Genomic chaos in peripheral blood lymphocytes of Hodgkin's lymphoma patients one year after ABVD chemotherapy/radiotherapy

Hodgkin's lymphoma (HL) is a lymphoid malignancy representing 5% of all cancers in children, 16% in adolescents, and 30-40% of all malignant lymphomas and has a survival rate of ~95% at 10 years. One of the most common treatment schemes uses a cocktail of genotoxic agents including adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) with or without radiotherapy. We investigated the occurrence of chromosomal damage in peripheral blood lymphocytes from five patients diagnosed with HL who provided samples before (BT), during chemotherapy (DT) and ~1 year after ABVD chemotherapy/radiotherapy (AT). Five healthy subjects served as controls. Chromosomal abnormalities were evaluated by multicolor fluorescence in situ hybridization. The average frequencies of structural chromosomal aberrations in HL samples were 0.11, 0.22, and 0.96 per cell in BT, DT, and AT samples, respectively. These frequencies were significantly different (P < 0.0001) with respect to control subjects (0.02 per cell). Interestingly, the highest frequency of structural damage, including genomic chaos and nonclonal abnormalities, was observed in the AT samples indicating that new aberrations were continuously produced. Rejoined structural chromosomal aberrations were the most common type of aberrations, although aneuploidies were also significantly increased. Finally, we found several chromosomal abnormalities linked to cancer secondary to treatment in all five HL patients. Our results show that ABVD chemotherapy plus radiotherapy is inducing genomic chaos in vivo; moreover, the persistence of genomic instability in the hematopoietic stem cells from HL patients may play a role in the occurrence of secondary cancer that is observed in 5-20% of HL patients. Environ. Mol. Mutagen. 59:755-768, 2018. © 2018 Wiley Periodicals, Inc.

Integration of sperm DNA damage assessment into OECD test guidelines for genotoxicity testing using the MutaMouse model

The Organisation for Economic Co-operation and Development (OECD) endorses test guidelines (TG) for identifying chemicals that are genotoxic, such as the transgenic rodent gene mutation assay (TG 488). Current OECD TG do not include assays for sperm DNA damage resulting in a critical testing gap. We evaluated the performance of the Sperm Chromatin Structure Assay (SCSA) and the Terminal Deoxynucleotidyl Transferase-Mediated Deoxyuridine Triphosphate Nick end Labeling (TUNEL) assay to detect sperm DNA damage within the recommended TG 488 protocol. MutaMouse males received 0, 0.5, 1, or 2 mg/kg/day triethylenemelamine (TEM), a multifunctional alkylating agent, for 28 days orally and tissues were collected two (blood) and three (sperm and bone marrow) days later. TEM significantly increased the frequency of lacZ mutants in bone marrow, and of micronuclei (MN) in both reticulocytes (%MN-RET) and normochromatic erythrocytes (%MN-NCE) in a dose-dependent manner (P < 0.05). The percentage of DNA fragmentation index (%DFI) and %TUNEL positive cells demonstrated dose-related increases in sperm (P < 0.05), and the two assay results were strongly correlated (R = 0.9298). Within the same animal, a good correlation was observed between %MN-NCE and %DFI (R = 0.7189). Finally, benchmark dose modelling (BMD) showed comparable BMD₁₀ values among the somatic and germ cell assays. Our results suggest that sperm DNA damage assays can be easily integrated into standard OECD designs investigating genotoxicity in somatic tissues to provide key information on whether a chemical is genotoxic in germ cells and impact its risk assessment.

Discovering human germ cell mutagens with whole genome sequencing: Insights from power calculations reveal the importance of controlling for between-family variability

Mutations in germ cells pose potential genetic risks to offspring. However, de novo mutations are rare events that are spread across the genome and are difficult to detect. Thus, studies in this area have generally been under-powered, and no human germ cell mutagen has been identified. Whole Genome Sequencing (WGS) of human pedigrees has been proposed as an approach to overcome these technical and statistical challenges. WGS enables analysis of a much wider breadth of the genome than traditional approaches. Here, we performed power analyses to determine the feasibility of using WGS in human families to identify germ cell mutagens. Different statistical models were compared in the power analyses (ANOVA and multiple regression for one-child families, and mixed effect model sampling between two to four siblings per family). Assumptions were made based on parameters from the existing literature, such as the mutation-by-paternal age effect. We explored two scenarios: a constant effect due to an exposure that occurred in the past, and an accumulating effect where the exposure is continuing. Our analysis revealed the importance of modeling inter-family variability of the mutation-by-paternal age effect. Statistical power was improved by models accounting for the family-to-family variability. Our power analyses suggest that sufficient statistical power can be attained with 4-28 four-sibling families per treatment group, when the increase in mutations ranges from 40 to 10% respectively. Modeling family variability using mixed effect models provided a reduction in sample size compared to a multiple regression approach. Much larger sample sizes were required to detect an interaction effect between environmental exposures and paternal age. These findings inform study design and statistical modeling approaches to improve power and reduce sequencing costs for future studies in this area.

Folate deficiency increases chromosomal damage and mutations in hematopoietic cells in the transgenic mutamouse model

Folate deficiency causes megaloblastic anemia and neural tube defects, and is also associated with some cancers. In vitro, folate deficiency increases mutation frequency and genome instability, as well as exacerbates the mutagenic potential of known environmental mutagens. Conversely, it remains unclear whether or not elevated folic acid (FA) intakes are beneficial or detrimental to the induction of DNA mutations and by proxy human health. We used the MutaMouse transgenic model to examine the in vivo effects of FA deficient, control, and supplemented diets on somatic DNA mutant frequency (MF) and genome instability in hematopoietic cells. We also examined the interaction between FA intake and exposure to the known mutagen N-ethyl-N-nitrosourea (ENU) on MF. Male mice were fed the experimental diets for 20 weeks from weaning. Half of the mice from each diet group were gavaged with 50 mg/kg body weight ENU after 10 weeks on diet and remained on their respective diet for an additional 10 weeks. Mice fed a FA-deficient diet had a 1.3-fold increase in normochromatic erythrocyte micronucleus (MN) frequency (P = 0.034), and a doubling of bone marrow lacZ MF (P = 0.035), compared to control-fed mice. Mice exposed to ENU showed significantly higher bone marrow lacZ and Pig-a MF, but there was no effect of FA intake on ENU-induced MF. These data indicate that FA deficiency increases mutations and MN formation in highly proliferative somatic cells, but that FA intake does not mitigate ENU-induced mutations. Also, FA intake above adequacy had no beneficial or detrimental effect on mutations or MN formation. Environ. Mol. Mutagen. 59:366-374, 2018. © 2018 Her Majesty the Queen in Right of Canada 2018.

