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S De Flora

Publications and source records attributed to S De Flora.

At least 37 records · Page 2Linked to original sources
PubMed1999

Detection of the '4977 bp' mitochondrial DNA deletion in human atherosclerotic lesions.

The presence of the 4977 bp deletion ('common deletion') in the mitochondrial DNA (mtDNA) is associated with defects in the metabolic machinery acquired during ageing as a hallmark of a degenerative phenotype. We analysed 27 samples (18 from surgical patients and nine from autopsy cases) of DNA extracted from smooth muscle cells of abdominal aorta fragments affected by atherosclerotic lesions. The deletion was detected by PCR amplification gel electrophoresis and characterized by sequencing of the PCR product. The mtDNA 'common deletion' was detected in all analysed samples. However, its levels were not particularly high, which may be ascribed to the fact that smooth muscle cells in atherosclerotic lesions have a lower energy requirement and an appreciable proliferation rate, as compared for instance with cardiac myocytes. When the subjects were divided into two numerically equivalent age classes (60-72 years plus a 45-year-old subject versus 73-95 years), the deletion had significantly higher levels in the older subjects. Conversely, its presence did not correlate with source (surgical or autoptic), sex, cigarettes consumption, other clinical and anamnestic parameters or with the levels of adducts and 8-hydroxy-2'-deoxyguanosine measured in the nuclear DNA of the same samples. A previously unreported deletion of 5111 bp was additionally found in the mtDNA from a 45-year-old woman. The origin of this lesion seems to be compatible with the slipped mispairing model proposed for the 'common deletion'.

Age Factors↗
PubMed1999

Modulation of genotoxic and related effects by carotenoids and vitamin A in experimental models: mechanistic issues.

The mechanisms involved in the modulation of genotoxic and related effects by carotenoids and vitamin A were inferred from a critical review of an ad hoc constructed database. Almost 500 results were generated in experimental models evaluating the activity of 32 structurally, metabolically and functionally related nutrients, including beta-carotene and 26 other carotenoids, retinol, retinal, all-trans-retinoic acid and retinyl esters. As many as 67 experimental test systems, either in vitro or in vivo, used a variety of cellular targets and/or end-points suggestive of distinctive mechanisms of action. The bulk of available data support the view that carotenoids and vitamin A do not induce genotoxic effects per se. Even in the absence of any genotoxic agent, these nutrients appeared, on the contrary, to display some mechanisms which play protective roles in tumor promotion and progression, such as inhibition of N-myc gene expression resulting in antiproliferative effects, up-regulation of cell-to-cell communication, an increase in connexin 43 gene expression, a decrease in the 'spontaneous' cell transformation frequency and induction of differentiation in vitro. A large number of studies investigated the modulation by carotenoids and vitamin A of genotoxic and related effects produced by 69 genotoxicants, including biological agents, physical agents, chemical compounds and complex mixtures. In spite of some discrepant data, the general trend was that both carotenoids and vitamin A are poorly effective in acting as nucleophiles, nor do they appear to substantially interfere with the induction or repair of DNA damage produced by direct-acting agents. In contrast vitamin A and carotenoids, irrespective of their provitamin A role, in most studies inhibited those genotoxicants which require metabolic activation to electrophilic derivatives in either bacterial or mammalian cells. Coupled with biochemical data, the distinctive patterns observed with genotoxic agents belonging to different chemical classes suggest a complex modulation of both phase I and phase II enzymes involved in the metabolism of xenobiotics. Furthermore, carotenoids and vitamin A shared other protective mechanisms, such as scavenging of genotoxic oxygen species, modulation of signal transduction pathways, inhibition of cell transformation induced by physical and chemical agents, and facilitation of intercellular communication inhibited by genotoxic compounds. Therefore, carotenoids and vitamin A appear to work via multiple mechanisms, which would support a potential protective role in cancer initiation and in the pathogenesis of other mutation-related diseases. These conclusions are consistent with the recognized cancer-preventive activity of these nutrients in certain animal models and with the evidence provided by observational epidemiological studies, which suggested cancer-protective effects at many sites as related to their dietary intake or plasma levels. However, all these lines of evidence and mechanistically based premises contrast with the unexpected outcome of recent clinical intervention trials, which raised the concern that supplemental use of beta-carotene and vitamin A may increase the risk of lung cancer amongst high risk individuals such as tobacco smokers and asbestos-exposed workers.

