In situ biomonitoring of PAH-contaminated sediments using juvenile coho salmon (Oncorhynchus kisutch)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous marine and freshwater sediment contaminants. Extensive data exist to confirm that PAHs are toxic to aquatic receptors. However, limited information is available regarding the bioavailability and genotoxicity of sediment PAHs to aquatic organisms. This study investigated an integrated biomonitoring approach using chemical analyses and biomarkers to characterize the bioavailability and genotoxicity of a complex PAH mixture in freshwater lake sediments associated with a former manufactured gas plant (MGP). Sediment PAH genotoxicity was assessed by flow cytometry (FCM), DNA adduct (32)P-postlabeling, and erythrocyte micronuclei in juvenile coho salmon (Oncorhynchus kisutch) caged in the water column. Significant PAH-induced genotoxicity was observed with FCM and (32)P-postlabeling, but not with erythrocyte micronuclei. Chromosome damage in peripheral blood and hepatic DNA adducts correlated with sediment, but not water column PAH concentrations. Total hepatic DNA adducts in salmon caged nearest the former MGP facility was 39+/-6.5 (RALx10(9)), while salmon caged in a reference lake had 28+/-2.3 total hepatic DNA adducts per 10(9) nucleotides. These results indicate that in situ biomonitoring using biomarkers and caged fish can be a sensitive indicator of genotoxic PAHs in sediments.     

Exposure to Ethylene Glycol Monomethyl Ether: Clinical and Cytogenetic Findings

Glycol ethers are known reproductive and developmental toxins in laboratory animals, but little is known about their genotoxic effects in humans. In the current article, the authors tested the hypothesis that human in utero exposure to ethylene glycol monomethyl ether (EGME) is associated with the development of specific congenital anomalies and elevated levels of chromosome aberrations. The authors conducted a clinical and cytogenetic evaluation of 41 offspring of 28 females occupationally exposed to EGME for an average duration of 4.6 yr. Six offspring of 5 women who were occupationally exposed to EGME during pregnancy exhibited characteristic dysmorphic features that were not observed in 35 offspring of 23 women who worked in the same facility, but who were not pregnant at the time of exposure. Persistent cytogenetic damage was observed exclusively in all 6 in-utero-exposed offspring, but not in their 12 match non-in-utero-exposed controls. The study characterizes EGME as a human teratogen, as indicated by the prevalence of characteristic dysmorphic features and persistent cytogenetic damage in individuals exposed in utero to this chemical     

Exposure to ethylene glycol monomethyl ether: clinical and cytogenetic findings

Glycol ethers are known reproductive and developmental toxins in laboratory animals, but little is known about their genotoxic effects in humans. In the current article, the authors tested the hypothesis that human in utero exposure to ethylene glycol monomethyl ether (EGME) is associated with the development of specific congenital anomalies and elevated levels of chromosome aberrations. The authors conducted a clinical and cytogenetic evaluation of 41 offspring of 28 females occupationally exposed to EGME for an average duration of 4.6 yr. Six offspring of 5 women who were occupationally exposed to EGME during pregnancy exhibited characteristic dysmorphic features that were not observed in 35 offspring of 23 women who worked in the same facility, but who were not pregnant at the time of exposure. Persistent cytogenetic damage was observed exclusively in all 6 in-utero-exposed offspring, but not in their 12 match non-in-utero-exposed controls. The study characterizes EGME as a human teratogen, as indicated by the prevalence of characteristic dysmorphic features and persistent cytogenetic damage in individuals exposed in utero to this chemical.     

Genetic polymorphisms and chromosome damage.

