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Sixth International Conference on Environmental Mutagens in Human Populations
- Conference date: 26-29 Mar 2012
- Location: Qatar National Convention Center, Doha, Qatar
- Volume number: 2012
- Published: 01 March 2012
1 - 50 of 107 results
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Environmental Carcinogens: Exposure and Impacts on Children’s Health
More LessAbstractEnvironmental factors play a major role in determining the health and well-being of children who comprise over one third of the world’s population. Arsenic and carcinogenic compounds in air pollution are examples that illustrate how exposure to these compounds can potentially impact children’s health. Prenatal arsenic exposure in the human population resulted in alarming gene expression changes in newborns. Class prediction algorithms identified gene expression signatures that predict arsenic exposure in a test population with about 80 percent accuracy. A highly predictive potential biomarker gene set composed of just 11 genes was identified. These genes are promising as genetic biomarkers for prenatal arsenic exposure. There is a robust prenatal response that correlates with arsenic-exposure levels that could modulate numerous biological pathways including apoptosis, cell signaling, inflammatory response, and other stress responses, and ultimately affect health status. The health impact of exposure to environmental carcinogens in air pollution during childhood was also examined. Personal monitoring of exposure and urinary metabolite excretion showed that city school children were exposed to benzene, 1,3-butadiene and PAHs at levels significantly higher than rural children, which was approximately two-fold for benzene, four-fold for 1,3-butadiene and four-fold for PAHs. The early biological effects from exposure to carcinogens were assessed from DNA damage measured as 8-OHdG and DNA strand breaks and DNA repair capacity. 8-OHdG in leukocyte DNA which was 2.5-fold higher in city school children compared with the rural school children was statistically significantly correlated with benzene exposure level. The levels of DNA strand breaks in peripheral blood samples from the city children were 1.5-fold higher than those in the rural children. Chromosome damage measured by the challenge assay was 1.7-fold higher in city children, indicating a reduction in DNA repair capacity in these children. Taken together, significantly higher levels of DNA damage believed to be the first step in development of cancer, coupled with a decreased DNA repair capacity, indicate that these children are at a higher risk of developing cancer later in life.
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Pollutions And Health: New Challenges, New Methods
By William DabAbstractFor a while, environment could be defined as "everything except genetic". The recent scientific progress show on the contrary that most of the health impacts of environmental pollutions are mediated through genetic and epigenetic mechanisms. It is now impossible to draw an impervious barrier between these two compartments. Environment and genetic, more particularly mutagenesis, are closely linked and this creates a new form of complexity. What is in stake is the definition of a new paradigm to understand the interactions between pollutants exposures and the onset of human diseases. The new paradigm has to encompass the four preceding ones that have guided the development of scientific research in the field of environmental health. The first one was the time of 'poisons' when Pasteur, Koch and the founders of biochemistry and physiology were thinking in terms of "one pollutants for each disease". The second one was of experimental nature with the development of modern toxicology using animal, tissue or cellular models. Then the epidemiology applied to the observational study of chronic diseases in populations emerged in the 50’s. This was the beginning of the understanding of the multifactorial nature of the determinants of many diseases. Thirty years ago, the US National Academy of Sciences promoted the quantitative risk assessment paradigm. Toxicological and epidemiological knowledge could be synthesized through four formal steps: hazard identification, dose-response relationship analysis, human exposure measurement and finally risk characterization. In this presentation, we will show that for each of these steps, recent advances in research challenge the way to assess the health impact of environmental pollutions. Using examples like bisphenol A, chemical-induced obesity, chlordecone and nanoparticles, we will discuss the desirable characteristics of the fifth paradigm that must integrate many disciplines from mathematics to social sciences.
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Traffic Related Pollutants And Their Effects On Allergic Respiratory Diseases
More LessAbstractThe prevalence and incidence of allergic respiratory diseases have increased in Europe during the last decades, as in most industrialized countries in other parts of the world. Persistent exposure to traffic related air pollution and especially particulate matter from motor vehicles has often been discussed as one of the factors responsible for this increase. It has been recently suggested by many epidemiological studies that traffic related air pollution may increase allergic symptoms and illnesses like asthma and allergic rhinitis, although for allergic sensitisation less consistent results have been found. This view seems to be supported by recent human and animal laboratory-based studies which have shown that particulate pollutants, and in particular diesel exhaust particles, can enhance allergic inflammation and induce the development of allergic immune responses. Indeed, recent in-vivo and in-vitro studies strongly suggest that diesel exhaust particles (DEP) induce pro-inflammatory products by activating their transcription. If pollutants are to be controlled in the urban environment in a cost-effective manner, it is important that the molecular targets of DEP-induced responses be elucidated. In particular, bronchial epithelial cells are the key regulators of airway inflammation, and therefore it is crucial to clarify the cellular and molecular mechanisms that are activated by DEP in these cells. Based on the available experimental and epidemiological studies, the World Health Organisation concluded cautiously that traffic related air pollution may increase the risk of allergy development and may exacerbate symptoms in particular in susceptible subgroups, although there are still many open questions.
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Incomplete Combustion: One of the World’s Biggest Killers
More LessAbstractA growing scientific evidence base shows that exposure to the products of poor combustion, particularly small particles, is responsible for as many as 12 million premature deaths in the world annually. Most well known is the impact of people putting burning material into their mouths—incomplete combustion of tobacco—which is responsible for about half this total. Only relatively recently, however, has the full impact of other sources of incomplete combustion become documented. Based on large international reviews of the evidence coming out this year, it is estimated that outdoor air pollution, primarily combustion-related particles, is responsible for nearly 3 million premature deaths around the world. Although people have traditionally thought of outdoor pollution as an urban phenomenon, recent studies using satellites as well as ground-level monitoring show that rural outdoor air pollution is also a serious problem in many poor countries, including much of Asia. It is also now understood that the smoke from biomass and coal use for cooking in poor countries is responsible for an even greater health burden than that from general outdoor pollution. This household air pollution directly affects 40 percent of the world population. Moving to clean combustion or non-combustion energy sources could therefore have immense health benefits globally.
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Laser Scanning Cytometry for Automation of the Micronucleus AssayIncomplete Combustion: One of the World’s Biggest Killers
More LessAbstractLaser scanning cytometry (LSC) provides a novel approach for automated scoring of micronuclei (MN) in different types of mammalian cells, serving as a biomarker of genotoxicity and mutagenicity. In this presentation I shall discuss the advances to date in measuring MN in cell lines, buccal cells and erythrocytes, describe the advantages and outline potential challenges of this distinctive approach of analysis of nuclear anomalies. The use of multiple laser wavelengths in LSC and the high dynamic range of fluorescence and absorption detection allow simultaneous measurement of multiple cellular and nuclear features such as cytoplasmic area, nuclear area, DNA content and density of nuclei and MN, protein content and density of cytoplasm as well as other features using molecular probes. This high content analysis approach allows the cells of interest to be identified (eg binucleated cells in cytokinesis-blocked cultures) and MN scored specifically in them. MN assays in cell lines (eg the CHO cell MN assay) using LSC are increasingly used in routine toxicology screening. More high-content MN assays and the expansion of MN analysis by LSC to other models (exfoliated cells, dermal cell models, etc) hold great promise for robust and exciting developments in MN assay automation as a high-content high-throughput analysis procedure
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Statistical Issues for Instrument Validation and Inter-laboratory Comparison of Automated Systems
More LessAbstractStatistical treatment of data for human biomonitoring has greatly improved within the last decade, and the most advanced techniques have been translated from the analysis of classic epidemiologic studies to molecular epidemiology. The use of more sophisticated techniques has improved the precision of estimates in human population studies, increasing the reliability of study results. In parallel, the increased popularity of pooled analyses, created the opportunity for a deeper insight into the sources of variability. Large collaborative studies published over the last few decades have revealed that the inter-laboratory and especially the inter-scorer variation are the most important source of variability, setting this heterogeneity as a priority field to address. The recent development of automated systems for chromosome damage scoring is going to dramatically change the level of reliability of these biomarkers. Before introducing these methods, robust standardization studies have to be started, aimed at comparing automated systems in different setting and the overlapping between different company systems. During the presentation we will discuss the list of priorities for systems standardization and the most suitable study design and the statistical analyses to be implemented for addressing these priorities.
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The MetaSystems Metafer System – Applications in Biomonitoring Studies and Measurement of Baseline Frequencies in Human Populations
More LessAbstractThe measurement of micronuclei (MN) in human peripheral blood lymphocytes is a frequently used method to assess chromosomal damage. The development and validation of the MetaSystems Metafer MNScore system for automated image analysis of MN in cytokinesis-blocked binucleated cells (BNC) offer alternative approaches beside traditional visual analysis. The application of this method was successful in research related to mutagen sensitivity phenotype in cancer risk, radiation biodosimetry and biomonitoring studies of air pollution. In biomonitoring studies, the results from a set of 885 subjects investigated by automated image analysis of MN were published between 2009 and 2011 by our laboratory. This dataset includes the subjects ranging from newborns to adults aged 65 years, as well as males and females and smokers and non-smokers. In these studies we analyzed 1,000-6,500 BNC per subjects in DAPI stained slides. The results for the effects of age, gender and smoking obtained from this set are very similar to the data obtained by visual scoring in The International Collaborative Project on Micronucleus Frequency in Human Populations. We can recommend the automated image analysis of MN using the Metafer Score system as a reliable tool for the assessment of chromosomal damage, which allows the analysis of large numbers of binucleated cells, with the additional advantage of limited subjectivity and a lack of scoring bias, and which are so critical for visual scoring.
