Assessment of genotoxic damage induced by exposure to binary mixtures of polycyclic aromatic hydrocarbons and three heavy metals in male mice

INTRODUCTION

Heavy metals (HM) and polycyclic aromatic hydrocarbons (PAHs) exposition has been associated with health problems. Therefore, this research evaluated genotoxicity induced in male mice strain CD-1 exposed to benzo[a]anthracene (B[a]A) and benzo[a]pyrene (B[a]P) and their interaction with Fe, Pb, and Al.

METHODS

Groups of animals were exposed intraperitoneally to HM, PAHs, and mixtures of both. Peripheral blood samples were taken from 0 to 96 h at 24 h intervals; genotoxicity was determined by micronucleus tests and comet assay. Additionally, toxicity and viability were evaluated.

RESULTS

HM and PAHs individually were genotoxic. About toxicity, only Al altered polychromatic erythrocytes number and did not change leukocytes viability. Concerning mixtures, Fe + B[a]P, Fe + B[a]A, Pb + B[a]P increased genotoxicity. There were no changes with Pb + B[a]A. Finally, Al mixtures with both PAHs damage was decreased.

CONCLUSIONS

Exposure to HM and PAH caused genetic damage. Fe, Al, and B[a]A, established a genotoxic potential. Every metal can interact with PAHs in different ways. Also, the micronucleus test and the comet assay demonstrated their high capacity and reliability to determine the genotoxic potential of the compounds evaluated in this work.

Biomimetic and bioorthogonal nanozymes for biomedical applications

Nanozymes mimic the function of enzymes, which drive essential intracellular chemical reactions that govern biological processes. They efficiently generate or degrade specific biomolecules that can initiate or inhibit biological processes, regulating cellular behaviors. Two approaches for utilizing nanozymes in intracellular chemistry have been reported. Biomimetic catalysis replicates the identical reactions of natural enzymes, and bioorthogonal catalysis enables chemistries inaccessible in cells. Various nanozymes based on nanomaterials and catalytic metals are employed to attain intended specific catalysis in cells either to mimic the enzymatic mechanism and kinetics or expand inaccessible chemistries. Each nanozyme approach has its own intrinsic advantages and limitations, making them complementary for diverse and specific applications. This review summarizes the strategies for intracellular catalysis and applications of biomimetic and bioorthogonal nanozymes, including a discussion of their limitations and future research directions.

Genotoxic and mutagenic evaluation in Eisenia foetida annelids exposed to iron ore tailings from the region of Brumadinho, MG, Brazil

Soils that have a disproportion of metallic elements due to anthropic activities endanger the terrestrial fauna. This study evaluated whether earthworms (Eisenia foetida) exposed to ore tailings from Brumadinho region presented a higher frequency of genotoxic and mutagenic damages than annelids from a reference area (control). The animals were exposed to substrates containing 0%, 25%, 50%, 75%, and 100% iron mining waste. The results indicated increased DNA damage (p < 0.05), detected by the comet assay at 25% and 50%. There was a three-fold increase in micronuclei in animals on the substrates with the highest concentrations (75% and 100%) [F = 3.095; p = 0.02]. The earthworms lost weight as the percentage of mining waste increased. We concluded that E. foetida presented DNA damage in the contaminated soils of Brumadinho. However, more research is fundamental, once the environmental disaster in Brumadinho was one of the biggest mining catastrophe in Brazil.

Environmental Influences on the Behavioural and Emotional Outcomes of Children: A Network Analysis

Background: Intellectual developmental disorders are a serious source of health morbidity with negative consequences for adults as well as children. However, there is limited evidence on the environmental, trace element, behavioural, and emotional outcomes in children. Here, we investigated whether there is any association between child behaviour and emotional outcomes and micronutrients using network analysis. Methods: A cross-sectional study was conducted in 9-year-old children within a Pacific Island Families study birth cohort. Elemental concentration was determined in children’s toenails after acid digestion and analysed using inductively coupled plasma mass spectrometry. We used network analysis to identify closely associated trace elements and tested the directions and strength of these trace elements. MANCOVA were used to identify the significant associations between individual elements and the behavioural/emotional function of the children using the children behaviour checklist (CBCL). At the final step, quantile regression analysis was used to assess and quantify the identified associations between CBCL function scores and manganese, adjusted by sex, ethnicity, and standardized BMI. Results: Three major nutrient networks were identified. In the Mn network, Mn was strongly positively associated with Al (0.63) and Fe (r = 0.65) and moderately associated with Pb (r = 0.45) and Sb (r = 0.42). Al was also strongly associated with Fe (r = 0.9). Children in the second or third clinical group, with an elevated externalized CBCL score, had a much higher mean and median level of Mn as compared to the normal range group. The aggression score was significantly associated with Mn concentration and sex. Higher Mn concentrations were associated with a higher aggression score. A 1 ug/g unit increase in Mn was associated with a 2.44-fold increase (95% confidence interval: 1.55–4.21) in aggression score, and boys had higher median aggression score than girls (difference: 1.7, 95% CI: 0.9–2.8). Attention and rule breaking scores were both significantly associated with Mn concentration. Higher Mn concentrations were associated with higher attention behaviour problem and rule breaking scores. A 1 ug/g unit increase in Mn was found to be associated with a 1.80-fold increase (95% confidence interval: 1.37–2.82) in attention score, and a 1.46-fold increase (95% confidence interval: 1.01–1.74) in the rule breaking score. Thought score was not significantly associated with Mn concentration (p = 0.13) but was significantly lower in boys (p = 0.004). Conclusions: Exceeding Mn levels is potentially toxic and has been identified to be associated with worse externalized children’s behavioural health and emotional well-being. Future studies are necessary to find the exposure paths so that advice shall be provided to family and care providers in public health and environmental protection.