Genetic polymorphisms that affect xenobiotic metabolism or cellular response to DNA damage can modulate individual sensitivity to genotoxins. Information on the effects of such polymorphisms on the level of chromosome damage may facilitate the identification of risk groups and increase the sensitivity of cytogenetic endpoints as biomarkers of genotoxic exposure and effect. Glutathione S-transferase M1 (GSTM1) is an important detoxification enzyme which, due to a homozygous gene deletion (null genotype), is lacking from about 50% of Caucasians. A higher level of DNA adducts and chromosome damage has been detected in lymphocytes of tobacco smokers and bus drivers who lack the GSTM1 gene. Other polymorphic glutathione S-transferases include GSTM3, GSTP1, and GSTT1. The GSTT1 null genotype (10-20% of Caucasians) has been associated with an increased "baseline" level of sister chromatid exchanges (SCEs) in lymphocytes. N-acetyltransferase 2 (NAT2), metabolizing xenobiotics with primary aromatic amine and hydrazine structures, is another important polymorphic phase II enzyme. Subjects having the NAT2 slow acetylator genotype appear to show an increased baseline frequency of lymphocyte CAs in the absence of identified environmental exposure. Besides human biomonitoring studies, genetic polymorphisms may be important in explaining individual variation in genotoxic response observed in genetic toxicology tests with human cells. Several studies have suggested that blood cultures from GSTT1 null and GSTM1 null individuals have increased in vitro sensitivity to various genotoxins. The best-known example is probably the diepoxybutane sensitivity of GSTT1 null donors. Recently discovered polymorphisms affecting DNA repair may be expected to be of special importance in modulating genotoxic effects; the first available studies have suggested that the exon 10 Arg399Gln polymorphism of XRCC1 gene (X-ray repair cross-complementing group 1) could affect individual genotoxic response. In conclusion, the genetic polymorphism of GSTM1 influences the frequency of chromosome damage in exposed humans, while that of GSTT1 and NAT2 affect the "baseline" level of such damage. Both GSTM1 and GSTT1 genotypes may shape the in vitro genotoxic response of human lymphocytes. The significance of DNA repair polymorphisms is presently unclear.     

心肌损伤标记物肌钙蛋白T的干化学分析及临床中的应用

对怀疑有心肌损伤的病人如何尽快确诊，以便快速有效地治疗？CCU的医护人员如何简便及时有效地了解病人的情况：医学研究发现肌钙蛋白T，可以做为心肌损伤的标记物，有其绝对特异性和灵活性；本文论述了肌钙蛋白T折性质及其干化学分析法的检测原理和仪器。     

Cytogenetic observations in human peripheral blood leukocytes following in vitro exposure to THz radiation: a pilot study

Emerging technologies are considering the possible use of Terahertz radiation in different fields ranging from telecommunications to biology and biomedicine. The study of the potential effects of Terahertz radiation on biological systems is therefore an important issue in order to safely develop a variety of applications. This paper describes a pilot study devoted to determine if Terahertz radiation could induce genotoxic effects in human peripheral blood leukocytes. For this purpose, human whole blood samples from healthy donors were exposed for 20 min to Terahertz radiation. Since, to our knowledge, this is the first study devoted to the evaluation of possible genotoxic effects of such radiation, different electromagnetic conditions were considered. In particular, the frequencies of 120 and 130 GHz were chosen: the first one was tested at a specific absorption rate (SAR) of 0.4 mW g-1, while the second one was tested at SAR levels of 0.24, 1.4, and 2 mW g-1. Chromosomal damage was evaluated by means of the cytokinesis block micronucleus technique, which also gives information on cell cycle kinetics. Moreover, human whole blood samples exposed to 130 GHz at SAR levels of 1.4 and 2 mW g-1 were also tested for primary DNA damage by applying the alkaline comet assay immediately after exposure. The results obtained indicate that THz exposure, in the explored electromagnetic conditions, is not able to induce either genotoxicity or alteration of cell cycle kinetics in human blood cells from healthy subjects.     