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Automated Image Analysis of the Human Micronucleus Cytome Assay for High Throughput Biomonitoring Studies: IMSTAR system
More LessAbstractAnalysis of micronuclei (MN) is widely used for human biomonitoring or in vitro/in vivo genotoxicity testing, and provides a sensitive and relatively easy method to assess genetic damage (Kirsch-Volders et al, 2011). The fact that baseline MN frequencies in cytokinesis-blocked (CB) lymphocytes have been shown to be a predictive biomarker for cancer risk strengthens the importance of the CBMN assay as a reliable method for human biomonitoring of early genetic effects. We showed (Kirsch-Volders and Fenech, 2001) that scoring MN frequencies in binucleated and mononucleated cells enhances the predictive capacity of the assay. However, automation of MN analysis is needed for quicker, more reliable detection while minimizing subjective judgment and scoring, and to allow multi-center cohort analysis for biomonitoring studies. Within the framework of NewGeneris, an EU project, we developed an automated image analysis system for scoring MN in human lymphocytes in collaboration with IMSTAR. The IMSTAR system is based on specific algorithms starting from the cell as a detection unit. The whole detection and scoring process are separated into two distinct steps: in the first step, the cells and nuclei are detected; then, in the second step, the MN are searched for in the detected cells. The fact that our designed software protocol started from the cell as a detection unit, and hence the identification of mono-, bi- and polynucleated cells, and MN in these different sub-populations of cells, allows the assessment of cell proliferation through nuclearity index, which is important for an efficient assessment of mitogen response and cytostasis in human biomonitoring as these are indicative of immune function and cytotoxicity (Decordier et al, 2011). Additional requirements that should be fulfilled for development of an automated MN analysis system include: a) The system should be applicable to the CBMN methodology and accurately distinguish mono, bi- and polynucleated cells; b) Well defined scoring criteria for cell type and MN (eg, Fenech et al, 2003); c) Experienced cytologists to score MN according to the HUMN criteria; d) A standardized slide preparation protocol to obtain uniformity in cell size, cell density, and reproducibility (Decordier et al, 2009); e) Validation of the automated versus manual scoring (Decordier et al, 2009, 2011). This methodology was successfully applied to study different mother-child cohorts within the EU-project NewGeneris (Vande Loock et al, 2011). Funded by the EU Integrated Project NewGeneris, (Contract No FOOD-CT-2005-016320). NewGeneris is the acronym of ‘Newborns and Genotoxic Exposure Risks’ and ECNIS stands for ‘Environmental Cancer Risk, Nutrition and Individual Susceptibility’ (FOOD-CT-2005-513943)
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Genetic Toxicology Research in Developing Countries: Challenges and Possibilities—Egypt as an Example
By Wagida AnwarAbstractEgypt, as many other developing countries, has several environmental exposure problems. There are exposures to chemical genotoxicants and to lifestyle factors that have been linked to increased risk for cancer. Infections can be associated with cancer development when the environmental factors interact with the infection and lead to the enhancement of the carcinogenic process. Currently, there is a growing interest to genetic toxicology research, the use of different biomarkers and genetic susceptibility testing, which can contribute effectively to risk assessment. Developing countries need to co-operate with developed countries to protect human health from disease determined or influenced by factors in the environment. The national and international research policies should highlight the need to mobilize resources for human resource development, networking, improving research culture, information sharing and pragmatic use of research findings. The exchange of experience and training is the most vital issue in developing new cadres of people with skills in health research, information and communication, needed to address the challenges facing the development of genetic toxicology research and prevention programs. Organizing international meetings and training courses may enforce this field of research and help to develop co-operative research projects which deal with different exposure conditions.
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Adverse Environmental and Health Effects from Electronics Recycling in China
By Xia HuoAbstractBackground and Objective: Electronic waste (e-waste) is an emerging environmental health issue because of its fast accumulation as well as inadequate development in recycling technology. Guiyu, a town in south China, is one of the biggest e-waste recycling centers in the world. E-waste is disassembled and recycled by locals with crude and uncontrolled methods that produce extensive environmental pollutants. The objective of this study is to provide evidence for association between risk to human health and exposure to this e-waste recycling. Methods: Heavy metals of blood were determined by graphite furnace atomic absorption spectrometry. Polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs) and Polychlorinated biphenyls (PCBs) of blood were determined by gas chromatography/mass spectrometry in the electron capture negative ionization mode. Questionnaires were used and involved examination and experiments were conducted. All data were analyzed statistically. Results: Guiyu children and/or neonates had significantly elevated blood lead (Pb), cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), PBDEs, PAHs and PCB, and with impairment of neurobehavioral development, temperament alterations, lower forced volume vital capacity (FVC), male neonatal AGD (Anogenital Distance) increment, damage of lymphocyte DNA and changes of antioxidant enzymes activities. Guiyu neonates showed much higher rates of adverse birth outcomes such as fetal death, low birth weight and preterm delivery. Conclusion: Our studies suggest that environmental pollution by improper e-waste process has adversely affected local health, and especially affected children and infant health and development. This kind of exposure to e-waste chemicals may cause long-term adverse outcomes for health.
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Molecular Genetic Studies of Radiation-exposed Human Population of the Semipalatinsk Nuclear Test Site in Kazakhstan
More LessAbstractIn the Republic of Kazakhstan, during the period between 1949 and 1989, nuclear weapon testing carried out by the former Soviet Union at the Semipalatinsk Nuclear Test Site (STS) resulted in local fallout affecting the residents of East Kazakhstan. The STS has been the site for more than 450 nuclear tests, including 26 on the ground and 87 atmospheric explosions. It is estimated that there are about 500,000 A-bomb victims around STS. These individuals have been repeatedly exposed to ionizing radiation from the radioactive cloud or environmental fallout for many years. To gain insight into the health concerns of the exposed population, we carried out a molecular genetic study to estimate health risk in a three-generation (Р0,F1,F2) sample from the STS population. We previously reported a 1.8-fold increase in minisatellite mutation (MM) rate in the exposed Р0 generation. Our results indicated that the radiation exposure from the nuclear tests had caused elevated MM rates and germ-line mutations. Although the underlying mechanisms for the instability are not known, the MM are considered as originating from genomic instability induced by radiation exposure. We further investigated the influence of polymorphisms in genes on the expression of MM in three generations of the exposed and control populations and the relationship between radiation exposure and MM expression. We chose the analyses of three polymorphic DNA-repair genes (XRCC1, XRCC2 and XRCC3) and two xenobiotic detoxification genes (GSTT1 and GSTM1). It was shown that among the exposed and in comparison with the wild-type gene, the functionally active XRCC1 Arg194Trp was significantly associated with low MM and over-represented in the exposed compared with the control populations. In a similar analysis, the functionally deficient XRCC1 Arg399Glu and XRCC3 Trp241Met were associated with increased and significantly reduced MM, respectively, but these variant genes were underrepresented in the exposed population. Both GSTT1 and GSTM1 nulls were significantly associated with increased MM. In summary, our results showed the role of susceptibility genes on the expression of MM in three generations of radiation-exposed population and the complexity of gene and environment interactions on health risk assessment.
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Role of Endocrine Disrupting Chemicals on the Occurrence of Female Reproductive Tumors in Tehran Sepideh Arbabi Bidgoli
More LessAbstractAryl Hydrocarbon Receptor (AhR) ligands are ubiquitous endocrine disrupting chemicals (EDCs) used in consumer products, diet, air and water. These chemicals are reproductive toxicants which promote tumor formation in some reproductive model systems but human data are limited. The occurrence of reproductive tumors was exponentially grown during the last three decades especially in Tehran but the underlying risk factors remained unclear. A cross-sectional case control study was conducted on the tissue and serological levels of AhR, sex steroid receptors and 120 lifestyle in relation to exposure to EDCs in 500 premenopausal women with history of endometriosis, uterine leiomyoma, breast fibroadenoma and breast cancer from 2007–2011.Differential levels of AhR, ER, PR ,AR, were determined in mentioned female reproductive tumors . Their association with lifestyle factors was also examined in different female tumors. Logistic regression was used to estimate odds ratios (ORs) and 95 percent confidence intervals (CIs), adjusting for potential risk factors. AhR overexpression in epithelial cells of premenopausal patients emphasized the susceptibility of these cells to environmental induced reproductive disorders. Living near PAHs producing factories, consumption of animal fat, abnormal weight gain, long term (>5yrs) OCP consumption, smoking, severe stress, hormonal deregulations and exposure to other sources of xenoestrogens were correlated with an increased risk of reproductive tumors which were correlated with elevated tissue levels of AhR. Adiposity and abnormal weight gain after 18 years were considered as two major background factors, which may contribute to the levels of endogenous estrogens. It seems that AhR overexpression is affected by exposure to xenoestrogens and by adiposity. Long term exposure to EDCs can increase the tissue levels of AhR and deregulate the expression pattern of sex steroid receptors and other genes in target tissues.
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Specific Environmental Health Concerns in Thailand: Focusing on Map Ta Phut Industrial Estate
More LessAbstractThailand, one of the countries in the South-East Asia Region, is largely tropical. People who live in this sun-intense area cannot avoid risking exposure to the high concentrations of UV radiation. The incidence of skin cancer in this country is not uncommon and is found in males more than females. Over the past few decades, Thailand's dramatic economic growth brought about new environmental challenges in the once-agrarian economy. The transition of a former agricultural and mainly rural, to a modern industrialized society has confronted the country with a wide range of environmental problems including air, water and soil pollution, as well as difficulties in the management of waste and hazardous chemicals. In parallel, such modern democratic developments and increasing societal complexity have resulted in both short-term and long-term public health issues in Thailand. Among the environmental problems listed above, air pollution appears to be the main factor. Air pollution in Thailand is obviously caused by vehicles, industrial emissions and fossil fuel power plants; other sources are garbage burning, open cooking and agricultural burning practices including deliberate forest fires. The health risks from being exposed to air pollution include nausea, headache, allergic reaction, respiratory disease, heart disease and cancer. Focusing on the Map Ta Phut district, Rayong Province, where a significant industrial base of Thailand is located, Map Ta Phut Industrial Estate consists of oil refineries, coal-fired power plants, steel industries, plastic factories and other petrochemical facilities that the cumulative amount of emitted air pollution, from industrial activity, has affected the environment and those who live nearby. Map Ta Phut came to public attention when a thousand pupils and teachers at a local school in the area had to be hospitalized from inhaling toxic emissions, leading to a number of studies. Detected in the environment were beyond-safety-standard airborne cancerous toxic chemicals, and several types of carcinogenic compounds. There were findings of unusually high levels of benzene, higher genetic damage levels of red blood cells, and significant elevation of some biomarkers of oxidative stress levels in the industrial estate workers and/or nearby residents. The terrifying outcome was from studies showing the unusually high cancer rates in the area. This serious impact on the environment and people’s health, has led to public movement and at the present time, Map Ta Phut Industrial Estate is proclaimed as a Pollution Control Zone. Environment quality has to be measured regularly and the pollution has to be reduced if is too high. This improvement is now under continuous observation.
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Population Studies for Health and Genetic Risk Assessments
By William AuAbstractChronic exposure to environmental toxic chemicals can cause DNA damage, disease and strong selection pressure on the gene pool of exposed populations. A mechanism that can link the exposure and biological consequences is DNA repair activity. Therefore, impairment of the DNA repair function can be a critical mechanism for the development of environmental health problems. In my laboratory, we have developed a Challenge assay to detect functional DNA repair deficiencies. In this assay, lymphocytes from exposed and control subjects are irradiated with X-rays or UV-light to induce DNA damage, thus challenging them to repair the damage. Abnormal repair will result in significantly elevated chromosome aberrations or DNA strand breaks in the Comet assay. Studies around the world have used the assay to indicate that excessive exposure to mutagenic and toxic substances can cause abnormal DNA repair responses. Thus, the risk for the development of health problems is increased. In studies in collaboration with Professor Bersimbaev of Kazakhstan, 3 generations of residents who have been exposed to radioactive fallouts from nuclear bomb testings were studied. The population had generation-based increase in mini-satellite instability and preferential retention of the GSTM1 null genotype. It appears that the chronic exposure to ionizing radiation has caused DNA repair defects and the alteration of the gene pool. The latter suggests that selection pressure can potentially alter the genetic makeup of the future generations. However, no clear cut evidence of such exists among exposed human populations. In summary, these studies indicate that excessive exposure to hazardous substances can cause functional alterations in the DNA repair machinery leading to increase health risk, including the possibility of alteration of gene pool in exposed population
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Chromosome Damage and the Damage Repair Capacity in Chinese Vinyl Chloride Monomer-exposed workers
By Zhao-Lin XiaAbstractVinyl chloride monomer (CH2=CHCl, VCM) is a certain human carcinogen and it has been proved to be a multi-organ and multi-system carcinogen. The mechanism of carcinogenesis was presumed to be related to the genetic material damage induced by electrophilic metabolites of VCM. VCM is widely used in industry, 95% of vinyl chloride was polymerized to polyvinyl chloride (PVC). China is one of the important PVC production countries, and its annual production accounts for about 10% of the global production.
