Are hydroxyapatite-based biomaterials free of genotoxicity? A systematic review

Hydroxyapatite (HA) is a biomaterial widely used in clinical applications and pharmaceuticals. The literature on HA-based materials studies is focused on chemical characterization and biocompatibility. Generally, biocompatibility is analyzed through adhesion, proliferation, and differentiation assays. Fewer studies are looking for genotoxic events. Thus, although HA-based biomaterials are widely used as biomedical devices, there is a lack of literature regarding their genotoxicity. This systematic review was carried out following the PRISMA statement. Specific search strategies were developed and performed in four electronic databases (PubMed, Science Direct, Scopus, and Web of Science). The search used "Hydroxyapatite OR Calcium Hydroxyapatite OR durapatite AND genotoxicity OR genotoxic OR DNA damage" and "Hydroxyapatite OR Calcium Hydroxyapatite OR durapatite AND mutagenicity OR mutagenic OR DNA damage" as keywords and articles published from 2000 to 2022, after removing duplicate studies and apply include and exclusion criteria, 53 articles were identified and submitted to a qualitative descriptive analysis. Most of the assays were in vitro and most of the studies did not show genotoxicity. In fact, a protective effect was observed for hydroxyapatites. Only 20 out of 71 tests performed were positive for genotoxicity. However, no point mutation-related mutagenicity was observed. As the genotoxicity of HA-based biomaterials observed was correlated with its nanostructured forms as needles or rods, it is important to follow their effect in chronic exposure to guarantee safe usage in humans.

Embryotoxic Effects of Pesticides in Zebrafish (Danio rerio): Diflubenzuron, Pyriproxyfen, and Its Mixtures

Diflubenzuron (DFB) and pyriproxyfen (PPF) are larvicides used in crops to control insect plagues. However, these pesticides are known to impact non-target organisms like fish and mammals. Here, we aimed at assessing the embryotoxicity of purified DFB, PPF, and their mixtures in a non-target organism-zebrafish. Zebrafish embryos were exposed to different concentrations for 120 h: 0.025, 0.125, 0.25, 1.25, 2.5, and 10 mg/L of purified PPF and purified DFB, while we used 0.025 mg/L PPF + 10 mg/L DFB (Mix A), 0.125 mg/L PPF + 10 mg/L DFB (Mix B), and 0.25 mg/L PPF + 10 mg/L DFB (Mix C) for the mixtures of PPF + DFB. We observed mortality, teratogenicity, and cardiotoxicity. For the neurotoxicity tests and evaluation of reactive oxygen species (ROS) levels in the brain, embryos were exposed for 120 h to 0.379 and 0.754 mg/L of PPF and 0.025 and 0.125 mg/L of DFB. We established the LC50 for PPF as 3.79 mg/L, while the LC50 for DFB was not determinable. Survival and hatching were affected by PPF concentrations above 0.125 mg/L, DFB concentrations above 1.25 mg/L, and the lower pesticide mixtures. PPF exposure and mixtures induced different types of malformations, while a higher number of malformations were observed for the mixtures, suggesting a potentiating effect. Pesticides diminished avoidance responses and increased the levels of ROS across all concentrations, indicating neurotoxicity. Our findings underscore the detrimental impact of PPF and DFB exposure, spanning from biochemistry to morphology. There is a critical need to reconsider the global use of these pesticides and transition to more ecologically friendly forms of pest control, raising an alarm regarding repercussions on human and animal health and well-being.

Individual differences in response to alcohol and nicotine in zebrafish: Gene expression and behavior

Alcohol and nicotine are psychoactive substances responsible for serious health consequences. Although the biological mechanisms of alcohol and nicotine have been studied extensively, individual differences in the response to these drugs have received little attention. Here we evaluated gene expression and behavior of bold and shy individuals after acute exposure to alcohol and nicotine. For this, zebrafish were classified as bold and shy individuals based on emergence tests, and then fish were exposed to 0.00, 0.10, and 0.50% alcohol or 0.00, 1.00, and 5.00 mg/L nicotine and their anxiety-like and locomotor behavior was observed. After behavioral assessment, brain mRNA expression (ache, bdnf, gaba1, gad1b, th1, and tph1) was evaluated. Locomotion patterns differed between profiles depending on alcohol and nicotine concentration. Anxiety increased in shy fish and decreased in bold fish after exposure to both drugs. Alcohol exposure induced an increase in tph1 mRNA expression in bold fish, while bdnf mRNA expression was increased in shy fish. Nicotine increased ache, bdnf, and tph1 mRNA levels in both profiles, but at higher levels in bold fish. Based on our research, we found that alcohol induces anxiogenic effects in both bold and shy zebrafish. Additionally, shy individuals exposed to a low concentration of nicotine exhibited stronger anxiety-like responses than their bold counterparts. These findings further support the validity of using zebrafish as a dependable tool for studying the effects of drugs and uncovering the underlying mechanisms associated with individual variations.

Reactive oxygen species-dependent transient induction of genotoxicity by retene in human liver HepG2 cells

Retene is a polycyclic aromatic hydrocarbon (PAH) emitted mainly by biomass combustion, and despite its ubiquity in atmospheric particulate matter (PM), studies concerning its potential hazard to human health are still incipient. In this study, the cytotoxicity and genotoxicity of retene were investigated in human HepG2 liver cells. Our data showed that retene had minimal effect on cell viability, but induced DNA strand breaks, micronuclei formation, and reactive oxygen species (ROS) formation in a dose- and time-dependent manner. Stronger effects were observed at earlier time points than at longer, indicating transient genotoxicity. Retene activated phosphorylation of Checkpoint kinase 1 (Chk1), an indicator of replication stress and chromosomal instability, which was in accordance with increased formation of micronuclei. A protective effect of the antioxidant N-acetylcysteine (NAC) towards ROS generation and DNA damage signaling was observed, suggesting oxidative stress as a key mechanism of the observed genotoxic effects of retene in HepG2 cells. Altogether our results suggest that retene may contribute to the harmful effects caused by biomass burning PM and represent a potential hazard to human health.

