Lumbosacral pain in a patient with psoriatic arthritis: when the rheumatic disease is innocent.

Lumbar pain is a very common symptom that derives from benign musculoskeletal conditions, rheumatic inflammatory diseases, neoplasms, and referred and/or nociplastic pain. A 70-year-old man with psoriatic arthritis presented with early-onset lumbosacral pain without evident red flags. Symptomatic treatment was unhelpful. Radiographic imaging showed subtle signs of a disease that could easily be missed. Magnetic resonance imaging revealed a massive prostatic malignancy with bone (sacral and iliopubic) metastasis. Awareness must be given not to disregard every lumbar pain as part of the preexisting rheumatic inflammatory disease (spondyloarthropathy in this case) or a common muscle/ligament/articular disarrangement. Persistence of pain, albeit not inflam-matory nor sharp in nature, despite adequate treatment might be just as important as an acute red flag and requires proper follow-up.

Developing and validating high-value patient digital follow-up services: a pilot study in cardiac surgery.

BACKGROUND: The existing digital healthcare solutions demand a service development approach that assesses needs, experience, and outcomes, to develop high-value digital healthcare services. The objective of this study was to develop a digital transformation of the patients' follow-up service after cardiac surgery, based on a remote patient monitoring service that would respond to the real context challenges. METHODS: The study followed the Design Science Research methodology framework and incorporated concepts from the Lean startup method to start designing a minimal viable product (MVP) from the available resources. The service was implemented in a pilot study with 29 patients in 4 iterative develop-test-learn cycles, with the engagement of developers, researchers, clinical teams, and patients. RESULTS: Patients reported outcomes daily for 30 days after surgery through Internet-of-Things (IoT) devices and a mobile app. The service's evaluation considered experience, feasibility, and effectiveness. It generated high satisfaction and high adherence among users, fewer readmissions, with an average of 7 ± 4.5 clinical actions per patient, primarily due to abnormal systolic blood pressure or wound-related issues. CONCLUSIONS: We propose a 6-step methodology to design and validate a high-value digital health care service based on collaborative learning, real-time development, iterative testing, and value assessment.

Do medicine and cell biology talk to each other? A study of vocabulary similarities between fields.

A close interaction between basic science and applied medicine is to be expected. Therefore, it is important to measure how far apart the field of cell biology and medicine are. Our approach to estimating the distance between these fields was to compare their vocabularies and to quantify the difference in word repertoire. We compared the vocabulary of the title and abstract of articles available in PubMed in two selected high-impact journals in each field: cell biology, medicine, and translational science. Although each journal has its own editorial policy, we showed that within each field there is a small vocabulary difference between the two journals. We developed a word similarity index that can measure how much journals share a common vocabulary. We found a high similarity index between each cell biology (91%), medical (71-74%), and translational journal (65%). In contrast, the comparison between medicine and biology journals produced low correlation values (22-36%), suggesting that their vocabularies are quite dissimilar. Translational medicine journals had medium similarity values when compared to cell biology journals (52-70%) and medicine journals (27-59%). This approach was also performed in 10-year periods to evaluate the evolution of each field. Using the "onomics" strategy presented here, we observed that differences in vocabulary of basic science and medicine have been increasing over time. Since translational medicine has an intermediate vocabulary, we confirmed that translational medicine is an efficient approach to bridge this gap.

How do presbylarynx and presbycusis affect the Voice Handicap Index and the emotional status of the elderly? A prospective case-control study.

OBJECTIVE: To assess the influence of presbylarynx and presbycusis on Voice Handicap Index and emotional status. METHODS: A case-control, prospective, observational, cross-sectional study was conducted of patients aged 65 years or older referred to an otorhinolaryngology department from January to September 2020. Presbycusis was assessed by pure tone and vocal audiometry. Each subject underwent fibre-optic videolaryngoscopy with stroboscopy, and presbylarynx was considered when two or more of the following endoscopic findings were identified: vocal fold bowing, prominence of vocal processes in abduction, and a spindle-shaped glottal gap. Each subject completed two questionnaires: Voice Handicap Index and Geriatric Depression Scale (short-form). RESULTS: The studied population included 174 White European subjects, with a mean age of 73.99 years, of whom 22.8 per cent presented both presbylarynx and presbycusis. Multivariate linear regression revealed that only presence and severity of presbylarynx had an influence on Voice Handicap Index-30 scores. However, both spindle-shaped glottal gap and presbycusis influenced Geriatric Depression Scale scores. CONCLUSION: Presbylarynx has a strong association with the impact of voice on quality of life. Presbylarynx and presbycusis seem to have a cumulative effect on emotional status.

Mechanical and electronic properties of boron nitride nanosheets with graphene domains under strain.

