Biomedical subjects

S De Flora

Publications and source records attributed to S De Flora.

At least 55 records · Page 3Linked to original sources

PubMed1996

Biomarker alterations produced in rat lung by intratracheal instillations of air particulate extracts and chemoprevention with oral N-acetylcysteine.

Organic matter extracts were obtained from particulates recovered from 10,000-m3 air samples collected in Sicily (Italy). The overall concentrations of acenaphthene, benzo(a)pyrene, phenanthrene, anthracene, fluoranthene, and pyrene were 526 ng/m3 air in a highly polluted urban area and 48 ng/m3 in a rural area affected by motor vehicle traffic pollution. After metabolic activation, both samples were mutagenic in Salmonella typhimurium his(-) strains of the TA and YG series, with potencies in TA100 of 140.7 and 11.8 revertants/m3 air, respectively. The samples, resuspended in tricaprylin, were instilled intratracheally in Sprague-Dawley rats for 5 consecutive days, accounting for a cumulative dose in each animal of the organic fractions extracted from 400 m3 air, which corresponds approximately to the volume of air inhaled by a man in 1 month. Treatment with the rural area sample and, at higher levels, with the urban area sample resulted in the formation of adducts to lung DNA, as assessed both by synchronous fluorescence spectrophotometry and by 32P postlabeling, which showed the appearance of up to six individual adducts emerging from diffuse diagonal radioactive zones. The adducts were more efficiently detected by extraction with butanol than by digestion with nuclease P1. DNA binding of air particulate extracts was followed by alterations of early damage biomarkers only in the rats treated with the urban area sample. Repair of DNA damage in lung cells was inferred from a significant stimulation of the nuclear enzyme poly(ADP-ribose) polymerase compared with that in sham-exposed rats. Among the cells recovered by bronchoalveolar lavage, an increase in polymorphonucleate leukocytes and cells of the ciliated respiratory epithelium was accompanied by a relative decrease in pulmonary alveolar macrophages. The frequency of micronuclei was significantly enhanced both in epithelial cells and alveolar macrophages, and binucleated macrophages were also more frequent in treated rats. The thiol N-acetylcysteine, one of the most promising cancer chemopreventive agents, was administered with drinking water to a group of animals receiving the air particulate polycyclic aromatic hydrocarbon fraction from the urban area. N-acetylcysteine prevented or considerably attenuated the alterations of all monitored parameters. These findings provide evidence that, even under outstandingly high exposure conditions, it is possible to protect the respiratory tract from DNA-binding and DNA-damaging air particulate carcinogens.

Acetylcysteine↗

PubMed1996

Induction by carcinogens and chemoprevention by N-acetylcysteine of adducts to mitochondrial DNA in rat organs.

Damage to mitochondrial DNA (mtDNA) has been postulated to be associated with aging, cancer, and other chronic degenerative diseases which are the predominant causes of death in the population. We used molecular dosimetry techniques, i.e., 32P postlabeling and synchronous fluorescence spectrophotometry, in order to evaluate the formation of adducts to both mtDNA and nuclear DNA (nDNA) in different organs of rats exposed to genotoxic carcinogens. Adducts to mtDNA were detected following administration of benzo(a)pyrene i.p. or 2-acetylaminofluorene by gavage as well as following exposure of animals to cigarette smoke. mtDNA adduct levels were consistently higher than those to nDNA in the same cells, and qualitative differences were also pointed out in the case of the aromatic amine. The oral administration of the thiol N-acetylcysteine, one of the most promising cancer chemopreventive agents endowed with nucleophilic and antioxidant properties, produced a significant decrease of mtDNA adducts in the liver of 2-acetylaminofluorene-treated rats and, sharply, in the lung and liver of rats exposed to cigarette smoke.

2-Acetylaminofluorene↗

PubMed1996

Activity profiles of antimutagens: in vitro and in vivo data.