Benzophenone-3 causes oxidative stress in the brain and impairs aversive memory in adult zebrafish

Oxybenzone (BP-3) is an ultraviolet (UV) filter widely used in industries that is directly or indirectly released into the aquatic environment. However, little is known about its effects on brain performance. Here, we investigated whether BP-3 exposure affects the redox imbalance in zebrafish and how they respond to a task that requires memory of an aversive situation. Fish were exposed to BP-3 10 and 50 μg L-1 for 15 days and then tested using an associative learning protocol with electric shock as a stimulus. Brains were extracted for reactive oxygen species (ROS) measurement and qPCR analysis of antioxidant enzyme genes. ROS production increased for exposed animals, and catalase (cat) and superoxide dismutase 2 (sod 2) were upregulated. Furthermore, learning and memory were reduced in zebrafish exposed to BP-3. These results suggested that BP-3 may lead to a redox status imbalance, causing impaired cognition and reinforcing the need to replace the toxic UV filters with filters that minimize environmental effects.

Empirical relationship between chromosomal damage and airborne particulate matter: A systematic review and meta-analysis of studies in exposed populations

Ambient particulate matter (PM) has gained significant attention as an environmental risk factor for human health. Although the association between ambient PM and micronucleus (MN) induction has been investigated, the quantitative association of PM and genomic instability is inconclusive. We conducted a systematic review and meta-analysis to study the association between PM exposure and MN endpoint. Four databases were systematically searched for studies published up to November 2022, to find papers investigating the relationship between ambient PM and MN induction. Random effect models were conducted to estimate the overall effect based on the Ratio of Means (RoM) with 95% confidence intervals (95% CIs). Subgroup analysis, funnel plot, and Egger and Begg tests, were also performed. Twenty-three studies across nine countries, including 4450 participants, were included. A meta-RoM of 2.13 for MN (95% CI 1.63-2.79) was observed for individuals exposed to ambient PM compared to non-exposed. A significant difference in the subgroup test was found for buccal cells (3.16, 95% CI 2.20-4.52) and low economy level (3.61, 95% CI 1.44-9.01). Our meta-analysis suggests the presence of an association between PM exposure and the frequency of MN and identified the kind of cells and economic status as possible effect modifiers. The use of effective methods, such as the MN assay, enables identification of early genetic damage in humans, which in turn may anticipate the risk of developing respiratory diseases, including lung cancer.

Embryotoxicity and visual-motor response of functionalized nanostructured hydroxyapatite-based biomaterials in zebrafish (Danio rerio)

Hydroxyapatite (HA) is a biomaterial widely used in biomedical applications. Many studies have shown that ionic substituents can be incorporated into HA to produce a mineral composition more similar to natural bone tissue with more favorable biological characteristics for application in bone regeneration. However, its potentially toxic effects need to be evaluated before full approval for human use. For this purpose, an embryotoxicity test was performed on zebrafish according to OECD guideline 236. Zebrafish embryos were exposed to 1 or 3 microspheres of alginate containing nanoparticles of HA and carbonate (CHA), strontium (SrHA), and zinc-substituted HA (ZnHA) from 4 to 120 h post-fertilization (hpf). Lethality and developmental endpoints were evaluated. In addition, larval behavior at 168 hpf was also analyzed to observe whether biomaterials adversely affect optomotor and avoidance responses (neurotoxicity), as well as the oxidative stress pattern through qPCR. After 120 h exposure to all microspheres with different patterns of crystallinity, porosity, nanoparticle size, surface area, and degradation behavior, there was no mortality rate greater than 20%, indicating the non-embryotoxic character of these biomaterials. All experimental groups showed positive optomotor and avoidance responses, which means that embryo exposure to the tested biomaterials had no neurotoxic effects. Furthermore, larvae exposed to one SrHA microsphere showed a better optomotor response than the control. Furthermore, the biomaterials did not change the pattern of mRNA levels of genes related to oxidative stress even after 120 hpf. The growing number of new HA-based biomaterials produced should be accompanied by increased studies to understand the biosafety of these compounds, especially in alternative models, such as zebrafish embryos. These results reinforce our hypothesis that ion-substituted HA biomaterials do not impose toxicological effects, cause development and neuromotor impairment, or increase oxidative stress in zebrafish embryos being useful for medical devices and in the process of bone regeneration.

Sulfated Glucan from the Green Seaweed Caulerpa sertularioides Inhibits Adipogenesis through Suppression of Adipogenic and Lipogenic Key Factors

Sulfated polysaccharides (SPS) from seaweeds have great biochemical and biotechnological potential. This study aimed to investigate the effect of SPS isolated from the seaweed Caulerpa sertularioides on adipogenic differentiation as a possible alternative treatment for obesity. The SPS-rich extract from the seaweed C. sertularioides was fractioned into three SPS-rich fractions (F0.5; F0.9; and F1.8) chemically characterized. Among these four samples, only F0.9 showed a significant inhibitory effect on adipogenesis of 3T3-L1 preadipocytes. Ten SPS-rich fractions were isolated from F0.9 through ion-exchange chromatography. However, only the fraction (CS0.2) containing a sulfated glucan was able to inhibit adipogenesis. CS0.2 reduces lipid accumulation and inhibits the expression of key adipogenic (PPARγ, C/EBPβ, and C/EBPα) and lipogenic markers (SREBP-1c, Fabp4, and CD36). The data points to the potential of sulfated glucan from C. sertularioides for the development of functional approaches in obesity management.

Behavioral genetics of alcohol's effects in three zebrafish (Danio rerio) populations

Alcohol abuse is one of the most dangerous and serious problems for patients and society. Interpopulation studies are important in understanding how genetic background contributes to the effects of alcohol. In this study, we applied a chronic alcohol exposure protocol in three zebrafish populations (Danio rerio; both sexes; AB, TU, and outbred fish - OB). We analyzed the behavioral responses and mRNA expression involved in neurotransmitter metabolism - th1, tph1, ache, ada1, gaba1, gad1b, and bdnf. Locomotion patterns were similar between populations (increased speed after acute alcohol and unaltered locomotion after chronic and withdrawal treatments). All populations exhibited increased expression of genes associated with locomotion (th1, gad1b, and gaba1) after acute alcohol exposure. Anxiety-like responses increased in AB and TU fish during withdrawal and decreased in AB fish after acute alcohol exposure. Genes related to anxiety-like behavior (tph1 and ada1) were overexpressed in AB and TU fish after acute and withdrawal treatments, while OB fish exhibited unaltered responses. Bdnf levels decreased during withdrawal in AB and OB fish, while TU showed upregulated levels in both chronic and withdrawal treatments. Our results suggest that zebrafish populations respond differently to alcohol exposure, which may contribute to understanding the mechanisms underlying alcohol use and dependence. Moreover, we found that a more diverse genetic background (OB) was related to higher variability in behavioral and mRNA expression, demonstrating that inbred populations (AB and TU) may be useful tools in identifying alcohol use and abuse mechanisms.