A review of the physiological impact of rare earth elements and their uses in biomedical Mg alloys

Magnesium (Mg) is well-tolerated by the body, displaying exceedingly low toxicity, rapid excretion, and numerous bioactive effects, including improved bone formation and protection against oxidative stresses; further, Mg alloys can be degraded in vivo to allow complete removal of an implant without surgical intervention, avoiding revision surgery and thrombosis concerns seen with permanent implants. Rare earth elements (REEs) have been of particular interest in alloying Mg alloys for nearly a century due to their unique chemical and physical properties but have attracted increasing attention in recent decades. The REEs contribute greatly to the mechanical and biological properties of metal alloys, and so are common in Mg alloys in a wide variety of applications; in particular, they represent the dominant alloying additions in current, clinically applied Mg alloys. Notably, the use of these elements may assist in the development of advanced Mg alloys for use as biodegradable orthopedic implants and cardiovascular stents. To this end, current research progress in this area, highlighting the physiological impact of REEs in Mg alloys, is reviewed. Clinical work and preclinical data of REE-containing Mg alloys are analyzed. The biological roles of REEs in cellular responses in vivo require further research in the development of biofunctional Mg alloy medical devices. STATEMENT OF SIGNIFICANCE: The presented work is a review into the biological impact and current application of rare-earth elements (REEs) in biodegradable Mg-based biomaterials. Despite their efficacy in improving corrosion, mechanical, and manufacturability properties of Mg alloys, the physiological effects of REEs remain poorly understood. Therefore, the present work was undertaken to both provide guidance in the development of new biomedical alloys, and highlight areas of existing concerns and unclear knowledge. Key findings of this review include a summary of current clinical and preclinical work, and the identification of Sc as the most promising REE with regards to physiological impact. Y, Ce, Pr, Gd, Dy, Yb, Sm, and Eu should be considered carefully before their use as alloying elements, with other REEs intermediate or insufficiently studied.

Acute Toxic and Genotoxic Effects of Aluminum and Manganese Using In Vitro Models

The objective of this study was to use the same concentrations of aluminum (Al) and manganese (Mn) detected previously in groundwater above those permitted by Brazilian law and assess their cytotoxic and genotoxic effects in hamster ovary cell lines and their mutagenic effects through the Salmonella microsome assay. Chinese hamster ovary (CHO) and CHO-XRS5 cells were treated with different concentrations of Al and Mn (0.2 to 2.0 mg/L and 0.1 to 3.0 mg/L, respectively). The Ames test was used to analyze the concentrations of Al and Mn ranging from 0.025 to 1.0 mg/L and 0.0125 to 1.5 mg/L, respectively. Both metals showed cytotoxic effects on both cell lines and two bacterial strains (TA98 and TA100). The genotoxic effects of the highest concentrations of Al and Mn in cell lines showed nuclear buds, micronuclei, and DNA damage; however, none of the concentrations showed a positive mutagenic response in the Ames test. This is one of the few studies to demonstrate the cytotoxic effects of Al and Mn through the Ames test. In addition, the metals caused genomic instability in cell lines. Therefore, this study may help hasten the review of established regulatory standards for human consumption of groundwater.