In this review, retinol, chlorophyllin, and N-acetylcysteine are examined and compared with regard to their antimutagenic activity against some promutagens and a group of direct-acting alkylating agents. The promutagens included aflatoxin B1, certain polycyclic aromatic hydrocarbons (e.g., benzo[a]pyrene), and certain heterocyclic amines (e.g., food pyrolysates). Results of antimutagenicity testing selected from data surveyed in the published literature are displayed graphically as activity profiles of antimutagens showing both the doses tested and the extent of inhibition or enhancement of mutagenic activity. All three antimutagens are discussed in terms of their putative mechanisms of action in vitro and in vivo with emphasis on the xenobiotic metabolizing enzyme systems.

Acetylcysteine↗

PubMed1996

Adducts to nuclear DNA and mitochondrial DNA as biomarkers in chemoprevention.

DNA adducts are biomarkers evaluating the biologically effective dose of carcinogens, which reflects, more realistically than the external exposure dose, an enhanced risk of developing cancer. Likewise, inhibition of DNA adduct formation can be assumed as an indicator of decreased risk. Molecular dosimetry techniques can be exploited in anticarcinogenicity studies in animal models as well as in Phase II clinical chemoprevention trials. We have extensively used these end points in animal studies using individual carcinogens and complex mixtures. As assessed by 32P-postlabelling, DNA adducts were formed in the liver of rats fed a diet supplemented with 2-acetylaminofluorene. DNA adducts were detected by synchronous fluorescence spectrophotometry (SFS) in rat liver, lung, heart and testis following intratracheal (l.t) instillations of benzo[a]pyrene. The whole-body exposure of rats to mainstream cigarette smoke resulted in the appearance of DNA adducts in lung, heart, aorta and kidney, whereas adducts were not detected by SFS in liver, brain, oesophagus and testis. Moreover, typical diagonal radioactive zones and multiple DNA adducts were revealed by 32P-postlabelling in the tracheal epithelium, nasal mucosa, aorta and testis of smoke-exposed rats. Formation of adducts to lung DNA, as assessed by both 32P-postlabelling and SFS, also occurred in rats receiving i.t. instillations of air particulate extracts from polluted urban and rural areas. The oral administration of the thiol N-acetylcysteine (NAC) significantly inhibited the formation of DNA adducts in all organs of the rats exposed to the aforementioned carcinogens, which correlated with the parallel inhibition of biochemical, cytogenetic and histopathological alterations as well as with inhibition of preneoplastic and neoplastic lesions in rodents. Our working hypothesis is that DNA adducts in trachea/lung, heart and aorta may be associated with lung cancer, cardiomyopathies and atherosclerosis, respectively. DNA adducts were consistently detectable in the DNA of smooth muscle cells from abdominal aorta specimens taken at surgery from atherosclerotic patients. Even broader are the consequences of mitochondrial (mt) DNA impairment, which has been associated with aging, cancer, and other degenerative diseases. Our data show that adduct levels are consistently higher in mtDNA than in the nuclear DNA in different organs of rats exposed either to benzo[a]pyrene, 2-acetylaminofluorene or cigarette smoke. NAC significantly decreased the formation of adducts to mtDNA when administered with drinking-water. Inhibition of adducts to nuclear DNA is one of the end points evaluated in ongoing Phase II chemoprevention trials in high-risk individuals.

Animals↗

PubMed1996

Smokers and urinary genotoxins: implications for selection of cohorts and modulation of endpoints in chemoprevention trials.

