100 research outputs found
Evidence for the role of nitric oxide in antiapoptotic and genotoxic effect of nicotine on human gingival fibroblasts
No full textResistance to apoptosis is essential for cancer survival and plays a critical role in carcinogenesis. Growing evidence suggests that nicotine can act as a tumor promoter, impairing apoptotic process in certain types of human cancer cell lines. Our previous study revealed in human gingival fibroblasts (HGFs) a concomitant antiapoptotic and genotoxic effect of nicotine, manifested by the attenuation of staurosporine (STP)-induced apoptosis and the increase of micronucleus frequency. The present report provides evidence that nitric oxide (NO) is critically involved in these actions. In vitro treatment with sodium nitroprusside as NO donor showed that NO produced similar effects as those observed with nicotine: it caused DNA damage and partially prevented apoptosis induced by staurosporine. Exposure of HGFs to nicotine, at concentrations similar to those found in the blood of habitual smokers, leads to the production of NO associated with the induction of inducible nitric oxide synthase (iNOS) expression. Experiments using an inhibitor of iNOS, N-monomethyl-L-arginine (NMA), together with nicotine confirmed the involvement of NO in the drug action, abrogating completely cell death and a good part of the genotoxicity. Finally, we show by different approaches that the inhibition of cell death by nicotine through NO release is related to modulation of caspase-1 activation
Genotoxic and antiapoptotic effect of nicotine on human gingival fibroblasts
No full textGrowing evidence suggests that nicotine, the addictive component of cigarettes, can have a direct role in tumor development by enhancing cell proliferation and impairing apoptotic process in certain types of human cancer cell lines. Since the correlation between apoptosis and DNA damage is already well documented, we investigated the response of human gingival fibroblasts (HGFs) to nicotine exposure by examining its effect on DNA damage induction and apoptotic process in parallel. To assess the genotoxicity of this drug, the cytokinesis-block micronucleus (CBMN) test was performed. Treatment of HGFs with nicotine, at a concentration of 1 muM, caused a statistically significant increase of micronucleus (MN) frequency at the tested time intervals, while no change was detected in cell growth under the same conditions. Furthermore, we found that preincubation of HGFs with 1 muM nicotine strongly attenuated staurosporine (STP)-induced apoptosis. Finally, we found that cultures exposed to nicotine showed an increase of reactive oxygen species, as determined by increased levels of 2,7-dichlorofluorescein (DCF). When cells were prelabeled with N-acetyl-cysteine (NAC), a substrate for glutathione synthesis, and catalase (CAT), the oxygen free radical scavenger, a significant reduction in cytogenetic damage was observed. Thus, for the first time, we report a concomitant genotoxic and antiapoptotic effect of nicotine in HGFs
The role of oxidative stress in the in vitro induction of micronuclei by pesticides in mouse lung fibroblasts
No full textThe involvement of the antioxidant enzymes catalase and glutathione peroxidase (both at 0.1 mg/ml) in defence against the genotoxicity of phosphamidon (80 μg/ml) and dieldrin (25 μM) was investigated in order to demonstrate that the two pesticides damage DNA through the generation of reactive oxygen species and therefore of oxidative stress. The pesticide genotoxicity was determined by the cytokinesis-block micronucleus test performed on primary mouse lung fibroblast cultures. Also, 3-aminotriazole (40 mM) and mercaptosuccinate (0.5 mM), inhibitors of catalase and glutathione peroxidase, respectively, were added to the cultures. Data indicate that catalase causes a decrease only in the damage induced by phosphamidon, while glutathione peroxidase protects against damage induced by both phosphamidon and dieldrin. Simultaneous treatment with antioxidant inhibitors and pesticides results in a decrease in micronucleus frequency and cell number, due to apoptotic death. Our results indicate that clastogenic DNA damage produced by the two pesticides is modulated by antioxidant enzymes and their inhibitors and thus could be due to oxidative stress induction
In vitro proliferation of achondroplastic and normal mouse chondrocytes, before and after basic fibroblast growth factor stimulation
No full textAchondroplasia in mice is a recessive genetic disorder, characterized by disproportionate dwarfism with reduced bone growth. The cause of this chondrodystrophy is unknown. In this study normal and achondroplastic mouse chondrocytes were cultured in monolayer primary culture, their differentiation was verified by immunofluorescence and their growth was compared. The results showed that achondroplastic cells exhibited a higher proliferative activity than control cells of the same age, confirmed also by a thymidine incorporation assay. Furthermore, basic fibroblast growth factor treatment was found to induce a strong increase in growth of normal mouse chondrocytes, while it did not stimulate statistically significant proliferation of achondroplastic mouse cells. We suppose that this different growth rate could play a role in achondroplastic phenotype development
Analysis of an SD second chromosome from a natural population of Drosophila melanogaster
No full textInduction of micronuclei in bone marrow by two pesticides and their differentiation with CREST staining: An in vivo study in mice
No full textTwo pesticides, organophosphate phosphamidon (PHO) and organochlorine dieldrin (DED) were assayed by the mouse bone marrow micronucleus test, to ascertain whether they showed genotoxic activity in vivo. Two doses, sub-lethal (PHO = 3 mg/kg b.wt.; DED = 60 mg/kg b.wt.) and lethal (PHO = 5 mg/kg b.wt.; DED = 90 mg/kg b.wt.), of each substance were administered intraperitoneally to 9-10-week old CBA male mice, in acute and repeated exposure. The sub-lethal dose was also administered at two different times and twice at 24-h intervals. Both PHO and DED proved able to induce a dose-dependent increase of micronucleated polychromatic erythrocytes (PCE). The two pesticides also showed a different detoxification time. Furthermore, the CREST staining with antikinetochore antibodies allowed us to conclude that the two chemicals are clastogens
Effects of single-wall nanotubes in human cells of the oral cavity:geno-cytoxicity risk.