Electroporation with nanosecond pulses and bleomycin or cisplatin results in efficient cell kill and low metal release from electrodes

Nanosecond electric pulses have several potential advantages in electroporation-based procedures over the conventional micro- and millisecond pulses including low level of heating, reduced electrochemical reactions and reduced muscle contractions making them alluring for use in biomedicine and food industry. The aim of this study was to evaluate if nanosecond pulses can enhance the cytotoxicity of chemotherapeutics bleomycin and cisplatin in vitro and to quantify metal release from electrodes in comparison to 100 μs pulses commonly used in electrochemotherapy. The effects of nanosecond pulse parameters (voltage, pulse duration, number of pulses) on cell membrane permeabilization, resealing and on cell survival after electroporation only and after electrochemotherapy with bleomycin and cisplatin were evaluated on Chinese hamster ovary cells. Application of permeabilizing nanosecond pulses in combination with chemotherapeutics resulted in successful cell kill. Higher extracellular concentrations of bleomycin - but not cisplatin - were needed to achieve the same decrease in cell survival with nanosecond pulses as with eight 100 μs pulses, however, the tested bleomycin concentrations were still considerably lower compared to doses used in clinical practice. Decreasing the pulse duration from microseconds to nanoseconds and concomitantly increasing the amplitude to achieve the same biological effect resulted in reduced release of aluminum ions from electroporation cuvettes.

Determination of the Elemental Composition of Ayahuasca and Assessments Concerning Consumer Safety

The consumption of ayahuasca, a brew prepared from the decoction of two Amazon plants, has increased worldwide in the last decades. This fact raised questions about the safety in its oral administration. In this sense, information concerning the chemical composition of ayahuasca is essential to find a comprehensive reply. Therefore, the aim of this study consisted of determining the elemental composition of ready-to-consume ayahuasca samples produced in Brazil, in order to evaluate the safety in the oral administration of this beverage, considering recommended macroelement and microelement daily intake values and the permitted limits of potentially toxic heavy metals. Real ayahuasca samples, obtained from Brazilian religious groups, underwent microwave radiation-assisted acid decomposition, and Li, Al, Mn, Fe, Co, Cu, Zn, As, Cd, Hg, and Pb concentrations were determined by ICP-MS, while Ca, Mg, K, and P concentrations were determined by ICP OES. Method accuracy was assessed by analyte addition and recovery assays. Recoveries ranged from 80 and 118%, indicating satisfactory accuracy. Limit of detection (LOD) and limit of quantification (LOQ) values were lower than 1 mg L^-1 for the macroelements determined by ICP OES and lower than 3.5 μg L^-1 for the microelements determined by ICP-MS. The concentrations of the elements determined in the samples were lower than the recommended or tolerable limits; hence, it is possible to affirm that ayahuasca presents safe administration levels regarding total elemental content.

Cytotoxic effects in transformed and non-transformed human breast cell lines after exposure to silver nanoparticles in combination with selected aluminium compounds, parabens or phthalates

This study was undertaken to assess cytotoxic effects of selected aluminium compounds, parabens and phthalates in combination with silver nanoparticles (AgNP, 15 and 45 nm by STEM, Ag15 and Ag45, respectively) on cell lines of the human breast epithelium, normal (MCF-10A) and transformed (MDA-MB-231 and MCF-7). Combination indices were the most spectacular at effective concentrations (ED) inducing 25 % decrease in viability for the combinations of Ag15 with AlCl₃ for MDA-MB-231 cells or aluminium zirconium tetrachlorohydrex Gly (AlZr) for MCF-10A and MCF-7 cells, where rather strong antagonism was revealed. As the ED values increased, those effects were enhanced (e.g. Ag15+AlCl₃ for MDA-MB-231) or reversed into synergism (e.g. Ag15+AlZr for MCF-7). Another strong effect was observed for aluminium chloride hydroxide, which increasing ED, induced synergistic effect with both Ag15 and Ag45 on MCF-10A cells. Another interesting synergistic effect was observed for DBPh, but only in combination with Ag45 on MCF-10A and MCF-7. The results on cytotoxicity, cell cycle and oxidative stress induction indicate complex response of the cell lines to combined treatment with silver nanoparticles and the chemicals, which were influenced by diverse factors, such as physico-chemical characteristics of AgNP, method of their synthesis, concentrations used, and finally cell type.

Removal of heavy metals using a novel sulfidogenic AMD treatment system with sulfur reduction: Configuration, performance, critical parameters and economic analysis