Dose-response mutation and spectrum analyses reveal similar responses at two microsatellite loci in benzo(a)pyrene-exposed mouse spermatogonia

Identifying chemical exposures that can cause germline mutations is important as these mutations can be inherited, impacting both individual and population health. However, germline mutations are extremely rare and difficult to detect. Chemically induced germline mutations can be detected through analysis of highly unstable tandem repeat DNA. We recently developed a single-molecule PCR (SM-PCR) approach to quantify mutations at a mouse microsatellite locus (Mm2.2.1) in sperm for such purposes. In this study, we refine this approach through the combined analysis of mouse microsatellites Mm2.2.1 and Mm19.2.3. Mice were exposed to 0, 25, 50 or 100 mg/kg/day benzo(a)pyrene (BaP) by oral gavage for 28 days and sperm sampled 42 days after the end of exposure to measure effects on dividing spermatogonia. DNA was diluted to a single genome per PCR well for amplification of microsatellites in singleplex and multiplex reactions, and alleles were sized to identify mutations using capillary electrophoresis. Analysis of ~300-500 molecules per animal at both microsatellite loci, when tested individually, showed a ~2-fold increase in mutations relative to the controls at both the 50 and 100 mg/kg/day BaP doses. Multiplex SM-PCR revealed similar increases in mutation frequencies in both microsatellites. Comparison with results from a previous lacZ mutation assay conducted on the same mice revealed that although microsatellite mutations are a sensitive endpoint for detecting changes in mutation frequencies at lower doses, they appear to be saturable and thus have a reduced dynamic range. These results confirm that BaP is a male germ cell mutagen that broadly impacts tandem repeat DNA. Likewise, addition of a second hypervariable microsatellite increases the sensitivity of this assay.

Analysis of negative historical control group data from the in vitro micronucleus assay using TK6 cells

The recent revisions of the Organisation for Economic Co-operation and Development (OECD) genetic toxicology test guidelines emphasize the importance of historical negative controls both for data quality and interpretation. The goal of a HESI Genetic Toxicology Technical Committee (GTTC) workgroup was to collect data from participating laboratories and to conduct a statistical analysis to understand and publish the range of values that are normally seen in experienced laboratories using TK6 cells to conduct the in vitro micronucleus assay. Data from negative control samples from in vitro micronucleus assays using TK6 cells from 13 laboratories were collected using a standard collection form. Although in some cases statistically significant differences can be seen within laboratories for different test conditions, they were very small. The mean incidence of micronucleated cells/1000 cells ranged from 3.2/1000 to 13.8/1000. These almost four-fold differences in micronucleus levels cannot be explained by differences in scoring method, presence or absence of exogenous metabolic activation (S9), length of treatment, presence or absence of cytochalasin B or different solvents used as vehicles. The range of means from the four laboratories using flow cytometry methods (3.7-fold: 3.5-12.9 micronucleated cells/1000 cells) was similar to that from the nine laboratories using other scoring methods (4.3-fold: 3.2-13.8 micronucleated cells/1000 cells). No laboratory could be identified as an outlier or as showing unacceptably high variability. Quality Control (QC) methods applied to analyse the intra-laboratory variability showed that there was evidence of inter-experimental variability greater than would be expected by chance (i.e. over-dispersion). However, in general, this was low. This study demonstrates the value of QC methods in helping to analyse the reproducibility of results, building up a 'normal' range of values, and as an aid to identify variability within a laboratory in order to implement processes to maintain and improve uniformity.

From sperm to offspring: Assessing the heritable genetic consequences of paternal smoking and potential public health impacts

Individuals who smoke generally do so with the knowledge of potential consequences to their own health. What is rarely considered are the effects of smoking on their future children. The objective of this work was to review the scientific literature on the effects of paternal smoking on sperm and assess the consequences to offspring. A literature search identified over 200 studies with relevant data in humans and animal models. The available data were reviewed to assess the weight of evidence that tobacco smoke is a human germ cell mutagen and estimate effect sizes. These results were used to model the potential increase in genetic disease burden in offspring caused by paternal smoking, with specific focus on aneuploid syndromes and intellectual disability, and the socioeconomic impacts of such an effect. The review revealed strong evidence that tobacco smoking is associated with impaired male fertility, and increases in DNA damage, aneuploidies, and mutations in sperm. Studies support that these effects are heritable and adversely impact the offspring. Our model estimates that, with even a modest 25% increase in sperm mutation frequency caused by smoke-exposure, for each generation across the global population there will be millions of smoking-induced de novo mutations transmitted from fathers to offspring. Furthermore, paternal smoking is estimated to contribute to 1.3 million extra cases of aneuploid pregnancies per generation. Thus, the available evidence makes a compelling case that tobacco smoke is a human germ cell mutagen with serious public health and socio-economic implications. Increased public education should be encouraged to promote abstinence from smoking, well in advance of reproduction, to minimize the transmission of harmful mutations to the next-generation.