A look beyond the priority: A systematic review of the genotoxic, mutagenic, and carcinogenic endpoints of non-priority PAHs

Knowledge of the toxic potential of polycyclic aromatic hydrocarbons (PAHs) has increased over time. Much of this knowledge is about the 16 United States - Environmental Protection Agency (US - EPA) priority PAHs; however, there are other US - EPA non-priority PAHs in the environment, whose toxic potential is underestimated. We conducted a systematic review of in vitro, in vivo, and in silico studies to assess the genotoxicity, mutagenicity, and carcinogenicity of 13 US - EPA non-priority parental PAHs present in the environment. Electronic databases, such as Science Direct, PubMed, Scopus, Google Scholar, and Web of Science, were used to search for research with selected terms without time restrictions. After analysis, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, 249 articles, published between 1946 and 2020, were selected and the quality assessment of these studies was performed. The results showed that 5-methylchrysene (5-MC), 7,12-dimethylbenz[a]anthracene (7,12-DMBA), cyclopenta[cd]pyrene (CPP), and dibenzo[al]pyrene (Db[al]P) were the most studied PAHs. Moreover, 5-MC, 7,12-DMBA, benz[j]aceanthrylene (B[j]A), CPP, anthanthrene (ANT), dibenzo[ae]pyrene (Db[ae]P), and Db[al]P have been reported to cause mutagenic effects and have been being associated with a risk of carcinogenicity. Retene (RET) and benzo[c]fluorene (B[c]F), the least studied compounds, showed evidence of a strong influence on the mutagenicity and carcinogenicity endpoints. Overall, this systematic review provided evidence of the genotoxic, mutagenic, and carcinogenic endpoints of US - EPA non-priority PAHs. However, further studies are needed to improve the future protocols of environmental analysis and risk assessment in severely exposed populations.

Polymorphisms of matrix metalloproteinase-7 and -9 are associated with oral tongue squamous cell carcinoma

Matrix degradation is an important event in the progression, invasion and metastasis of malignant head and neck lesions. Imbalances, mutations and polymorphisms of MMPs and their inhibitors are observed in several cancer subtypes. The aim of this study was to evaluate the association of the MMP-7 gene promoter (181 A/G) and MMP-9 (-1562 C/T) polymorphisms in oral tongue squamous cell carcinoma (OTSCC). MMP-7 (rs11568818) and MMP-9 (rs3918242) single-nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis in 71 cases of OTSCC. Normal tissue specimens were obtained from 60 healthy volunteers to serve as the control. The MMP-7 G allele and MMP-9 T allele were more frequent in the OTSCC group than the control group, but only when these two SNPs were taken together was a significant association found with the nodal metastasis of OTSCC (p < 0.001). Based on our results, SNPs in the promoter region of MMP-7 and MMP-9 appear to be associated with greater risk of developing OTSCC, and with a higher propensity to form metastatic tumors. In this respect, molecular studies investigating polymorphisms may be useful in predicting tumor behavior.

Genotoxicity of root canal sealers: a literature review

OBJECTIVES

Root canal sealers are widely used worldwide in endodontics to prevent reinfection and growth of surviving microorganisms. Considering the strong correlation between genetic damage and carcinogenesis, evaluation of genotoxicity induced by endodontic sealers is recommended for elucidating the true health risks to patients and professionals. The purpose of this article was to provide a comprehensive review of studies involving genotoxicity analysis of endodontic sealers and the used methodologies.

MATERIALS AND METHODS

A literature search was made in PubMed using the following combination of words "genotoxicity," "mutagenicity," "endodontic sealers," and "root canal sealers." A total of 39 articles with genotoxicity studies were selected for the present study.

RESULTS

Sealers have been ranked in decreasing order of their genotoxicity as: ZOE sealers > GIC sealers > S sealers > ER sealers > MR sealers > Novel sealers > CH sealers > CS sealers.

CONCLUSIONS

All published data showed some evidence of genotoxicity for most of the commercial root canal sealers; however, contradictory results were found, mainly for AH Plus, the most studied sealer.

CLINICAL RELEVANCE

The information provided would direct the endodontists to use the less genotoxic materials in endodontic treatment in a way to reduce DNA damage promoting oral healthcare.

Genotoxicity and DNA damage signaling in response to complex mixtures of PAHs in biomass burning particulate matter from cashew nut roasting

Approximately 3 billion people world-wide are exposed to air pollution from biomass burning. Herein, particulate matter (PM) emitted from artisanal cashew nut roasting, an important economic activity worldwide, was investigated. This study focused on: i) chemical characterization of polycyclic aromatic hydrocarbons (PAHs) and oxygenated (oxy-) PAHs; ii) intracellular levels of reactive oxygen species (ROS); iii) genotoxic effects and time- and dose-dependent activation of DNA damage signaling, and iv) differential expression of genes involved in xenobiotic metabolism, inflammation, cell cycle arrest and DNA repair, using A549 lung cells. Among the PAHs, chrysene, benzo[a]pyrene (B[a]P), benzo[b]fluoranthene, and benz[a]anthracene showed the highest concentrations (7.8-10 ng/m³), while benzanthrone and 9,10-anthraquinone were the most abundant oxy-PAHs. Testing of PM extracts was based on B[a]P equivalent doses (B[a]P_eq). IC₅₀ values for viability were 5.7 and 3.0 nM B[a]P_eq at 24 h and 48 h, respectively. At these low doses, we observed a time- and dose-dependent increase in intracellular levels of ROS, genotoxicity (DNA strand breaks) and DNA damage signaling (phosphorylation of the protein checkpoint kinase 1 - Chk1). In comparison, effects of B[a]P alone was observed at micromolar range. To our knowledge, no previous study has demonstrated an activation of pChk1, a biomarker used to estimate the carcinogenic potency of PAHs in vitro, in lung cells exposed to cashew nut roasting extracts. Sustained induction of expression of several important stress response mediators of xenobiotic metabolism (CYP1A1, CYP1B1), ROS and pro-inflammatory response (IL-8, TNF-α, IL-2, COX2), and DNA damage response (CDKN1A and DDB2) was also identified. In conclusion, our data show high potency of cashew nut roasting PM to induce cellular stress including genotoxicity, and more potently when compared to B[a]P alone. Our study provides new data that will help elucidate the toxic effects of low-levels of PAH mixtures from air PM generated by cashew nut roasting.