A novel sulfidogenic acid mine drainage (AMD) treatment system with a sulfur reduction process was developed. During the 220-d operation, >99.9% of 380-mg/L ferric, 150-mg/L aluminum, 110-mg/L zinc, 20-mg/L copper and 2.5-mg/L lead ions, and 42.6-44.4% of 100-mg/L manganese ions in the synthetic AMD were step-by-step removed in the developed system with three pre-posed metal precipitators and a sulfur reduction reactor. Among them, zinc, copper and lead ions were removed by the biogenic hydrogen sulfide that produced through elemental sulfur reduction; while ferric, aluminum and manganese ions were removed by the alkali precipitation. Compared with the reported sulfate reduction reactors, the sulfur reduction reactor significantly reduced the chemical cost by 25.6-78.9% for sulfide production, and maintained a high sulfide production rate (1.12 g S^2-/L-d). The pH level in the sulfidogenic reactor driven by sulfur-reducing bacteria posed a significant effect on the sulfide production rate. Under a nearly neutral condition (pH 7.0-7.5), elemental sulfur dissolved into polysulfide to increase the bioavailability of S⁰. At acidic conditions (pH < 6.0), polysulfide formation was limited and sulfate reduction became dominant. Therefore, maintaining the sulfidogenic reactor driven by sulfur-reducing bacteria at neutral condition is essential to realize high-rate and low-cost AMD treatment. Moreover, the escape of residual hydrogen sulfide from the system was eliminated by employing a 17% recirculation from effluent to the sulfidogenic reactor.

Novel ultrafine-grained β-type Ti-28Nb-2Zr-8Sn alloy for biomedical applications

Titanium alloys are widely accepted as orthopedic or dental implant materials in the medical field. It is important to evaluate the biocompatibility of an implant material prior to use. A new β-type ultrafine-grained Ti-28Nb-2Zr-8Sn (TNZS) alloy with low Young's modulus of 31.6 GPa was fabricated. This study aims to evaluate the biocompatibility of TNZS alloy. In this study, we examined the microstructure, chemical composition and surface wettability of the TNZS alloy. The mouse embryonic osteoblast MC3T3-E1 cells and human umbilical vein endothelial cells (HUVECs) were cultured to study the cytocompatibility of TNZS alloy. Also, we evaluated the proinflammatory response of TNZS alloy in vitro and in vivo. The results show that the TNZS did not cause cytotoxicity, genotoxicity to MC3T3-E1 cells and HUVECs. Whereas, the TNZS alloy could significantly promote the cell proliferation, cell spreading and cell adhesion of MC3T3-E1 cells and HUVECs, as well as facilitate the osteogenic differentiation of MC3T3-E1 cells. Moreover, the TNZS alloy did not induce any remarkable proinflammatory response in vitro and in vivo. Thus, the novel TNZS alloy with an elasticity closer to that of human bone is biologically safe and could be a potential candidate for biomedical implant application. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1628-1639, 2019.

Drosophila melanogaster as model organism for monitoring and analyzing genotoxicity associated with city air pollution

This study evaluated the genotoxic potential of atmospheric pollution associated with urbanization using the model organism Drosophila melanogaster and the Comet assay with hemolymph cells. Larvae were exposed to atmospheric compounds in an urban and a rural area in the municipality of Vitória de Santo Antão, Pernambuco, Brazil, for 6 days (from the embryo stage to the third larval stage) in April 2015 and April 2017. The results were compared to a negative environmental control group exposed to a preserved area (Catimbau National Park) and to a negative control exposed to the laboratory room conditions. The Comet assay demonstrated significant genetic damage in the organisms exposed to the urban area compared with those exposed to the rural area and negative control groups. The evidences were supported by particulate matter analysis showing higher photopeaks of chemical elements such as aluminum, silicon, sulfur, potassium, calcium, titanium, and iron, associated to road dust fraction in urban environment. Once again, the results confirm D. melanogaster an ideal bioindicator organism to monitor genotoxic hazard associated with atmospheric pollution.

The Mechanical Properties and In Vitro Biocompatibility of PM-Fabricated Ti-28Nb-35.4Zr Alloy for Orthopedic Implant Applications

A biocompatible Ti-28Nb-35.4Zr alloy used as bone implant was fabricated through the powder metallurgy process. The effects of mechanical milling and sintering temperatures on the microstructure and mechanical properties were investigated systematically, before in vitro biocompatibility of full dense Ti-28Nb-35.4Zr alloy was evaluated by cytotoxicity tests. The results show that the mechanical milling and sintering temperatures have significantly effects on the density and mechanical properties of the alloys. The relative density of the alloy fabricated by the atomized powders at 1500 °C is only 83 ± 1.8%, while the relative density of the alloy fabricated by the ball-milled powders can rapidly reach at 96.4 ± 1.3% at 1500 °C. When the temperature was increased to 1550 °C, the alloy fabricated by ball-milled powders achieve full density (relative density is 98.1 ± 1.2%). The PM-fabricated Ti-28Nb-35.4Zr alloy by ball-milled powders at 1550 °C can achieve a wide range of mechanical properties, with a compressive yield strength of 1058 ± 35.1 MPa, elastic modulus of 50.8 ± 3.9 GPa, and hardness of 65.8 ± 1.5 HRA. The in vitro cytotoxicity test suggests that the PM-fabricated Ti-28Nb-35.4Zr alloy by ball-milled powders at 1550 °C has no adverse effects on MC3T3-E1 cells with cytotoxicity ranking of 0 grade, which is nearly close to ELI Ti-6Al-4V or CP Ti. These properties and the net-shape manufacturability makes PM-fabricated Ti-28Nb-35.4Zr alloy a low-cost, highly-biocompatible, Ti-based biomedical alloy.