This study investigated the relationship between chromosome damage (Cytokinesis-block micronucleus, CBMN) induced by VCM and the cumulative exposure dose of the VCM-exposed workers. At the same time, the DNA repair capacity test based on CBMN assay was carried out to evaluate the DNA repair capacity of the workers.
188 VCM-exposed workers are the target population, and 68 workers who did not exposed to VCM are the control population for the cross-section study. The result shows that the frequencies of CBMN in the exposed group were higher than those of the control group, and there was a dose-response relationship between VCM-exposure and the frequency of MN. In additional, Based on previous prevalence study, a follow up study on 43 VCM-exposed workers, whose frequency of MN was normal in 2004, was established to explore the relationship between abnormal frequency of MN and the VCM exposure levels. Until 2010, we found that there was different frequency of MN between groups of different VCM exposure levels. The frequency of MN for group with high VCM exposure levels is significantly higher than those of group with low VCM exposure levels, and the risk is 2.28. Moreover, 66 VCM-exposed workers were followed up for 6 years with Cytokinesis-block micronucleus (CBMN) assay in 2004, 2007 and 2010 to explore the progress of genetic damage and its influencing factors. The result shows that compared with 2004, the frequency of MN significantly increased in 2007 and 2010, and the risk were 1.11 and 1.45, respectively. The abnormal frequencies of MN in 2007 and 2010 are both higher than that of 2004, and the risk were 1.15 and 2.45, respectively, which pointed that the genetic damage are increasing year by year induced by VCM. Among all the influencing factors of DNA damage, gender had the prominent effect both on the severity and progress of chromosomal damage. Female workers had higher MN rates and changes of the both MN rates than male. Therefore, the frequency of MN of peripheral blood lymphocyte can be used as an effective and sensitive biomarker for early DNA damage and follow-up under low-level VCM exposure.
The study also focused on the DNA repair capacity of 80 VCM-exposed workers and 30 workers unexposed to VCM, as well as 30 controls. We found that the 3AB index shows the rising tendency with the increasing exposure level, which pointed the VCM exposure can decrease DNA repair capacity, and further increase the chromosomal damage. The results showed that DNA repair capacity was a comprehensive indicator with great potential to detect health damage induced by VCM and damage risk of susceptible workers. Moreover, the frequencies of MN of middle and high DNA repair capacity group are both lower than that of low DNA repair capacity group, the FR is 0.74 and 0.56, respectively. There was a dose-response relationship between DNA repair capacity and the frequency of MN. It indicated that DNA repair capacity might tightly associate with chromosomal damage induced by VCM. The DNA repair capacity would be worse, and the risk of chromosomal damage induced by VCM could be higher, so the DNA repair capacity could provide scientific evidence about the risk of chromosomal damage induced by VCM so as to protect the susceptible workers.
In conclusion, VCM can induce chromosomal damage even when the exposure level is lower than the national occupational health standard in China and the VCM exposure can decrease DNA repair capacity. The level of DNA repair capacity may be an important step of the genetic damage induced by VCM. Therefore, the health education and health surveillance should be strengthened so as to protect susceptible workers and improve the quality of working life.
This work was partly supported by the National Natural Science Foundation of China (NSFC81072280),973 program of China (2011CB503801), the Shanghai Bureau of Public Health (grants 08GWD12). We thank physicians Mr. Jun LI, Shuli FENG for their help for physical examination of the workers and data collection of VCM exposure.
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Cytogenetic Biological Dosimetry Past, Present and Future Perspectives
More LessAbstractHuman risk assessments at low doses, low dose rates and high doses following acute exposure to ionizing radiation are of prime importance in radiation protection. These issues are of continuing importance in respect of social/economic policy relating to the industrial and medical uses of ionizing radiation, and for risk assessment among people occupationally being exposed to low and/or high LET radiation, such as astronauts, pilots, stewardess and nuclear power plant workers, as well as victims of radiation accidents. Consequently, several biological assays were developed and attempts were made to investigate formation of radiation-induced chromosome aberrations and induction of genomic instability in human lymphocytes and fibroblasts. The fluorescence in situ hybridization (FISH) technique using chromosome, chromosome-arm, chromosome region, centromere and telomere-specific DNA libraries has improved the resolution of detecting all classes of radiation-induced chromosomal inter- and intra-changes. Consequently, this has increased significantly the accuracy and detection limit of biological dosimetry. Newly obtained data indicate that (a) Premature chromosome condensation assay (cell fusion assay) is a unique method to be used for immediate dose assessment at low (5cGy) as well as high doses (≥3 Gy) and can accurately discriminate between whole- and partial-body exposure in case of mass casualties and accidental over-exposure to high doses of ionizing radiation, (b) Chemically induced PCC assay has the potential to be applied for biological dosimetry (by analyzing ring-chromosomes) in cases of high doses (> 4 Gy). This assay has been further validated in combination with M-FISH to assess genomic instability of primary tumors, (c) FISH-based translocation assay has the potential to assess acute as well as chronic exposure in cases of accidental as well as occupational exposure to ionizing radiation, either immediately following exposure or retrospectively by defining accumulative effects to red bone marrows. (d) There are distinct fingerprints (such as insertions and complex translocations) for high LET radiation in comparison to low LET radiation. The importance of these findings, their applications in different scenarios of accidental and occupational over-exposure to ionizing radiations, such as Japan atomic bomb survivors, Chernobyl, Istanbul, Mayak and Techa River cohorts, and future perspectives for biological dosimetry will be discussed.
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Pooled Analysis: A Powerful Tool for Human Population Studies
More LessAbstractThe number of epidemiological studies involving biological markers has dramatically increased over the last few years. These studies are generally small sized and this feature has called attention to the need to summarize the individual results, while waiting for the completion of larger studies, designed to answer questions that have been raised by preliminary studies. An increasingly frequent approach is the pooled analysis of published (existing) data, which seems to provide a relevant improvement over meta-analysis in molecular epidemiology studies. The presentation will address some of the methodological issues related to pooling data of biomarker studies, taking advantage of the experience accumulated by pooled analyses of data coming from large international collaborative studies such as ESCH, HUMN, HUMNxl, and ComNet. Topics that will be discussed in more detail are: data standardization, population selection and bias, statistical analysis, ethical issues.
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Comet Assay: An Exposure Biomarker for Human Biomonitoring
By Alok DhawanAbstractA global concern on the adverse effects of chemicals to human health has led toxicologists, and in particular genetic toxicologists, to identify environmental genotoxins. The conventional method of identification involves techniques such as Ames test, chromosomal aberrations, micronucleus assay, alkaline elution assay, etc. However, these methods are cumbersome, time consuming as well as resource-intensive. During the last two decades, a state-of-the-art technique, the single cell gel electrophoresis (SCGE) /Comet assay, has gained importance as a rapid, visual and sensitive technique for qualitative and quantitative assessment of DNA damage and repair. It is a valuable technique for detection of a variety of DNA damages, which include single and double strand breaks, alkali labile sites and oxidative base damages. Comet assay can be performed on any eukaryotic and some prokaryotic cells and may be used for both in vitro and in vivo screening of geno- and anti-genotoxic potential of chemicals. Its non-invasive nature and requirement of few cells for processing has made this assay widely accepted for monitoring human genotoxicity. Its sensitivity has enabled genetic toxicologists to monitor low-level, long-term exposure to chemicals, thus predicting genetic damage at an early stage. Our studies, in the Indian population, using the alkaline Comet assay have revealed significant gender-related differences in the extent of DNA damage in lymphocytes. DNA damage was also found to vary with eating and smoking habits, age, exercise as well as occupational exposure. In vitro Comet assay studies have also been performed using human peripheral blood lymphocytes and cell lines such as MCF-7, CHO, JM-1 to assess the genotoxic potential of environmental chemicals. The versatility of the Comet assay has indeed proven it to be a Rosetta Stone in the garden of Genetic Toxicology.
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Chemoprofiling Of Mycotoxigenic Fungi Occurring In Maize, Sorghum And Millet Grains In Africa
More LessAbstractSorghum (Sorghum bicolor (L.) Moench) and pearl millet (Pennisetum glaucum (L.) R.Br) are indigenous crops to the African continent. Apart from maize, rice and wheat, these crops are basic staple foods for many rural communities in Africa. The growth and production of these grains can be negatively affected by plant diseases caused by diverse fungal genera. The ability of Fusarium species to produce mycotoxins, including fumonisins (FUM) and moniliformin (MON), that have detrimental health effects for both humans and animals make it important to evaluate their toxin production in crops that are intended for human consumption. Fusarium species occur naturally in maize, sorghum and millet, among other grains. Potentially toxigenic species isolated from grain samples from Nigeria harboured high FUM and MON producing strains. This was confirmed by molecular identification and by chemoprofiling in in vitro grain cultures. Mycotoxin levels of Fusarium species grown on maize patty cultures were compared to levels produced on sorghum and millet patty cultures. FUM and MON profiles of 18 Fusarium proliferatum and two other Fusarium control strains, ie high producers of either one of these toxins, were analyzed. FUM (fumonisin B1, B2 and B3) were extracted with methanol/water and MON with acetonitrile/water. The mycotoxin extracts were cleaned up using strong anion exchange solid phase extraction prior to quantification by reversed-phase HPLC. Results indicated that under conducive conditions, all the strains tested produced FUM, some in relatively large quantities (11/18), ranging from 694-17421 mg/kg culture material. For 8/18 strains the MON levels were >500 mg/kg and up to 8892 mg/kg culture material. Although there are variations in the potential or ability of F. proliferatum isolates to produce either FUM or MON, these fungi can use several grains as a source for toxin production irrespective of their original hosts. This study gives insight into the potential and ability of Fusarium species, isolated from maize, sorghum and millet, to produce mycotoxins on several grain sources, which may have a marked influence on food safety and security, and the potential health risk they hold for many rural communities in Africa.
Vismer HF, Shephard GS, Imrie G, Van der Westhuizen L, Volkwyn Y, Mngqawa P
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Regulatory Measures Of Genetic Toxicology Testing In The Local Industries Of Drug, Cosmetics, Food Additives And Environmental Pollutants
By Fouad BadrAbstractNational and international efforts to promote research and communicate knowledge into the causes and consequences of damage to the human genome aimed to inform and support measures to ensure a healthy and sustainable environment for future generations. Developed countries have realized the need to regulatory bodies (e.g. FDA, EPA, EMEA, ICH and WHO) to be responsible for approval and administration of drugs, medical devices, cosmetics , food additives and chemicals before marketing their products. Developing countries are building their economy with a focus on industrialization programs at a pace exceeding measures which counteract hazards to both human and environment. Growing na tional industries in the fields of pharmaceuticals, food and petrochemicals will definitely impose a range of hazards to the population and the environment. The challenge facing countries of the gulf region and its neighbours is the lack of a local or regional infrastructure body which focuses on promotion of research and applications of knowledge into genetic toxicology testing, risk assessment, and regulatory policy-making to protect human health and environment. For the last few years attempts by concerned scientists in the region were practiced to fill in gaps and come up with practical solutions to overcome the need for an organization with academic and legislative power to set up regulations and guidelines for the safe marketing, labelling of pharmaceuticals, cosmetics, consumer products, pesticides and chemicals. A proposal for the establishment of a Regional Center of Excellence for Environmental Mutagenesis and Carcinogenesis Research in one of the rich Gulf countries is ready for disclosure. The proposal is based on initiatives of the European safety program REACH (Registration, Evaluation, and Authorization of Chemicals), and the well established regulatory requirements of the Food and Drug Administration, European and Japanese regulatory agencies, which requires manufacturers to conduct testing to identify potential hazards to human health and to the environment, and to submit the test data to regulatory authorities.