Animals↗
PubMed1999

Induction and prevention of micronuclei and chromosomal aberrations in cultured human lymphocytes exposed to the light of halogen tungsten lamps.

Previous studies have shown that the light emitted by halogen tungsten lamps contains UV radiation in the UV-A, UV-B and UV-C regions, induces mutations and irreparable DNA damage in bacteria, enhances the frequency of micronuclei in cultured human lymphocytes and is potently carcinogenic to the skin of hairless mice. The present study showed that the light emitted by an uncovered, traditional halogen lamp induces a significant, dose-related and time-related increase not only in micronuclei but also in chromosome-type aberrations, such as breaks, and even more in chromatid-type aberrations, such as isochromatid breaks, exchanges and isochromatid/chromatid interchanges, all including gaps or not, in cultured human lymphocytes. All these genotoxic effects were completely prevented by shielding the same lamp with a silica glass cover, blocking UV radiation. A new model of halogen lamp, having the quartz bulb treated in order to reduce the output of UV radiation, was considerably less genotoxic than the uncovered halogen lamp, yet induction of chromosomal alterations was observed at high illuminance levels.

Adult↗
PubMed1999

N-acetylcysteine inhibits endothelial cell invasion and angiogenesis.

The thiol N-acetylcysteine (NAC) is a chemopreventive agent that acts through a variety of mechanisms and can prevent in vivo carcinogenesis. We have previously shown that NAC inhibits invasion and metastasis of malignant cells as well as tumor take. Neovascularization is critical for tumor mass expansion and metastasis formation. We investigated whether a target of the anti-cancer activity of NAC could be the inhibition of the tumor angiogenesis-associated phenotype in vitro and in vivo using the potent angiogenic mixture of Kaposi's sarcoma cell products as a stimulus. Two endothelial (EAhy926 and human umbilical vein endothelial [HUVE]) cell lines were utilized in a panel of assays to test NAC ability in inhibiting chemotaxis, invasion, and gelatinolytic activity in vitro. NAC treatment of EAhy926 and HUVE cells in vitro dose-dependently reduced their ability to invade a reconstituted basement membrane, an indicator of endothelial cell activation. Invasion of HUVE cells was inhibited with an ID50 of 0.24 mM NAC, whereas inhibition of chemotaxis required a 10 fold higher doses, indicating that invasion is a preferential target. NAC inhibited the enzymatic activity and conversion to active forms of the gelatinase produced by endothelial cells. The matrigel in vivo assay was used for the evaluation of angiogenesis; NAC strongly inhibited neovascularization of the matrigel sponges in response to Kaposi's sarcoma cell products. NAC prevented angiogenesis while preserving endothelial cells, implying that it could be safely used as an anti-angiogenic treatment.

Acetylcysteine↗
PubMed1998

Chemoprevention by N-acetylcysteine of urethane-induced clastogenicity and lung tumors in mice.

A major goal in pre-clinical cancer chemoprevention research is to assess the predictive value of intermediate biomarker modulation towards tumor prevention. With this aim, BALB/c mice were treated with 10 daily i.p. injections of urethane (ethyl carbamate), each of 400 mg/kg body weight. Groups of mice received with drinking water either a drug containing the thiol N-acetylcysteine (NAC), at 0.1 or 0.5 g/kg body weight, or its excipient, starting 27 days before the first injection of the carcinogen until the end of the experiment. Out of the 30 mice, 10 per group were identified and individually monitored for 8 sequential times in order to assess the course of micronucleated normochromatic erythrocytes in peripheral blood. This systemic genotoxicity biomarker increased during the 10-day period of treatment with urethane, reached a peak 2 to 6 days after the last injection, and was still significantly higher than the baseline after 10 additional days. Clastogenicity was significantly inhibited by NAC, with a dose-related effect, but not by the drug excipient. As evaluated 4 months after the first injection of urethane, most mice developed lung tumors, whose multiplicity was not affected by the drug excipient but was significantly decreased in the presence of NAC. Correlation between the frequency of micronucleated normochromatic erythrocytes at peak levels and lung-tumor multiplicity was highly significant when evaluated in the context of all 40 mice undergoing cytogenetic analyses (r = 0.561, p = 0.0002). It was similarly high, but did not reach the significance threshold, within each treatment group, due to the lower number of animals and some deviations from the regression line. Therefore, the prediction of lung-tumor yield based on the intensity of the early genotoxicity biomarker is justified when formulated within a sufficiently large group of animals, but is not absolute at individual level.