Next generation testing strategy for assessment of genomic damage: A conceptual framework and considerations

For several decades, regulatory testing schemes for genetic damage have been standardized where the tests being utilized examined mutations and structural and numerical chromosomal damage. This has served the genetic toxicity community well when most of the substances being tested were amenable to such assays. The outcome from this testing is usually a dichotomous (yes/no) evaluation of test results, and in many instances, the information is only used to determine whether a substance has carcinogenic potential or not. Over the same time period, mechanisms and modes of action (MOAs) that elucidate a wider range of genomic damage involved in many adverse health outcomes have been recognized. In addition, a paradigm shift in applied genetic toxicology is moving the field toward a more quantitative dose-response analysis and point-of-departure (PoD) determination with a focus on risks to exposed humans. This is directing emphasis on genomic damage that is likely to induce changes associated with a variety of adverse health outcomes. This paradigm shift is moving the testing emphasis for genetic damage from a hazard identification only evaluation to a more comprehensive risk assessment approach that provides more insightful information for decision makers regarding the potential risk of genetic damage to exposed humans. To enable this broader context for examining genetic damage, a next generation testing strategy needs to take into account a broader, more flexible approach to testing, and ultimately modeling, of genomic damage as it relates to human exposure. This is consistent with the larger risk assessment context being used in regulatory decision making. As presented here, this flexible approach for examining genomic damage focuses on testing for relevant genomic effects that can be, as best as possible, associated with an adverse health effect. The most desired linkage for risk to humans would be changes in loci associated with human diseases, whether in somatic or germ cells. The outline of a flexible approach and associated considerations are presented in a series of nine steps, some of which can occur in parallel, which was developed through a collaborative effort by leading genetic toxicologists from academia, government, and industry through the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) Genetic Toxicology Technical Committee (GTTC). The ultimate goal is to provide quantitative data to model the potential risk levels of substances, which induce genomic damage contributing to human adverse health outcomes. Any good risk assessment begins with asking the appropriate risk management questions in a planning and scoping effort. This step sets up the problem to be addressed (e.g., broadly, does genomic damage need to be addressed, and if so, how to proceed). The next two steps assemble what is known about the problem by building a knowledge base about the substance of concern and developing a rational biological argument for why testing for genomic damage is needed or not. By focusing on the risk management problem and potential genomic damage of concern, the next step of assay(s) selection takes place. The work-up of the problem during the earlier steps provides the insight to which assays would most likely produce the most meaningful data. This discussion does not detail the wide range of genomic damage tests available, but points to types of testing systems that can be very useful. Once the assays are performed and analyzed, the relevant data sets are selected for modeling potential risk. From this point on, the data are evaluated and modeled as they are for any other toxicology endpoint. Any observed genomic damage/effects (or genetic event(s)) can be modeled via a dose-response analysis and determination of an estimated PoD. When a quantitative risk analysis is needed for decision making, a parallel exposure assessment effort is performed (exposure assessment is not detailed here as this is not the focus of this discussion; guidelines for this assessment exist elsewhere). Then the PoD for genomic damage is used with the exposure information to develop risk estimations (e.g., using reference dose (RfD), margin of exposure (MOE) approaches) in a risk characterization and presented to risk managers for informing decision making. This approach is applicable now for incorporating genomic damage results into the decision-making process for assessing potential adverse outcomes in chemically exposed humans and is consistent with the ILSI HESI Risk Assessment in the 21st Century (RISK21) roadmap. This applies to any substance to which humans are exposed, including pharmaceuticals, agricultural products, food additives, and other chemicals. It is time for regulatory bodies to incorporate the broader knowledge and insights provided by genomic damage results into the assessments of risk to more fully understand the potential of adverse outcomes in chemically exposed humans, thus improving the assessment of risk due to genomic damage. The historical use of genomic damage data as a yes/no gateway for possible cancer risk has been too narrowly focused in risk assessment. The recent advances in assaying for and understanding genomic damage, including eventually epigenetic alterations, obviously add a greater wealth of information for determining potential risk to humans. Regulatory bodies need to embrace this paradigm shift from hazard identification to quantitative analysis and to incorporate the wider range of genomic damage in their assessments of risk to humans. The quantitative analyses and methodologies discussed here can be readily applied to genomic damage testing results now. Indeed, with the passage of the recent update to the Toxic Substances Control Act (TSCA) in the US, the new generation testing strategy for genomic damage described here provides a regulatory agency (here the US Environmental Protection Agency (EPA), but suitable for others) a golden opportunity to reexamine the way it addresses risk-based genomic damage testing (including hazard identification and exposure). Environ. Mol. Mutagen. 58:264-283, 2017. © 2016 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc.

Main issues addressed in the 2014-2015 revisions to the OECD Genetic Toxicology Test Guidelines

The Organization for Economic Cooperation and Development (OECD) recently revised the test guidelines (TGs) for genetic toxicology. This article describes the main issues addressed during the revision process, and the new and consistent recommendations made in the revised TGs for: (1) demonstration of laboratory proficiency; (2) generation and use of robust historical control data; (3) improvement of the statistical power of the tests; (4) selection of top concentration for in vitro assays; (5) consistent data interpretation and determination of whether the result is clearly positive, clearly negative or needs closer consideration; and, (6) consideration of 3R's for in vivo assay design. The revision process resulted in improved consistency among OECD TGs (including the newly developed ones) and more comprehensive recommendations for the conduct and the interpretation of the assays. Altogether, the recommendations made during the revision process should improve the efficiency, by which the data are generated, and the quality and reliability of test results. Environ. Mol. Mutagen. 58:284-295, 2017. © 2017 Wiley Periodicals, Inc.

Modular Synthesis of Diverse Natural Product-Like Macrocycles: Discovery of Hits with Antimycobacterial Activity

A modular synthetic approach was developed in which variation of the triplets of building blocks used enabled systematic variation of the macrocyclic scaffolds prepared. The approach was demonstrated in the synthesis of 17 diverse natural product-like macrocyclic scaffolds of varied (12-20-membered) ring size. The biological relevance of the chemical space explored was demonstrated through the discovery of a series of macrocycles with significant antimycobacterial activity.

In Utero Exposure to Benzo[a]Pyrene Increases Mutation Burden in the Soma and Sperm of Adult Mice

BACKGROUND

Mosaicism, the presence of genetically distinct cell populations within an organism, has emerged as an important contributor to disease. Mutational events occurring during embryonic development can cause mosaicism in any tissue, but the influence of environmental factors on levels of mosaicism is unclear.