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Exposure To Desert Cyanobacteria May Pose A Risk To Human Health
More LessAbstractStudies on the occurrence of cyanotoxins in desert environments are relatively rare, compared with aquatic environments. Cyanobacteria are, however, important primary-producers in desert environments where they grow rapidly after seasonal rains, stabilizing and fertilizing arid habitats. As cyanobacteria can produce toxins, we tested whether desert cyanobacteria presented a risk to human health.
Cyanobacterial crust coverage was measured using random quadrats, and representative samples of cyanobacterial crust from wadis and sabkha were removed for analysis. Extracts were produced using standard methods and toxins were measured by hplc, uplc, mass spectrometry, elisa and enzyme inhibition assays.
Cyanobacterial crusts were found to cover 80 percent of the state of qatar, and up to 87 percent of the land was covered with cyanobacteria. The neurotoxic amino acids β-n-methylamino-l-alanine (bmaa) and 2,4-diaminobutyric acid (dab) were detected in the crust material. Microcystins were detected at concentrations between 3.8 and 238 ng/g crust, equivalent to between 7 and 40µg/m2. Pcr products for the mycd gene for microcystin biosythesis were detected after amplification of dna from desert crust samples. In addition, the presence of anatoxin-a(s) was inferred by acetylcholine esterase inhibition assay. Based on the concentration of microcystins detected in crust, with reference to previously published inhalation toxicity for microcystins, in combination with the amount of dust potentially inhaled by a person, the dose of microcystins could exceed a tdi value of 3ng/kg/day for an average adult.
The presence of cyanotoxins in desert crusts has important implications for human health and further studies are required to monitor desert dust storms which may contain these crusts. Furthermore, an understanding of the risks of inhaling particles containing cyanotoxins is warranted.
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Susceptibility of Cancer among Tannery Workers Exposed to Chromium
More LessAbstractThere is inadequate evidence about the carcinogenic effect of human exposure to chromium compound. This study aimed to estimate cytogenetic and carcinogenic effects of occupational exposure to chromium in tannery workers, and comparison of the diagnostic value of urinary cytology, nuclear matrix protein (NMP) and Kontron Image Analysis System for the detection of occult bladder cancer. Methodology: The study included 38 tannery workers and 40 unexposed subjects. Cytogenetic analysis was carried out with standard procedures on heparinised venous blood leukocytes. Urine samples were tested for abnormal cells through cytopathological examination and DNA image analysis for any abnormality in the cell life cycle, in addition to NMP, a tumor marker specific for bladder cancer, to detect suspected bladder lesions. Results: Statistical analyses revealed that there was no significant difference in chromosomal aberrations and sister chromatic exchange between tannery workers and their control. But, there were significant differences between the examined groups according to the cytopathological examination of the urine samples and DNA images. In smoking tannery workers, 4C and S phase were significantly higher and 2C was significantly lower compared to those not smoking. There was no significant difference between the two groups according to NMP. The percent of positive NMP in smoking workers was higher compared to non-smokers in both groups. Conclusion: Tannery workers were at high risk for bladder pre-cancerous lesions, but, cytogenetic changes were not approved. Urinary cytology as well as NMP can provide useful excluding information, and can be used in screening for bladder cancer in the population at risk to exclude the presence of the condition, but not as a diagnostic methods.
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Testing the Genotoxicity of Sodium Arsenate in Human Lymphocytes
More LessAbstractSodium arsenite (SA) is a compound with formula NaAsO2. It is the sodium salt of arsenous acid which was tested for its clastogenic effect alone and in combination with gamma rays on the whole blood culture and on isolated lymphocyte culture. The results showed a significant difference in the yield of aberrations induced with respect to the culture time of 48 hours. Whole blood culture showed significant increase in gaps and breaks, whereas isolated lymphocytes culture showed significant inhibition of cell cycle and 75 percent of the lymphocytes were in their first cell cycle at 72 hours. Arsenite showed co-mutagenicity with different doses of gamma rays delivered immediately or few hours after treatment of the culture with SA. The results suggest that SA also is mutagenic at the dose level used and provide support for the indispensability of whole blood culture for evaluation of the in vivo effect of any suspected mutagen. Using isolated lymphocytes appear to have problems leading to extensive cell cycle delay.
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In Vivo Mutagenesis by UVB Irradiation: Detection and the Underlying Mechanisms
More LessAbstractHuman genome is continuously exposed to endogenous and exogenous genotoxic agents. To evaluate genotoxicity of the agents, we have developed gpt delta mice transgenic gene mutation assay, which allows detection of mutations in vivo in any organ of mice. The mice have been established by microinjection of lambda EG10 phage DNA into fertilized eggs of C57Bl/6J mice. A feature of the transgenic mice assay is incorporation of two selections to detect different types of mutations, i.e., point mutations such as base substitutions and frameshifts by gpt or 6-thioguanine selection and deletion mutations by Spi- (sensitive to P2 interference) selection. The gpt assay effectively detects point mutations induced by a variety of chemical agents that induce DNA adducts while Spi- assay exclusively detects deletions with the molecular sizes from 1 base pair (bp) to several kilo bps (kb). We report that UVB irradiation induces base substitutions and deletions in the epidermis of gpt delta mice and also that p53 suppresses the deletions and complex mutations in vivo. The mice were exposed to UVB at single doses of 0.3, 0.5, 1.0, 1.5 and 2.0 kJ/m2. At four weeks after irradiation, mutations in the epidermis were analyzed. The UVB irradiation induced G:C to A:T mutations at dipyrimidine sites, such as 5’-TC-3’ and 5’-CC-3’. Tandem transitions such as CC to TT were also observed. In addition to point mutations, UVB induced deletions with the size of more than 1 kb. More than half of the large deletions occurred between short homologous sequences from 1 to 6 bps while others had flush ends. The results suggest that the deletions are generated by end-joining of double-strand breaks in DNA. To examine protective roles of p53 against UVB-induced mutagenesis, mutations were measured in the epidermis of UVB-induced p53+/+ and p53-/- gpt delta mice. The mice were exposed to UVB at single doses of 0.5, 1.0 and 2.0 kJ/m2, and the mutant frequencies (MF) were determined in the epidermis 4 weeks after the irradiation. Although UVB enhanced gpt MF more than 10 times over the unirradiated mice, there were no significant differences in gpt MF and the mutation spectra between p53+/+ and p53-/- mice. In contrast, the frequency of Spi- large deletions of more than 1 kb and complex mutations were significantly higher in unirradiated p53-/- mice than in unirradiated p53+/+ mice. These large deletions and complex mutations increased in a UVB-dose-dependent manner in p53+/+ mice, while no increase was observed in p53-/- mice. These results suggest that p53 does not suppress point mutations induced by UVB but suppresses large deletions and complex mutations in vivo.
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Genotoxicity Induced By Nanomaterials
More LessAbstractNanomaterials are useful for their characteristic properties and are commonly used in various fields. The assessment of genotoxicity and safety of nanomaterials are, therefore, of serious concern. So far, we have examined genotoxic effects of various nanomaterials, including fullerenes, kaolins, multi-wall carbon nanotubes and magnetite, using in vitro and in vivo assay systems. All of these nanomaterials significantly induced micronuclei and enhanced frequency of sister chromatid exchange in cultured mammalian cells. When ICR mice were intratracheally instilled with a single dose (0.2 mg/animal) of these nanomaterials, DNA damage of the lungs analyzed by Comet assay increased about two to three times that of the vehicle control. We also analyzed the formation of DNA adducts related to oxidative stress (8-oxo-2’-deoxyguanosine and heptanone etheno-deoxyribonucleosides) in lungs of mice exposed to nanomaterials using the stable-isotope dilution LC-MS/MS method. These DNA adduct levels were increased in the nanomaterial-treated mice compared with a vehicle control. Moreover, we examined in vivo mutagenicity of nanomaterials using gpt delta transgenic mice intratracheally-instilled with four consecutive doses of 0.2 mg per animal. All nanomaterials increased gpt mutant frequencies in the lungs of gpt delta transgenic mice. Mutation spectra analysis showed transversions were predominant, and among these, the G:C to C:G was commonly increased by these nanomaterials. Based on these observations, it is suggested that oxidative stress and inflammatory responses are probably involved in the genotoxicity induced by nanomaterials. To further clarify the mechanisms of genotoxicity by nanomaterials, comprehensive DNA adduct analysis (DNA adductome) is now being investigated for DNA samples derived from lungs of mice exposed to nanomaterials. On the other hand, the effects of atypical nanomaterials such as difference of surface structure on genotoxicity are not fully elucidated yet. In the present study, we investigated the DNA damaging potency of two types of kaolins by Comet assay, and found out that genotoxicity differs between two types of kaolins. We are now investigating the incorporation rate into mammalian cells, and reactive oxygen species generation of these kaolins.
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Basic Mechanisms in Spontaneous and Induced Mutagenesis
More LessAbstractLiving cells possess a panel of specialized DNA polymerases that deal with the large diversity of DNA lesions that occur in their genomes. How specialized DNA polymerases gain access to the replication intermediate in the vicinity of the lesion is unknown. Using a model system in which a single replication-blocking lesion can be bypassed concurrently by two pathways that leave distinct molecular signatures, we analyzed the complex interplay among replicative and specialized DNA polymerases. In Escherichia coli, the DNA damage response entails several processes such as stalling of the replication fork, activation of the SOS response and induction of dNTP synthesis. Following UV-irradiation, the ribonucleotide reductase (RNR) NrdAB that catalyzes the limiting step in dNTP synthesis, is up-regulated, leading to an increase in dNTP levels. In the present study, we investigate the effect of increased dNTP levels on the process of translesion synthesis (TLS) under DNA damage conditions. We present direct evidence that an elevated dNTP pool level facilitates translesion synthesis (TLS). TLS is a two-step mechanism involving the insertion of a nucleotide opposite the lesion and the subsequent extension steps. Although Pol III, the replicative DNA polymerase, can insert a nucleotide across certain lesion, its proofreading activity usually recognizes the inserted base across the lesion site as a mispair and removes it, thus preventing the subsequent extension steps. Our results suggest that high dNTP levels bolster the polymerase activity of Pol III, in turn reducing its exonuclease activity. The shift in the equilibrium from the exonuclease activity towards the polymerase activity of Pol III favors the production of a key TLS intermediate, ie the intermediate that contains a base inserted across from the lesion site. This intermediate is subsequently elongated by the specialized TLS polymerases. In support of the hypothesis of proofreading activity attenuation of Pol III, we show a robust increase in spontaneous mutagenesis under conditions of elevated dNTP levels referred to as the spontaneous dNTP mutator phenotype.