Acetylcysteine↗
PubMed1998

Mechanisms of inhibitors of mutagenesis and carcinogenesis.

For a rational implementation of chemoprevention strategies it is essential not only to assess the efficacy and safety of putative inhibitors by using a variety of test systems but also to understand the mechanisms involved. This article proposes a detailed classification of mechanisms along with pertinent examples of agents which may be potentially exploited in the host-addressed prevention of cancer and other mutation-related diseases. The classification, presented in tabulated form, covers a variety of mechanisms interfering with different phases of mutagenesis and carcinogenesis. However, the reported sequence of events is not meant to follow a rigid scheme, and several mechanisms are reiterated throughout evolution of these processes. Similarly, a number of protective agents are shown to work through multiple and often interconnected mechanisms.

Animals↗
PubMed1998

DNA fragmentation, DNA-protein crosslinks, postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine.

An in vivo study was carried out with the objectives of evaluating (a) the localization of DNA lesions resulting from exposure to chromium(VI) by the respiratory route, (b) the molecular nature of DNA alterations, and (c) modulation of DNA damage by a known chemopreventive agent. To this purpose, Sprague-Dawley rats received intratracheal instillations of sodium dichromate (0.25 mg/kg body weight) for three consecutive days, and the day after the last treatment lung and liver were removed for DNA purification. The results showed a selective localization of DNA lesions in the lung but not in the liver, which can be ascribed to toxicokinetics and metabolic characteristics of chromium(VI). DNA alterations included DNA-protein crosslinks, DNA fragmentation, nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine. The last two endpoints were evaluated, for the first time in chromium toxicology, by means of postlabeling procedures. This methodology was adapted to the detection of the DNA damage produced by those reactive oxygen species which result from the intracellular reduction of chromium(VI). The oral administration of the thiol N-acetylcysteine completely prevented any induction of DNA lesions in lung cells.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1998

DNA alterations in rat organs after chronic exposure to cigarette smoke and/or ethanol ingestion.

In spite of the epidemiological evidence supporting a synergism between alcohol consumption and cigarette smoking in the pathogenesis of cancers of the aerodigestive tract, there is a paucity of experimental studies evaluating the effects of these agents under well-controlled conditions and exploring the mechanisms involved. We exposed groups of female BD6 rats, aged 8 months, to ethanol (5% in drinking water for 8 consecutive months) and/or whole-body to mainstream cigarette smoke (1 h/day, 5 days/week for 8 months). DNA was purified from different organs and analyzed for the presence of DNA-protein crosslinks and 32P-postlabeled DNA adducts after butanol enrichment. No significant increase of DNA-protein crosslinks, compared to untreated controls, was induced by any treatment in liver, lung, or heart. 'Spontaneous' nucleotidic modifications were detected by 32P-postlabeling in organs of untreated rats, with the highest levels occurring in the heart. Ingestion of ethanol did not affect DNA adduct levels in any of the organs examined: esophagus, liver, lung, and heart. Exposure to cigarette smoke induced formation of DNA adducts in the lung and heart, but not in the esophagus or liver. The combined ingestion of ethanol resulted in a significant formation of smoke-related DNA adducts in the esophagus and in their further, dramatic increase in the heart. It thus appears that ethanol consumption increases the bioavailability of DNA binding smoke components in the upper digestive tract and favors their systemic distribution. The mechanisms responsible for the interaction between ethanol and smoke and for the selective localization of DNA alterations in different organs are discussed. Formation of DNA adducts in the organs examined may be relevant in the pathogenesis of lung and esophageal cancers as well as in the pathogenesis of other types of chronic degenerative diseases, such as chronic obstructive pulmonary diseases and cardiomyopathies.