Oxidative stress, mutagenic effects, and cell death induced by retene

Retene (RET) is the most abundant polycyclic aromatic hydrocarbon (PAH) released upon burning of cellulose, although it is not considered as one of the priority PAHs and is not included for risk assessments by the US Environmental Protection Agency (US-EPA). There are only a few studies concerning the toxic effects of RET. To the best of our knowledge, this study is the first one to examine whether RET, in an environmental concentration, plays a crucial role in the induction of oxidative stress in A549 lung cell line, and its consequence as such as mutagenicity and cell death. Our results revealed that RET was able to significantly decrease cell viability only at 72 h of exposure, increase oxidative stress, mitochondrial membrane potential and mitochondrial contents, leading an increased reactive oxygen species (ROS) production. Mutagenic activity was not detected in Salmonella strains, suggesting that RET does not induce base-pair substitution (TA100), frameshift (TA98 and TA97a) and transition/transversion (TA102) mutations. However, exposure to RET led to a significant increase in micronuclei (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs) frequency, as well as cell death, mainly due to necrosis. Taken together, the results of our study provide new evidence suggesting that RET promotes oxidative stress, contributes to the processes of genomic instability, and favors necrosis. Thus, we highlight the importance of including RET in routine environmental analyses in the future as a potential risk factor involved in complex diseases and carcinogenesis.

Leukocyte Telomere Length and Chronic Conditions in Older Women of Northeast Brazil: A Cross-Sectional Study

This study assessed whether telomere length is related to chronic conditions, cardiovascular risk factors, and inflammation in women aged 65 to 74 from Northeast Brazil. Participants were selected from two sources, a representative sample of the International Mobility in Aging Study (n = 57) and a convenience sample (n = 49) recruited at senior centers. Leukocyte telomere length was measured by quantitative polymerase chain reaction from blood samples in 83 women. Natural log-transformed telomere/single copy gene ratio was used as the dependent variable in the analysis. Blood analyses included inflammatory markers (high-sensitivity C-reactive protein and interleukin-6), total, low-density lipoprotein and high-density lipoprotein cholesterol, triglycerides, glucose and glycosylated hemoglobin. Self-rated health, chronic conditions, cardiovascular risk factors and inflammatory markers were not associated with telomere length. No significant independent association was found between telomere length and anthropometric measures or blood markers, even after adjusting for age, education and adverse childhood events among these older women in Northeast Brazil. Our results did not confirm the hypothesis that chronic conditions, cardiovascular risk factors or inflammation are associated with shorter telomere length in these women who have exceptional survival relative to the life expectancy of their birth cohort.

Genotoxicity and osteogenic potential of sulfated polysaccharides from Caulerpa prolifera seaweed

Marine algae are sources of novel bioactive molecules and present a great potential for biotechnological and biomedical applications. Although green algae are the least studied type of seaweed, several of their biological activities have already been described. Here, we investigated the osteogenic potential of Sulfated Polysaccharide (SP)-enriched samples extracted from the green seaweed Caulerpa prolifera on human mesenchymal stem cells isolated from Wharton jelly (hMSC-WJ). In addition, the potential genotoxicity of these SPs was determined by cytokinesis-block micronucleus (CBMN) assay. SP-enriched samples did not show significant cytotoxicity towards hMSCs-WJ at a concentration of up to 10μg/mL, and after 72h of exposure. SP enrichment also significantly increased alkaline phosphatase (ALP) activity, promoting calcium accumulation in the extracellular matrix. Among the SP-enriched samples, the CP0.5 subfraction (at 5μg/mL) presented the most promising results. In this sample, ALP activity was increased approximately by 60%, and calcium accumulation was approximately 6-fold above the negative control, indicating high osteogenic potential. This subfraction also proved to be non-genotoxic, according to the CBMN assay, as it did not induce micronuclei. The results of this study highlight, for the first time, the potential of these SPs for the development of new therapies for bone regeneration.

Biomass burning particles in the Brazilian Amazon region: Mutagenic effects of nitro and oxy-PAHs and assessment of health risks

Emissions from burning of biomass in the Amazon region have adverse effects on the environment and human health. Herein, particulate matter (PM) emitted from biomass burning in the Amazon region during two different periods, namely intense and moderate, was investigated. This study focused on: i) organic characterization of nitro- and oxy-polycyclic aromatic hydrocarbons (PAHs); ii) assessment of the excess lifetime cancer risk (LCR); and iii) assessment of the in vitro mutagenic effects of extractable organic matter (EOM). Further, we compared the sensitivity of two mutagenicity tests: Salmonella/microsome test and cytokinesis-block micronucleus (CBMN) with human lung cells. Among the nitro-PAHs, 2-nitrofluoranthene, 7-nitrobenz[a]anthracene, 1-nitropyrene, and 3-nitrofluoranthene showed the highest concentrations, while among oxy-PAHs, 2-metylanthraquinone, benz[a]anthracene-7,12-dione, and 9,10-anthraquinone were the most abundant. The LCR calculated for nitro-PAH exposure during intense biomass burning period showed a major contribution of 6-nitrochrysene to human carcinogenic risk. The EOM from intense period was more mutagenic than that from moderate period for both TA98 and YG1041 Salmonella strains. The number of revertants for YG1041 was 5-50% higher than that for TA98, and the most intense responses were obtained in the absence of metabolic activation, suggesting that nitroaromatic compounds with direct-acting frameshift mutagenic activity are contributing to the DNA damage. Treatment of cells with non-cytotoxic doses of EOM resulted in an increase in micronuclei frequencies. The minimal effective dose showed that Salmonella/microsome test was considerably more sensitive in comparison with CBMN mainly for the intense burning period samples. This was the first study to assess the mutagenicity of EOM associated with PM collected in the Amazon region using Salmonella/microsome test. The presence of compounds with mutagenic effects, particularly nitro- and oxy-PAHs, and LCR values in the range of 10^-5 indicate that the population is potentially exposed to an increased risk of DNA damage, mutation, and cancer.