Urinary genotoxicity assays measure the internal dose of genotoxic carcinogens, thereby providing a particularly sensitive endpoint for selecting cohorts of individuals exposed to cigarette smoke or other mutagens excreted with urines, as well as for evaluating the modulation of this parameter after administration of chemopreventive agents. Mutagenicity of urines was investigated in smoking Italian volunteers, who received oral N-acetylcysteine (NAC) at the same doses which are usually prescribed for the long-term treatment of chronic bronchitis. The daily excretion of mutagens, concentrated on XAD-2 columns and tested in Salmonella typhimurium YG1024 with S9 mix, was significantly and remarkably decreased by NAC in the majority of the subjects examined so far. Time-course experiments showed that this effect starts since the first day of drug administration and reverses when treatment is withdrawn. In addition, NAC administration almost totally prevented urinary genotoxicity in one subject whose concentrated urines induced a differential lethality in Escherichia coli strains having distinctive DNA repair capacities. The decrease of urinary genotoxicity produced by NAC in the majority of smokers correlates with the ability of this thiol to prevent tumors and to affect a variety of intermediate biomarkers in animal models. Modulation of the urinary excretion of mutagens is one of the biomarkers evaluated in two ongoing Phase II chemoprevention trials. One study involves the oral administration of NAC in Dutch smokers. The pretreatment urine samples of all the subjects so far recruited are clearly mutagenic. The other study involves the oral administration of the dithiolethione oltipraz to individuals living in the Qidong County of the People's Republic of China, an area of high endemy for HBV infection and of high exposure to aflatoxins. Additionally, a large proportion of the recruited male subjects are smokers. A total of 500 urine specimens will be assayed from 240 subjects according to a complex protocol arranged in three consecutive phases.

Acetylcysteine↗

PubMed1996

DNA adducts and chronic degenerative disease. Pathogenetic relevance and implications in preventive medicine.

Chronic degenerative diseases are the leading causes of death in developed countries. Their control is exceedingly difficult due to their multiplicity and diversity, the interconnection with a network of multiple risk factors and protective factors, the long latency and multistep pathogenesis, and the multifocal localization. Adducts to nuclear DNA are biomarkers evaluating the biologically effective dose, reflecting an enhanced risk of developing a mutation-related disease more realistically than the external exposure dose. The localization and accumulation of these promutagenic lesions in different organs are the composite result of several factors, including (a) toxicokinetics (first-pass effect); (b) local and distant metabolism; (c) efficiency and fidelity of DNA repair; and (d) cell proliferation rate. The last factor will affect not only the dilution of DNA adducts but also the possible evolution towards either destructive processes, such as emphysema or cardiomyopathies, or proliferative processes, such as benign or malignant tumors at various sites. They also include heart tumors affecting fetal myocytes after transplacental exposure to DNA-binding agents, blood vessel tumors, and atherosclerotic plaques. In this article, particular emphasis is given to molecular alterations in the heart, which is the preferential target for the formation of DNA adducts in smokers, and in human aorta, where an extensive molecular epidemiology project is documenting the systematic presence of adducts to the nuclear DNA of smooth muscle cells from atherosclerotic lesions, and their significant correlation with known atherogenic risk factors. Exocyclic DNA adducts resulting from lipid peroxidation, and age-related indigenous adducts (I-compounds) may also originate from endogenous sources, chronic infections and infestations, and inflammatory processes. Type II I-compounds are bulky DNA lesions resulting from oxidative stress, whereas type II-compounds are presumably normal DNA modifications, which display positive correlations with median life span and are decreased in cancer and other pathological conditions. Profiles of type II-compounds strongly depend on diet and are related to the antidegenerative effects of caloric/ dietary restriction. Even broader is the possible meaning of adducts to mitochondrial DNA, which have been detected in rodents exposed to genotoxic agents and complex mixtures, as well as in untreated rodents, in larger amounts when compared to the nuclear DNA of the same cells. Mutations in mitochondrial DNA increase the number of oxidative phosphorylation-defective cells, especially in energy-requiring postmitotic tissues such as brain, heart and skeletal muscle, thereby playing an important role in aging and a variety of chronic degenerative diseases. A decreased formation of DNA adducts is an indicator of reduced risk of developing the associated disease. Therefore, these molecular dosimeters can be used as biomarkers in the prevention of chronic degenerative diseases, pursued either by avoiding exposure to adduct-forming agents or by using chemopreventive agents. Interventions addressed to the human organism by means of dietary measures or pharmacological agents have encountered a broad consensus in the area of cardiovascular diseases, and are deserving a growing interest also in cancer prevention. The efficacy of chemopreventive agents can be assessed by evaluating inhibition of nuclear DNA or mitochondrial DNA adduct formation in vitro, in animal models, and in phase II clinical trials in high-risk individuals.