OBJECTIVES

We investigated whether in utero exposure to the widespread environmental mutagen benzo[a]pyrene (BaP) has an impact on the burden and distribution of mutations in adult mice.

METHODS

We used the Muta™Mouse transgenic rodent model to quantify and characterize mutations in the offspring of pregnant mice exposed to BaP during postconception days 7 through 16, covering the major period of organogenesis in mice. Next-generation DNA sequencing was then used to determine the spectrum of mutations induced in adult mice that were exposed to BaP during fetal development.

RESULTS

Mutation frequency was significantly increased in the bone marrow, liver, brain, and sperm of first filial generation (F1) males. Developing embryos accumulated more mutations and exhibited higher proportions of mosaicism than exposed adults, particularly in the brain. Decreased sperm count and motility revealed additional negative impacts on the reproductive function of F1 males.

CONCLUSION

In utero exposure to environmental mutagens contributes to somatic and germline mosaicism, permanently affecting both the genetic health of the F1 and the population gene pool. Citation: Meier MJ, O'Brien JM, Beal MA, Allan B, Yauk CL, Marchetti F. 2017. In utero exposure to benzo[a]pyrene increases mutation burden in the soma and sperm of adult mice. Environ Health Perspect 125:82-88; http://dx.doi.org/10.1289/EHP211.

Next generation sequencing of benzo(a)pyrene-induced lacZ mutants identifies a germ cell-specific mutation spectrum

De novo mutations are implicated in a variety of genetic diseases and arise primarily in the male germline. We investigated whether male germ cells have unique mechanisms for spontaneous or chemically-induced mutation relative to somatic cells using the MutaMouse model. We recovered lacZ transgenes from sperm 42 days after a 28-day exposure to benzo(a)pyrene (BaP, 100 mg/kg/day) to assess mutations arising in dividing spermatogonia. BaP caused a 3.4-fold increase in lacZ mutant frequency over controls which increased to 4.1-fold after clonal correction. We then used next generation sequencing to compare the spontaneous and BaP-induced mutation spectra in sperm and bone marrow. The spontaneous spectrum in sperm had significantly more G:C to A:T transitions and fewer mutations at A:T basepairs than bone marrow. BaP predominantly induced G:C to T:A transversions in both cell types, and both were enriched for mutations at CpG dinucleotides. However, BaP induced significantly more deletions in sperm, but more G:C to A:T transitions and G:C to C:G transversions in bone marrow. Differences in error-prone translesion DNA synthesis polymerases may underlie the observed spectrum differences between sperm and bone marrow. These findings suggest that mutations in sperm can arise via mechanisms that are unique to male germ cells.

Mitochondrial DNA exhibits resistance to induced point and deletion mutations

The accumulation of somatic mitochondrial DNA (mtDNA) mutations contributes to the pathogenesis of human disease. Currently, mitochondrial mutations are largely considered results of inaccurate processing of its heavily damaged genome. However, mainly from a lack of methods to monitor mtDNA mutations with sufficient sensitivity and accuracy, a link between mtDNA damage and mutation has not been established. To test the hypothesis that mtDNA-damaging agents induce mtDNA mutations, we exposed Muta^TMMouse mice to benzo[a]pyrene (B[a]P) or N-ethyl-N-nitrosourea (ENU), daily for 28 consecutive days, and quantified mtDNA point and deletion mutations in bone marrow and liver using our newly developed Digital Random Mutation Capture (dRMC) and Digital Deletion Detection (3D) assays. Surprisingly, our results demonstrate mutagen treatment did not increase mitochondrial point or deletion mutation frequencies, despite evidence both compounds increase nuclear DNA mutations and demonstrated B[a]P adduct formation in mtDNA. These findings contradict models of mtDNA mutagenesis that assert the elevated rate of mtDNA mutation stems from damage sensitivity and abridged repair capacity. Rather, our results demonstrate induced mtDNA damage does not readily convert into mutation. These findings suggest robust mitochondrial damage responses repress induced mutations after mutagen exposure.

Haemodynamic CHIVA correction surgery versus compression for primary venous ulcers: first year results

Objective: To compare two different treatments for primary venous ulcers: a minimally invasive surgical technique for the haemodynamic correction of reflux, versus a traditional compression treatment.

Method: From a cohort of 87 lower extremities affected by the first episode of venous ulcers, 45 mobile patients affected by primary chronic venous insufficiency were randomized to receive either the haemodynamic correction procedure (CHIVA) or compression treatment.

Results: Mean follow up lasted one year. The rate of healing in the surgical group was 100% in a mean time of 29 days with a velocity of 2.86 mm2/day,and in the conservative group the rate was 96% in 61 days, with a velocity of 1.66 mm2/day ( P<0.02). All air plethysmographic parameters, with the exception of ejection fraction, significantly improved at six months in the surgical group. Finally, quality of life significantly improved in both groups, but in the surgical group the following domains were significantly different compared with the compression group: RP, role limitations due to physical problems; VT, energy/vitality; SF, social functioning; RE, role limitations due to emotional problems; and MH, mental health.

Conclusions: Surgical haemodynamic correction of reflux has been demonstrated to improve venous function, time to ulcer healing and quality of life when compared with compression treatment.