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Mechanisms of Liver Carcinogenesis: Studies of Co-morbidity Factors Using Animal Models
By Ivan RusynAbstractHepatocellular carcinoma (HCC) is the most common type of primary malignancy in the liver. Main risk factors of HCC are well-defined and include hepatitis B virus (HBV); lifestyle, diet and environmental factors (e.g., alcoholic beverages, aflatoxin B1 (AFB1), and tobacco smoking); and metabolic diseases (e.g., obesity, diabetes and non-alcoholic steatohepatitis). Importantly, the rise in incidence of HCC in the developed countries has been attributed, at least in part, to an increase in hepatitis C virus (HCV) infections and non-alcoholic steatohepatitis, pathological states whose prevalence is growing in the US and Europe. In addition, liver fibrosis and cirrhosis are well known precursor liver disease states for hepatocellular HCC in humans. While animal model studies of HCC have contributed much of the understanding of the molecular events leading to disease initiation, progression and promotion, few publications examined co-morbidity factors that are known to contribute to HCC in humans. This presentation will describe two examples of experimental animal models of HCC where co-morbidity factors (HCV+AFB1, or genotoxic carcinogen diethylnitrosamine+liver fibrosis) were explored. These studies afford an opportunity to examine the molecular mechanisms that are crucial for the synergy between co-morbidity factors.
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Low-Dose Carcinogenicity Studies and Mechanisms
More LessAbstractOne of the major deficiencies of cancer risk assessments is the lack of low-dose carcinogenicity data. Most assessments require extrapolation from high to low doses, which is subject to various uncertainties. Only four low-dose carcinogenicity studies and five low-dose biomarker/pre-neoplastic studies have been performed. The four carcinogenicity studies involved exposures of 24,192 mice to two acetylaminofluorene, 4,080 rats to nitrosamines (NDMA and NDEA), 40,000 rainbow trout to dibenz[a,l]pyrene, and 20,00 trout to aflatoxin B1. The low-dose biomarker/pre-neoplastic studies involved exposure of 1,145 rats to MeIQx, 2,000 rats each to DEN or DMN, 1,920 rats to PhIP, and 50 rats to potassium bromate. In most cases there was some evidence for a threshold effect for the induction of cancer or biomarkers of cancer. However, absolute proof of a threshold effect for carcinogenicty could not be demonstrated unambiguously by any of the carcinogenicity studies due to the limited number of animals used. The induction of stable DNA adducts was not predictive of tumors in the mouse and trout studies. All of the biomarkers evaluated, including stable DNA adducts, oxidative damage, mutation, and pre-neoplastic foci, exhibited threshold effects, ie, they were not inducible or detectable at the lowest doses tested. Clear proof of a threshold effect for any of the carcinogens tested is lacking. However, the limited data available suggest that these carcinogens may exhibit threshold effects for the induction of carcinogenic biomarkers and cancer. Given the fact that some mutagens clearly show threshold effects and that cancer is a multi-step process, it is possible that carcinogens may also show a threshold effect.
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Environmental Toxicogenomics: How Genomic Technologies are Impacting the Science of Toxicology
More LessAbstractDecision-makers in safety assessment of exposures to environmental stressors and health care providers need improved biomarkers of toxic exposures and biomarkers of adverse events that precede the development of overt injury or disease. Two toxicogenomic studies will be presented that demonstrate the utility of genomic approaches for developing potential biomarkers of toxicity for both nephrotoxicity and hepatotoxicity. The use of calcineurin inhibitor (CI) immunosuppressants has revolutionized the clinical practice of organ transplantation. However, chronic nephrotoxicity limits their long-term utility. In order to understand the pathophysiology that underlies the development of CI-associated nephrotoxicity and to develop CI-specific biomarkers of toxicity, rats were dosed with cyclosporine A (CsA) or FK506, or rapamycin, and gene expression profiling was performed on RNA isolated from kidneys 24 hours after one, seven, 14 or 28 daily doses. A gene expression signature was identified that was correlated with CI-specific kidney damage and responded with an earlier onset than the more general kidney injury biomarkers Kim-1 and Clusterin, and is CI-specific. We have been interested in gene expression patterns derived from peripheral blood cells as they would provide useful early indicators of acute toxicity. With respect to hepatotoxicity, the case of acetaminophen (APAP) intoxication is particularly important, as this is the leading cause of liver failure in the United States. We generated a blood gene expression data set from rats exposed to APAP to train genomic classifiers of toxicity. Prediction accuracy was tested on a blinded, independent rat blood test data set and ranged from 88.9% to 95.8%. Genomic markers outperformed predictions based on traditional clinical parameters. We are currently testing the hypothesis that gene expression data from peripheral blood cells can provide valuable information about hepatotoxicity to humans, well before liver damage is detected by classical parameters. Our results support the potential use of genomic markers in the blood as surrogates for clinical markers of potential acute liver damage.
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Genetic, Genomic and Proteomic Approaches to Identify Arsenic Susceptibility and Carcinogenicity
More LessAbstractIn West Bengal, India, more that 26 million people are exposed to arsenic through drinking water. However, only less than 15% to 20% of them show arsenic-induced skin lesions. Hence it is assumed that genetic variations might play an important role in arsenic-induced toxicity and carcinogenicity. Major genetic, genomic and proteomic approaches have been made to find out the cause of arsenic susceptibility. For this reason, the Chromosomal Aberrations (CA), Comet assay and challenge assay were performed and single nucleotide polymorphisms (SNPs) studies were carried out for a number of genes that may involve the different pathways in arsenic metabolism and detoxification SNPs of p53 gene, PNP, ERCC2 and XRCC3 genes were also analyses. Attempts have also been made to identify the different proteins in the plasma of the individuals exposed to arsenic that may be responsible for arsenic susceptibility. Individuals with p53 codon 72 Arg/Arg genotype are overrepresented, indicating that this genotype is more susceptible to arsenic-induced toxicity. Lys/Lys genotype in the ERCC2 polymorphism was almost five fold overrepresented in the arsenic-induced hyperkeratosis skin lesions group when compared to the group with no skin lesions. In each of these cases, individuals with risk genotype were found to have significantly higher genetic damage, functionally validating our associations. In case of XRCC3 T241M polymorphism, presence of at least one M allele (M/M or T/M) was protective toward development of arsenic-induced skin lesions, and also toward arsenic-related peripheral neuropathy and conjunctivitis. A significant correlation was observed between protective genotype and decreased frequencies of chromosomal aberrations. Results of DNA repair studies through Challenge and Comet assay show that the individuals with arsenic-induced skin lesions have suboptimal DNA repair capacity and are hence inefficient in combating the DNA damage induced by chronic arsenic exposure. Thus the above results indicate that the suboptimal DNA repair and genetic variations are responsible for arsenic induced toxicity and carcinogenicity. Attempts were made to identify the proteins that are differentially expressed in the arsenic unexposed and arsenic exposed skin symptomatic and asymptomatic individuals through iTraq. A number of proteins were found to be differentially expressed between exposed individuals with and without arsenic-induced skin lesions and might thus play a critical role in arsenic susceptibility.
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Genomic Approach for Understanding the Mutagenic and Carcinogenic Mechanisms of Heavy Metal Nickel in terms of Gene-environment Interaction.
By Young R SeoAbstractNickel is a toxic metal that causes mutagenesis and promotes carcinogenesis. Its toxicological properties are partially related to the generation of reactive oxygen species (ROS) that can induce DNA damage and mutation. It also interfere redox-sensitive transcription factors, particularly p53 and hypoxia-inducible factor 1 (HIF-1), which might lead to genomic expression change. Nuclear factor erythroid-2 related factor 2 (Nrf2) is a redox factor which is responsible for control of oxidation/reduction status and consequent cytoprotection against environmental toxicants. First, we confirmed the protective effect of the Nrf2 gene under oxidative stress and DNA damage induced by 20uM nickel at sub-lethal doses in terms of gene-environment interactions. Here, we attempted to identify potential nickel and Nrf2-responsive targets and the relevant pathway via microarray, qRT-PCR, and pathway analysis. Under nickel exposure conditions, we detected significantly higher amounts of DNA damage via a comet assay, in addition to increased intracellular ROS generation, in Nrf2 lacking cells in comparison to Nrf2 wild-type cells. Additionally, gene expression data were analyzed via microarray assays for the selection of Nrf2-responsive genes under nickel treatment. In particular, altered expressions of 10 genes (CAV1, FOSL2, MICA, PIM2, RUNX1, SLC7A6, APLP1, CLSPN, PCAF, and PRAME) were verified by qRT-PCR. These genes functioned principally in a variety of biological processes, including oxidative stress response, DNA repair, necrosis, and cell survival. These findings indicate that Nrf2 is an important factor that performs a protective role in the suppression of oxidative stress-induced DNA damage by environmental nickel exposure. Furthermore, we describe the potential biomarkers regarded as molecular targets for Nrf2-related cellular protection against nickel exposure.
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Proteomic Profiling of Lung Cancer Specific Plasma Proteins: Novel Diagnostic Strategy for Environmentally Exposed Male Lung Cancer Patients
By Rita SinghAbstractLung carcinomas are highly heterogeneous malignancies and the patient survival rate for lung cancer is very low. This is due to the lack of diagnostic markers for lung cancer and for predicting response or monitoring recurrence after treatments of the lung carcinomas. Human blood plasma proteomics has become one of most preferred method for cancer biomarker discovery. In this study, we used plasma for the detection of lung cancer-specific proteomic biomarker pattern by one-dimensional SDS- Polyacrylamide Gel Electrophoresis followed by nLC-MS/MS. Panels of low molecular weight proteins were found to be lung cancer specific or were not found in the parallel samples from ovarian and breast cancer plasma. To reveal the interactions of identified proteins we analyzed them by I2D - Interologous interaction software. Out of 30 identified proteins, 10 showed association with albumin. Albumin is the most abundant protein in plasma and serum and protects the smaller proteins and peptides from renal clearance. On integrating bioinformatics data with published literature 50% of identified proteins were found to be albumin associated. A list of proteins was identified such as apolipoprotein, transthyretin, haptoglobin alpha, haemoglobin, alpha-1 acid glycoprotein, zinc-alpha-2-glycoproteins known to be associated with lung cancer. To assess the potential usefulness of the identified proteomic pattern for diagnostic purpose, we raised the antibodies to the lung cancer specific proteins. Western blot analysis of lung, ovarian and breast cancer plasma samples with the lung cancer specific antibodies confirmed our findings on the specificity of the proteomic pattern to lung cancer. Validation of the lung cancer specific proteomic pattern would have significant implications for the early detection and diagnosis of lung cancer and better management of high risk patients.
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Inactivation of the Putative Tumour Suppressor Gene DOK1 by Epigenetic Modifications in Human Cancers
By Bakary SyllaAbstractEpigenetics investigates heritable changes in gene expression that occur without changes in DNA sequence. Several epigenetic mechanisms, including DNA methylation and histone modifications, can change genome function under exogenous influence. Results obtained from animal models indicate that in utero, or early-life environmental exposures, produce effects that can be inherited transgenerationally and are accompanied by epigenetic alterations. The search for human equivalents of the epigenetic mechanisms identified in animal models is in progress. I will present evidence from human environmental studies indicating that epigenetic alterations may mediate effects caused by exposure to environmental toxicants. In these investigations, we have shown that air pollution exposure is associated with altered methylation of human repetitive elements or genes. In recent preliminary studies, we have shown alterations of histone modifications in subjects exposed to metal-rich airborne particles. I will present original data demonstrating that altered DNA methylation in blood and other tissues is associated with environmentally induced disease, such as cardiovascular disease and asthma. On the basis of current evidence, I will propose possible models for the interplay between air pollution exposure and the human epigenome.