Animals↗

PubMed1995

No effect of treatment with carcinogens on cytosine methylation of mitochondrial DNA isolated from rat organs by phenol-free alkaline extraction.

Due to the postulated role of mitochondrial DNA damage in aging as well as in the pathogenesis of several chronic degenerative diseases, including tumors, there is a need for easy, safe, rapid and inexpensive methods for mitochondrial DNA isolation. We propose a simple, 1-day protocol based on alkaline extraction, which avoids time-consuming gradient centrifugations and use of toxic phenol. This procedure was used for the recovery of mitochondrial DNA from different rat organs (liver, kidney, heart, lung, brain and testis). The yield was quite high. Purity was sufficient enough to perform restriction analyses with several endonucleases. No changes were observed in the structure or methylation patterns of -CCGG- sites in liver mitochondrial DNA isolated from rats exposed whole-body to mainstream cigarette smoke or treated with the carcinogens benzo[alpha]pyrene, 2-acetylaminofluorene or diethylnitrosamine.

5-Methylcytosine↗

PubMed1995

Enhanced levels of DNA adducts in the liver of woodchucks infected with hepatitis virus.

Liver DNA specimens from woodchucks kept in captivity, 10 naturally infected with hepatitis virus (WHV) and five WHV-free, were examined for the presence of carcinogen-DNA adducts by 32P-postlabeling. The number of adducts was significantly higher in WHV carriers than in uninfected animals, and the total amounts of adducts per 10(9) nucleotides were also considerably enhanced by WHV infection, when using both butanol extraction (22.2 +/- 7.1 vs. 12.6 +/- 2.8, means +/- S.D.) and nuclease P1 enrichment (8.5 +/- 5.9 vs. 2.8 +/- 1.7). Two individual adducts were also significantly higher in WHV carriers. No significant variation occurred as related to age, sex or time length of captivity. These findings are consistent with our previous studies supporting an enhanced metabolism of chemical hepatocarcinogens in both human and woodchuck hepadnavirus infections. Several significant and remarkable correlations were pointed out by relating DNA adduct data to more than 30 virological, histopathological and metabolic parameters which had been previously evaluated in the same animals. For instance, numbers and/or levels of adducts were positively related to the amounts of virus present in hepatocytes, to cell damage (gamma-glutamyltranspeptidase activity), to the severity of the liver histopathological picture, and to monooxygenase activities, while they were inversely related to cellular glutathione concentrations and to detoxification of the direct-acting mutagen 4-nitroquinoline 1-oxide. The major adduct significantly correlated with the metabolic activation of the aromatic amine 2-aminofluorene and of the heterocyclic amines 3-amino-1-methyl-5H-pyrido(4,3)indole (Trp-P-2) and 2-amino-3,4-dimethylimidazo(4,5-f)quinoline (MeIQ), whereas another adduct significantly correlated with the metabolic activation of the mycotoxin aflatoxin B1. Thus, the enhanced metabolism of chemical hepatocarcinogens and the increased formation of carcinogen-DNA adducts in the liver of WHV carriers appear to represent one of the mechanisms contributing to the association between chronic hepadnavirus infection and development of primary hepatocellular carcinoma.

4-Nitroquinoline-1-oxide↗

PubMed1995

Inhibition of invasion, gelatinase activity, tumor take and metastasis of malignant cells by N-acetylcysteine.