Buccal micronucleus cytome assay of populations under chronic heavy metal and other metal exposure along the Santiago River, Mexico

The Santiago River is one of the most contaminated rivers in Mexico, with heavy metal levels above the allowed limits. Scientific evidence indicates that chronic heavy metal exposure leads to cytogenotoxic effects. The aims of this study were to evaluate the genotoxic and cytotoxic effects of such exposure in buccal mucosa cells by micronucleus (MN) assay and to identify other nuclear abnormalities (NAs), such as nuclear buds (NBUDs), binucleated cells (BNs), pyknotic nuclei (PNs), karyorrhexis (KX), karyolysis (KL), and abnormally condensed chromatin (CC). Assays were performed on samples from four populations located alongside the Santiago River that are under chronic exposure to heavy metals and other metals (HMMs), and the results were compared with those of a population without exposure to HMMs. The exposed group showed increased frequencies of NAs (KX, CC, and KL), which are associated with cytotoxic damage, and NBUDs, which are associated with genotoxic damage. Increased frequencies of NBUDs and CC were observed in subjects from El Salto/Juanacatlán, Ocotlán, and Paso de Guadalupe, and an increase in KX frequency was observed in subjects from El Salto/Juanacatlán. Significant differences in KL frequency were observed in subjects from La Barca, El Salto/Juanacatlán, Paso de Guadalupe, and Ocotlán. Predictors for increased development of MNs and NBUDs were high concentrations of Al, Zn, and Cu. In conclusion, chronic exposure to HMMs, especially Al, Cu, and Zn, in the studied population could be related to increased frequencies of NAs, such as NBUDs, KX, CC, and KL, in the buccal mucosa cells.

Toxicity of two effluents from agricultural activity: Comparing the genotoxicity of sugar cane and orange vinasse

Vinasse, produced by several countries as a by-product of agricultural activity, has different alternatives for its reuse, mainly fertirrigation. Several monocultures, such as sugar cane and orange crops, produce this effluent. Sugar cane vinasse is already widely used in fertirrigation and orange vinasse has potential for this intention. However, its use as a fertilizer has caused great concern. Thus, ecotoxicological evaluation is extremely important in order to assess the possible effects on the environment. Therefore, the aim of this study was to evaluate the potential toxicity of vinasse of two different crops: sugar cane and orange. For this purpose, bioassays with Allium cepa as a test organism were performed with two vinasse dilutions (2.5% and 5%) to detect chromosomal aberrations and micronucleus induction. The results showed that both types of vinasse are able to induce chromosomal aberrations in meristematic cells, mainly nuclear and anaphasic bridges, suggesting genotoxic potential. The induction of micronuclei in cells of the F₁ region suggests that the two residues have mutagenic potential. Thus, caution is advised when applying these effluents in the environment.

Evaluation of in vivo and in vitro toxicological and genotoxic potential of aluminum chloride

Aluminum and its compounds are common contaminants of water and food, as well as medications and cosmetics. The wide distribution of the element facilitates the demand for detailed studies of its biological and toxicological effects. This work aimed to evaluate the possible genotoxic and toxic activity resulting from in vivo and in vitro exposure to Al. For in vivo analysis, 40 Swiss mice were used, various concentrations of hydrated aluminum chloride were administered orally. They were analyzed for possible genic activity and metal cytotoxicity using a micronucleus test (MN), and for toxicity through histopathological evaluation of the extracted organs. For in vitro analysis, lymphocytes from the peripheral blood of 3 healthy donors were used. These cells were exposed to the same chemical agent in various concentrations. In vivo study revealed a significant increase in the number of MN in all Al concentrations. Furthermore, significant alterations in all the organs evaluated were verified by the presence of irreversible lesions (such as necrosis). Corroborating these findings, a significant increase in the quantity of MN in all concentrations with lymphocytes in vitro. In light of this, we suggest that this metal presents genotoxic potential and is potentially a cause of pathological disorders.

