Xanthium strumariumL. is a member of the Asteraceae commonly used in Cuba, mainly as diuretic. Some toxic properties of this plant have also been reported and, to date, very little is known about its genotoxic properties. The present work aims was to evaluate the potential cytotoxic and genotoxic risk of whole extract fromXanthium strumariumL. whole extract of aerial parts. No positive response was observed in a battery of fourSalmonella typhimuriumstrains, when exposed to concentrations up to 5 mg/plate, with and without mammalian metabolic activation (liver microsomal S9 fraction from Wistar rats). In CHO cells, high concentrations (25–100 μg/mL) revealed significant reduction in cell viability. Results from sister chromatid exchanges, chromosome aberrations, and comet assay showed thatX. strumariumextract is genotoxic at the highest concentration used, when clear cytotoxic effects were also observed. On the contrary, no increase in micronuclei frequency in bone marrow cells was observed when the extract was orally administered to mice (100, 500, and 2000 mg/Kg doses). The data presented here constitute the most complete study on the genotoxic potential ofX. strumariumL. and show that the extract can inducein vitroDNA damage at cytotoxic concentrations.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders whose etiology is multifactorial including both hereditary and environmental factors. Currently, pathogenic mutations in at least five genes have been implicated in familial PD generally accounting for less than 10 % of all PD cases in most populations. It has been suggested that polymorphisms in other genes such as those encoding enzymes involved in oxidative metabolism and detoxification could be involved in predisposition to PD since oxidative stress in dopaminergic neurons is thought to be of central importance in the pathogenesis of the disease. The aim of our work was to study the association of genetic polymorphisms in genes involved in oxidative metabolism and detoxification mechanism, namely GSTM1, GSTT1, GSTP1, and those involved in DNA damage repair, OGG1 and XRCC1, in an Italian cohort of sporadic PD patients. We did not detect any association between GSTT1 and GTTM1 null polymorphisms and PD, whereas the 104GSTP1 polymorphism was associated with PD in male patients but not in females. Furthermore, we detected a protective effect of wild type genotype of XRCC1 in women.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders characterized by decreased levels of the neurotransmitter dopamine (DA) in the striatum of the brain, as a result of degeneration of DA neurons. Levodopa (L-Dopa) crosses the blood-brain barrier and its administration replenishes the loss of DA in dopaminergic neurons in PD patients. Despite the evident beneficial effects, L-Dopa use may cause side effects and its toxicity found in in vitro assays has been attributed to the generation of reactive oxygen species (ROS): L-Dopa is converted to DA and its metabolism and autoxidation gives rise to quinones, semiquinones, and hydrogen peroxide. Despite this evidence, L-Dopa in some in vivo and in vitro experiments showed no toxic effects, or even antioxidant effects. Two major peripheral L-Dopa metabolic pathways, driven by the enzymes Aromatic L-amino acid decarboxylase (AADC) and catechol-O-methyl transferase (COMT), significantly deplete the amount of L-Dopa reaching the brain. The low bioavailability of L-Dopa may cause a wide variation in clinical response between patients. Strategies addressing to improve the bioavailability of L-Dopa include coadministering L-Dopa with carbidopa, a decarboxylase inhibitor, as multiple daily doses. We utilized catecholaminergic human neuroblastoma cells to study DNA damage and ROS production after L-Dopa and carbidopa treatments. Our data lead us to confirm that L-Dopa may have a protective effect on dopaminergic cells especially at certain concentrations, in particular, toward the production of ROS and their toxic effects on DNA. Furthermore in the combined treatment, with induction of ROS following administration of H(2)O(2), carbidopa is effective in reducing the damage caused by reactive oxygen intermediates both alone and in combination with L-Dopa.

Parkinson’s disease is one of the most common progressive neurodegenerative disorder. It is characterized by the depletion of dopamine in the dopaminergic neurons of the striatum of the brain. Pharmacological treatment involves the administration of a dopamine precursor, levodo- pa (L-Dopa), which crosses the blood-brain barrier and replaces the loss of dopamine in the brain. One of the main drawbacks of the ad- ministration of L-Dopa is its short half-life, due to the presence of enzymes, such as the amino acid decarboxylase (AADC), able to rapidly me- tabolize L-Dopa. For this reason the intake of L-Dopa takes always place together with an AADC inhibitor such as carbidopa. The assumption of carbidopa increases L-Dopa half-life, but several patients need to increase the dosage of the pharmacological therapy during the progression of the disease. Another area of dispute is represented by the possibility that L-Dopa can exert a toxic effect on the cells, both in peripheral and in central nervous system, increasing the production of ROS following its conversion to dopamine. Past studies reported toxic effects of L-Dopa in vitro and show conflicting data in in vivo experiments. More recent studies have however shown that L-dopa may exert a protective and antioxidant effect on dopaminergic cells, and its combination with carbidopa in pharmacological treatment amplifies antioxidant capability.

Resveratrol, a stilbene found in grapes and wine, is one of the most interesting natural compound due to its role exerted in cancer prevention and therapy. In particular, resveratrol is able to delay cell cycle progression and to induce apoptotic death in several cell lines. Here we report that resveratrol treatment of human glioblastoma cells induces a delay in cell cycle progression during S phase associated with an increase in histone H2AX phosphorylation. Furthermore, with an in vitro assay of topoisomerase IIα catalytic activity we show that resveratrol is able to inhibit the ability of recombinant human TOPO IIα to decatenate kDNA, so that it could be considered a TOPO II poison.