Alcohol Drinking↗
PubMed1998

In vitro inhibition by N-acetylcysteine of oxidative DNA modifications detected by 32P postlabeling.

Reactive oxygen species are involved in the pathogenesis of cancer and other chronic degenerative diseases through a variety of mechanisms, including DNA damage. We investigated by 32p and 33P postlabeling analyses the nucleotidic modifications induced in vitro by treating calf thymus DNA with H2O2 and CuSO4, interacting in a Fenton type reaction. Six different enrichment procedures and three chromatographic systems were comparatively assayed. The chromatographic system using phosphate/urea, which is more suitable for detecting bulky DNA adducts, was rather insensitive. In contrast, the system using acetic acid/ammonium formate revealed high levels of mononucleotidic modifications. In terms of ratio of adduct levels in treated and untreated DNA, the enrichment procedures ranked as follows: nuclease P1 (19.6), no enrichment (18.3), digestion to trinucleotides (17.6), digestion to monophosphate mononucleotides (8.4), digestion to dinucleotides (3.4), and extraction with butanol (<1.0). The system using formic acid/ammonium formate was quite efficient in detecting 8-hydroxy-2'-deoxyguanosine. Labeling with 33p further enhanced the sensitivity of the method. The oxidative damage was so intense to produce a strong DNA fragmentation detectable by agarose gel electrophoresis, and nucleotidic modifications were more intense when DNA fragmentation was greater. The DNA alterations produced by H2O2 alone were significantly lower than those produced following reaction of H2O2 with CuSO4. The thiol N-acetylcysteine (NAC) was quite efficient in inhibiting both nucleotidic modifications and DNA fragmentation produced in vitro by either H2O2 or the .OH generating system. These results support at a molecular level the findings of previous studies showing the ability of NAC to inhibit the genotoxicity of peroxides and of reactive oxygen species generated by electron transfer reactions.

Acetylcysteine↗
PubMed1998

Inhibition by oral N-acetylcysteine of doxorubicin-induced clastogenicity and alopecia, and prevention of primary tumors and lung micrometastases in mice.

The thiol N-acetylcysteine (NAC), an analog and precursor of glutathione, displays cancer preventive properties not only in early stages of the carcinogenesis process but also in its advanced stages. NAC inhibited type-IV collagenase activity as well as invasion, tumor take, and metastasis of malignant cells in murine models. Previously, we provided evidence for synergistic effects of oral NAC with intravenously injected doxorubicin (DOX). In the present study B16-BL6 melanoma cells were injected s.c. into the footpad of C57BL/6 mice. The animals were divided into 5 groups: i) untreated mice; ii) mice receiving daily NAC with drinking water (12.25 mmol/kg body weight) starting 16 h after injection of cancer cells; iii) mice receiving a single i.v. injection of DOX (2 micromol/kg body weight) 24 h after injection of cancer cells; iv) mice receiving a combination of NAC and DOX, with NAC treatment starting 72 h before injection of cancer cells; and v) mice treated as in iv) but with NAC treatment starting 16 h after injection of cancer cells. Both NAC and DOX, either individually or in combination, significantly enhanced the survival time as compared to controls. The weight of local primary tumors was significantly decreased by either drug, and was further decreased to a significant extent, compared to the individual treatments, in the two groups of mice receiving combinations of NAC and DOX. No lung micrometastases, evaluated by immunohistochemistry as S-100-positive foci of melanocytic cells, were detectable in the two groups of mice receiving the combined treatments. NAC significantly, attenuated the time-related increase of micronucleated polychromatic erythrocytes in the peripheral blood of DOX-treated mice. All mice individually treated with DOX developed a partial but well evident alopecia, diffusely affecting their back hair, which was totally prevented by NAC, irrespective of the combination schedule. Thus, besides preventing DOX cardiotoxicity, as extensively documented in the literature, oral NAC protects mice from DOX-induced myelogenotoxicity and alopecia, and at the same time interacts with this cytotoxic agent in inhibiting cancer cell invasion and metastasis.

Acetylcysteine↗
PubMed1997

Estimates of the chromium(VI) reducing capacity in human body compartments as a mechanism for attenuating its potential toxicity and carcinogenicity.