Investigations into Ti-(Nb,Ta)-Fe alloys for biomedical applications

In this study, a Ti-(Ta,Nb)-Fe system was investigated with aims toward the development of high strength, biocompatible titanium alloy suitable for the development of porous orthopedic biomaterials with minimal processing. Notable findings include yield strengths of 740, 1250 and 1360 MPa for the Ti-12Nb-5Fe, Ti-7Ta-5Fe and Ti-10Ta-4Fe alloys, respectively, with elastic moduli comparable to existing Ti-alloys, yielding admissible strains of 0.9 ± 0.3, 1.2 ± 0.2 and 1.13 ± 0.02% for the Ti-12Nb-5Fe, Ti-7Ta-5Fe and Ti-10Ta-4Fe alloys, respectively; more than twice that of human bone. Observed microstructure varied significantly depending on alloy; near pure β-phase was seen in Ti-12Nb-5Fe, β with some ω precipitation in Ti-10Ta-4Fe, and a duplex α+β structure was observed throughout the Ti-7Ta-5Fe. In addition to suitable mechanical parameters, all investigated alloys exhibited promising corrosion potentials on the order of -0.24 V SCE, equalling that seen for a C.P.-Ti control at -0.25V SCE, and substantially more noble than that seen for Ti-6Al-4V. Electrochemical corrosion rates of 0.5-3 μm/year were likewise seen to agree well with that measured for C.P.-Ti. Further, no statistically significant difference could be seen between any of the alloys relative to a C.P.-Ti control regards to cell proliferation, as investigated via MTS assay and confocal microscopy. As such, the combination of high admissible strain and low corrosion indicate all investigated alloys show significant promise as potential porous biomaterials while in the as-cast state, with the Ti-10Ta-4Fe alloy identified as the most promising composition investigated.

STATEMENT OF SIGNIFICANCE

The findings of this paper are of significance to the field of metallic biomaterials as they detail the development of alloys of satisfactory biocompatibility and electrochemical behaviour, that furthermore display exceptional mechanical properties. Notably, both extremely high compressive yield strengths and admissible strains, up to 1.36 GPa and 1.2% respectively, are reported, exceeding or rivalling that seen in traditional alloys such as Ti-6Al-4V, which typically displays compressive yield strengths and admissible strains on the order of 895 MPa and 0.81% respectively, as well as modern alloys such as Gum Metal or TNZT. That this is achieved in the absence of thermomechanical processing represents a significant and novel outcome of substantial benefit for application as a porous biomaterial.

Flooding modifies the genotoxic effects of pollution on a worm, a mussel and two fish species from the Sava River

Extreme hydrological events, such as water scarcity and flooding, can modify the effect of other stressors present in aquatic environment, which could result in the significant changes in the ecosystem functioning. Presence and interaction of various stressors (genotoxic pollutants) in the environment can influence the integrity of DNA molecules in aquatic organisms which can be negatively reflected on the individual, population and community levels. Therefore, in this study we have investigated the impact of flooding, in terms of genotoxicity, on organisms belonging to different trophic levels. The study was carried out on the site situated in the lower stretch of the Sava River which faced devastating effects of severe flooding in May 2014. The flooding occurred during our field experiment and this event provided a unique opportunity to assess its influence to the environment. The in situ effects of this specific situation were monitored by measuring physical, chemical and microbiological parameters of water, and by comparing the level of DNA damage in coelomocytes and haemocytes of freshwater worms Branchiura sowerbyi, haemocytes of freshwater mussels Unio tumidus and blood cells of freshwater fish Abramis bjoerkna/Abramis sapa, by means of the comet assay. Our study indicated that the flooding had a significant impact on water quality by decreasing the amount and discharge rate of urban wastewaters but simultaneously introducing contaminants from the nearby fly ash disposal field into river by runoff, which had diverse effects on the level of DNA damage in the studied organisms. This indicates that the assessment of genotoxic pollution in situ is strongly affected by the choice of the bioindicator organism.

Cytotoxic, genotoxic, and neurotoxic effects of Mg, Pb, and Fe on pheochromocytoma (PC-12) cells

Metals such as lead (Pb), magnesium (Mg), and iron (Fe) are ubiquitous in the environment as a result of natural occurrence and anthropogenic activities. Although Mg, Fe, and others are considered essential elements, high level of exposure has been associated with severe adverse health effects including cardiovascular, hematological, nephrotoxic, hepatotoxic, and neurologic abnormalities in humans. In the present study we hypothesized that Mg, Pb, and Fe are cytotoxic, genotoxic and neurotoxic, and their toxicity is mediated through oxidative stress and alteration in protein expression. To test the hypothesis, we used the pheochromocytoma (PC-12) cell line as a neuro cell model and performed the LDH assay for cell viability, Comet assay for DNA damage, Western blot for oxidative stress, and HPLC-MS to assess the concentration levels of neurological biomarkers such as glutamate, dopamine (DA), and 3-methoxytyramine (3-MT). The results of this study clearly show that Mg, Pb, and Fe, respectively in the form of MgSO4 , Pb(NO3 )2 , FeCl2 , and FeCl3 induce cytotoxicity, oxidative stress, and genotoxicity in PC-12 cells. In addition, exposure to these metallic compounds caused significant changes in the concentration levels of glutamate, dopamine, and 3-MT in PC-12 cells. Taken together the findings suggest that MgSO4 , Pb(NO3 )2 , FeCl2 , and FeCl3 have the potential to induce substantial toxicity to PC-12 cells.