Hybrid structures comprised of graphene domains embedded in larger hexagonal boron nitride (h-BN) nanosheets were first synthesized in 2013. However, the existing theoretical investigations on them have only considered relaxed structures. In this work, we use Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations to investigate the mechanical and electronic properties of this type of nanosheet under strain. Our results reveal that the Young's modulus of the hybrid sheets depends only on the relative concentration of graphene and h-BN in the structure, showing little dependence on the shape of the domain or the size of the structure for a given concentration. Regarding the tensile strength, we obtained higher values using triangular graphene domains. We find that the studied systems can withstand large strain values (between 15% and 22%) before fracture, which always begins at the weaker C-B bonds located at the interface between the two materials. Concerning the electronic properties, we find that by combining composition and strain, we can produce hybrid sheets with band gaps spanning an extensive range of values (between 1.0 eV and 3.5 eV). Our results also show that the band gap depends more on the composition than on the external strain, particularly for structures with low carbon concentration. The combination of atomic-scale thickness, high ultimate strain, and adjustable band gap suggests applications of h-BN nanosheets with graphene domains in wearable electronics.

Investigating size effects in graphene-BN hybrid monolayers: a combined density functional theory-molecular dynamics study.

We combine Density Functional Theory (DFT) and classical Molecular Dynamics (MD) simulations to study graphene-boron nitride (BN) hybrid monolayers spanning a wide range of sizes (from 2 nm to 100 nm). Our simulations show that the elastic properties depend on the fraction of BN contained in the monolayer, with Young's modulus values decreasing as the BN concentration increases. Furthermore, our calculations reveal that the mechanical properties are weakly anisotropic. We also analyze the evolution of the stress distribution during our MD simulations. Curiously, we find that stress does not concentrate on the graphene-BN interface, even though fracture always starts in this region. Hence, we find that fracture is caused by the lower strength of C-N and C-B bonds, rather than by high local stress values. Still, in spite of the fact that the weaker bonds in the interface region become a lower fraction of the total as size increases, we find that the mechanical properties of the hybrid monolayers do not depend on the size of the structure, for constant graphene/BN concentrations. Our results indicate that the mechanical properties of the hybrid monolayers are independent of scale, so long as the graphene sheet and the h-BN nanodomain decrease or increase proportionately.

Do medicine and cell biology talk to each other? A study of vocabulary similarities between fields

A close interaction between basic science and applied medicine is to be expected. Therefore, it is important to measure how far apart the field of cell biology and medicine are. Our approach to estimating the distance between these fields was to compare their vocabularies and to quantify the difference in word repertoire. We compared the vocabulary of the title and abstract of articles available in PubMed in two selected high-impact journals in each field: cell biology, medicine, and translational science. Although each journal has its own editorial policy, we showed that within each field there is a small vocabulary difference between the two journals. We developed a word similarity index that can measure how much journals share a common vocabulary. We found a high similarity index between each cell biology (91%), medical (71-74%), and translational journal (65%). In contrast, the comparison between medicine and biology journals produced low correlation values (22-36%), suggesting that their vocabularies are quite dissimilar. Translational medicine journals had medium similarity values when compared to cell biology journals (52-70%) and medicine journals (27-59%). This approach was also performed in 10-year periods to evaluate the evolution of each field. Using the "onomics" strategy presented here, we observed that differences in vocabulary of basic science and medicine have been increasing over time. Since translational medicine has an intermediate vocabulary, we confirmed that translational medicine is an efficient approach to bridge this gap.

Electronic, optical and thermoelectric properties of boron-doped nitrogenated holey graphene.

We employ first principles calculations to investigate the electronic, optical, and thermoelectric properties of ten boron-doped nitrogenated holey graphene (NHG) monolayers. We find that most of the proposed structures remain stable during ab initio molecular dynamics simulations, in spite of their increased formation energies. Density functional theory calculations employing a hybrid functional predict band gaps ranging from 0.73 eV to 2.30 eV. In general, we find that boron doping shifts optical absorption towards the visible spectrum, and also reduces light reflection in this region. On the other hand, the magnitude of optical absorption coefficients are reduced. Regarding the thermoelectric properties, we predict that boron doping can enhance the figure of merit ZT of NHG by up to 55%. Our results indicate that boron-doped NHG monolayers may find application in solar cells and thermoelectric devices.