Genotoxicity analysis of two halonitromethanes, a novel group of disinfection by-products (DBPs), in human cells treated in vitro

Halonitromethanes (HNMs) constitute an emerging class of disinfection by-products (DBPs) produced when chlorine and/or ozone are used for water treatment. The HNMs are structurally similar to halomethanes, but have a nitro-group in place of hydrogen bonded to the central carbon atom. Since little information exists on the genotoxic potential of HNMs, a study has been carried out with two HNM compounds, namely trichloronitromethane (TCNM) and bromonitromethane (BNM) by using human cells. Primary damage induction has been measured with the Comet assay, which is used to determine both the repair kinetics of the induced damage and the proportion of induced oxidative damage. In addition, the fixed DNA damage has been evaluated by using the micronucleus (MN) assay. The results obtained indicate that both compounds are genotoxic, inducing high levels of DNA breaks in the Comet assay, and that this DNA damage repairs well over time. In addition, oxidized bases constitute a high proportion of DNA-induced damage (50-75%). Contrarily, no positive effects were observed in the frequency of micronucleus, which measures both clastogenic and aneugenic effects, neither using TK6 cells nor peripheral blood lymphocytes. This lack of fixed genetic damage would minimize the potential mutagenic risk associated with HNMs exposure.     

The cytogenetic assay as a measure of genetic instability induced by genotoxic agents

Human genetic integrity is compromised by the intense industrial activity, which emphasizes the importance to determine an "acceptable" genetic damage level and to carry out routine genotoxicity assays in the populations at risk. Micronuclei are cytoplasmatic bodies of nuclear origin which correspond to genetic material that is not correctly incorporated in the daughter cells in the cellular division; they reflect the existence of chromosomal aberrations and are originated by chromosomal breaks, replication errors followed by cellular division of the DNA and/or exposure to genotoxic agents. There are several factors able to modify the number of micronuclei present in a given cell, among them are age, gender, vitamins, medical treatments, daily exposure to genotoxic agents, etc. The cytogenetic assay for the detection of micronuclei (CBMN: cytokinesis-block micronucleus) is based on the use of a chemical agent, cytochalasin-B, which is able to block cytocinesis but allowing the nuclear division, therefore yielding binucleated and monodivided cells. The micronuclei scoring is performed on 1000 binucleated cells and the starting sample may vary, although most studies are performed on peripheral blood lymphocytes. The micronuclei assay is considered a practical, universally validated and technically feasible protocol which is useful to evaluate the genetic instability induced by genotoxic agents.     

An in vitro blood culture for evaluating the genotoxicity of titanium dioxide: the responses of antioxidant enzymes

Titanium dioxide (TiO2) is extensively used in many industrial areas, including cosmetics, pharmaceutical, paint and paper production. Although the uses of TiO2 have become so widespread, there is limited information concerning its toxicity on humans. However, the genotoxicity of TiO2 remains to be controversial. The possible genotoxic effects of TiO2 have been evaluated in human whole blood cultures (WBCs) related to oxidative status. The blood was processed to examine the following oxidative stress markers: glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase. In addition, the frequencies of sister-chromatid exchanges (SCEs) and micronuclei (MN) were scored as genetic endpoints. Different concentrations of TiO2 (1, 2, 3, 5, 7.5 and 10 microM) were tested. From the results, it appeared that TiO2 was able to induce genotoxic effects, as observed by the increases found in SCE and MN frequencies in TiO2-treated cultures. Present results also show that treatments with TiO2 promoted oxidative stress in human WBC with an increase in concentrations. In conclusion, our data indicate that TiO2 can enhance oxidative stress-mediated DNA damage in vitro.     

Urine osmolality in a population study of hypertension

High blood pressure occurs in the majority of cases of chronic kidney disease, while renal damage is common in the more advanced cases of essential hypertension. In a population study of hypertensive disease, therefore, it is important to provide information on renal function. Determination of plasma creatinine concentration fails as a screening test since a normal or nearly normal plasma creatinine value does not necessarily exclude severe reduction of filtration ability. The specific gravity is the most widely used index of the concentration power of the kidneys. The disadvantage of this method is that considerable variation of specific gravity may occur in urines of like osmolality. In a sample of 855 50-year-old men selected at random, the authors of this article have correlated the lowered osmolality of an early morning urine specimen with hypertension. Renal involvement and/or altered rhythm of water and solute excretion can be the cause of lowered osmolality. The determination of the concentration of early morning urine samples has a legitimate place in population studies of cardiovascular diseases. A method of determining urine osmolality is described that requires relatively simple equipment and gives results with a small standard error.     