Identification of new genes associated to senescent and tumorigenic phenotypes in mesenchymal stem cells

Although human mesenchymal stem cells (hMSCs) are a powerful tool for cell therapy, prolonged culture times result in replicative senescence or acquisition of tumorigenic features. To identify a molecular signature for senescence, we compared the transcriptome of senescent and young hMSCs with normal karyotype (hMSCs/n) and with a constitutional inversion of chromosome 3 (hMSC/inv). Senescent and young cells from both lineages showed differentially expressed genes (DEGs), with higher levels in senescent hMSCs/inv. Among the 30 DEGs in senescent hMSC/inv, 11 are new candidates for biomarkers of cellular senescence. The functional categories most represented in senescent hMSCs were related to cellular development, cell growth/proliferation, cell death, cell signaling/interaction, and cell movement. Mapping of DEGs onto biological networks revealed matrix metalloproteinase-1, thrombospondin 1, and epidermal growth factor acting as topological bottlenecks. In the comparison between senescent hMSCs/n and senescent hMSCs/inv, other functional annotations such as segregation of chromosomes, mitotic spindle formation, and mitosis and proliferation of tumor lines were most represented. We found that many genes categorized into functional annotations related to tumors in both comparisons, with relation to tumors being highest in senescent hMSCs/inv. The data presented here improves our understanding of the molecular mechanisms underlying the onset of cellular senescence as well as tumorigenesis.

Cell death pathways of particulate matter toxicity

Humans are exposed to various complex mixtures of particulate matter (PM) from different sources. Long-term exposure to high levels of these particulates has been linked to a diverse range of respiratory and cardiovascular diseases that have resulted in hospital admission. The evaluation of the effects of PM exposure on the mechanisms related to cell death has been a challenge for many researchers. Therefore, in this review, we have discussed the effects of airborne PM exposure on mechanisms related to cell death. For this purpose, we have compiled literature data on PM sources, the effects of exposure, and the assays and models used for evaluation, in order to establish comparisons between various studies. The analysis of this collected data suggested divergent responses to PM exposure that resulted in different cell death types (apoptosis, autophagy, and necrosis). In addition, PM induced oxidative stress within cells, which appeared to be an important factor in the determination of cell fate. When the levels of reactive oxygen species were overpowering, the cellular fate was directed toward cell death. This may be the underlying mechanism of the development or exacerbation of respiratory diseases, such as emphysema and chronic obstructive pulmonary diseases. In addition, PM was shown to cause DNA damage and the resulting mutations increased the risk of cancer. Furthermore, several conditions should be considered in the assessment of cell death in PM-exposed models, including the cell culture line, PM composition, and the interaction of the different cells types in in vivo models.

Laser-modified titanium surfaces enhance the osteogenic differentiation of human mesenchymal stem cells

Background

Titanium surfaces have been modified by various approaches with the aim of improving the stimulation of osseointegration. Laser beam (Yb-YAG) treatment is a controllable and flexible approach to modifying surfaces. It creates a complex surface topography with micro and nano-scaled patterns, and an oxide layer that can improve the osseointegration of implants, increasing their usefulness as bone implant materials.

Methods

Laser beam irradiation at various fluences (132, 210, or 235 J/cm²) was used to treat commercially pure titanium discs to create complex surface topographies. The titanium discs were investigated by scanning electron microscopy, X-ray diffraction, and measurement of contact angles. The surface generated at a fluence of 235 J/cm² was used in the biological assays. The behavior of mesenchymal stem cells from an umbilical cord vein was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a mineralization assay, and an alkaline phosphatase activity assay and by carrying out a quantitative real-time polymerase chain reaction for osteogenic markers. CHO-k1 cells were also exposed to titanium discs in the MTT assay.

Results

The best titanium surface was that produced by laser beam irradiation at 235 J/cm² fluence. Cell proliferation analysis revealed that the CHO-k1 and mesenchymal stem cells behaved differently. The laser-processed titanium surface increased the proliferation of CHO-k1 cells, reduced the proliferation of mesenchymal stem cells, upregulated the expression of the osteogenic markers, and enhanced alkaline phosphatase activity.

Conclusions

The laser-treated titanium surface modulated cellular behavior depending on the cell type, and stimulated osteogenic differentiation. This evidence supports the potential use of laser-processed titanium surfaces as bone implant materials, and their use in regenerative medicine could promote better outcomes.

Biomass burning in the Amazon region causes DNA damage and cell death in human lung cells

Most of the studies on air pollution focus on emissions from fossil fuel burning in urban centers. However, approximately half of the world's population is exposed to air pollution caused by biomass burning emissions. In the Brazilian Amazon population, over 10 million people are directly exposed to high levels of pollutants resulting from deforestation and agricultural fires. This work is the first study to present an integrated view of the effects of inhalable particles present in emissions of biomass burning. Exposing human lung cells to particulate matter smaller than 10 µm (PM10), significantly increased the level of reactive oxygen species (ROS), inflammatory cytokines, autophagy, and DNA damage. Continued PM10 exposure activated apoptosis and necrosis. Interestingly, retene, a polycyclic aromatic hydrocarbon present in PM10, is a potential compound for the effects of PM10, causing DNA damage and cell death. The PM10 concentrations observed during Amazon biomass burning were sufficient to induce severe adverse effects in human lung cells. Our study provides new data that will help elucidate the mechanism of PM10-mediated lung cancer development. In addition, the results of this study support the establishment of new guidelines for human health protection in regions strongly impacted by biomass burning.

