PubMed Health⌕ Search

Biomedical subjects

C Vigreux

Publications and source records attributed to C Vigreux.

10 recordsLinked to original sources
PubMed2000

Inhibitory effect of melatonin on 7, 12-dimethylbenz[a]anthracene-induced carcinogenesis of the uterine cervix and vagina in mice and mutagenesis in vitro.

Forty female CBA mice aged 3-4 months were exposed twice a week during 2 months to intravaginal applications of polyurethane sponges impregnated with 0.1% solution of 7,12-dimethylbenz[a]anthracene (DMBA) in triethyleneglycol. Three hours after each application the sponges were taken out. Starting from the day of the 1st DMBA application a part of mice was exposed five times a week during 4 months with melatonin in tap water (20 mg/l) given at night time (from 18:00 to 09:00 h). Additional 20 female CBA mice were intact and served as a control. All mice were sacrificed in 6 months after start of the experiment. Seven of 20 mice exposed to DMBA alone developed malignancies in the vagina and cervix uteri and two mice developed benign cervical tumors. No malignancies in vagina and uterine cervix and three vaginal papillomas were observed in mice exposed to DMBA+melatonin. There were no any tumors in intact controls. Two in vitro tests were used for mutagenicity studies: the Ames test (strains TA 97 and TA 98 of Salmonella typhimurium) and the single cell gel electrophoresis assay (SCGE assay or COMET assay) performed on CHOK1 cells. In tested strains melatonin significantly reduced the mutagenicity of DMBA. In the SCGE assay preincubation with melatonin led to a strong inhibition of clastogenic activities of DMBA. Thus, our data indicate that pineal indole hormone melatonin inhibits cervical and vaginal carcinogenesis induced by DMBA in mice and possess antimutagenic and anticlastogenic effect in vitro.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

Comet assay and DNA flow cytometry analysis of staurosporine-induced apoptosis.

BACKGROUND: The ability of the comet assay to quantify DNA strand breaks and alkali labile sites has been widely demonstrated. In this study, this assay was tested for its ability to identify DNA fragmentation occurring during apoptosis in comparison with standard DNA flow cytometry analysis. METHODS: Staurosporine-induced apoptosis in CHO cells is an adequate model to study a rapid time- and dose-dependent appearance of this process. RESULTS: Nuclear staining with DAPI confirmed the induction of apoptosis with a typical chromatin condensation and fragmentation. Analysis of propidium-iodide- (PI) stained DNA by flow cytometry showed the presence of a pre-G1 peak, characteristic of apoptotic cells, 6 h after drug treatment. The detection of highly damaged cells (HDC) by the comet assay after 3 h treatment occurred earlier than the detection of apoptotic cells by flow cytometry. However, HDC were missed when the DNA fragmentation was too high, preventing accurate quantification of late apoptotic cells. CONCLUSIONS: The comet assay is more sensitive than standard DNA flow cytometry to detect early DNA fragmentation events occurring during apoptosis. However, the comet assay modified by omitting electrophoresis was necessary to quantify apoptotic fraction at later stages.

Animals↗
PubMed1999

Effects of melatonin on N-nitroso-N-methylurea-induced carcinogenesis in rats and mutagenesis in vitro (Ames test and COMET assay).

The effect of melatonin, an indole hormone of the pineal gland, on the initiation of N-nitroso-N-methylurea (NMU)-induced carcinogenesis in rats and mutagenesis in vitro has been investigated. Two-month-old female LIO rats (groups 1 and 2) were exposed to a single injection of NMU (50 mg/kg of body weight, i.v.). Rats from group 2 were given melatonin orally (20 mg/l) from 18:00 to 09:00 h over 3 days (2 days before and 1 day after NMU injection). Animals from group 1 (control) were administered the solvent (ethanol/water, 1:1000). Rats were followed up to natural death or were sacrificed when moribund. Tumors developed both in rats treated with NMU alone (50.0%) and in rats exposed to NMU plus melatonin (34.8%). The percentage of malignant tumor-bearing rats in group 2 (21.7%) was lower (P < 0.02) than that in the other group (41.7%). Melatonin also decreased the multiplicity of malignant tumors 1.3-fold and reduced the incidence of malignancies in some organs. Two in vitro tests were used for mutagenesis studies: the Ames test (strains TA 100 and TA 102 of Salmonella typhimurium) and the Single Cell Gel Electrophoresis assay (SCGE assay or COMET assay) performed on CHOK1 cells. Melatonin itself revealed no genotoxic effect in either of the tests. No protective action of melatonin (at doses of up to 2 micromol/plate) towards NMU was found in the Ames test. In contrast, in the SCGE assay a slight, but statistically significant (P < 0.001), dose-related anticlastogenic effect of melatonin (10(-10)-10(-7) M) was observed. Thus, our data indicate that melatonin may act as an anti-initiating hormone in NMU-induced carcinogenesis and possess anticlastogenic activity towards NMU in CHOK1 cells.