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Epigenetic Effects of Early Environmental Exposures on Whole Genomes and Repetitive Elements
More LessAbstractIncreasing evidence suggests that environmental exposures during in utero development impact adult health through epigenetic modifications of the genome. High production-volume chemicals such as bisphenol A (BPA), and known toxins including lead (Pb), are ubiquitous in the environment and may contribute to disease susceptibility through epigenetic mechanisms. Developmental and adult exposure to environmentally relevant levels of BPA has been shown to affect both global and gene-specific DNA methylation patterns. Preliminary studies also indicate that Pb exhibits epigenetic effects that may contribute to its known neurotoxic and obesogenic activities. During early embryogenesis, epigenetic marks, including DNA methylation, are reset at specific times in both rodents and humans. Utilizing the viable yellow agouti (Avy) mouse as a biosensor, we assess the impact of BPA and Pb on the DNA methylation status of the genome by examining coat color shifts, whole genome methylation, and repetitive element methylation. Since repetitive elements comprise nearly half of the human genome and contribute to disease when reactivated, the suppressive methylation of these elements during development is crucial to human health outcomes. Previously, only a handful of repetitive elements were known to be epigenetically variable; here we describe additional novel and environmentally responsive epigenetic elements. To illustrate the long-term biological dysregulation caused by BPA and Pb, we survey the epigenomic changes on repetitive elements and the whole genome induced by developmental exposure in mice as well as humans. The characterization of epialleles in the mouse, the most widely used model for human health, is crucial for the identification of human epialleles and the development of epigenetic therapies for the prevention and treatment of human disease throughout the life course.
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Correlation Among Epigenetic, Environmental and Genetic Factors in Colorectal Carcinoma and Alzheimer's Disease
More LessAbstractIt has been postulated that dietary components, in conjunction with the presence of susceptibility genes, can influence the epigenome, altering genetic expression and potentially modifying colorectal cancer (CRC) as well as Alzheimer’s disease (AD) risk. The aim of two ongoing projects is to investigate the interaction of dietary components (folate levels) with genetic susceptibility (polymorphisms of genes involved in the folate metabolic pathway) in influencing the methylation levels of genes critical for colon cancer or for neurodegeneration. We are currently analyzing the methylation status of CRC related genes including RASSF1A, MGMT, APC, hMLH1, and CDKN2A in the DNA obtained from epithelial cancerous cells isolated from either early or late stage CRC tissues through immuno-magnetic method, in order to evaluate the association between methylation and clinicopathological features. Promoter methylation profiles are evaluated by means of Methylation-Sensitive High-Resolution Melting (MS-HRM) technique. Results on a subgroup of 30 CRC patients suggest that APC is the most frequently methylated gene in our cohort, and all the other genes are found to be methylated in approximately 20-25% of the cases. Several CRC patients had elevated plasma Hcy levels (above the normal range), consistent with a condition of impaired one-carbon metabolism. We also screened blood DNA from 20 late-onset AD patients, 20 healthy controls and 20 individuals with Mild Cognitive Impairment (MCI) for CpG methylation analyses in the promoter of the β-secretase gene (BACE1). Our epigenetic analysis revealed that the BACE1 gene might be subject to epigenetic regulation due to methylation/demethylation processes of different CpG islands. The outcomes of these studies comprise more knowledge of predisposing conditions (diet, genetic variants) to develop colon cancer or neurodegeneration with the possibility to undergo a primary prevention, moreover to get information on epigenetic biomarkers associated with susceptible individuals, easily detectable and useful to design a precocious diagnostic tool.
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Serum Organochlorines Pesticides Level, Cyp1a1, Cyp1b1 Genetic Polymorphism and Risk of Breast Cancer
More LessAbstractThe aim of this study was to find the relationship between the Organochlorine and PCBs pesticides residues and female breast cancer, together with the related genetic polymorphisms, biochemical parameters and anthropometric measurements in Sudanese female breast cancer patients attending the Wad-Madina teaching hospital, Gezira State, Sudan. The prospective study was performed on 200 female breast cancer patients (of ages ranging between 25-80 years). 100 healthy persons of a range of ages and from different community areas were chosen to form a control group. The Organochlorine and PCBs pesticides residues were measured in serum and adipose tissues. We used Gas chromatographs, Thermoquest-Trace GC with 63Ni selective Electron- Capture Detector with advanced software and Nucon-GC-5765 series equipped with Nitrogen Phosphorus Detector. The genetic polymorphisms was determined the Cytochrome P- 450 (CYP1A1) in the blood and tissues. The DNA extraction by QIAamp DNA Mini Kits .PCR Technique was used for laboratory genetic analysis by using Genotypes Restriction Enzymes Length Polymorphisms (RFLP). Anthropometrics measurements were determined by weight, height and body mass index (BMI). A questionnaire was completed in order to obtain information regarding: sociodemographic characteristics, obstetric and gynaecological variables and nutritional information. The risk of breast cancer increased among women with higher serum concentrations of any Organochlorine: o, p’-DDT, p, p’-DDT, p, p’-dichlorodiphenyldichloroethylene, hexachlorobenzene, beta-hexachlorocyclohexane, trans-nonachlor, cis-nonachlor, oxychlordane, mirex, or PCBs. The high serum levels of PCBs were associated with a decreased risk of breast cancer; CYP1A1 polymorphisms were more frequent in younger patients and in patients with high level Organochlorine pesticides. Organochlorine pesticide residues may increase the risk of breast cancer in females, particularly in premenopausal women in Sudan. CYP1A1 polymorphisms probably predispose to an earlier onset of breast cancer and might be associated with a higher Organochlorine pesticides level, but further studies on a much larger group are required to substantiate our findings.
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Cytogenetic Biomarkers, DNA Repair Efficiency and Susceptibility to Gentoxic Exposure of Lymphocytes from Persons Exposed to Low and High Doses of Iodine –131.
More LessAbstractIn case of any accidental mass exposure and particularly in cases of radiation contamination, there is a need to estimate possible effects in a short time. The best known, gold standard, accurate and associated to cancer risk increase proofed measurement of absorbed dose via classic cytogenetics is unfortunately laborious and time consuming. The aim of our human monitoring studies performed on subjects from various cities and countries was to investigate if exposures to genotoxic agents, environmental, occupational, diagnostic or therapeutic can cause a detectable increase risk. Exposures to ionizing radiation, pesticides, mercury ions, benzene related compounds have significantly elevated levels of cytogenetic damage. The 25 years follow up studies revealed significantly increased risk of cancer in the group of subjects characterized by the highest levels of the detected chromosomal damage. Results of DNA repair competence assay, with a use of challenging dose of X-rays and the detection of induced DNA damage by the SCGE assay, have correlated to levels of induced chromosome damage detected by classic and FISH cytogenetic methods. Results from studies on the influence of occupational exposure to environmental PAHs, on the efficiency of the radiation induced DNA damage’s repair, have shown a strong variability between donors and significant decrease of the DNA repair efficiency in exposed subjects, that was strongly differentiated between groups stratified first according to various genotypes for genes, encoding enzymes involved in the process of bio-transformation (CYP1A1(Ile/Val), GSTM1, NAT2) or DNA repair (EPHX4 or XRCC1)1 and then to levels of exposures. Results of our studies in various groups of (prostate or colon cancers or thyroid diseases) patients have also shown the higher levels of chromosome aberrations frequencies and associated significant reduction of cellular DNA repair efficacy in comparison to healthy subjects groups. Thyroid patients were examined first after low diagnostic 131 one, and another time five weeks after medical treatments with higher doses. Strong inter individual variability was observed. Preliminary study of polymorphisms XRCC1 and XRCC3 genes encoding enzymes involved in the repair process, confirmed strong influence of genes of the DNA damage induced by IR and stepped up levels of biomarkers, the predictor of cancer risk. Our results demonstrate also that the DNA repair competence biomarker (RCB), fast and inexpensive, can reliably detects an influence of ontogenetic or exogenous factors on biological effects, which via alteration of the DNA repair processes can rise levels of chromosome aberrations and result in increased health risk. That knowledge might be key factor in stratification of the population at risk, or in predicting beneficial range for high dose therapeutic procedures.
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Research Strategies to Advance Our Understanding Early Life Exposures to Improve Child Health and Reduce Disease Burden.
By William SukAbstractThe environment is a fundamental determinant of human health. Targeting the best scientific research to environmental problems, wherever they arise, can lead to breakthroughs in our understanding that can be of great benefit to all. Environmental factors cause or influence an array of conditions that lead to illness and death among mothers and children, populations at greatest risk for premature death and illness. Exposures during pregnancy can influence maternal conditions during pregnancy, such as: asthma, anemia, and infectious disease susceptibility, and result in adverse pregnancy outcomes, such as: miscarriage, intra- uterine growth retardation, prematurity. These exposures can also adversely affect long-term health outcomes for the offspring, leading to chronic diseases. Developmental-stage specific exposures and windows of susceptibility are critically important since the effects of any given exposure are determined largely by the time in the developmental and maturational process when exposure occurs. Therefore, it is important to gain a better understanding of developmental toxicology: the effect of in utero exposures that may cause permanent functional changes that result in increased susceptibility to disease/dysfunction later in the life span. There is evidence that some environmental agents, especially those with endocrine agonist or antagonist activity, may alter developmental programming via alteration in gene expression or gene imprinting resulting in functional deficits that become apparent later in life. It is essential to translate research findings and knowledge into information, resources, and/or tools used by public health and medical professionals, and by the public to improve overall health and well-being. This can be accomplished by launching a globally strategic series of networks to enhance collaborations and communications between and amongst environmental health investigators, integrating investigator-initiated research, establishing and maintaining partnerships, and developing community-based primary-care and health services for vulnerable populations. The objective is fundamental: to translate the basic discoveries that prevents disease and improves health..