Benzo(a)pyrene Is Mutagenic in Mouse Spermatogonial Stem Cells and Dividing Spermatogonia

Although many environmental agents are established male germ cell mutagens, few are known to induce mutations in spermatogonial stem cells. Stem cell mutations are of great concern because they result in a permanent increase in the number of mutations carried in sperm. We investigated mutation induction during mouse spermatogenesis following exposure to benzo(a)pyrene (BaP). MutaMouse males were given 0, 12.5, 25, 50, or 100 mg/kg bw/day BaP for 28 days by oral gavage. Germ cells were collected from the cauda epididymis and seminiferous tubules 3 days after exposure and from cauda epididymis 42 and 70 days after exposure. This design enabled targeted investigation of effects on post-spermatogonia, dividing spermatogonia, and spermatogonial stem cells, respectively. BaP increased lacZ mutant frequency (MF) in cauda sperm after exposure of dividing spermatogonia (4.2-fold at highest dose, P < .01) and spermatogonial stem cells (2.1-fold at highest dose, P < .01). No significant increases in MF were detected in cauda sperm or seminiferous tubule cells collected 3 days post-exposure. Dose-response modelling suggested that the mutational response in male germ cells to BaP is sub-linear at low doses. Our results demonstrate that oral exposure to BaP causes spermatogonial stem cell mutations, that different phases of spermatogenesis exhibit varying sensitivities to BaP, with dividing spermatogonia representing a window of peak sensitivity, and that sampling spermatogenic cells from the seminiferous tubules at earlier time-points may underestimate germ cell mutagenicity. This information is critical to optimize the use of the international test guideline for transgenic rodent mutation assays for detecting germ cell mutagens.

The adverse outcome pathway (AOP) for chemical binding to tubulin in oocytes leading to aneuploid offspring

The Organisation for Economic Co-operation and Development (OECD) has launched the Adverse Outcome Pathway (AOP) Programme to advance knowledge of pathways of toxicity and improve the use of mechanistic information in risk assessment. An AOP links a molecular initiating event (MIE) to an adverse outcome (AO) through intermediate key events (KE). Here, we present the scientific evidence in support of an AOP whereby chemicals that bind to tubulin cause microtubule depolymerization resulting in spindle disorganization followed by altered chromosome alignment and segregation and the generation of aneuploidy in female germ cells, ultimately leading to aneuploidy in the offspring. Aneuploidy, an abnormal number of chromosomes that is not an exact multiple of the haploid number, is a well-known cause of human disease and represents a major cause of infertility, pregnancy failure, and serious genetic disorders in the offspring. Among chemicals that induce aneuploidy in female germ cells, a large majority impairs microtubule dynamics and spindle function. Colchicine, a prototypical chemical that binds to tubulin and causes microtubule depolymerization, is used here to illustrate the AOP. This AOP is specific to female germ cells exposed during the periovulation period. Although the majority of the data come from rodent studies, the available evidence suggests that the MIE and KEs are conserved across species and would occur in human oocytes. The development of AOPs related to mutagenicity in germ cells is expected to aid the identification of potential hazards to germ cell genomic integrity and support regulatory efforts to protect population health.

A ruthenium derivative of quercetin with enhanced cholesterol-lowering activity

A ruthenium(ii)p-cymene derivative of quercetin was synthesized and functionally tested for cholesterol-lowering abilityviadirect 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) inhibition.

Estimated costs attributable to events of "out-of-temperature" in the stockpiling of hexavalent vaccines occurring in Italy

BACKGROUND

Antigens contained in vaccines are inherently unstable biologically; such a characteristic is conferred by their three-dimensional structure. Preserving the ability of the vaccines to protect against disease is necessary to ensure the supervision and monitoring of all steps of the cold chain. DTPa-HBV-IPV/Hib vaccine (Infanrix hexaTM, GSK Vaccines, Belgium) is designed to prevent disease due to diphtheria, tetanus, pertussis (DTP), hepatitis B virus (HBV), poliomyelitis and Haemophilus influenzae type b (Hib); it was first licensed for use in Europe in 2000 and is currently licensed in at least 95 countries. Since October 2013, more than 102 million doses of GSK's DTPa-HBV-IPV/Hib vaccine have been distributed globally, with nearly 15 million doses distributed in Italy. DTPa-HBV-IPV/Hib components are stable up to a temperature of 25°C for 72 hours. Lacking of officially approved stability data may generate some concern in case of cold chain accidents.

METHODS

An analysis based on collected data was carried out to estimate potential costs attributable to events of "out-of-temperature" in the stockpiling of hexavalent vaccines occurring in Italy in 2014.

RESULTS

The analysis, based on real data, documented that the loss for the National Health Service (NHS) was in the range of 100,000 - 400,000 euros in one year. However, the amount of money that in principle could have been lost would have ranged between nearly half and one million euros/year.

CONCLUSIONS

A substantial loss of money was avoided thanks to the availability of officially approved stability data for GSK's DTPa-HBV-IPV/Hib vaccine.

Development of the adverse outcome pathway "alkylation of DNA in male premeiotic germ cells leading to heritable mutations" using the OECD's users' handbook supplement

The Organisation for Economic Cooperation and Development's (OECD) Adverse Outcome Pathway (AOP) programme aims to develop a knowledgebase of all known pathways of toxicity that lead to adverse effects in humans and ecosystems. A Users' Handbook was recently released to provide supplementary guidance on AOP development. This article describes one AOP-alkylation of DNA in male premeiotic germ cells leading to heritable mutations. This outcome is an important regulatory endpoint. The AOP describes the biological plausibility and empirical evidence supporting that compounds capable of alkylating DNA cause germ cell mutations and subsequent mutations in the offspring of exposed males. Alkyl adducts are subject to DNA repair; however, at high doses the repair machinery becomes saturated. Lack of repair leads to replication of alkylated DNA and ensuing mutations in male premeiotic germ cells. Mutations that do not impair spermatogenesis persist and eventually are present in mature sperm. Thus, the mutations are transmitted to the offspring. Although there are some gaps in empirical support and evidence for essentiality of the key events for certain aspects of this AOP, the overall AOP is generally accepted as dogma and applies broadly to any species that produces sperm. The AOP was developed and used in an iterative process to test and refine the Users' Handbook, and is one of the first publicly available AOPs. It is our hope that this AOP will be leveraged to develop other AOPs in this field to advance method development, computational models to predict germ cell effects, and integrated testing strategies.

Characterizing Benzo[a]pyrene-induced lacZ mutation spectrum in transgenic mice using next-generation sequencing

BACKGROUND

The transgenic rodent mutation reporter assay provides an efficient approach to identify mutagenic agents in vivo. A major advantage of this assay is that mutant reporter transgenes can be sequenced to provide information on the mode of action of a mutagen and to identify clonally expanded mutations. However, conventional DNA sequence analysis is laborious and expensive for long transgenes, such as lacZ (3096 bp), and is not normally implemented in routine screening.