Animals↗
PubMed1999

Early detection of staurosporine-induced apoptosis by comet and annexin V assays.

Comet, TUNEL, and annexin V assays were used to identify DNA fragmentation and plasma membrane alterations occurring during staurosporine-induced apoptosis in Chinese hamster ovary cells. TUNEL assay detected apoptotic cells after 6 h treatment. The occurrence of annexin V immunofluorescence staining after 1 h treatment confirms that exposure of phosphatidylserine (PS) residues is an early biochemical feature of apoptosis. According to intensity, three annexin staining patterns were distinguished, related to different steps in the apoptotic process. The detection of highly damaged cells by the comet assay after 3 h treatment occurred earlier than the detection of DNA modifications by the TUNEL assay, but later than the exposure of PS residues. However, late apoptotic cells, otherwise characterized by plasma membrane disruption and high annexin V staining, were not detected by the comet assay. In this case, comet assay modified by omitting electrophoresis (halo assay) was more sensitive for an accurate quantification of the apoptotic fraction.

Animals↗
PubMed1998

DNA damaging effects of pesticides measured by the single cell gel electrophoresis assay (comet assay) and the chromosomal aberration test, in CHOK1 cells.

One herbicide (isoproturon), two fungicides (carbendazim and chlorothalonil) and etoposide (an effective antitumor agent used as a positive control), were tested for their ability to induce cytotoxic and genotoxic effects in Chinese Hamster Ovary (CHOK1) cells. Etoposide induced DNA damage detectable both by the alkaline Single Cell Gel Electrophoresis (SCGE) assay and the chromosomal aberration (CA) test in absence of noticeable cytotoxicity. With the SCGE assay, a clear induction of DNA damage was observed for chlorothalonil within a 0.2 to 1 microM concentration range. In the CA test, chlorothalonil gave also positive results, inducing mainly chromosome breaks. In contrast, no DNA damage was observed with the SCGE assay for carbendazim and isoproturon. In the CA test, carbendazim induced only numerical aberrations in the concentration range of 25 microM to 100 microM, and isoproturon did not induce any significant increase in CA. In conclusion, chlorothalonil appears genotoxic in proliferative CHOK1 cells, and as expected, the aneugenic compound, carbendazim, did not induce DNA strand breaks in the SCGE assay.

Animals↗
PubMed1998

Modulatory effects of melatonin on genotoxic response of reference mutagens in the Ames test and the comet assay.

The effect of a potent endogenous antioxidant, the pineal gland indole melatonin (MLT) on the mutagenicity of twelve well-known mutagens and carcinogens has been investigated using two in vitro tests the Ames test and the single cell gel electrophoresis assay (SCGE assay or COMET assay). The 12 mutagens used were 7, 12-dimethylbenz(a)anthracene (DMBA), benzo(a)pyrene (BP), 2-aminofluorene (AF), 1,2-dimethylhydrazine (DMH), bleomycin, cyclophosphamide (CP), 4-nitroquinoline-N-oxide (NQO), 2,4, 7-trinitro-9-fluorenone (TNF), 9-aminoacridine (AA), N-nitrosomethylurea (NMU), mitomycin C and sodium azide tested in the absence or in the presence of S9 mix. MLT alone turned out neither toxic nor mutagenic in the Ames test and revealed clastogenic activity at the highest concentration tested (100 microM) in the SCGE assay. In four Salmonella typhimurium tester strains TA 97, TA 98, TA 100 and TA 102 MLT significantly reduced the mutagenicity of chemicals which require S9 activation. In the SCGE assay performed on CHO cells, preincubation with MLT led to a strong inhibition of clastogenic activities of DMBA and CP, and in a lesser extent with BP and NMU. With mitomycin C, MLT exacerbated responses in both tests. The possible mechanisms of MLT's inhibitory action are discussed.

Animals↗
PubMed1998

DNA damage in mononuclear leukocytes of farmers measured using the alkaline comet assay: discussion of critical parameters and evaluation of seasonal variations in relation to pesticide exposure.