Occupational chemical risk: elements for a diagnostic in Spain

BACKGROUND: Lack of information and accurate knowledge about the properties of chemicals and the exposure derived from its use; hinder health and safety measures to protect exposed workers. The aim of this study is to identify the elements that will help us draw a balance of chemical hazards in Spain and register the most dangerous chemicals at the workplace (by sector or field of activity). METHODS: Study of secondary sources, identification of risk perception by workers' representatives and study of the approach on chemical risk in risk assessments. The last step is to set up a Chemical Exposure Database arranged by industrial sectors. RESULTS: Great volumes of production and consumption of chemicals, generalization of exposure, but insufficient data on specific use; little information is provided on specific dangerous factors of commonly used chemicals; chemicals are barely identified in risk assessments. High levels of exposure in industrial sectors; damage is not adequately registered; there are difficulties in risk perception. Set-up of a preliminary database on exposure by sector of activity. CONCLUSIONS: Data is collected; information sources and procedures, which allow a forecast of chemical risk, are identified. A database on exposure by sector of activity is developed (to be checked and enhanced as new evidence is found).     

Assessment of DNA damage in nuclear medicine personnel--comparative study with the alkaline comet assay and the chromosome aberration test

Despite much research over the last few decades, there still remains considerable uncertainty as to the genetic impact of ionizing radiation on human populations, particularly at low levels. The aim of the present study was to provide data on the genetic hazards due to occupational exposure of low doses of ionizing radiation in nuclear medicine departments. The assessment of primary DNA damage in peripheral blood leukocytes of medical staff was performed using the alkaline comet assay and the data obtained were compared with the results of conventional cytogenetic biodosimetry using the chromosome aberration (CA) test. Altogether 120 subjects (60 exposed and 60 controls) participated in the study. Statistically significant increases in primary DNA damage and increased frequencies of CAs compared to controls were observed. Within the exposed population, significant inter-individual differences in DNA damage were found, indicating differences in genome sensitivity. Age and gender were not confounding factors, while smoking enhanced the levels of primary DNA damage only in control subjects, as revealed by both biomarkers studied. The present study suggests that genotoxic damage results from exposure to chronic low doses of ionizing radiation in nuclear medicine departments. Therefore, the exposed medical personnel should carefully comply with the radiation protection procedures and should minimize radiation exposure where possible to avoid potential genotoxic effects. The results obtained in this study point to the significance of biological indicators providing information on the actual risk to the radiation exposed individuals. According to our results, the alkaline comet assay and CA test are sensitive biomarkers that can be used as additional complements to physical dosimetry for assessing exposure to radiation in nuclear medicine personnel.     

Integrating enzymatic responses to organic chemical exposure with total oxyradical absorbing capacity and DNA damage in the European eel Anguilla anguilla

In this work, susceptibility to oxidative stress was analyzed under laboratory conditions in the European eel Anguilla anguilla. Eels were treated with increasing concentrations of benchmark environmental pollutants, namely, benzo[a]pyrene ([BaP], at 0, 0.1, 1, 10, and 50 mg/kg), beta-naphthoflavone ([BNF], at 0, 0.1, 1, 10, and 50 mg/kg), Arochlor 1254 (at 0, 0.1, 1, 10, and 50 mg/kg), and 2,3,7,8-tetrachlorodibenzo p-dioxin ([TCDD], at 0, 0.01, 0.1, 1, and 2 microg/kg). The integral relationships were analyzed between induction of ethoxyresorufin O-deethylase (EROD) activity, its involvement in perturbing oxyradical metabolism, and the role of cytochrome P450 and/or oxidative stress in mediating genotoxic effects. To reveal whether the oxidative status in exposed organisms was altered as a result of chemical exposure, measurements of the main endogenous antioxidant defenses were integrated with the measurement of total oxyradical scavenging capacity (TOSC) toward peroxyl radicals and hydroxyl radicals (*OH). This approach permits discriminating the resistance of a tissue toward different forms of oxyradicals, thereby indicating a differential role for specific reactive oxygen species (ROS) in perturbing the balance between prooxidant and antioxidant mechanisms. All the analyzed chemicals promoted EROD induction (reflective of CYP1A) and altered either the levels or the activities of the antioxidants studied, which might be anticipated to exert alterations in oxyradical metabolism. Analysis of TOSC suggested the prevalence of metabolic oxidative pathways leading to the more reactive *OH on exposure to the chemicals studied. Of these chemicals, enhanced EROD activity correlated with genotoxic damage only in the cases of the nonhalogenated hydrocarbons BaP and BNF. The highest degree of genotoxic damage was consistently observed in organisms in which the capacity to absorb or scavenge OH was lowest. These data suggest a general relationship between oxidative stress and loss of DNA integrity in juvenile eels exposed to the chemicals studied herein.     