The thiol N-acetylcysteine (NAC) is currently considered one of the most promising cancer chemopreventive agents by virtue of its multiple and coordinated mechanisms affecting the process of chemical carcinogenesis. Recent studies have shown that an unpaired cysteine residue in the propeptide plays a key role in inactivation of latent metastasis-associated metalloproteinases: the present study was designed to assess whether NAC could also affect tumor take, invasion and metastasis of malignant cells. As assessed by zymographic analysis, NAC completely inhibited the gelatinolytic activity of type-IV collagenases in the cells tested (gelatinases A and B). Moreover, NAC was efficient in inhibiting the chemotactic and invasive activities of tumor cells of human (A2058 melanoma) and murine origin (K1735 and B16-F10 melanoma cells as well as C87 Lewis lung carcinoma cells) in Boyden-chamber assays, which are predictive of the invasive and metastatic properties. Reduced glutathione (GSH) had a similar, although less effective activity. The number of lung metastases decreased sharply when B16-F10 murine melanoma cells, injected i.v. into nude mice, were pre-treated with NAC and resuspended in medium supplemented with 10 mM NAC. In other experiments NAC was given in drinking water, starting 48-72 hr before subcutaneous inoculation of either B16-F10 cells or of their highly metastatic variant B16-BL6, or intramuscular injection of LLC cells. In all experiments NAC treatment decreased the weight of the locally formed primary tumor and produced a dose-related delay in tumor formation. Spontaneous metastasis formation by B16-F10 and B16-BL6 tumors was slightly yet significantly reduced by oral administration of NAC. However, this was not observed for Lewis lung tumors. These data indicate that NAC affects the process of tumor-cell invasion and metastasis, probably due to inhibition of gelatinases by its sulfhydryl group, with the possible contribution of other mechanisms, including the potent antioxidant activity of this thiol.

3T3 Cells↗

PubMed1995

Chemopreventive properties and mechanisms of N-Acetylcysteine. The experimental background.

The thiol N-acetylcysteine (NAC), now under clinical trial for cancer chemoprevention both in Europe (project Euroscan) and in the US (National Cancer Institute), has been shown during the past decade to exert protective effects in a variety of experimental test systems. NAC inhibited spontaneous mutagenicity and that induced by a number of chemical compounds and complex mixtures. Moreover, NAC significantly decreased the incidence of neoplastic and preneoplastic lesions induced by several chemical carcinogens in rodents (mice, rats, hamsters), e.g., in lung, trachea, colon, liver, mammary gland, Zymbal gland, bladder and skin. Our studies provided evidence that multiple mechanisms contribute to NAC antimutagenicity and anticarcinogenicity. They include extracellular mechanisms, such as detoxification of reactive compounds due to the nucleophilic and antioxidant properties of NAC, inhibition of nitrosation products, and enhancement of thiol concentration in intestinal bacteria; trapping and enhanced detoxification of carcinogens in long-lived non-target cells, such as erythrocytes and bronchoalveolar lavage cells; mechanisms working in the cytoplasm of target cells, such as replenishment of GSH stores, modulation of metabolism of mutagens/carcinogens, blocking of electrophiles, and scavenging of reactive oxygen species; and nuclear effects, such as inhibition of DNA adduction by metabolites of carcinogens, inhibition of "spontaneous" mutations, attenuation of carcinogen-induced DNA damage, and protection of nuclear enzymes, such as poly(ADP-ribose) polymerase.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcysteine↗

PubMed1995

Inhibition by N-acetylcysteine of carcinogen-DNA adducts in the tracheal epithelium of rats exposed to cigarette smoke.

The ability of the aminothiol N-acetylcysteine (NAC) to prevent the formation of carcinogen-DNA adducts in tracheal epithelial cells was investigated in Sprague-Dawley rats exposed whole-body to mainstream cigarette smoke for either 40 or 100 consecutive days. 32P-Postlabelling analyses showed the occurrence of DNA adducts (12.49 adducts/10(8) nucleotides) after 40 days of exposure, with a trend to formation of characteristic diagonal radioactive zones. Total adduct levels were not further enhanced after 100 days of exposure to smoke, although significant changes occurred in the amounts of individual adducts. NAC, given by gavage in the 40 day study and in drinking water in the 100 day study, significantly inhibited the formation of smoke-related carcinogen-DNA adducts in the tracheal epithelium, to such an extent that adduct levels were not significantly higher than those detected in sham-exposed control rats. Together with a variety of other molecular, clastogenicity, metabolic, cytological and histopathological end-points investigated in rodents and with the preliminary evidence arising from a study in humans, these results document the considerable efficacy of oral NAC in inhibiting smoke-related carcinogen-DNA adducts.