BACKGROUND: In eukaryotic cells the nuclear envelope isolates and protects DNA from molecules that could damage its structure or interfere with its processing. Moreover, selected protection enzymes and vitamins act as efficient guardians against toxic compounds both in the nucleoplasm and in the cytosol. The observation that a cytosolic detoxifying and antioxidant enzyme i.e. glutathione transferase is accumulated in the perinuclear region of the rat hepatocytes suggests that other unrecognized modalities of nuclear protection may exist. Here we show evidence for the existence of a safeguard enzyme machinery formed by an hyper-crowding of cationic enzymes and proteins encompassing the nuclear membrane and promoted by electrostatic interactions. METHODOLOGY/PRINCIPAL FINDINGS: Electron spectroscopic imaging, zeta potential measurements, isoelectrofocusing, comet assay and mass spectrometry have been used to characterize this surprising structure that is present in the cells of all rat tissues examined (liver, kidney, heart, lung and brain), and that behaves as a "nuclear shield". In hepatocytes, this hyper-crowding structure is about 300 nm thick, it is mainly formed by cationic enzymes and the local concentration of key protection enzymes, such as glutathione transferase, catalase and glutathione peroxidase is up to seven times higher than in the cytosol. The catalytic activity of these enzymes, when packed in the shield, is not modified and their relative concentrations vary remarkably in different tissues. Removal of this protective shield renders chromosomes more sensitive to damage by oxidative stress. Specific nuclear proteins anchored to the outer nuclear envelope are likely involved in the shield formation and stabilization. CONCLUSIONS/SIGNIFICANCE: The characterization of this previously unrecognized nuclear shield in different tissues opens a new interesting scenario for physiological and protection processes in eukaryotic cells. Selection and accumulation of protection enzymes near sensitive targets represents a new safeguard modality which deeply differs from the adaptive response which is based on expression of specific enzymes.

This study aimed to assess whether haplotypes in XRCC1 and SNPs in OGG1 and XRCC3 were associated with an increased risk of developing breast cancer (BC) and early adverse reactions after radiotherapy.

Cystic Fibrosis (CF) is an autosomal recessive multisystemic disorder showing a highly heterogeneous phenotype, even among siblings carrying identical CFTR mutations. Moreover, oxidative stress is of central importance in the pathogenesis of cystic fibrosis. The present study seeks to value the presence of oxidative damage in CF patients and the possible modifier effect of repair and glutathione-S-transferase genes. We analysed the presence of DNA damage in leukocytes of 63 CF patients at an Italian CF centre and 63 controls, through the alkaline Comet assay to detect DNA strand breaks. Furthermore, controls and 93 CF subjects were genotyped for 5 genes by RFLP-PCR (XRCC1,0GG1,GSTP1) and PCR assay (GSTM1, GSTT1). No difference in Comet assay values was observed comparing controls to CF patients, although CF subjects showed slightly higher mean values. The crude Odds-Ratio (OR) was higher than one for XRCC1 and GSTP1 genotypes and liver status and for XRCC1 and OGG1 genotypes and pancreatic insufficiency, but in all cases the p-values were not significant. In this case-control study, neither DNA damage ñor gene polymorphisms seem to influence CF manifestation.

Resveratrol (3,4',5-trihydroxystilbene) is a polyphenol synthesized by a wide variety of plant species in response to injury, UV irradiation and fungal attack. Many studies have revealed a variety of resveratrol intracellular targets whose modulation gives rise to overlapping responses leading to growth arrest and death. Many authors have reported different human cancer cell lines, treated with resveratrol at micromolar concentrations, arrested their proliferative cycle in the G1/S boundary or in the S phase and this cell cycle arrest was followed by apoptotic death. Less is known about the ability of resveratrol to modify the effect of radiation exposure in normal and cancer cells. Considering that controlled exposure to ionizing radiation is one of the most used treatments in cancer patients and that these schedules are not always effective in medical practice, as in the case of glioma patients, the testing of combined treatment protocols (resveratrol and ionizing radiation) could be of interest, opening the door to future studies which would examine the pharmacological activity of resveratrol. In this study we have looked into whether resveratrol is able to modulate cell cycle progression in human glioblastoma cells and to regulate GJs expression in cancer cells. With this aim in mind we have performed a cytofluorimetric multiparameter assay to quantify the presence of GJs in U87 glioma cells treated with resveratrol and/or X rays. We report that resveratrol induces a delay in cell cycle progression and both alone and in combination with X rays is able to enhance gap junction Intercellular Communications.

Purpose: To study the repair capacity after X-ray irradiation in human peripheral blood cells of healthy subjects, in relation to their genotypes.Methods and Materials: The peripheral blood of 50 healthy subjects was irradiated in vitro with 2Gy of X rays and the induced DNA damage was measured by Comet assay immediately after irradiation. DNA repair was detected by analyzing the cells at defined time intervals after the exposure. Furthermore, all subjects were genotyped for XRCC1, OGG1, and XPC genes.Results: After X-ray irradiation, persons bearing XRCC1 homozygous variant (codon 399) genotype exhibited significantly lower Tail DNA values than those bearing wild-type and heterozygous genotypes. These results are also confirmed at 30 and 60 min after irradiation. Furthermore, XPC heterozygous subjects (variant codon 939) showed lower residual DNA damage 60 min after irradiation compared with wild-type and homozygous genotypes.Conclusion: The results of the present study show that polymorphisms in DNA repair genes could influence individual DNA repair capacity. (c) 2006 Elsevier Inc.