Estimates of the overall reducing capacity of hexavalent chromium(VI) in some human body compartments were made by relating the specific reducing activity of body fluids, cell populations or organs to their average volume, number, or weight. Although these data do not have absolute precision or universal applicability, they provide a rationale for predicting and interpreting the health effects of chromium(VI). The available evidence strongly indicates that chromium(VI) reduction in body fluids and long-lived non-target cells is expected to greatly attenuate its potential toxicity and genotoxicity, to imprint a threshold character to the carcinogenesis process, and to restrict the possible targets of its activity. For example, the chromium(VI) sequestering capacity of whole blood (187-234 mg per individual) and the reducing capacity of red blood cells (at least 93-128 mg) explain why this metal is not a systemic toxicant, except at very high doses, and also explain its lack of carcinogenicity at a distance from the portal of entry into the organism. Reduction by fluids in the digestive tract, e.g. by saliva (0.7-2.1 mg/day) and gastric juice (at least 84-88 mg/day), and sequestration by intestinal bacteria (11-24 mg eliminated daily with feces) account for the poor intestinal absorption of chromium(VI). The chromium(VI) escaping reduction in the digestive tract will be detoxified in the blood of the portal vein system and then in the liver, having an overall reducing capacity of 3300 mg. These processes give reasons for the poor oral toxicity of chromium(VI) and its lack of carcinogenicity when introduced by the oral route or swallowed following reflux from the respiratory tract. In terminal airways chromium(VI) is reduced in the epithelial lining fluid (0.9-1.8 mg) and in pulmonary alveolar macrophages (136 mg). The peripheral lung parenchyma has an overall reducing capacity of 260 mg chromium(VI), with a slightly higher specific activity as compared to the bronchial tree. Therefore, even in the respiratory tract, which is the only consistent target of chromium(VI) carcinogenicity in humans (lung and sinonasal cavities), there are barriers hampering its carcinogenicity. These hurdles could be only overwhelmed under conditions of massive exposure by inhalation, as it occurred in certain work environments prior to the implementation of suitable industrial hygiene measures.

Biological Availability↗
PubMed1997

Modulation of the potency of promutagens and direct acting mutagens in bacteria by inhibitors of the multidrug resistance mechanism.

Multiple drug resistance (MDR) mechanisms are known to limit the effectiveness of some cancer chemotherapies, probably through enhancing P-glycoprotein-mediated drug efflux from mammalian cells. Similar mechanisms appear to act in other organisms, including bacteria, and may affect not only the toxicity but also the mutagenicity of certain chemicals. At least in some experimental situations, MDR can be overcome through concomitant treatment of the cells with various types of inhibitors. Two MDR inhibitors, verapamil, a calcium channel blocker, and trifluoperazine, a calmodulin inhibitor, were assayed for their ability to modulate the potency of nine mutagens with varying mechanisms of action in various Salmonella typhimurium his- strains. Neither verapamil nor trifluoperazine affected the direct mutagenicity of sodium dichromate and 2-methoxy-6-chloro-9[3-(2-chloroethyl)amino-propyl-amino] dihydrochloride (ICR 191) or the S9-mediated mutagenicity of benzo[a]pyrene and 2-amino-3,4-dimethyl-amidazo[4,5-f]quinoline (MeIQ). Both modulators enhanced the direct mutagenicity of doxorubicin. Moreover, trifluoperazine sharply increased the S9-mediated mutagenicity of cyclophosphamide and 2-aminofluorene, while it consistently decreased the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The contrasting effect towards the aromatic amine 2-aminofluorene and the heterocyclic amine Trp-P-2, representative of important chemical families responsible for the bacterial mutagenicity of cigarette smoke, may explain the observed lack of influence of trifluoperazine on the mutagenicity of a cigarette smoke condensate. These observations extend the known range of chemical types whose mutagenicity can be modulated by inhibitors of MDR and suggest that there may be value in adding MDR inhibitors, especially trifluoperazine, to optimize the detection of mutagenicity by certain types of chemicals in the Salmonella/mammalian microsome mutagenicity test.

Acridines↗
PubMed1997

Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment.