Evaluation of the genotoxic potential of soil contaminated with mineral coal tailings on snail Helix aspersa

Coal remains an important source of energy, although the fuel is a greater environmental pollutant. Coal is a mixture of several chemicals, especially inorganic elements and polycyclic aromatic hydrocarbons (PAH). Many of these compounds have mutagenic and carcinogenic effects on organisms exposed to this mineral. In the town of Charqueadas (Brazil), the tailings from mining were used for landfill in the lower areas of the town, and the consequence is the formation of large deposits of this material. The purpose of this study was to evaluate the genotoxic potential of soil samples contaminated by coal waste in different sites at Charqueadas, using the land snail Helix aspersa as a biomonitor organism. Thirty terrestrial snails were exposed to different treatments: 20 were exposed to the soil from two different sites in Charqueadas (site 1 and 2; 10 in each group) and 10 non-exposed (control group). Hemolymph cells were collected after 24h, 5days and 7days of exposure and comet assay, micronucleus test, oxidative stress tests were performed. Furthermore, this study quantified the inorganic elements present in soil samples by the PIXE technique and polycyclic aromatic hydrocarbons (PAH) by HPLC. This evaluation shows that, in general, soils from sites in Charqueadas, demonstrated a genotoxic effect associated with increased oxidative stress, inorganic and PAH content. These results demonstrate that the coal pyrite tailings from Charqueadas are potentially genotoxic and that H. aspersa is confirmed to be a sensitive instrument for risk assessment of environmental pollution.

Development of Ti-Nb-Zr alloys with high elastic admissible strain for temporary orthopedic devices

A new series of beta Ti-Nb-Zr (TNZ) alloys with considerable plastic deformation ability during compression test, high elastic admissible strain, and excellent cytocompatibility have been developed for removable bone tissue implant applications. TNZ alloys with nominal compositions of Ti-34Nb-25Zr, Ti-30Nb-32Zr, Ti-28Nb-35.4Zr and Ti-24.8Nb-40.7Zr (wt.% hereafter) were fabricated using the cold-crucible levitation technique, and the effects of alloying element content on their microstructures, mechanical properties (tensile strength, yield strength, compressive yield strength, Young's modulus, elastic energy, toughness, and micro-hardness), and cytocompatibilities were investigated and compared. Microstructural examinations revealed that the TNZ alloys consisted of β phase. The alloy samples displayed excellent ductility with no cracking, or fracturing during compression tests. Their tensile strength, Young's modulus, elongation at rupture, and elastic admissible strain were measured in the ranges of 704-839 MPa, 62-65 GPa, 9.9-14.8% and 1.08-1.31%, respectively. The tensile strength, Young's modulus and elongation at rupture of the Ti-34Nb-25Zr alloy were measured as 839 ± 31.8 MPa, 62 ± 3.6 GPa, and 14.8 ± 1.6%, respectively; this alloy exhibited the elastic admissible strain of approximately 1.31%. Cytocompatibility tests indicated that the cell viability ratios (CVR) of the alloys are greater than those of the control group; thus the TNZ alloys possess excellent cytocompatibility.

Stress-induced selection of a single species from an entire meiobenthic nematode assemblage: is this possible using iron enrichment and does pre-exposure affect the ease of the process?

The present work proposes a new experimental design using iron enrichment to select a single species from an entire meiobenthic nematode community. The high diversity of nematodes makes it impossible to study their responses to stressors in terms of chemical biomarkers, as this kind of research demands a single species as a form of biological material. Two assemblages, one from a control site (Canal) and one from an iron-contaminated site (Fouledh) in Bizerte Lagoon (Tunisia), were used to validate the protocol and to study whether pre-exposure to iron could affect the ease of the selection process. Analyses of variance suggested that the abundance and species number of nematodes from the Canal and Fouledh sites decreased discernibly with exposure to iron. Multivariate analyses performed on nematode abundances revealed that Oncholaimus campylocercoides, Sabatieria granifer, Sabatieria punctata and Theristus flevensis were the most tolerant species, probably due to their deposit-feeding behaviour. Species with a restricted feeding spectrum showed a low tolerance potential. At the end of the experiment, O. campylocercoides became the unique component of the nematode community from both sites. The complete alteration of the community was achieved with more difficulty for nematodes from Fouledh than for those from Canal. The identity of the selected species was confirmed at both the morphological levels and by sequencing the nuclear small subunit ribosomal DNA (18S rDNA).