Differential induction of micronuclei in peripheral lymphocytes and exfoliated urothelial cells of workers exposed to 4,4'-methylenebis-(2-chloroaniline) (MOCA) and bitumen fumes

Cytogenetic end-points used to estimate risk of genotoxic events in workers include the measurement of micronuclei (MN) in exfoliated cells, lymphocytes, and other tissues. Micronuclei are chromatin-containing bodies outside the cell nucleus resulting from contaminant-induced DNA damage. A review of 71 reports of human genotoxic responses to chemical or physical agents published between 1999 and 2001 revealed that 14% of such studies measured genotoxicity endpoints in specific target tissues relevant to the site of disease for the agent examined; 18% used endpoints in surrogate or non-target tissues but considered the relations between endpoints in surrogate and disease target tissues, and 68% measured genotoxicity endpoints in accessible tissues without reference to specific targets for disease. Methylenebis-(2-chloroaniline) (MOCA), used in polyurethane manufacture, is a suspected bladder carcinogen. Bitumen, used in road surfacing, contains skin and lung carcinogens. In this study, we aimed to compare genotoxicity in urothelial cells and in lymphocytes of workers exposed to these materials. Twelve men employed in polyurethane manufacture, twelve bitumen road layers, and eighteen hospital stores personnel (controls) were recruited and all provided blood and urine samples on the same day. Blood cultures were prepared using a cytochalasin B-block method. Exfoliated urothelial cells were collected from urine and stained for light microscopy. The number of MN in urothelial cells was higher in MOCA-exposed (14.27 +/- 0.56 MN/1000, 9.69 +/- 0.32 MN cells/1000) than in bitumen exposed workers (11.99 +/- 0.65 MN/1000, 8.66 +/- 0.46 MN cells/1000) or in control subjects (6.88 +/- 0.18 MN/1000, 5.17 +/- 0.11 MN cells/1000). Conversely, in lymphocytes, MN were higher in bitumen-exposed (16.24 +/- 0.63 MN/1000, 10.65 +/- 0.24 MN cells/1000) than in MOCA-exposed workers (13.25 +/- 0.48 MN/1000, 8.54 +/- 0.14 MN cells/1000) or in control subjects (9.24 +/- 0.29 MN/ 1000, 5.93 +/- 0.13 MN cells/1000). The results of this study suggest that genotoxins can cause different rates of micronuclei formation in different tissues. Thus, the sensitivity and relevance to cancer risk may be greater if the tissues selected for genotoxicity studies reflect the target tissue for the chemicals concerned.     

No increased DNA damage in peripheral lymphocytes of sewage workers as evaluated by alkaline single cell gel electrophoresis.

OBJECTIVES: To study whether sewage workers are exposed to genotoxic substances. An increased risk of cancers among sewage workers has been noted. If this increased risk is due to an exposure to genotoxic agents, primarily DNA damage could be used as a biological marker of exposure. METHODS: In a cross sectional study, DNA damage in peripheral lymphocytes from 35 sewage workers and 30 controls was compared with alkaline single cell gel electrophoresis, a technique for detecting single strand breaks and alkali labile sites in DNA. The controls were selected from among municipal workers matched for age and smoking habit. Information about occupational exposures and possible confounders was collected by means of a questionnaire. RESULTS: No increase in DNA damage was found among the sewage workers when compared with the unexposed controls. CONCLUSIONS: The failure to detect increased damage to DNA in peripheral lymphocytes by alkaline single cell gel electrophoresis suggests that the sewage workers studied here were not exposed to genotoxic agents to a greater extent than other municipal workers. It may be, however, that the lymphocyte is not the appropriate target cell to study, or that sewage workers are exposed to carcinogens which do not damage the genetic material.     