N-acetylcysteine (NAC), an analogue and precursor of reduced glutathione, has been in clinical use for more than 30 yrs as a mucolytic drug. It has also been proposed for and/or used in the therapy and/or prevention of several respiratory diseases and of diseases involving an oxidative stress, in general. The objective of the present study was to evaluate the effect of long-term treatment with NAC on influenza and influenza-like episodes. A total of 262 subjects of both sexes (78% > or = 65 yrs, and 62% suffering from nonrespiratory chronic degenerative diseases) were enrolled in a randomized, double-blind trial involving 20 Italian Centres. They were randomized to receive either placebo or NAC tablets (600 mg) twice daily for 6 months. Patients suffering from chronic respiratory diseases were not eligible, to avoid possible confounding by an effect of NAC on respiratory symptoms. NAC treatment was well tolerated and resulted in a significant decrease in the frequency of influenza-like episodes, severity, and length of time confined to bed. Both local and systemic symptoms were sharply and significantly reduced in the NAC group. Frequency of seroconversion towards A/H1N1 Singapore 6/86 influenza virus was similar in the two groups, but only 25% of virus-infected subjects under NAC treatment developed a symptomatic form, versus 79% in the placebo group. Evaluation of cell-mediated immunity showed a progressive, significant shift from anergy to normoergy following NAC treatment. Administration of N-acetylcysteine during the winter, thus, appears to provide a significant attenuation of influenza and influenza-like episodes, especially in elderly high-risk individuals. N-acetylcysteine did not prevent A/H1N1 virus influenza infection but significantly reduced the incidence of clinically apparent disease.

Acetylcysteine↗
PubMed1997

Molecular epidemiology of atherosclerosis.

It has been hypothesized that mutational events may be involved in the atherogenetic process and that at least a portion of atherosclerotic plaques may develop according to an initiation-promotion process of arterial smooth muscle cells, akin to benign tumors. We conducted a study to evaluate the occurrence of oxidative DNA damage and formation of DNA adducts in human atherosclerotic lesions and to assess the relationships of these promutagenic alterations with exposure to atherogenic risk factors. Pure DNA was extracted from the tunica media (composed mainly of smooth muscle cells) of abdominal aorta fragments taken at surgery from 85 patients suffering from severe atherosclerotic lesions. DNA adducts were detected by synchronous fluorescence spectrophotometry and 32P postlabeling after enrichment of adducts with either butanol or nuclease P1. 8-Hydroxy-2'-deoxyguanosine (8-OH-dG), a typical indicator of oxidative DNA damage, was measured by HPLC/electrochemical detection. A complete questionnaire reporting general, clinical, and laboratory characteristics was available for each patient. All 84 samples tested by 32P postlabeling were positive by displaying the presence of diagonal radioactive zones and up to 9 individual DNA adducts. Of 52 samples tested, 32 (61.5%) yielded typical positive signals at synchronous fluorescence spectrophotometry. All but one of 39 samples tested had very high levels of 8-OH-dG, thus showing a remarkable oxidative DNA damage. Statistically significant correlations were found between the levels of molecular biomarkers and atherogenic risk factors including age, number of currently smoked cigarettes, ratio of total-to-high density lipoprotein blood cholesterol, blood triglycerides, and blood pressure. The DNA alterations detected in our study may be only one component of the genetic basis of atherogenesis. Moreover, no causal role in the atherogenetic process can be inferred from our results. However, DNA alterations, including oxidative damage and adduction of reactive molecules of either endogenous or exogenous source, were systematically present in the smooth muscle cells of human atherosclerotic lesions and their intensity was significantly correlated with the occurrence of atherogenic risk factors in the patients studied.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

Oltipraz chemoprevention trial in Qidong, Jiangsu Province, People's Republic of China.