Acetylcysteine↗

PubMed1995

Bacterial mutagenicity of cigarette smoke and its interaction with ethanol.

The mutagenicities of mainstream cigarette smoke (CS), a cigarette smoke condensate (CSC) and smokers' urines were investigated by using batteries of Salmonella typhimurium and Escherichia coli strains. The S9-mediated mutagenicity of CSC was remarkably enhanced when using nitroreductase- and especially O-acetyltransferase-overproducing derivatives of the classical strains TA98 and TA100, with the following rank of sensitivity: YG1024 > YG1029 > YG1021 > TA98NR > YG1026 > TA98 > TA100 > TA100-DNP6 > TA100NR > TA98-1,8-DNP6. With YG1024, a doubling of spontaneous revertants was observed with as little as 1/110 of the smoke condensate recovered from one cigarette under our experimental conditions. Similarly, the S9-mediated mutagenicity of mainstream CS was considerably increased in YG1024 and YG1029, the O-acetyltransferase-overproducing derivatives of TA98 and TA100, respectively. In the absence of S9 mix, the concentrates of 23 urine specimens from five smokers failed to revert S. typhimurium TA98 and YG1024, and were equitoxic in E. coli WP2 and its repair-deficient counterpart CM871 (uvrA-, recA-, lexA-). In the presence of S9 mix, all specimens were mutagenic, with an average YG1024:TA98 ratio of 6.6:1. These patterns suggest that the bacterial mutagenicity of smoke-associated complex mixtures is mainly due to aromatic amines. The mutagenicities of other typical constituents of CS, i.e. the polycyclic aromatic hydrocarbon benzo[a]pyrene (BP) and the tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), were not appreciably enhanced in the O-acetyltransferase-overproducing strain YG1029, compared to its parental strain TA100. Moreover, BP and NNK induced less than additive mutagenic responses when combined at high doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetyltransferases↗

PubMed1995

Biotransformation of genotoxic agents in marine sponges. Mechanisms and modulation.

Marine sponges do not appear to suffer from neoplastic diseases, in spite of possible high exposures resulting from their nature as sessile bottom filter feeders which pump large volumes of sea water. The assessment of several parameters related to the biotransformation of mutagens/carcinogens showed that the metabolic machinery of sponge medulla cells is mainly oriented towards detoxification, with some differences depending on species (Geodia cydonium or Tethya aurantium). Glutathione (GSH) levels were unexpectedly high in these cells, especially in Geodia, in which the concentration of this tripeptide was more than twice that measured in liver preparations from untreated rats, at least when related to the protein content. The oxidoreductive enzyme activities involved in the glutathione cycle were balanced in such a way as to favour a high GSH: oxidized glutathione (GSSG) ratio. GSH S-transferase activity was conversely rather low, compared to that of rat liver, and the dehydrogenases involved in the hexose monophosphate shunt were high in Tethya but low in Geodia. The metabolism of mutagens was investigated by using the Salmonella typhimurium his- strains TA100, TA98 and YG1024. Sponge S12 fractions failed to activate aflatoxin B1, benzo[a]pyrene and the two heterocyclic amines 3-amino-1-methyl-5H-pyrido[4,3-b]indole and 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoline. Although far less efficiently than untreated rat liver S12 fractions, Geodia and especially Tethya preparations weakly activated the three aromatic amines 2-acetyl-aminofluorene, 2-aminofluorene and 2-aminoanthracene. On the other hand, sponge S12 fractions were remarkably efficient in decreasing the mutagenic potency of the direct-acting mutagens 4-nitroquinoline 1-oxide and sodium dichromate.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Acetylaminofluorene↗

PubMed1995

Cancer biomarkers in human atherosclerotic lesions: detection of DNA adducts.