The application of the cytokinesis-block micronucleus assay on peripheral blood lymphocytes for the assessment of genome damage in long-term residents of areas with high radon concentration

Estimating the effects of small doses of ionising radiation on DNA is one of the most important problems in modern biology. Different cytogenetic methods exist to analyse DNA damage; the cytokinesis-block micronucleus assay (CBMN) for human peripheral blood lymphocytes is a simple, cheap and informative cytogenetic method that can be used to detect genotoxic-related markers. With respect to previous studies on radiation-induced genotoxicity, children are a poorly studied group, as evidenced by the few publications in this area. In this study, we assessed radon genotoxic effects by counting micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in the lymphocytes of children who are long-term residents from areas with high radon concentrations. In the exposed group, radon was found to cause significant cytogenetic alterations. We propose that this method can be employed for biomonitoring to screen for a variety of measures.     

The importance of lymphocyte micronucleus test for the detection of genotoxic events

DNA lesion induced by xenobiotics is implemented either through direct interaction of the chemical with DNA through covalent binding or intercalation, or indirectly, through interference with the processes of DNA replication and repair, interaction with proteins, nuclease release from lysosomes etc. The present study emphasizes that the assessment of genotoxic risk arising from xenogenous substances demands the development of sensitive, direct and more exact genotoxic testing methods. One of them is micronucleus assay. It is a simple and quick test for investigating of cytogenic damage with the advantage that exposure to both clastogens and aneugens may be detected.     

Flow cytometry for monitoring contaminant exposure in black-crowned night-herons

The flow cytometry method (FCM) was employed to determine cellular DNA content of black-crowned night-heron (Nycticorax nycticorax) embryos and 10-day-old chicks collected at sites differing in types of chemical contamination. The coefficient of variation of DNA content (CV) in blood collected from embryos suggested cytogenetic damage at a site in Louisiana known to be contaminated with petroleum. Blood CV from chicks suggested genetic damage at a site in Texas also known to be contaminated with petroleum. Spleen CVs in chicks were significantly lower than respective means from the reference site. The CVs of chick blood and liver and spleen negatively correlated, suggesting recovery of spleen and liver cells after exposure to a clastogenic compound. Thus, the lower CVs may also have been indicative of genetic damage. Based on the findings of this study, FCM is a potential indicator of certain environmental contaminants in black-crowned night-herons.     

The genotoxic potentials of some atypical antipsychotic drugs on human lymphocytes

Olanzapine (OLZ), risperidone (RPD) and quetiapine (QTP) are atypical antipsychotic drugs and are commonly used for the treatments of schizophrenia and bipolar disorders. However, recent reports indicated that these drugs could exhibit toxic effects on nervous and cardiovascular systems. To our best knowledge, there are scarce data considering the genotoxic damage potentials of OLZ, RPD and QTP on human lymphocyte culture system. Therefore, in this study, the genotoxic potentials of OLZ, RPD and QTP (0-400 mg/L) have been evaluated in human whole blood cultures (WBCs; n = 4). The single cell gel electrophoresis (SCGE) and micronucleus (MN) assays were applied to estimate the DNA damage. The results of the present study indicated that the tested antipsychotic drug did not induce genotoxicity. In fact, the mean values of the total scores of cells showing DNA damage (for SCGE assay) and MN/1000 cell were not found significantly different from the control values (p > 0.05). However, the application of the highest drug concentrations (250 mg/L and above) caused the sterility in lymphocyte cultures. It is concluded that the tested three different atypical antipsychotic drugs can be used safely, but it is necessary to consider the cytotoxic effects that are likely to appear depending on the doses exposed.