Lifecourse Adversity and Telomere Length in Older Women from Northeast Brazil

We examined associations between adverse childhood experiences (ACEs) and shorter telomere length (TL) in 83 older women, including 42 women with less than secondary education and 41 with secondary or more education in a city of Northeast Brazil, a region with substantial socioeconomic inequalities. The low education sample was selected from a representative survey at local neighborhood health centers, while the high education group consisted of a convenience sample recruited by advertising in community centers and centers affiliated with the local university. Relative leukocyte TL was measured by quantitative polymerase chain reaction from blood samples. ACEs were self-reported. Spline linear regression was fitted to assess the strength of the associations between ACEs and TL. Among women with low education, median TL was 1.02 compared with 0.64 in the high education group (p = 0.0001). Natural log-transformed T/S ratio as the dependent variable was used in analysis. Women with low education had been exposed to more ACEs, and among them those experiencing two or more ACEs had longer TL than women exposed to ≤1 ACEs (p = 0.03); among women with high education, this difference was not significant (p = 0.49). In analyses adjusted by age, education, and parental abuse of alcohol, the linear trend of higher TL with increasing ACEs was confirmed (p = 0.02), and the mean difference in TL between groups remained significant (p = 0.002). The unexpected positive relationship between low education and ACEs with TL suggests that older adults who have survived harsh conditions prevailing in Northeast Brazil have the longest TL of their birth cohort.

Characterization of the particulate matter and relationship between buccal micronucleus and urinary 1-hydroxypyrene levels among cashew nut roasting workers

The present study is the first assessment of occupational risk associated with artisanal cashew nut roasting using exposure and effect biomarkers, as well as a characterization and dispersion analysis of the released particulate matter (PM). A real-time particle monitor was used to quantify PM_1.0, PM_2.5 and PM₁₀. Furthermore, the PM was sampled using a Handi-vol sampler, and the physicochemical characteristics were determined by SEM-EDS analysis. Trajectories, dispersion and deposition of the emitted material were calculated using the NOAA-HYSPLIT model. Urinary 1-hydroxypyrene (1-OHP) levels were analyzed by HPLC. DNA damage, chromosomal instability and cell death were measured by a buccal micronucleus cytome assay (BMCyt). The PM concentrations for all measurements in the exposed area were higher than in the non-exposed area. SEM-EDS analyses exhibited a wide variety of particles, and K, Cl, S and Ca biomass burning tracers were the major inorganic compounds. In addition, atmospheric modeling analysis suggested that these particles can reach regions farther away than 40 kilometers. Occupational polycyclic aromatic hydrocarbon exposure was confirmed by increases in 1-OHP levels in cashew nut workers. Frequencies of BMCyt biomarkers of genotoxicity (micronuclei and nuclear bud) and cytotoxicity (pyknosis, karyolysis, karyorrhexis and condensed chromatin) were higher in the exposed group compared with the controls. The influence of factors, such as age, on the micronuclei frequencies was demonstrated, and a correlation between 1-OHP and micronuclei was observed. To the best of our knowledge, no other study has demonstrated a correlation between these types of biomarkers. The use of exposure (1-OHP) and effect (BMCyt) biomarkers were therefore efficient in assessing the occupational risk associated with artisanal cashew nut roasting, and the high rates of PM_2.5 are considered to be a potential contributor to this effect.

Association of the XPD and XRCC3 gene polymorphisms with oral squamous cell carcinoma in a Northeastern Brazilian population: A pilot study

OBJECTIVE

to evaluate the association between XPD and XRCC3 polymorphisms and oral squamous cell carcinoma (OSCC).

DESIGN

the sample consisted of 54 cases of OSCC and 40 cases of inflammatory fibrous hyperplasia (IFH). Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

XPD-Lys/Gln was more common in IFH (n=28; 70%) than in OSCC (n=24; 44.4%) (OR: 0.3; p<0.05). XPD-Gln was more frequent in high-grade lesions (0.48) than in low-grade lesions (0.21) (OR: 3.4; p<0.05). The Gln/Gln genotype was associated with III and IV clinical stages (OR: 0.07; p<0.05). XRCC3-Met was more frequent in OSCC (0.49) than in IFH (0.35) (OR: 2.6; p<0.05). The Met/Met genotype was associated with the presence of metastases (OR: 8.1; p<0.05) and with III and IV clinical stages (OR: 0.07; p<0.05).

CONCLUSIONS

in this sample, the frequency of XPD-Gln in IFH suggests that this variant may protect against OSCC. The presence of the XRCC3-Met allele seems to contribute to the development of OSCC, metastases and more advanced stages in these lesions.

Violacein induces cell death by triggering mitochondrial membrane hyperpolarization in vitro

Background

Violacein is a purple pigment from Chromobacterium violaceum that possesses diverse biological and pharmacological properties. Among these, pro-oxidant and antioxidant activities have been suggested. However, the cytotoxic mechanisms induced by violacein are poorly understood and the improvement in knowledge regarding these cell death mechanisms will be useful to develop new therapeutic approaches. Considering this, in our work, we investigated the pro-oxidant effects of violacein in non-tumor (CHO-K1 and MRC-5) and tumor (HeLa) cell lines, searching for a better understanding of reactive oxygen species (ROS) production and cell death induction.

Results

Cytotoxicity induced by violacein was observed in the three cell lines; however, MRC-5 and HeLa cells were shown to be more sensitive to violacein treatment. Although punctual alterations in the antioxidant apparatus and increase in oxidative stress biomarkers was observed in some violacein concentrations, no association was found between increased oxidative stress and induction of cell death. However, the increase of mitochondrial membrane potential was observed.

Conclusions

In fact, the increase of mitochondrial membrane potential in MRC-5 and HeLa cells suggests that mitochondrial membrane hyperpolarization might be the main cause of cell death triggered by violacein.

Nutraceutical preconditioning with arginine and oil mixes. Effects on inflammatory mediators, oxidative stress and lipid profile in patients undergoing radical prostatectomy

PURPOSE

To investigate whether there is any effect resulting from preconditioning with nutraceutical supplementation containing arginine and oil mixes with high ω9:ω6 ratio and low ω6:ω3 ratio containing EPA and DHA, ALA fatty acids on inflammatory mediators, antioxidant and lipid profile modulation in surgical trauma.

