Effects of oxazaphosphorine cytostatics on granuloid progenitor cell (CFUc) proliferation in mice.

The effects of oxazaphosphorine cytostatics were studied on granulocytic/monocytic colony forming cells from mice bone marrow in methylcellulose culture. Cyclophosphamide, ifosfamide, trofosfamide and two secondary metabolites show a weak activity in vitro (Inhibitory Dose--50% (ID50) between 5 X 10(-4) M and 5 X 10(-5) M). By contrast, a high cytostatic activity was observed with phosphoramide mustard and especially with hydroperoxycyclophosphamide (ID50: 2.5 X 10(-6) and 4 X 10(-7) M). These results suggest that these metabolites are active. The differentiation of the three types of colonies (granulocytic, monocytic and mixed) showed no specific effect of the drugs for a given series. After in vivo treatment, cyclophosphamide, ifosfamide and trofosfamide induce an important decrease of nucleated bone marrow cells. This decrease is maximum on the third day and regresses when the treatment is interrupted. On the first day of the culture an inhibition of the proliferation of granulocytic/monocytic progenitor cells is observed. An important statistically significant stimulation of these same progenitor cells is however noted later.

Effect of sodium cis-beta-4-methoxybenzoyl-beta-bromacrylate (Cytembena) on HeLa cell kinetics.

The treatment of HeLa cells with various concentrations of sodium beta-4-methoxybenzoyl-beta-bromacrylate (Cytembena) results in inhibition of growth and modification of cell cycle distribution. These phenomena were observed at concentrations between 7.5 x 10(-5) and 2.5 x 10(-5) M. The estimation of DNA content by flow cytometry showed an important shift in the distribution of cycling cells with a relative decrease of G0 + G1 cells and a striking accumulation of G2 + M cells. According to our experimental conditions, the blocking up in G2 + M is irreversible at 7.5 and 5 x 10(-5) M.

[Comparison of the antimitotic properties of cyclophosphamide and its biotransformation products on meristema plant cells and animal cells in in vitro culture]. / Comparaison des propriétés antimitotiques du cyclophosphamide et de ses produits de biotransformation sur la cellule méristématique végétale et sur la cellule animale en culture in vitro.

N-mustard diamide phosphoric and above all 4-hydroperoxycyclophosphamide are clearly more cytotoxic than same kind, which is in accordance with the fact that these compounds are the active metabolites of cyclophosphamide. On the contrary, 4-ketocyclophosphamide and carboxyphosphamide, secondary metabolites inapt to be activated, are not more cytotoxic than cyclophosphamide. No tolerance does occur with these metabolites, contrary to cyclophosphamide itself.

Effect of three alkylating antimitotic agents and their metabolites on in vitro monogranulocytic colony forming cells from mouse bone marrow.

The effects of oxazaphosphorine cytostatics were studied on monogranulocytic colony forming cells from mouse bone marrow in methylcellulose culture. Cyclophosphamide, ifosfamide, trofosfamide and two secondary metabolites showed a weak activity (ED50 between 5 x 10(-4) mol/l and 5 x 10(-5) mol/l). On the contrary, a high toxicity was observed with phosphoramide mustard and especially hydroperoxycyclophosphamide (ED50: 2.5 x 10(-6) mol/l and 4 x 10(-7) mol/l). These results suggest that these metabolites are the carriers of cytotoxic specificity. The differentiation of the three types of colonies (granulocytic, monocytic and mixed) revealed no specific effect of the drugs for a given series. On the other hand, the staining of colonies revealed some mitotic abnormalities (agglutination bridge, micronuclei and cytodieretic alteration).

[Inhibitory effect of cytembena (sodium-cis-beta-methoxybenzoyl-beta-bromoacrylate) on the cell kinetics of HeLa cells in culture]. / Effet inhibiteur du Cytembena (cis-beta-methoxybenzoyl-beta-bromacrylate de sodium) sur la cinétique des cellules HeLa en culture.

The inhibiting effect of Cytembena on HeLa cell kinetics has been demonstrated and analyzed. The percentage of cycling cells decreases, according to the concentration, between 7.5 and 2.5 x 10(-5) M. Estimation of DNA by cell flow cytophotometry shows an important shift in the distribution of cycling cells with a relative decrease of G1 cells and a very important accumulation of G2 cells. According to our experimental conditions, the blocking up in G2 is irreversible only at 7.5 x 10(-5) M.

[The action of antimitotics and the cell cycle]. / L'action des antimitotiques et le cycle cellulaire.