Since somatic mutations are suspected to contribute to the pathogenesis not only of cancer but also of atherosclerotic plaques, we measured DNA adducts in the smooth muscle layer of atherosclerotic lesions in abdominal aorta specimens taken at surgery from seven patients. DNA adducts were evaluated in three laboratories by means of different molecular dosimetry methods, including: (a) HPLC/fluorescence, which specifically identifies the DNA adducts of the anti-benzo(a)pyrene (BPDE) isomer; (b) two- and three-dimensional synchronous fluorescence spectrophotometries, which detect DNA adducts of BPDE and other reactive metabolites of polycyclic aromatic hydrocarbons; and (c) 32P postlabeling, which reveals the presence of a variety of types of DNA adducts. The HPLC/fluorescence method provided for the first time evidence for the presence of BPDE-DNA specific adducts in three of six specimens tested. Synchronous fluorescence spectrophotometry displayed broad areas of fluorescence in all seven specimens, thereby suggesting the occurrence not only of BDPE-DNA but also of other DNA adducts with similar fluorescence characteristics. All specimens were also positive at 32P postlabeling, which revealed multiple spots detectable following enrichment either with nuclease P1 or butanol, indicative of the presence of different aromatic DNA adducts. Thus, the data obtained by applying typical cancer biomarkers provide further support to the hypothesis that there may be similarities between the carcinogenic and the atherogenic processes, and in particular that genetic alterations caused by DNA-binding agents in the artery wall may be detected in atherosclerotic lesions.

Aged↗

PubMed1995

Cancer biomarkers in human atherosclerotic lesions: no evidence of p53 involvement.

In order to assess similarities between the atherogenic and the carcinogenic processes, we investigated whether the p53 tumor suppressor gene, the most commonly altered gene in human cancer, may be also involved in human atherosclerotic lesions. The medium layers of abdominal aorta fragments taken at surgery from 32 patients were subjected to immunohistochemical analysis, using either monoclonal (Pab 1801) or polyclonal (CM-1) antibodies, and to molecular analysis by the PCR-based denaturing gradient gel electrophoresis approach. The results obtained indicated that p53 mutations are not involved in the pathogenesis of atherosclerotic lesions, and that no accumulation of the wild-type protein occurs in smooth muscle cells of these lesions. A polymorphism characterized by an AT to GC transition at codon 213 (CGA --> CGG) causing no aminoacid substitution (Arg --> Arg) was detected in the 10.5% of the examined patients. Our negative findings do not support the hypothesis that the atherosclerotic plaques may be pathogenetically akin to benign tumors yet they are not in contrast with this theory, since in most cases p53 is involved in advanced stages of the carcinogenesis process.

Aged↗

PubMed1995

[Molecular epidemiology and prevention of bronchopulmonary carcinoma].

Lung cancer represents by far the most important cause of death within neoplastic diseases in developed western countries. Mortality profiles are closely related to tobacco consumption, which is the dominant cause of this disease (85-90% of cases). After several decades of steep escalation, during the past years the mortality curve tended to decline in the Italian population as well as in other populations, e.g., in US white males, thereby highlighting the concept that primary prevention can be successful on a very large scale. Minor risk factors are passive smoke and other indoor pollutions, e.g., by radon or uncontrolled combustion products, air pollution, and occupational exposures. Lung cancer epidemiology is strongly affected by protective factors; in particular, a diet rich in fruit and vegetables halves cancer risks in exposed individuals. The "black box" representing the latency period elapsing between exposure to risk factors and clinical manifestation was recently decoded, due to the discovery of intermediate biomarkers evaluating the internal exposure, the biologically effective dose and functional alterations or early biological damage predictive of the ultimate pathological event. These biomarkers are used for several purposes, including molecular epidemiology studies, clinical intervention trials and attempts at identifying high risk individuals. Primary prevention is based on the control of carcinogenic risk factors either through regulations or health education measures. A complementary strategy is provided by chemoprevention, aimed at favouring the intake of protective factors and at fortifying the host defenses either through public health interventions addressed to the general population or targeted interventions in high risk individuals.