METHODS

Twenty-six men scheduled for radical prostatectomy were randomized into three groups and treated as follows: Group 1 (skim milk, 0% fat), Group 2 (supplement with ω6:ω3 ratio of 8:1 and arginine) and Group 3 (supplement with high ω9:ω6 ratio of 3.2:1 and low ω6:ω3 ratio of 1.4:1 and arginine). Patients received skin milk or supplements twice a day (200 ml) during five days prior to surgery. Peripheral venous blood samples were collected at three different timepoints: five days before surgery (PRE), before anesthesia induction (IND) and on the 2nd postoperative day (POS). Parameters analyzed included inflammatory cytokines (IL-1β, IL-6, IL-8 and TNF-α), antioxidants (catalase), lipid profile and heat shock protein (HSP-27).

RESULTS

There were no significant differences between groups on inflammatory mediators and antioxidant parameters. However, lipid profile values (Cholesterol, LDL, Triglycerides, VLDL), were significantly different.

CONCLUSION

Preconditioning with arginine and oil mixes containing high ω9:ω6 ratio and low ω6:ω3 ratio, has no effects on inflammatory mediators and oxidative stress in patients undergoing radical prostatectomy. Reduction of cholesterol, triglycerides, LDL and VLDL profiles may be related to the trauma effect.

Cashew nut roasting: chemical characterization of particulate matter and genotocixity analysis

BACKGROUND

Particulate matter (PM) is potentially harmful to health and related to genotoxic events, an increase in the number of hospitalizations and mortality from respiratory and cardiovascular diseases. The present study conducted the first characterization of elemental composition and polycyclic aromatic hydrocarbon (PAH) analysis of PM, as well as the biomonitoring of genotoxic activity associated to artisanal cashew nut roasting, an important economic and social activity worldwide.

METHODS

The levels of PM2.5 and black carbon were also measured by gravimetric analysis and light reflectance. The elemental composition was determined using X-ray fluorescence spectrometry and PAH analysis was carried out by gas chromatography-mass spectrometry. Genotoxic activity was measured by the Tradescantia pallida micronucleus bioassay (Trad-MCN). Other biomarkers of DNA damage, such as nucleoplasmic bridges and nuclear fragments, were also quantified.

RESULTS

The mean amount of PM2.5 accumulated in the filters (January 2124.2 µg/m(3); May 1022.2 µg/m(3); September 1291.9 µg/m(3)), black carbon (January 363.6 µg/m(3); May 70 µg/m(3); September 69.4 µg/m(3)) and concentrations of Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br and Pb were significantly higher than the non-exposed area. Biomass burning tracers K, Cl, and S were the major inorganic compounds found. Benzo[k]fluoranthene, indene[1,2,3-c,d]pyrene, benzo[ghi]perylene, phenanthrene and benzo[b]fluoranthene were the most abundant PAHs. Mean benzo[a]pyrene-equivalent carcinogenic power values showed a significant cancer risk. The Trad-MCN bioassay revealed an increase in micronucleus frequency, 2-7 times higher than the negative control and significantly higher in all the months analyzed, possibly related to the mutagenic PAHs found.

CONCLUSIONS

This study demonstrated that artisanal cashew nut roasting is a serious occupational problem, with harmful effects on workers׳ health. Those involved in this activity are exposed to higher PM2.5 concentrations and to 12 PAHs considered potentially mutagenic and/or carcinogenic. The Trad-MCN with T. pallida was sensitive and efficient in evaluating the genotoxicity of the components and other nuclear alterations may be used as effective biomarkers of DNA damage.

Genetic damage of organic matter in the Brazilian Amazon: a comparative study between intense and moderate biomass burning

BACKGROUND

The biomass burning that occurs in the Amazon region has an adverse effect on environmental and human health. However, in this region, there are limited studies linking atmospheric pollution and genetic damage.

OBJECTIVE

We conducted a comparative study during intense and moderate biomass burning periods focusing on the genetic damage and physicochemical analyses of the particulate matter (PM).

METHOD

PM and black carbon (BC) were determined; organic compounds were identified and quantified using gas chromatography with flame ionization detection, the cyto-genotoxicity test was performed using two bioassays: cytokinesis-block micronucleus (CBMN) in A549 cells and Tradescantia pallida micronucleus (Trad-MCN) assay.

RESULTS

The PM10 concentrations were lower than the World Health Organization air quality standard for 24h. The n-alkanes analyses indicate anthropogenic and biogenic influences during intense and moderate biomass burning periods, respectively. Retene was identified as the most abundant polycyclic aromatic hydrocarbon during both sampling periods. Carcinogenic and mutagenic compounds were identified. The genotoxic analysis through CBMN and Trad-MCN tests showed that the frequency MCN from the intense burning period is significantly higher compared to moderate burning period.

CONCLUSIONS

This is the first study using human alveolar cells to show the genotoxic effects of organic PM from biomass burning samples collected in Amazon region. The genotoxicity of PM can be associated with the presence of several mutagenic and carcinogenic compounds, mainly benzo[a]pyrene. These findings have potential implications for the development of pollution abatement strategies and can minimize negative impact on health.

Cytokinesis-block micronucleus assay adapted for analyzing genomic instability of human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) are multipotent cells used in cell therapy research. One of the problems involving hMSCs is the possibility of genetic instability during in vitro expansion required to obtain a suitable number of cells for clinical applications. The cytokinesis-block micronucleus (CBMN) assay measures genetic instability by analyzing the presence of micronucleus (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs) in binucleated cells. The present study describes modifications in the CBMN assay methodology to analyze genetic instability in hMSCs isolated from the umbilical vein and in vitro expanded. The best protocol to achieve binucleated hMSCs with preserved cytoplasm was as follows: cytochalasin B concentration (4.0 μg/mL), use of hypotonic treatment (3 min), and the fixative solution (9 methanol:1 acetic acid). These adaptations were reproduced in three hMSC primary cell cultures and also in XP4PA and A549 cell lines. The frequency of hMSCs treated with mitomycin-C presenting MN was lower than that with other nuclear alterations, indicating that the hMSCs contain mechanisms to avoid a high level of chromosomal breaks. However, a high frequency of cells with NPBs was detected and spontaneous anaphase bridges under normal hMSC in vitro culture were observed. Considering that anaphase bridges are characteristic alterations in tumor cells, the CBMN assay is indicated as an important tool associated with other genetic analyses in order to ensure the safe clinical use of hMSCs in cell therapy.