METHODS

We developed a high-throughput next-generation sequencing (NGS) approach to simultaneously sequence large numbers of barcoded mutant lacZ transgenes from different animals. We collected 3872 mutants derived from the bone marrow DNA of six Muta™Mouse males exposed to the well-established mutagen benzo[a]pyrene (BaP) and six solvent-exposed controls. Mutants within animal samples were pooled, barcoded, and then sequenced using NGS.

RESULTS

We identified 1652 mutant sequences from 1006 independent mutations that underwent clonal expansion. This deep sequencing analysis of mutation spectrum demonstrated that BaP causes primarily guanine transversions (e.g. G:C → T:A), which is highly consistent with previous studies employing Sanger sequencing. Furthermore, we identified novel mutational hotspots in the lacZ transgene that were previously uncharacterized by Sanger sequencing. Deep sequencing also allowed for an unprecedented ability to correct for clonal expansion events, improving the sensitivity of the mutation reporter assay by 50 %.

CONCLUSION

These results demonstrate that the high-throughput nature and reduced costs offered by NGS provide a sensitive and fast approach for elucidating and comparing mutagenic mechanisms of various agents among tissues and enabling improved evaluation of genotoxins.

Hydroxyurea induces chromosomal damage in G2 and enhances the clastogenic effect of mitomycin C in Fanconi anemia cells

Fanconi's anemia (FA) is a recessive disease; 16 genes are currently recognized in FA. FA proteins participate in the FA/BRCA pathway that plays a crucial role in the repair of DNA damage induced by crosslinking compounds. Hydroxyurea (HU) is an agent that induces replicative stress by inhibiting ribonucleotide reductase (RNR), which synthesizes deoxyribonucleotide triphosphates (dNTPs) necessary for DNA replication and repair. HU is known to activate the FA pathway; however, its clastogenic effects are not well characterized. We have investigated the effects of HU treatment alone or in sequential combination with mitomycin-C (MMC) on FA patient-derived lymphoblastoid cell lines from groups FA-A, B, C, D1/BRCA2, and E and on lymphocytes from two unclassified FA patients. All FA cells showed a significant increase (P < 0.05) in chromosomal aberrations following treatment with HU during the last 3 h before mitosis. Furthermore, when FA cells previously exposed to MMC were treated with HU, we observed an increase of MMC-induced DNA damage that was characterized by high occurrence of DNA breaks and a reduction in rejoined chromosomal aberrations. These findings show that exposure to HU during G2 induces chromosomal aberrations by a mechanism that is independent of its well-known role in replication fork stalling during S-phase and that HU interfered mainly with the rejoining process of DNA damage. We suggest that impaired oxidative stress response, lack of an adequate amount of dNTPs for DNA repair due to RNR inhibition, and interference with cell cycle control checkpoints underlie the clastogenic activity of HU in FA cells. Environ. Mol. Mutagen. 56:457-467, 2015. © 2015 Wiley Periodicals, Inc.

Sublinear response in lacZ mutant frequency of Muta™ Mouse spermatogonial stem cells after low dose subchronic exposure to N-ethyl-N-nitrosourea

The transgenic rodent mutation assay was used to compare the dose-response relationship of lacZ mutant frequency (MF) in spermatogonial stem cells exposed acutely or subchronically to N-ethyl-N-nitrosourea (ENU). Muta(™) Mouse males were exposed orally to 0, 25, 50, or 100 mg/kg ENU for acute exposures and 0, 1, 2, or 5 mg/(kg day) for 28-day subchronic exposures. LacZ MF was measured in sperm collected 70 days post-exposure to target spermatogonial stem cells. Dose-response data were fit to linear, quadratic, exponential, or power models. Acute exposure resulted in a dose-dependent increase in MF that was significant (P < 0.05) at all doses tested and was best described by a quadratic dose-response model that was linear in the low dose range. In contrast, similar total doses fragmented over a 28-day subchronic exposure only resulted in a significant increase in lacZ MF at the highest dose tested. Therefore, the subchronic no observable genotoxic effect level (NOGEL) was 2 mg/(kg day) (or 56 mg/kg total dose). The subchronic dose-response was best described by the exponential and power models, which were sublinear in the low dose range. Benchmark dose lower confidence limits (BMDLs) for acute and subchronic exposure were 3.0 and 1.0 mg/(kg day) (or 27.4 mg/kg total dose), respectively. These findings are supportive of a saturable DNA repair mechanism as the mutagenic mode of action for ENU in spermatogonia and imply that sufficiently low exposures would not cause appreciable genotoxic effects over background. This may have important implications for the quantitative risk assessment of germ cell mutagens.

Single-molecule PCR analysis of an unstable microsatellite for detecting mutations in sperm of mice exposed to chemical mutagens

Single-molecule PCR (SM-PCR) analysis of long and repetitive DNA sequences, known as expanded simple tandem repeats (ESTRs), has been the most efficient method for studying germline mutation induction in endogenous sequences to date. However, the long length of these sequences makes mutation detection imprecise and laborious, and they have been characterized only in mice. Here, we explore the use of unstable microsatellite sequences that can be typed with high precision by capillary electrophoresis as alternative loci for detecting germline mutations. We screened 24 microsatellite loci across inbred mouse strains and identified Mm2.2.1 as the most polymorphic microsatellite locus. We then optimized SM-PCR of Mm2.2.1 to detect mutations in sperm. SM-PCR analysis of sperm from untreated B6C3F1 and Muta(™)Mouse samples revealed mutation frequencies that are consistent with rates derived from family pedigree analysis (∼ 5 × 10(-3)). To determine whether this locus can be used to detect chemically induced germline mutations, Muta(™)Mouse males were exposed by oral gavage to a single dose of 100mg/kg of N-ethyl-N-nitrosourea (ENU) or to 100mg/kg of benzo(a)pyrene (BaP) for 28 days alongside vehicle treated controls. Sperm were collected 10 weeks post-ENU exposure to sample sperm exposed as spermatogonial stem cells and 6 weeks post-BaP exposure to sample sperm that were dividing spermatogonia when the exposure was terminated. Both treatments resulted in a significant (approximately 2-fold) increase in mutation frequency in sperm compared to the control animals. The work establishes the utility of this microsatellite for studying mutation induction in the germ cells of mice. Because microsatellites are found in virtually every species, this approach holds promise for other organisms, including humans.