Acetylcysteine↗

PubMed1994

Detection of p53 and histopathological classification of skin tumours induced by halogen lamps in hairless mice.

Skin lesions induced by exposure of three strains of female hairless mice to the light emitted by uncovered halogen quartz lamps were subjected to histopathological analysis. We examined 170 representative specimens out of a total of 597 skin lesions, i.e. 38 out of 74 SKH-1 mice, 110 out of 472 MF-1 mice, and 42 out of 51 C3H mice. The results provided evidence of various types of alterations, including preneoplastic changes, such as epidermal hyperplasia, and benign tumours, such as papillomas, as well as tumours with an increasing degree of malignancy, i.e., keratoacanthoma-like tumours, appendage/basal tumours, actinic keratoses/carcinomas in situ, and squamocellular carcinomas. SKH-1 was the most sensitive strain to the far-ultraviolet wavelengths delivered by halogen lamps, as shown not only by the shortest latency time and the highest multiplicity of skin lesions but also by the highest frequency of malignant tumours. Some areas of atypical melanocyte proliferation were only detected in C3H pigmented mice. Eighty-two of the lesions excised from MF-1 mice were additionally examined for p53 protein by immunohistochemical methods. Formalin-fixed, paraffin-embedded sections and frozen sections were analyzed in parallel by using polyclonal CM-1 antibody and monoclonal PAb240 antibody, respectively. A positive response for p53 was only observed in squamocellular carcinomas, and was related to the size of cancers; in fact, six out of 10 cancers of 10-30 mm in diameter were positive, whereas all 16 cancers of 2-9 mm in diameter were negative. All six positive squamocellular carcinomas were detected by using the CM-1 antibody, which recognizes both wild-type and mutant forms of p53 protein, and five of them were also positive with the PAb 240 antibody, which only recognizes the mutant form. Thus, p53 mutation appears to be a late event in the development of halogen-induced skin tumours in hairless mice, requiring a severe degree of malignancy and an advanced stage of the neoplastic mass growth.

Animals↗

PubMed1994

Potent carcinogenicity of uncovered halogen lamps in hairless mice.

Uncovered halogen quartz lamps, which are potently genotoxic both in prokaryotic and human cells due to the emission of far-UV radiation (UVB and UVC), were assayed for carcinogenicity in three strains of hairless mice (SKH-1, MF-1, and C3H) of both sexes. As assessed in 5 independent experiments, no spontaneous skin tumor was observed, even after more than 2 years, in 49 animals used as unexposed controls or in 29 animals exposed to halogen lamps equipped with a common glass cover. In contrast, almost all of the 185 mice exposed to the light emitted by low-voltage (12 V) and low-power (50 W) tungsten bulbs, equipped with dichroic diffusers, contracted multiple skin tumors of various histological type, both benign and malignant. Tumors were induced over a range of illuminance levels (1,000, 3,333, 5,000, and 10,000 lux) and daily exposure times (1.5, 3, 6, and 12 h). The tumor latency times were quite short and significantly correlated with the daily exposure times, as well as with the square of the distance (46-194 cm) from the illumination source. A carcinogenic effect was even observed when exposure was discontinued well before the appearance of skin lesions. Both in vitro genotoxicity data and animal carcinogenicity data support the view that the light emitted by uncovered halogen lamps, to which an enormous number of individuals are exposed, may pose carcinogenic risks to humans. Without renouncing the benefits of this modern illumination system, UV-blocking devices should be compulsory.

Animals↗