No full textSingle-wall carbon nanotubes (SWCNTs) are one of the most extensively produced carbon materials and
the environmental, public and professional exposure is therefore dramatically increasing. Consequently
the studies on bio-effects and safety of SWCNTs are highly needed. The goal of this study was investigate
the effects in vitro of SWCNTs in cells of the oral cavity, never employed in this research field. We exposed
human gingival fibroblasts to 50, 75, 100, 125, 150 lg/ml SWCNTs for 24 h and we investigated genotoxicity
(Comet assay and micronucleus test), cytotoxicity, oxidative stress, as reactive oxygen species (ROS)
generation, and stress response, as Heat shock protein 70 (Hsp70) expression. SWCNTs produced genotoxic
effects at all doses, even if detected with different sensitiveness by the two tests, and at the two
highest doses induced a strong decrease of the cell proliferation and cell survival, causing apoptosis
too. Furthermore, we proved the ability of these nanomaterials to induce oxidative stress and Hsp70
expression. Finally, by inhibition of Hsp70 expression, we demonstrated that this heat shock protein conferred
protection against SWCNT geno-cytotoxicit
Investigations on the PGM (phosphoglucomutase) polymorphism by isoelectric focusing in Drosophila melanogaster
No full textThe segregation distortion (SD) phenomenon in wild populations of Drosophila melanogaster: interaction between chromosomes 3 and SD chromosomes 2
No full textThe Segregation Distortion (SD) phenomenon is a typical case of non-Mendelian segregation in Drosophila melanogaster, due to the dysfunction of sperm bearing a non-SD homologous chromosome. In nature, several factors involved in the expression of the SD phenomenon have been described; among these, a genetic modifier carried by chromosome 3, which enhances the distortion effect of the SD chromosomes. The analysis of natural Sardinian populations, carried out in order to evaluate the presence of chromosome 3 bearing these enhancer factors, has enabled us to ascertain that (a) also in these populations chromosomes 3 with enhancer factors are present, although with frequencies lower than those previously reported in other publications; (b) among these enhancer chromosomes 3, some increase the k of certain chromosomes 2 from values of chromosomes considered non-distorting (k≤0.66) to values typical of SD chromosomes. The data obtained also allow us to put forward some considerations regarding the dynamics of the SD phenomenon in Sardinian populations, where the frequency of SD chromosomes is fairly elevated. © 1990 Kluwer Academic Publishers
The 'natural' hybrid haemoglobin from mule. Interrelationships with its parent haemoglobins from horse and donkey
No full textThe equilibrium O2-binding properties of the hybrid haemoglobin (Hb) present in vivo in erythrocytes from mule and of its parent Hbs from horse and donkey were compared with special reference to the effect of heterotropic ligands such as Cl-, D-glycerate 2,3-bisphosphate (DPG) and inositol hexakisphosphate. All these Hbs display a decreased effect by polyphosphates, confirming that what has been observed for horse Hb [Giardina, Brix, Clementi, Scatena, Nicoletti, Cicchetti, Argentin & Condò (1990) Biochem. J. 266, 897-900] is common to other equine species, at least from a qualitative standpoint. However, different quantitative aspects can be detected, which can be accounted for by a different role for the two types of chain in characterizing the binding free energy for the various heterotropic effectors. In particular, it is shown that the binding mode of DPG and inositol hexakisphosphate displays different features since long-range effects can be observed clearly for inositol hexakisphosphate but not for DPG. In general terms, in spite of a different intrinsic O2 affinity, the modulation of functional properties by third ligands leads these Hbs to behave, under physiological conditions, similarly to human HbA. It might represent an interesting example of how different species with similar functional needs find different ways to produce a similar functional behaviour
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