The alkaline comet assay was used to quantify, using visual and image analyses, the level of DNA damage in mononuclear leukocytes of farmers who were occupationally exposed to pesticides. Hematological parameters were also measured on the same samples. Enrollment of farmers was based on handling of heavily used pesticides at particular periods during one spraying season. Forty-one blood samples from 29 different farmers were collected at the beginning of the season (n = 11) and at the intermediate (n = 14) and final (n = 16) periods of intense spraying activity. The mean numbers of lymphocytes and eosinophils were nonsignificantly higher in groups 3, 1, and 4 than they were in group 2. No individual characteristics significantly influenced the mean number of lymphocytes or eosinophils, and no correlation was observed between pesticide exposure-related parameters and hematological parameters. The level of DNA damage was significantly (P < 0.01) higher in groups 3, 1, and 4 than it was in group 2. In addition, DNA damage quantification was not significantly different among investigators or among slides. Prescription medicine, alcohol consumption, and age had no statistically significant effect on DNA damage level. Conversely, smoking (smokers versus non- and ex-smokers) significantly influenced DNA damage level (P < 0.0001). A significant (P < 0.05) negative correlation was detected between the number of days without pesticide spraying and DNA damage level, particularly among non- and ex-smokers. DNA damage detected by the alkaline comet assay seems to reflect ongoing exposure to genotoxic agents but not an accumulation of damage.

Adult↗
PubMed1998

DNA damage in mononuclear leukocytes of farmers measured using the alkaline comet assay: modifications of DNA damage levels after a one-day field spraying period with selected pesticides.

The alkaline comet assay was used to assess DNA damage in mononuclear leukocytes of farmers before and after a 1-day spraying period with selected pesticides under usual conditions. Two blood samples were collected, one in the morning of the day of spraying (S0) and the second in the morning of the day after (S1). Here, we assessed variations in DNA damage levels between these two sampling times. Four groups of farmers were formed, according to exposure to: (a) various fungicide-insecticide mixtures (including chlorothalonil; group 1, n = 8), (b) the herbicide isoproturon (group 2, n = 11), (c) fungicide triazoles (group 3, n = 14), and (d) a fungicide (chlorothalonil)-insecticide mixture (group 4, n = 8). An increase in DNA damage levels was observed at S1 for groups 1 and 4, who were exposed to similar pesticides. This increase was correlated with area sprayed between S0 and S1 and with the number of spraying tanks used over this 1-day period. No effect was observed on cell viability or on hematological parameters for these two groups. No statistically significant modification of DNA damage level was observed the day after spraying for groups 2 and 3, when each was observed as a whole. However, some farmers presented significantly more DNA damage after exposure, and others presented less damage. In these two groups, a significant decrease of neutrophils was observed at S1, and a decrease of red blood cells was observed in group 3. In parallel, a significant loss of lymphocyte viability was observed in these two groups. A 1-day spraying period seems to be sufficient to significantly modify DNA damage levels in mononuclear leukocytes, but the correlation of this change with pesticide-related exposure parameters depends on the kind of pesticide concerned.

Adult↗
PubMed1997

Assessment of DNA damage induced in vitro by etoposide and two fungicides (carbendazim and chlorothalonil) in human lymphocytes with the comet assay.

The effects of two fungicides (carbendazim and chlorothalonil) on the induction of DNA damage in human peripheral blood lymphocytes (human PBL) have been investigated using the single cell gel electrophoresis assay (SCGE assay or comet assay) immediately after a 1-h treatment and after a 24-h post-treatment incubation. The assessment of etoposide (an effective antitumour agent) effects on human PBL in terms of cell viability and dose-DNA damage relationships was made and etoposide selected as a positive control. The results indicate that etoposide induces significant (p < 0.01) dose-dependent DNA damages for concentrations at which the loss of cell viability is low. After a 24-h recuperation period, all observed DNA damages has disappeared. With SCGE assay performed after a 1-h treatment, similar positive results were observed with chlorothalonil alone or in association with carbendazim, without any loss of cell viability. However, a dramatic loss of cell viability was measured after 24 h and was associated with a large proportion of highly damaged cells. In contrast, carbendazim was not cytotoxic on human PBL and did not induced DNA damage using the SCGE assay either immediately after treatment or after a 24-h post-treatment incubation. These results point to the necessity of an adequate evaluation of immediate and long-term cytotoxicity of compounds that are to be assessed by the SCGE assay.

Adult↗