Approaches for identifying germ cell mutagens: Report of the 2013 IWGT workshop on germ cell assays(☆)

This workshop reviewed the current science to inform and recommend the best evidence-based approaches on the use of germ cell genotoxicity tests. The workshop questions and key outcomes were as follows. (1) Do genotoxicity and mutagenicity assays in somatic cells predict germ cell effects? Limited data suggest that somatic cell tests detect most germ cell mutagens, but there are strong concerns that dictate caution in drawing conclusions. (2) Should germ cell tests be done, and when? If there is evidence that a chemical or its metabolite(s) will not reach target germ cells or gonadal tissue, it is not necessary to conduct germ cell tests, notwithstanding somatic outcomes. However, it was recommended that negative somatic cell mutagens with clear evidence for gonadal exposure and evidence of toxicity in germ cells could be considered for germ cell mutagenicity testing. For somatic mutagens that are known to reach the gonadal compartments and expose germ cells, the chemical could be assumed to be a germ cell mutagen without further testing. Nevertheless, germ cell mutagenicity testing would be needed for quantitative risk assessment. (3) What new assays should be implemented and how? There is an immediate need for research on the application of whole genome sequencing in heritable mutation analysis in humans and animals, and integration of germ cell assays with somatic cell genotoxicity tests. Focus should be on environmental exposures that can cause de novo mutations, particularly newly recognized types of genomic changes. Mutational events, which may occur by exposure of germ cells during embryonic development, should also be investigated. Finally, where there are indications of germ cell toxicity in repeat dose or reproductive toxicology tests, consideration should be given to leveraging those studies to inform of possible germ cell genotoxicity.

Synthesis of novel lanthanide acylpyrazolonato ligands with long aliphatic chains and immobilization of the Tb complex on the surface of silica pre-modified via hydrophobic interactions

Immobilization of a Tb acylpyrazolonato complex on silica surfaces via hydrophobic interactions.

Efficacy and safety of oral ketamine for the relief of intractable chronic pain: A retrospective 5-year study of 51 patients

BACKGROUND

This work summarizes the efficiency, failures and adverse effects of oral administration of ketamine at home for intractable pain.

METHODS

This 5-year retrospective study involved testing ketamine by intravenous in-hospital administration, then a conversion to an oral route, or oral treatment directly administered at home. The daily intravenous dose was increased by steps of 0.5 mg/kg to attain an effective daily dose of 1.5-3.0 mg/kg. Pain was evaluated on a numeric scale from 0 to 10, and evidence of adverse effects was collected every day. The effective daily dose was delivered orally (three to four intakes). If effective, ketamine was continued for 3 months. Short infusions or direct oral treatment began with a 0.5-mg/kg dose, then the daily ketamine dose was increased in 15- to 20-mg increments.

RESULTS

Among 55 cases (51 patients, neuropathic pain 60%), the mean effective oral dose was 2 mg/kg. Ketamine was effective in 24 patients (44%, mean pain reduction 67 ± 17%), partially effective in 20% (mean pain reduction 30 ± 11%), with a mean opioid sparing of 63 ± 32%, and failure in 22%. Half of the patients experienced adverse effects, but only eight had to stop treatment. For patients with opioid therapy, failure of ketamine was less frequent (7% vs. 36%; p < 0.02), with fewer adverse effects (33% vs. 68%; p < 0.01).

CONCLUSIONS

Pain was reduced or abolished in two-thirds of patients under ketamine therapy; ketamine was effective for patients taking opioids and resulted in few adverse effects.

Transgenic rodent assay for quantifying male germ cell mutant frequency

De novo mutations arise mostly in the male germline and may contribute to adverse health outcomes in subsequent generations. Traditional methods for assessing the induction of germ cell mutations require the use of large numbers of animals, making them impractical. As such, germ cell mutagenicity is rarely assessed during chemical testing and risk assessment. Herein, we describe an in vivo male germ cell mutation assay using a transgenic rodent model that is based on a recently approved Organisation for Economic Co-operation and Development (OECD) test guideline. This method uses an in vitro positive selection assay to measure in vivo mutations induced in a transgenic λgt10 vector bearing a reporter gene directly in the germ cells of exposed males. We further describe how the detection of mutations in the transgene recovered from germ cells can be used to characterize the stage-specific sensitivity of the various spermatogenic cell types to mutagen exposure by controlling three experimental parameters: the duration of exposure (administration time), the time between exposure and sample collection (sampling time), and the cell population collected for analysis. Because a large number of germ cells can be assayed from a single male, this method has superior sensitivity compared with traditional methods, requires fewer animals and therefore much less time and resources.

Human sperm sex chromosome disomy and sperm DNA damage assessed by the neutral comet assay

STUDY QUESTION

Is there an association between human sperm sex chromosome disomy and sperm DNA damage?

SUMMARY ANSWER

An increase in human sperm XY disomy was associated with higher comet extent; however, there was no other consistent association of sex chromosome disomies with DNA damage.

WHAT IS KNOWN ALREADY

There is limited published research on the association between sex chromosome disomy and sperm DNA damage and the findings are not consistent across studies.

STUDY DESIGN, SIZE, AND DURATION

We conducted a cross-sectional study of 190 men (25% ever smoker, 75% never smoker) from subfertile couples presenting at the Massachusetts General Hospital Fertility Clinic from January 2000 to May 2003.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Multiprobe fluorescence in situ hybridization for chromosomes X, Y and 18 was used to determine XX, YY, XY and total sex chromosome disomy in sperm nuclei using an automated scoring method. The neutral comet assay was used to measure sperm DNA damage, as reflected by comet extent, percentage DNA in the comet tail, and tail distributed moment. Univariate and multiple linear regression models were constructed with sex chromosome disomy (separate models for each of the four disomic conditions) as the independent variable, and DNA damage parameters (separate models for each measure of DNA damage) as the dependent variable.