Oltipraz has been used clinically in many regions of the world as an antischistosomal agent and is an effective inhibitor of aflatoxin hepatocarcinogenesis in rats. This chemopreventive action of oltipraz results primarily from an altered balance in aflatoxin metabolic activation and detoxication. In 1995, a randomized, placebo-controlled, double-blind intervention was conducted in residents of Qidong, People's Republic of China, who are at high risk for exposure to aflatoxin and development of hepatocellular carcinoma. The major study objectives were to define a dose and schedule for oltipraz that would reduce levels of aflatoxin biomarkers in biofluids of the participants, and to further characterize dose-limiting side effects. Two hundred thirty-four healthy eligible individuals, including those infected with HBV, were randomized to receive either 125 mg oltipraz daily, 500 mg oltipraz weekly, or placebo. Blood and urine specimens were collected to monitor potential toxicities and evaluate biomarkers over the 8-week intervention and subsequent 8-week follow-up periods. Overall, compliance in the intervention was excellent; approximately 85% of the participants completed the study. Objective evaluation of adverse events was greatly facilitated by inclusion of a placebo arm in the study design. A syndrome involving numbness, tingling, and pain in the fingertips was the only event that occurred more frequently among the active groups (18 and 14% of the daily 125 mg and weekly 500 mg arms, respectively) compared to placebo (3%). These symptoms were reversible and could be relieved with non-steroidal antiinflammatory agents. A more complete understanding of the chemopreventive utility of oltipraz awaits completion of an assessment of the efficacy of oltipraz in modulating levels of aflatoxin biomarkers.

Animals↗
PubMed1996

Lack of mutations in K-ras codons 12 and 13 in human atherosclerotic lesions.

In the framework of a project investigating the possible involvement of cancer biomarkers in human atherogenesis, we evaluated the occurrence of K-ras mutations in the DNA extracted from smooth muscle cells of abdominal aorta atherosclerotic lesions. The molecular analysis of the DNA from 32 surgical specimens, using PCR-based denaturing gradient gel electrophoresis (DGGE), did not reveal any variant in K-ras codons 12 and 13, which are the most frequently involved codons among the ras genes mutated in various types of human tumors. Analysis of the DNA extracted from four cell lines carrying known K-ras mutational alleles showed typically positive DGGE patterns. Thus, on the whole, the conclusions of this study and of previous studies using the same biological material are consistent with the occurrence of DNA adducts in human atherosclerotic lesions but in the absence of p53 involvement or of K-ras mutations in codons 12 and 13. The search for candidate genes which may possibly be involved in the atherogenetic process warrants further studies.

Aged↗
PubMed1996

Synergism between N-acetylcysteine and doxorubicin in the prevention of tumorigenicity and metastasis in murine models.

The thiol N-acetylcysteine (NAC) is a promising cancer chemopreventive agent which acts through a variety of mechanisms, including its nucleophilic and antioxidant properties. We have recently shown that NAC inhibits type-IV collagenase activity as well as invasion, tumor take and metastasis of malignant cells in mice. NAC is also known to attenuate the cardiotoxicity of the cytostatic drug doxorubicin (DOX, Adriamycin). The present study was designed to evaluate whether the combination of NAC and DOX treatments in mice injected with cancer cells could affect their tumorigenic and metastatic properties. Six separate experiments were carried out, using a total of 291 adult female mice. In experimental metastasis assays, in which B16-F10 melanoma cells were injected i.v. into (CD-1)BR nude mice, DOX significantly reduced the number of lung metastases when administered i.v. at a dose of 10 mg/kg body weight, 3 days after the i.v. injection of cancer cells. NAC inhibited lung metastases when added to the medium of cancer cells before their i.v. injection. The combined treatment with DOX and NAC, under various experimental conditions, was highly effective, showing a synergistic reduction in the number of mestastases. In tumorigenicity and spontaneous metastasis assays, in which B16-BL6 melanoma cells were injected s.c. into the footpad of C57BL/6 mice, DOX decreased the number of lung metastases when given i.p. at 2 mg/kg body weight. Oral NAC exerted significant protective effects, and considerably prolonged survival of mice. The combined treatment with DOX and NAC again showed synergistic effects on the frequency and weight of primary tumors and local recurrences, and completely prevented the formation of lung metastases in the experiment in which these end-points were evaluated at fixed times. While injection of DOX 7 days after implantation of cancer cells failed to improve the cancer-protective effects of NAC, its injection after I day resulted in a striking inhibition of lung metastases. These findings demonstrate an evident synergism between DOX (given parenterally) and NAC (given with drinking water) in preventing tumorigenicity and metastases. The indications of these animal studies warrant further evaluation in clinical trials.

Acetylcysteine↗