Cell kinetics, which for a long time could only be worked out at the level of mitosis, has now at its disposal a set of technics which make it possible to label cells which replicate their DNA, to appraise the DNA content of individual cells and to synchronise cell populations. First of all, the meaning and the scope of results obtained by cell kinetics technics in the study of the action mechanism of antimitotic substances are discussed. The main results obtained are exposed, pointing to the complexity of the mechanisms concerned. A more detailed discussion of some personal results concerning the action of anti-inflammatory substances, of protein inhibitors and of hydroyure allows to underline the difficulties met with and the importance of the choice of an adequate methodology.

Contribution to the understanding of the mechanism of cytokinesis in plant cells: the action of deoxyguanosine on the kinetics of a root meristem cell population.

The kinetics of binucleate cells, formed by the action of deoxyguanosine, are studied using three methods: in a population synchronized with hydroxyurea, by autoradiography after pulse-labelling, and in a sample of a cell population morphologically located at the M--G1 limit. Deoxyguanosine induces a slowing down in S and G2, independent of the inhibition of cytokinesis. It is only when it takes effect during the G2 stage that deoxyguanosine brings about the formation of binucleate cells.

[Cell kinetics and experimental rearrangement of daughter chromosomes at the end of mitotic division]. / Clinétique cellulaire et désorientation expérimentale des deux lots de chromosomes-fils en fin de division mitotique

The action of hexamethylene-tetramine (HMT), which causes a late disorientation of the two sets of chromosomes during telophase in Allium sativum L. meristematic root cells, has not been found again, in the same material after synchronization by hydroxyurea. The explanation put forward takes into account the special feature of cells synchronized by chemical methods. Besides, the toxicity of HMT is not the same according to the stage of the cell cycle during the treatment.

[Partial disorganization of the anaphasic segregation of chromosomes in plant cells: combined actions of griseofulvin, producer of pluripolar anaphases and 2 ipecac alkaloids, producers of floating pole anaphases]. / Désorganisation partielle de la ségrégation anaphasique des chromosomes dans la cellule végétale: actions combinées de la griséofulvine, productrice d'anaphases pluripolaires, et de deux alcaloïdes de l'ipéca, producteurs d'anaphases à pôles flottants.

Anaphasis may be slightly checked by various treatments which however result in a normal chromosomic separation. Griseofulvin exerts a direct though partial influence on the mitotic apparatus, which entails "pluripolar anaphasis"; on the other hand Ipecac alkaloïds act indirectly and produce "floating poles anaphases". Treatments combining griseofulvin with cepheline or tubulosine show that there is never any synergy between the two processes. These results support our hypothesis that floating poles anaphases are not a sign of slight C-mitotic action but only come from a lag between the appearance/disappearance of microtubules and that of chromosomes during anaphasis.

[Microtubule inhibitors]. / Recherches sur les inhibiteurs microtubulaires

This lecture is divided into 3 parts. The first one is a general survey of mitoclasic agents with a review of the main categories and a summary of the conclusions obtained from a comparative study of the antimitotic properties of various compounds on animal cells and plant cells. The second part describes the results of personal ultrastructural studies carried out on plant cells. They include researches on the normal behavior of microtubules in the cells and an analysis of various kinds of inhibition. The last part deals with the action mechanism of mitoclasic compounds, especially colchicine.

[New researches on protein synthesis inhibition under the action of aurintricarboxylic acid during cell cycle : Study on meristematic cells of Allium sativum L]. / Nouvelles recherches sur l'inhibition des synthèse protéiques sous l'action de l'acide aurine tricarboxylique au cours du cycle cellulaire : étude sur cellules méristématiques d'Allium sativum L

Aurin tricarboxylic acid, an inhibitor of protein synthesis, prevents cells from entering mitosis in Allium sativum L. root meristems. When the uptake of 3H-leucine comes back up to the control rate after removal of roots from the drug, mitotoic activity is resumed. Furthermore, the percent of labelled cells obtained by continuous labelling with H3-thymidine shows a reversible arrest of cell progress from G1 to S.

[Cytotoxicity of cadmium : study on root meristems of Allium sativum L]. / Cytotoxicité du cadmium: étude sur les méristémes radicularies d'Allium sativum L

Cadmium nitrate, acetate and sulphate cause death of root meristems of Allium sativum at 5.10(-7) Mol/ml concentration for the two first ones and 10(-7) Mol/ml for the last one. Lower concentrations do not induce chromosomal aberrations. As to the cellular toxicity, cadmium salts are between phenyl-mercuric-hydroxid and lead nitrate, the first one being the most active.