A histological study of toxic effects of aluminium sulfate on rat hippocampus

Aluminium has toxic effects on many organ systems of the human body. Aluminium toxicity also is a factor in many neurodegenerative diseases. We investigated changes in numbers of hippocampal neurons in rats exposed to aluminium using an optical fractionator and we investigated aluminium-induced apoptosis using the transferase mediated dUTP nick end labeling (TUNEL) assay. Twenty-four female rats were divided equally into control, sham and aluminium-exposed groups. The control group received no treatment. The two treatment groups were injected intraperitoneally with 1 ml 0.9% saline without (sham) and with 3 mg/ml aluminium sulfate every day for two weeks. Following the treatments, the brains were removed, the left hemisphere was used for hippocampal neuron counting using an optical fractionator and the right hemisphere was investigated using hippocampal TUNEL assay to determine the apoptotic index. The number of neurons in the stratum pyramidale of the hippocampus was significantly less in the aluminium group than in the control and sham groups; there was no significant difference between the control and sham groups. The apoptotic index also was significantly higher in the aluminium group than in the other two groups. We quantified the toxic effects of aluminium on the rat hippocampus and determined that apoptosis was the mechanism of aluminium-induced neuron death in the hippocampus.

Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts

Abstract Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007) . Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of "total Al"assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al(+3) to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)(+2) and Al(H2O)6 (+3)] that after complexation with O2(•-), generate Al superoxides [Al(O2(•))](H2O5)](+2). Semireduced AlO2(•) radicals deplete mitochondrial Fe and promote generation of H2O2, O2 (•-) and OH(•). Thus, it is the Al(+3)-induced formation of oxygen radicals that accounts for the oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.

Metal-mediated DNA damage and cell death: mechanisms, detection methods, and cellular consequences

Metal ions cause various types of DNA damage by multiple mechanisms, and this damage is a primary cause of cell death and disease.

Baccharis trimera (Less.) DC as genotoxicity indicator of exposure to coal and emissions from a thermal power plant

During coal combustion, hazardous elements are discharged that impair environmental quality. Plant cover is the first available surface for the atmospheric pollutants in terrestrial ecosystems. The aim of this study was to evaluate genotoxicity in the aqueous extract of the native plant, Baccharis trimera, exposed to coal and emissions from a thermal power plant (coal-fired power plant in Candiota, Brazil), correlating seasonality, wind tunnel predominance, and presence of inorganic elements. The presence of inorganic elements in the aerial parts of B. trimera was analyzed by particle-induced X-ray emission (PIXE) spectrometry, and genotoxicity was evaluated by ex vivo comet assay. The genotoxic effects of aqueous extracts of B. trimera from four sites located in the area around power plant were analyzed by comet assay in peripheral human lymphocytes. Winter samples showed greater levels of metals than summer samples. Genotoxicity was detected in B. trimera extracts collected from the region exposed to extraction and burning coal. Extracts from the site impacted by the dominant wind induced more damage to DNA than those from other sites. Based on our data, we can suggest that in winter the inorganic elements from extraction and burning of coal and carried through the wind tunnel were responsible for the genotoxicity observed in aqueous extract of B. trimera.

A new look at biomedical Ti-based shape memory alloys

Shape memory alloys (SMAs) are materials that exhibit a distinct thermomechanical coupling, one that gives rise to a wide variety of applications across a broad range of fields. One of the most successful roles is in the construction of novel medical implants. Unfortunately, concerns have been raised about the biocompatibility of the most popular SMA, nitinol (NiTi), due to the known toxic, allergenic and carcinogenic properties of nickel. Given the unique capabilities of SMAs, it is apparent that there is a need for a new class of alloys - alloys that exhibit the full range of shape memory abilities yet are also free of any undesirable side effects. This article reviews the literature surrounding SMAs and identifies the metals Ti, Au, Sn, Ta, Nb, Ru and Zr as candidates for the production of thoroughly biocompatible SMAs. Hf and Re are also promising, though more research is necessary before a definitive statement can be made. Further, the Ti-(Ta,Nb)-(Zr,Hf) alloy system is particularly suited for orthopaedic implants due to a reduced Young's modulus. However, concerns over this system's shape memory properties exist, and should be taken into consideration. Alternate alloy systems that demonstrate higher bulk moduli may still be considered, however, if they are formed into a porous structure. Due to the nature of the alloying components, blended elemental powder metallurgy is recommended for the manufacture of these alloys, particularly due to the ease with which it may be adapted to the formation of porous alloys.