect to the primary cultures of the 20 breast cancers under study. We are now conducting new experiments using chemically defined media to study the influence of new antineoplastic compounds on primary cultures of breast cancers.

Animals↗

PubMed1991

In vitro influence of gastrin, oestradiol and gonadotropin-releasing hormone on HCT-15 and LoVo human colorectal neoplastic cell proliferation.

We set up in vitro several human colorectal neoplastic cell lines that we labelled "hormone-sensitive" (HS) in comparison to the original cell lines which appeared to be rather "hormone-insensitive" (HI). We used LoVo and HCT-15 human colorectal neoplastic cell lines and studied the influence of 17 beta-oestradiol (E2), gastrin and two gonadotropin-releasing hormone (GnRH) analogues, HRF and buserelin, on the proliferation of the HS and HI variants of the LoVo and HCT-15 cell lines. Cell proliferation was evaluated by a colorimetric assay, the MTT test. Our results show that E2, gastrin, HRF and buserelin did not induce a significant stimulatory influence on the HI variants of the LoVo and HCT-15 cells, i.e. the cells that were cultured in a hormone-free 10% FCS-supplemented medium. In sharp contrast, the colorectal cells cultured for 30 passages in an E2 and/or gastrin + 1% FCS-supplemented medium showed a marked tropic response to E2, gastrin, HRF and buserelin. However, the HS variants of the HCT-15 cells appeared less sensitive to the two GnRH analogues than did the HS variants of the LoVo cells.

Cell Count↗

PubMedDate not supplied

The combination of the tetrazolium derivative reduction (MTT) and digital cell image analysis to monitor in vitro the cytotoxicity of anti-neoplastic drugs.

We assessed the in vitro drug-induced cytotoxicity by means of the rapid low-cost but weakly sensitive Thiazolyl blue (MTT) test, and the less rapid, higher cost, but highly sensitive cell image analysis (CIA) test. We studied the influence of three drugs, i.e. a vinca-alkaloid (Navelbine), an alkylating investigational agent (PE1001), and an intercalating drug, i.e. adriamycin, on the proliferation (MTT test) and cell kinetics (CIA test) of the mouse MXT and the MCF-7 mammary cancer cell lines. Adriamycin and PE1001 decreased MXT and MCF-7 cell proliferation in a dose-dependent manner as assessed by both the MTT and CIA tests. Navelbine was highly cytotoxic in a dose-dependent manner. We demonstrated that Navelbine arrests cells in the M phase without altering the G2 phase. In sharp contrast, PE1001 arrest cells in the G2 phase without altering the M phase. An adriamycin-induced effect was apparent on S phase. Thus, the MTT test allows the screening of a great number of drugs analyzed at the cell proliferation level and, in the case of MTT positive drug-induced response, the CIA test enabled the drug-induced effect at cell cycle kinetic level to be investigated.

Adenocarcinoma↗

PubMedDate not supplied

Chemoresistant cell lines: morphonuclear characteristics and chemosensitivity development during long-term culture.

The aims of the present work were first to study the stability of the sensitivity and resistance of various cancer cell lines over the period of one year, and second to attempt to correlate the morphological aspects of the lines with the results obtained. To this end we used one mammary and two human vesical lines, each consisting of three different phenotypes: a primitive phenotype (the sensitive line); a phenotype able to proliferate in the presence of three antineoplastic agents (the resistant line); and a phenotype derived from the resistant line but cultivated in the absence of drugs for more than 50 passages. We studied the stability of these lines not only in terms of their chemosensitivity to drugs, but also from the point of view of the morphological characteristics of their nuclei as described by digital image analysis. The results obtained show that the resistant lines retained their resistance even after treatment by antineoplastic agents had been discontinued. However, in this latter case variations became noticeable in their sensitivity to drugs, variations which shifted the line towards either the sensitive or the resistant phenotype. Results obtained from image analysis show that, for each of the lines studied, the morphological aspects of the continuously treated resistant and sensitive lines were phenotype-specific. However, the resistant lines no longer cultivated in the presence of anti-cancer agents exhibited morphonuclear characteristics varying across those of the other two phenotypes. We attribute these variations to modifications in the quality of the serum used.

Adenocarcinoma↗

PubMedDate not supplied

Evidence of difference between cytotoxicity, cell cycle and morphonuclear effects of polyamines on sensitive and multidrug resistant P388 cell lines.

This paper reports studies on the influence of multidrug resistance (MDR) on the mechanism of polyamine toxicity. The effects of putrescine (PUT), spermidine (SPD) and spermine (SPM) on morphonuclear parameters and cell cycle were studied by means of digital cell image analysis. This reveals that only SPD and SPM condense chromatin inducing a strong decrease in the nuclear area and a cell-cycle arrest in phase G2 in P388/s and the two MDR sublines. A significant difference was observed between the sensitivity of the two phenotypes, which confirms results obtained by means of a microculture tetrazolium test which showed that SPD and SPM were highly, but very differently, cytotoxic on sensitive and MDR sublines, unlike PUT, which was not toxic. This encourages us to study more thoroughly possible differences in polyamine metabolic enzymes and uptake in these cells, to enable us to acquire a better understanding of the impact of MDR phenotype on the polyamine pathway.

Animals↗