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Recent Findings from the Health Effects of Arsenic Longitudinal Study in Bangladesh
More LessAbstractThe Health Effects of Arsenic Longitudinal Study (HEALS), a large multidisciplinary prospective cohort study in Araihazar, Bangladesh, was established in 2000 to evaluate the effects of a wide range of arsenic (As) exposures on various health outcomes, including premalignant and malignant skin lesions, total mortality, and children’s neuropsychological development (1). In this presentation, some important recent findings will be presented. Approximately 12,000 adults, aged 18-75, were recruited for the study; their well water As concentrations ranged from 0.1 to 864 ug/L. Since 2000, each participant has been evaluated roughly every other year. A total of 7.31, 9.95 and 2.03% of the participants completing 4 years of active follow-up reported having a chronic cough, breathing problem or blood in their sputum, respectively, as assessed by trained physicians. We found a dose-response relationship between As exposure and clinical symptoms of respiratory diseases (2). The mechanism of this effect, also reported in other countries, is not known. In particular, these adverse respiratory effects of As were clearly evident in the low to moderate dose range. We have also studied the association between As exposure and total mortality. 407 deaths were ascertained between October 2000 and February 2009. Multivariate adjusted hazard ratios for all-cause mortality in a comparison of arsenic at concentrations of 10•1–50•0 μg/L, 50•1–150•0 μg/L, and 150•1–864•0 μg/L with at least 10•0 μg/L in well water were 1•34 (95% CI 0•99–1•82), 1•09 (0•81–1•47), and 1•68 (1•26–2•23), respectively (3). Deaths due to diseases of circulatory system accounted for 43% of total mortality in the population. The mortality rate for cardiovascular disease was 214.3 per 100 000 person years in people drinking water containing <12.0 μg/L arsenic, compared with 271.1 per 100 000 person years in people drinking water with ≥12.0 μg/L arsenic. There was a dose-response relation between exposure to arsenic in well water assessed at baseline and mortality from ischaemic heart disease and other heart disease (4). The children of HEALS participants have been involved in several cross-sectional studies that examined the relationships between As exposure and several neuropsychological outcomes. We have observed dose-dependent deficits in intelligence in 8- to 11-year-old children (5, 6) and in 6-year-old children (7). More recently, we have also investigated the associations of water As and water manganese (Mn) with motor function in 304 children in Bangladesh, aged 8 to 11 years. In addition to water, we measured As and Mn concentrations in blood, urine and toenails. We assessed motor function with the Bruininks-Oseretsky Test (BOT-2), which can be summarized with a total score of overall motor proficiency (TMC) or in four subscales: fine manual control (FMC), manual co-ordination (MC), body co-ordination (BC) and strength and agility (SA). After adjustment for covariates, water As (but not Mn) levels were associated with decreases in FMC, BC and TMC; similar findings were observed when we used urinary or blood As as the exposure measure (8). Collectively, the findings from the HEALS study and a growing body of basic science and population-based evidence indicate the urgent need to provide As-free drinking water to the many affected populations around the world.
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Impact of Air Pollution on Health of Children – Czech Experience
By Radim J SramAbstractThe Ostrava region in northern Moravia (Silesia) is the most polluted region in the Czech Republic by carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) as benzo[a]pyrene (B[a]P), especially by the steel industry. In the most polluted part of Ostrava City, Bartovice (OB), in the year 2008 was B[a]P 9.3±14.4 ng/ m3 vs control district of Prachatice (PRA) in the southern Bohemia, where B[a]P was 1.0±1.3 ng/ m3. We studied a group of 200 children living in OB (100 asthmatic and 100 healthy, aged eight-15 years) and a control group of 200 children living in PRA(100 asthmatic and 100 healthy, aged eight-15 years). As biomarkers of oxidative damage were followed 8-oxodG in urine, lipid peroxidation and protein oxidation in plasma, as biomarkers of effect gene expression profiles in lymphocytes using Illumina HumanHT-12 BeadChip and genetic polymorphisms in 768 SNPs by Illumina GoldenGate Assay. Oxidative damage by 8-oxodG was significantly higher in OB vs PRA (OR=2.27, P<0.001, 95%CI 1.40-3.70). Gene expression profiles significantly differ between OB and PRA. Comparing asthmatic vs control children, we observed nine deregulated genes in Ostrava and 17 deregulated genes in Prachatice. These changed genes are specific for each locality and asthma. Microarray results were verified by qPCR, five genes selected for Ostrava, another five for Prachatice. The verification confirmed previous results. In the asthmatic children from Ostrava were upregulated genes HPG2, AHSP and DEFA4. In the asthmatic children from Prachatice were upregulated genes SIGLEC8, CCL23, CLC and CACNG6. Gene expression profiles of asthma children seem to be specific and different in two regions. We detected also SNPs specific for the asthma children in OB. Results indicate that higher exposure to c-PAHs may induce non-allergic form of asthma bronchiale in children. We also studied the effect of exposure to B[a]P to DNA adducts, micronuclei and transcriptome in pregnancies from Prague and Ceske Budejovice. Exposure to B[a]P was three months before delivery 1.9±0.5 ng/m3 vs 3.2±0.2 ng/m3. Samples obtained from 35 mothers from Prague and 52 mothers from Ceske Budejovice were analyzed. All subjects were nonsmokers. DNA adducts were determined by 32P-postlabeling. Total DNA adducts were in cord blood 0.98±0.89 vs 1.40±1.31/108 nucleotides (p<0.001), in placentas 1.15±1.06 vs 1.94±1.80/108 nucleotides (p<0.001) from Prague and Ceske Budejovice, respectively. The frequencies of micronuclei (MN) determined by automated image analysis as MN per 1000 binucleated cells were 2.17±1.32 3.82±2.43 (p<0.001) for newborns from Prague and Ceske Budejovice, respectively. Using microarrays we assayed gene expression profiles in peripheral blood and placentas of the mothers, and in cord blood of their newborns. Comparative analysis of the profiles between the areas indicated that the pregnancies from Ceske Budejovice showed up-regulation of genes whose activity is associated with exposure to genotoxic compounds (eg, genes for xenobiotic enzymes, compensation of oxidative stress and inflammatory factors). This finding corresponded with the increased level of DNA adducts as well as micronuslei detected in the cord blood from Ceske Budejovice.
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Establishing a Toxins in Desert Environments (TIDE) Network in Qatar
By Renee RicherAbstractObjectives: To establish a forum to discuss issues and share information related to research on Toxins in Desert Environments (TIDE network). Methods: We will solicit researchers, students, educators, and dignitaries who have published and studied desert toxins or have expressed an interest in toxins and deserts, to join a network to encourage research and an understanding of toxins in desert environments. We will target a variety of disciplines, including microbiology, zoology, botany, chemistry, anthropology, sociology, and toxicology. We will establish an interactive website to facilitate communication and hold a yearly workshop and conference in Qatar to build networking capacity and promote the network. The conference will be a three-day event including a keynote speaker and a guided field trip. Results: Topics will include information, and showcase current research and future needs for education and research on a variety of toxins as it relates to plants, animals, and people in desert environments. Human and ecosystem health will be an important focus of this group and attempts at protection and remediation will be discussed. This network will encourage and promote researchers interested in desert environments and natural and man-made toxins. Participants will liaise with other researchers and educators and foster links to maximize resources and disseminate information. Conclusions: The goal will be to cross disciplines and broaden discussions to develop a network of scientists, create international interest in the region and involve local scientists, students, and dignitaries. The desire is to establish Qatar as a center for research concerning a wide range of natural and anthropogenic toxins found in desert environments. The TIDE network will promote research, conservation and public outreach, and be a center to support scientists, students and media. The network will benefit the State of Qatar locally, but it will also draw international attention to the facilities and opportunities present, while protecting the citizens of Qatar from the potential adverse effects of toxins.
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Genotoxic Evaluation of Occupational Exposure to Antineoplastic Agents and its Association with Polymorphisms of Enzymes Involved in DNA Repair
More LessAbstractThe increased use of combined chemotherapy in the management of different kinds of neoplasms allows us to question the adverse biological effects of occupational exposure to antineoplastic drugs, and generate studies to visualize the potential toxicity of these substances on the affected staff. Over the last few years, several reports have provided evidence about the increased presence of abortions, malformations and risk of diseases like cancer in the hospital staff responsible for the preparation and administration of these drugs. For that reason it becomes necessary to implement new methodologies to assess the genotoxic potential of these substances. Because of its sensitivity to detect mainly single chain ruptures and al-alkali labile sites in individual cells, the alkaline comet essay is an inexpensive and rapid method to evaluate the effects of these substances on the DNA of occupationally exposed staff. The aim of this study was to evaluate DNA damage in a population of individuals employed in oncology units in the city of Bogotá, Colombia and compare it with a control group. Due to genetic variants possibly determining the response to DNA damage we studied the possible effect of polymorphisms of repair genes XRCC1 and XRCC3 on damage levels of genetic material. Some characteristics and confounding factors such as age, gender, alcohol consumption, smoking, and exercise routines were also taken into account. Peripheral blood samples were obtained from 40 people between exposed workers and people from the control group. The comet essay was performed using isolated lymphocytes, for which the samples were embedded in agarose and placed on a glass slide; then they were exposed to lysis with detergent solution and finally subjected to an electric current with an alkaline buffer. The genotyping for XRCC1 and XRCC3 genes was performed by PCR-RFLP. Compared with those of the control group, partial results of exposed personnel evaluations show a significant increase in DNA damage. No influence of age, gender or time exposure was observed on the results of the comet essay. The presence of the XRCC1 polymorphism was associated with the increase of genotoxic effects of these substances, generating a greater individual susceptibility to the undesirable effect of dangerous agents. The results suggest that occupational exposure to antineoplastic drugs without the appropriate security measures can be a high risk to human health.
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Prevention of Waterborne Disease: translating Research into Public Health Policy
By Paul HunterAbstractWaterborne disease is a major contributor to the disease burden globally, causing substantial morbidity and mortality. Whilst of most of this burden of disease falls on the very young in the poorest countries, outbreaks of waterborne disease continue to affected wealthy nations. The main influencing agency in public health policy globally is the World Health Organization (WHO). Although WHO has no statutory or legislative power with regard to water safety and the prevention of waterborne disease, the guidance documents it publishes has a major impact on national legislation throughout the world with many countries simply transposing WHO guidance directly into law. This presentation considers how scientific advice may influence WHO guidance. Initially, we will consider the nature and strength of medical and public health scientific evidence, particularly focusing on the strengths and weaknesses of expert opinion and systematic review. Systematic reviews are potentially powerful tools for summarising scientific evidence. However, as with all tools they can be misused. Furthermore, even when properly conducted, it is still not always possible to translate such reviews directly into policy. We will then consider the issue of uncertainty in the scientific evidence. Some such uncertainties can be quantified, but others cannot. The precautionary principle is often heralded as the most appropriate approach to take in such issue but this leaves the question of how unlikely a risk or costly an intervention needs to be before this is set aside. One of the key issues regarding the formulation of good policy is the influence of political lobbying. Probably the most dramatic evidence of such lobbying comes for the disclosure concerning the activities of the tobacco industry which systematically abused the scientific evidence to prevent and delay public health interventions. Perhaps a modern day example of this is the political manoeuvring over the Climate Change issue. However, lobbying is not always one- sided and other lobby groups may push for public health interventions that are not warranted. The issues will be illustrated with recourse to two case studies, one centring on Household Water Treatment and the other on the issue of the health benefits of Magnesium in drinking water. A strategic approach to incorporating scientific evidence into public health policy formulation will be set out that will include approaches such as the GRADE scheme to quantify the strength of scientific evidence and cope with uncertainty in the evidence base.
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What Causes Seasonal Variation in Disease Prevalence and Rapid Evolutionary Changes in Virulence Mycoplasma gallisepticum?