Surface modification by argon plasma treatment improves antioxidant defense ability of CHO-k1 cells on titanium surfaces

Titanium is one of the most used materials in implants and changes in its surface can modify the cellular functional response to better implant fixation. An argon plasma treatment generates a surface with improved mechanical proprieties without modifying its chemical composition. Oxidative stress induced by biomaterials is considered one of the major causes of implant failure and studies in this field are fundamental to evaluate the biocompatibility of a new material. Therefore, in this work, induction of oxidative stress by titanium surfaces subjected to plasma treatment (PTTS) was evaluated. The viability of CHO-k1 cells was higher on PTTS discs. Cells grown on titanium surfaces are subjected to intracellular oxidative stress. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular survival. These were associated with improved cellular antioxidant response in Plasma Treated Titanium Surface (PTTS). Furthermore, a decrease in protein and DNA oxidative damage was observed on cells grown on the roughed surface when compared to the smooth one. In conclusion, our data suggest that the treatment of titanium with argon plasma may improve its biocompatible, thus improving its performance as implants or as a scaffold in tissue engineering.

Micronucleus frequency in children exposed to biomass burning in the Brazilian Legal Amazon region: a control case study

BACKGROUND

The Amazon represents an area of 61% of Brazilian territory and is undergoing major changes resulting from disorderly economic development, especially the advance of agribusiness. Composition of the atmosphere is controlled by several natural and anthropogenic processes, and emission from biomass burning is one with the major impact on human health. The aim of this study was to evaluate genotoxic potential of air pollutants generated by biomass burning through micronucleus assay in exfoliated buccal cells of schoolchildren in the Brazilian Amazon region.

METHODS

The study was conducted during the dry seasons in two regions of the Brazilian Amazon. The assay was carried out on buccal epithelial cells of 574 schoolchildren between 6-16 years old.

RESULTS

The results show a significant difference between micronucleus frequencies in children exposed to biomass burning compared to those in a control area.

CONCLUSIONS

The present study demonstrated that in situ biomonitoring using a sensitive and low cost assay (buccal micronucleus assay) may be an important tool for monitoring air quality in remote regions. It is difficult to attribute the increase in micronuclei frequency observed in our study to any specific toxic element integrated in the particulate matters. However, the contribution of the present study lies in the evidence that increased exposure to fine particulate matter generates an increased micronuclei frequency in oral epithelial cells of schoolchildren.

Genotoxicity and composition of particulate matter from biomass burning in the eastern Brazilian Amazon region

In the present study Tradescantia pallida micronucleus (Trad-MCN) bioassay was used to assess the genotoxicity of particulate matter with a mass median aerodynamic diameter less than 10 μm (PM₁₀) in Tangara da Serra (MT), a Brazilian Amazon region that suffers the impact of biomass burning. The levels of PM (coarse and fine size fractions) and black carbon (BC) collected were also measured. Furthermore, the alkanes and polycyclic aromatic hydrocarbons (PAHs) were identified and quantified in the samples taken during the burning period by gas chromatography with flame ionization detection (GC-FID). The PM and BC results for both fractions indicate a strong correlation (p < 0.001). The analysis of alkanes indicates an anthropic influence. Retene was the most abundant PAH found, an indicator of biomass burning, and 12 other PAHs considered to be potentially mutagenic and/or carcinogenic were identified in this sample. The Trad-MCN bioassay showed a significant increase in micronucleus frequency during the period of most intense burning, possibly related to the mutagenic PAHs that were found in such extracts. This study demonstrated that Trad-MCN was sensitive and efficient in evaluating the genotoxicity of organic compounds from biomass burning. It further emphasizes the importance of performing chemical analysis, because changes in chemical composition generally have a negative effect on many living organisms. This bioassay (ex situ), using T. pallida with chemical analysis, is thus recommended for characterizing the genotoxicity of air pollution.

Use of native species Crenicichla menezesi (Ariidae) as a model for in situ evaluation of genotoxicity in surface water

The aim of this work was to analyze the genotoxicity in surface water from the Pitimbú River (Natal, Brazil) using a neotropical species Crenicichla menezesi as bioindicator for in situ evaluation. The genotoxicity was analyzed using the micronucleus (MN) and comet assays in erythrocytes. The animals were collected from five sites of the river. A significant increase of MN frequency and comet class L1 to L4 were observed only in specimens collected from three sampling sites (SS3, SS4 and SS5) located into urban areas. These same sites also presented high metals concentration. Correlation of DNA damage and concentrations of Cu (Spearman r=0.8080), Cr (Spearman r=0.9772), and Ni (Spearman r=0.9909) were observed. These data indicate the presence of genotoxic agents. Moreover the C. menezesi species showed to be a good indicator for prompt analyses since this species presents sedentary and carnivore habits.

DNA repair in Chromobacterium violaceum

Chromobacterium violaceum is a Gram-negative beta-proteobacterium that inhabits a variety of ecosystems in tropical and subtropical regions, including the water and banks of the Negro River in the Brazilian Amazon. This bacterium has been the subject of extensive study over the last three decades, due to its biotechnological properties, including the characteristic violacein pigment, which has antimicrobial and anti-tumoral activities. C. violaceum promotes the solubilization of gold in a mercury-free process, and has been used in the synthesis of homopolyesters suitable for the production of biodegradable polymers. The complete genome sequence of this organism has been completed by the Brazilian National Genome Project Consortium. The aim of our group was to study the DNA repair genes in this organism, due to their importance in the maintenance of genomic integrity. We identified DNA repair genes involved in different pathways in C. violaceum through a similarity search against known sequences deposited in databases. The phylogenetic analyses were done using programs of the PHILYP package. This analysis revealed various metabolic pathways, including photoreactivation, base excision repair, nucleotide excision repair, mismatch repair, recombinational repair, and the SOS system. The similarity between the C. violaceum sequences and those of Neisserie miningitidis and Ralstonia solanacearum was greater than that between the C. violaceum and Escherichia coli sequences. The peculiarities found in the C. violaceum genome were the absence of LexA, some horizontal transfer events and a large number of repair genes involved with alkyl and oxidative DNA damage.