MAIN RESULTS AND THE ROLE OF CHANCE

Men with current or past smoking history had significantly greater comet extent (µm: regression coefficients with 95% CI) [XX18: 15.17 (1.98, 28.36); YY18: 14.68 (1.50, 27.86); XY18: 15.41 (2.37, 28.45); Total Sex Chromosome Disomy: 15.23 (2.09, 28.38)], and tail distributed moment [XX18: 3.01 (0.30, 5.72); YY18: 2.95 (0.24, 5.67); XY18: 3.04 (0.36, 5.72); Total Sex Chromosome Disomy: 3.10 (0.31, 5.71)] than men who had never smoked. In regression models adjusted for age and smoking, there was a positive association between XY disomy and comet extent. For an increase in XY disomy from 0.56 to 1.47% (representing the 25th to 75th percentile), there was a mean increase of 5.08 µm in comet extent. No other statistically significant findings were observed.

LIMITATIONS, REASONS FOR CAUTION

A potential limitation of this study is that it is cross-sectional. Cross-sectional analyses by nature do not lend themselves to inference about directionality for any observed associations; therefore we cannot determine which variable is the cause and which one is the effect. A small sample size may be a further limitation. Comparison of these findings to other studies is limited due to methodological differences.

WIDER IMPLICATIONS OF THE FINDINGS

Although consistent associations across sex chromosome disomies or DNA damage measures were not observed, this study highlights the need to explore etiologies of sperm DNA damage and sex chromosome disomy to better understand the potential mechanistic overlaps between the two.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by NIOSH Grant T42 OH008416, and NIH/NIEHS Grants ES 009718, ES 000002, and R01 ES017457. During the study M.E.M. was affiliated with the Department of Environmental Health at the Harvard School of Public Health.

TRIAL REGISTRATION NUMBER

N/A.

Increasing Resistance According to Patient's Age and Sex inEscherichia coliIsolated from Urine in Italy

The prevalence of Escherichia coli among the uropathogens routinely isolated in non-hospital laboratories (Labs) and its susceptibility profiles were investigated. Thirty-three Labs were selected throughout Italy. In vitro assays were performed by means of disk diffusion according to the CLSI. Females were prevalent (79.9%) and the mean patient age was 58.6 (sd 20.4) years. Overall, the prevalence of E. coli was 55.3% (1375 strains), with Enterococcus spp 10.2 %, Proteus mirabilis 4.8%, coagulase-negative staphylococci 4.3% and Klebsiella 3.8% being the next most frequently encountered species. High compliance with quality control program was observed. Susceptibility figures in E. coli were consistently low for many antimicrobial agents such as ampicillin (51.3%) and co-trimoxazole (74.6%) and higher for others such as gentamicin (87.9%) and ceftazidime (95.1%). Resistance rates were higher among male patients and increased according to the patient's age.

Cutaneous flaps in the treatment of 338 pressure sores: a better choice

AIM

Muscular flaps are considered by many surgeons as a treatment of choice for pressure sores. Nevertheless fasciocutaneous and adipofascial flaps are less sensitive to ischemia, more resistant to pressure and have higher mechanical resistance. The aim of this study is to evaluate the results of our integrated rehabilitative and surgical protocol in pressure sore management based on the use of cutaneous flaps.

MATERIAL OF STUDY

Since 1998, we treated 338 pressure sores (PS) in 195 patients (120 males; 75 females), 189 patients were affected by paraplegia and tetraplegia and 6 of them by neurological disorders.

RESULTS

Ninety sacral, 156 ischiatic, 75 trochanteric, 9 calcanean and 8 sores of the iliac-crest were succesfully treated. All showed an involvement of the bone element, with osteitis and/or periosteitis. 14 cases of trocanteric sores showed a deeper bone involvement, with evidences of osteomyelitis. Follow up ranges from 7 years to 2 months. Median time for wound healing was 18 days.

DISCUSSION

The use of fasciocutaneous flaps, as an alternative to the traditional muscolocutaneous flaps in the treatment of pressure sores leads to good and statistically comparable, healing rate, time and incidence of complications. Reconstructive plastic surgery as is a decisive factor to reach a good rehabilitative outcome, minimizing the time of rehabilitation with a following decrease of hospitalization costs. In spinal cord injured patients, surgical treatment of pressure sores is not proposed as the main procedure, but it is an important stage during the natural history of pressure sores.

CONCLUSIONS

Cutaneous, adipofascial and fasciocutaneous flaps are less invasive, of a relatively easy execution, provided by a reliable vascular pedicle and they could be "re-used" in case of recurrences.

A Pilot Study on Prevention of Catheter-Related Urinary Tract Infections with Fluoroquinolones

The objective of this multicenter, randomized, controlled, parallel group trial was to evaluate the efficacy of levofloxacin 250 mg oral, once daily (LVFX), placebo one tablet oral once daily (Placebo [P] group) and ciprofloxacin (CPFX) 500 mg oral, twice daily (single blind), prophylaxis in preventing bacteriuria (> or = 10(3) CFU/ml) in post-surgical catheterized patients. In the modified intention-to-treat (M-ITT) population of the 82 enrolled patients, negative bacteriuria was observed in 92% of LVFX group, in 80% of P group and in 100% of CPFX group while in the per-protocol (PP) population figures were: 100%, 86.4% and 100% respectively. Only one symptomatic urinary tract infection and one surgical wound infection were observed in the P group. Both drugs were well tolerated, showing a safety profile comparable to placebo. The high frequency of negative bacteriuria in the placebo group sounds encouraging as it underlines that the adoption of closed urinary drainage system catheters in hospital setting may reduce the frequency of hospital-acquired infections.