By Andre DhondtAbstractBackground: Mycoplasma gallisepticum is a widespread bacterial pathogen that is economically important in poultry. A novel strain, causing severe conjunctivitis in wild passerines, emerged in 1994, and spread rapidly across eastern North America. In house finches the pathogen causes severe conjunctivitis. As the epidemic spread through the eastern (introduced) part of the finch’s range it caused massive declines in host abundance. In 2002 it successfully spread to the western (native) range of the host. There it spread much more slowly and disease prevalence and effects on host abundance are much lower than in the east. Mycoplasmal conjunctivitis in house finches is a system with strong seasonal variation: conjunctivitis prevalence is minimal (often zero) during the breeding season (April July); In late summer and fall, prevalence increases gradually reaching a maximum in October to November. In December, prevalence reaches a new low, followed by a second smaller peak in late February and early March, after which prevalence returns to the breeding season minimum. The objective was to 1. determine the factors driving seasonal variation in disease prevalence, and test the hypothesis that relapse of recovered individuals can be the origin of fall epidemics; and 2. determine factors driving changes in virulence once the disease is established. In the first study, birds not previously exposed to Mycoplasma gallisepticum were held in large aviaries. After one individual had been inoculated and horizontal transmission had caused all birds in the group to be exposed, birds recovered and were allowed to breed. In September naïve juveniles were added to the group and to test if the recovered adults would infect them. In March, when disease prevalence was declining naturally, Mycoplasma gallisepticum was reintroduced in the flock. In the second study, birds were sequentially exposed with two Mycoplasma gallisepticum strains that differed in virulence to test for cross‐immunity between strains. The first result showed n naive juveniles added to a flock of asymptomatic, fully recovered adults became infected with Mycoplasma gallisepticum showing that previously‐exposed, recovered and asymptomatic individuals can be the source of a new epidemic. The introduction of Mycoplasma gallisepticum in March, when in the wild disease prevalence is low to zero, caused a new outbreak whereby previously exposed and recovered individuals relapsed. The second result showed that after recovery individuals reinfected with a more virulent strain became very sick, while individuals reinfected with a less virulent strain were resistant to reinfection. We drew two conclusions from the study. First, that asymptomatic individuals can be the source of a new outbreak. The introduction of the pathogen in recovered groups is sufficient to cause a new disease outbreak. Seasonality in outbreaks is most likely tightly linked to seasonal variation in bird movements and behavior, rather than with external seasonal drivers. Secondly, in this system there exists partial cross‐immunity, whereby more virulent strains are able to cause disease in individuals recovered from a previous infection with a less virulent one. This result has two implications. First partial cross‐immunity selects for more virulent strains in nature. Second, incomplete vaccination would also cause an increase in pathogen virulence, which might have implications for vaccination strategies in humans.
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Effect of TiO2 Nanoparticles in Human Cells from Healthy Individuals and Patients with Respiratory Diseases
More LessAbstractNanotechnology has preceded nanotoxicology and little is known of the effects of nanoparticles in human systems, let alone in diseased individuals. Therefore, the effects of titanium dioxide (TiO2) nanoparticles in peripheral blood lymphocytes from patients with respiratory diseases (lung cancer, chronic obstructive pulmonary disease (COPD) and asthma) were compared with those in healthy Individuals to determine differences in sensitivity to insult from nanoparticles. Ethical permission was obtained to collect peripheral blood lymphocytes from respiratory disease patients and healthy individuals. The Comet assay was performed according to guidelines recommended by Tice et al (1). The micronucleus assay was conducted according to Fenech (2) and ras oncoprotein detection according to Anderson et al (3). The means of Olive tail moments and % tail DNA in peripheral blood lymphocytes were compared in the Comet assay after treatment for 30 minutes with different non-cytotoxic TiO2 concentrations (10, 30 and 50 µg/ml), as well as the negative control of untreated lymphocytes and the positive control of 80 µM (2.72 µg/ml) H2O2 . The results showed statistically significant concentration–dependent DNA damaging effects of TiO2 in both respiratory patient and healthy control groups. In the micronucleus (CBMN) assay, micronuclei (MN) per 1000 binucleated cells of healthy controls, lung cancer, COPD and asthma patients were examined after treatment of blood cultures with two different TiO2 concentrations (5 and 10µg/ml), as well as the negative control of untreated blood cultures and the positive control of 0.4 µM MMC. There was an increase in micronuclei without statistical significance when compared with the untreated control of the patients, but with significance when compared with the negative control of healthy individuals. Furthermore, when modulation of ras p21 expression was investigated, regardless of TiO2 treatment, only lung cancer and COPD patients expressed measurable ras p21 levels.
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Environmental Determinants of Malaria Transmission in Africa
More LessAbstractA new mechanistic and spatially-explicit model of hydrological and entomological processes that lead to malaria transmission has been developed recently at MIT. This unique model was tested against field observations from Africa. HYDREMATS (Hydrology, Entomology, and Malaria Transmission Simulator) is described in (Bomblies, Duchemin, and Eltahir, WRR, 44, 2008). HYDREMATS is suitable for low cost screening of environmental management interventions, and for studying the impact of climate change on malaria transmission. Examples of specific applications will be presented for two villages from Niger in Africa.
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Insects as model animals to examine the harmful effects of agricultural pesticides on the environment
More LessAbstractChanges in modern agricultural practice have allowed an increased production of fertilizers, herbicides and other pesticides causing important negative effects on the environment worldwide. Organic fertilizers are also extensively applied to agricultural lands, but they can contain bacteria and a large variety of microbial communities and parasites that can be rather pathogenic for wildlife. Also, because trace elements are often added to poultry diets to increase resistance to diseases of farm animals, poultry litter can also contain trace elements which are potentially toxic to living systems when present in high concentrations. We have examined experimentally the effect of commonly used mixtures of organic and mineral fertilizers and herbicides on the mortality of insects. Mealworms of Tenebrio molitor (n = 300) were exposed for four weeks to four different treatments: organic liquid fertilizer (pig manure), organic solid fertilizer (turkey litter), mineral fertilizer (nitrates), and herbicides (a mixture of glyphosate and 2, 4-D). After four weeks in direct contact with all treatments, mealworm mortality ranged from 74 percent to 88 percent. Surprisingly, control mealworms placed in the same room with the other treatments also experienced high mortality (72 percent) while mortality of control-isolated mealworms was low (eight percent), suggesting that volatile compounds from tested products can be noxious to insects. Our results also indicate that more individuals escaped from the herbicides and nitrate treatments than from the others, suggesting some kind of behavioural avoidance of toxic environments. The traditional organic fertilizers appear to be less toxic than inorganic fertilizers for the species studied. Organic fertilizers from farms should be adequately treated before being dispersed into the environment. Also, mineral fertilizers and herbicides should be used with moderation and well in the prescribed proportions to reduce their damage to the environment.
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The Relevance of the Deer as an Animal Model for Studying the Contaminant Effect on Early Embryo Development
More LessAbstractNowadays, environmental contaminants are a ubiquitous part of the ecological scenario, as is the ability of many of these chemicals to alter embryo development. There is therefore a need for researching and clarifying the effects of contaminants during different phases of early embryo development in humans. The use of alternative animal models may provide new insights into research on human embryo development, and the Iberian red deer may be a viable option. The main advantage of this animal model is the availability of samples which have not been sacrificed for this purpose, as we have access to samples (mature spermatozoa and oocytes) from animals killed during hunting activities. Therefore, our aim was to optimize the system that allows us to carry out in vitro fertilization (IVF) in deer, to then assess the effect of different contaminants on embryonic development. The aim of this work was to test two different oxygen concentrations (5 percent or 20 percent) on the in vitro fertilization. We have also assessed the addition, or not, of fetal calf serum (FCS) during embryo culture after IVF. Ovaries and testicles were transported to the laboratory at 20 ºC. Oocytes were matured in TCM 199 supplemented with 10 percent foetal calf serum, 100 mM cysteamine and 10 µgmL-1 FSH and LH during 24 h with 20 percent CO2. Matured oocytes were inseminated with thawed epididymal spermatozoa during 18 h at 38.5ºC with 5 percent or 20 percent O2.The presumptive embryos were cultured with synthetic oviductal fluid (SOF) supplemented with FCS at 0 hour, at 2 days post insemination (d.p.i.), 4 d.p.i. and without FCS at 38.5ºC with 5 percent CO2. Our results showed that treatment rendering best results for cleavage and blastocyst rates included five percent oxygen and embryo culture without fetal calf serum, as these conditions are quite similar to those used in human IVF. In conclusion, the optimization of the in vitro embryo development system in deer might prove useful information for the role of contaminants during this critical physiological period. Alternative animal models may contribute to advance our understanding of the effect of contaminants on early embryo development in humans.
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Maintaining Drug Quality Standards
More LessAbstractMedicines are manufactured, sold, distributed, and dispensed across the globe today, bringing enormous benefits for patients. However, this globalisation has also increased the spread and prevalence of medicines that are unsafe or may be ineffective. Substandard medicines, according to the WHO, are “products whose composition and ingredients do not meet the correct scientific specifications and which are consequently ineffective and often dangerous to the patient”. Substandard drugs are able to gain approval in countries that do not have robust regulatory standards for drug quality. Legitimate generic medicines meet accepted regulatory standards, typically through bioequivalence evaluation with rigorous identity and quality testing verified by a stringent regulatory evaluation process. These quality drugs provide a vital and cost-effective way to meet the pharmaceutical needs of patients around the world. Substandard medicines can arise due to the lack of scientific expertise of the manufacturer, problems with the manufacturing processes and/or quality and testing system deficiencies. The negative consequences of substandard drugs are serious and can contribute to significant mortality and morbidity due to treatment failure, toxicity or promotion of drug resistance. The theoretical scientific concerns regarding comparability between different versions of drugs containing the same active ingredient (originator, generic or substandard) have been borne out in investigations of the purity and clinical performance of specific copies relative to the originator drug. These studies can reveal insight into the extent to which substandard drugs have become available around the world and the impact they can have on healthcare. This presentation will present an overview of the healthcare issues that arise due to substandard drugs. The presentation will give examples of clinical and technical issues that give rise to substandard drugs and the potential impact of these formulations on individual patients and healthcare systems.
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Health Impact of Substandard Medicines in the Developing World: Risk of Genotoxic Impurities
More LessAbstractSubstandard medicines are becoming a global concern that is particularly endemic in developing countries. According to the WHO Substandard medicines are genuine drugs produced by legitimate manufacturers which do not meet the recognized quality and purity standards. A substandard drug is a medicine that does not meet specifications necessary to ensure quality, efficacy and safety; has not demonstrated bioequivalence to the originator; or does not have sufficient evidence to demonstrate originator data can be referenced. In general the substandard drugs are copies of medicines that have been approved in countries with limited regulatory standards and thus might not be made to high quality standards or be sufficiently tested to be approved in countries with more stringent regulatory standards and controls, eg, US, EU, Japan, and Australia. The synthesis of pharmaceutical products frequently involves the use of reactive reagents and the formation of intermediates and by-products. Low levels of some of these may be present in the final drug substance and/or drug product as impurities resulting either from the synthesis process or from degradation. Such chemically reactive impurities may have the potential for unwanted toxicities including genotoxicity and carcinogenicity. So, besides not providing any benefit to patients they may, if not tightly controlled, be hazardous. The pharmaceutical industry and the regulatory agencies (e.g. US-FDA, EMA) recognize their respective obligation to limit specifically genotoxic impurities. Therefore, substantial efforts are made during development to control all impurities at safe concentrations. Control of impurities in the drug substance and degradants in drug product are addressed in the respective ICH Quality Guidelines. Justification of limits per these ICH guidelines is normally based on the qualification of batches of the active pharmaceutical ingredient including its impurities in pivotal toxicity studies that include genetic toxicology tests. According to current regulatory practice it is assumed that genotoxic compounds with a direct interaction with DNA have the potential to damage DNA at any level of exposure and that such damage may lead/contribute to tumor development. Therefore the use of poor quality and potentially harmful substandard medicines especially with high levels of genotoxic impurities could lead to therapeutic failure, exacerbation of disease, resistance to medicines and sometimes death.
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