Adenocarcinoma pulmonar associado à infecção por Mycobacterium sp. em vaca - relato de caso / [Pulmonary adenocarcinoma associated with infection by Mycobacterium sp. in a cow - case report]

Descrevem-se os aspectos clínicos, anatomopatológicos, imuno-histoquímicos, microbiológicos e moleculares de um caso de adenocarcinoma pulmonar associado à infecção por Mycobacterium sp. em uma vaca. O animal apresentou hiporexia, emagrecimento, vocalizações, postura ortopneica, ingurgitamento da jugular, estase venosa positiva, gemido expiratório e morte. Na necropsia, os pulmões estavam aumentados e apresentavam, na superfície pleural, nódulos branco-amarelados, firmes, multifocais a coalescentes, interpostos por áreas avermelhadas. Ao corte, os nódulos aprofundavam-se ao parênquima e possuíam múltiplos focos de aspecto caseoso e friável e áreas de mineralização. O saco pericárdico e os linfonodos traqueobrônquicos, ilíacos, lombares aórticos e mamários apresentavam lesões semelhantes. Histologicamente, observou-se neoformação carcinomatosa associada a áreas multifocais de necrose e mineralização. As células neoplásicas foram fortemente imunomarcadas pelo anticorpo antipancitoqueratina AE1/AE3. Na cultura microbiológica de fragmentos dos pulmões, houve crescimento de colônias bacterianas compatíveis com micobactérias atípicas. O sequenciamento molecular submetido ao BLASTn identificou o Mycobacterium sp. WCM 7299 (ID: gb|KJ873243.1|).(AU)

The clinical, anatomopathological, immunohistochemical, microbiological and molecular aspects of a case of pulmonary adenocarcinoma associated with infection by Mycobacterium sp. in a cow are described. The animal presented hyporexia, weight loss, vocalizations, orthopneic posture, jugular engorgement, positive venous stasis, expiratory groaning and death. At necropsy, the lungs were enlarged and presented firm, multifocal to coalescent yellowish nodules, interposed by reddish areas on the pleural surface. At cut, the nodules deepened to the parenchyma and had multiple foci of caseous and friable appearance and areas of mineralization. The pericardial sac and tracheobronchial, iliac, aortic lumbar and mammary lymph nodes showed similar lesions. Histologically, a carcinomatous neoformation, associated with multifocal areas of necrosis and mineralization, was observed. Neoplastic cells were strongly immunolabelled by anti-PanCytokeratin antibody AE1/AE3. Microbiological culture of lung fragments showed growth of bacterial colonies compatible with atypical mycobacteria. Molecular sequencing submitted to BLASTn identified the Mycobacterium sp. WCM 7299 (ID: gb|KJ873243.1|).(AU)

Chlorophyll treatment combined with photostimulation increases glycolysis and decreases oxidative stress in the liver of type 1 diabetic rats

Photodynamic therapy (PDT) promotes cell death, and it has been successfully employed as a treatment resource for neuropathic complications of diabetes mellitus (T1DM) and hepatocellular carcinoma. The liver is the major organ involved in the regulation of energy homeostasis, and in pathological conditions such as T1DM, changes in liver metabolic pathways result in hyperglycemia, which is associated with multiple organic dysfunctions. In this context, it has been suggested that chlorophyll-a and its derivatives have anti-diabetic actions, such as reducing hyperglycemia, hyperinsulinemia, and hypertriglyceridemia, but these effects have not yet been proven. Thus, the biological action of PDT with chlorophyll-a on hepatic parameters related to energy metabolism and oxidative stress in T1DM Wistar rats was investigated. Evaluation of the acute effects of this pigment was performed by incubation of isolated hepatocytes with chlorophyll-a and the chronic effects were evaluated by oral treatment with chlorophyll-based extract, with post-analysis of the intact liver by in situ perfusion. In both experimental protocols, chlorophyll-a decreased hepatic glucose release and glycogenolysis rate and stimulated the glycolytic pathway in DM/PDT. In addition, there was a reduction in hepatic oxidative stress, noticeable by decreased lipoperoxidation, reactive oxygen species, and carbonylated proteins in livers of chlorophyll-treated T1DM rats. These are indicators of the potential capacity of chlorophyll-a in improving the status of the diabetic liver.

Chlorophyll treatment combined with photostimulation increases glycolysis and decreases oxidative stress in the liver of type 1 diabetic rats.

Photodynamic therapy (PDT) promotes cell death, and it has been successfully employed as a treatment resource for neuropathic complications of diabetes mellitus (T1DM) and hepatocellular carcinoma. The liver is the major organ involved in the regulation of energy homeostasis, and in pathological conditions such as T1DM, changes in liver metabolic pathways result in hyperglycemia, which is associated with multiple organic dysfunctions. In this context, it has been suggested that chlorophyll-a and its derivatives have anti-diabetic actions, such as reducing hyperglycemia, hyperinsulinemia, and hypertriglyceridemia, but these effects have not yet been proven. Thus, the biological action of PDT with chlorophyll-a on hepatic parameters related to energy metabolism and oxidative stress in T1DM Wistar rats was investigated. Evaluation of the acute effects of this pigment was performed by incubation of isolated hepatocytes with chlorophyll-a and the chronic effects were evaluated by oral treatment with chlorophyll-based extract, with post-analysis of the intact liver by in situ perfusion. In both experimental protocols, chlorophyll-a decreased hepatic glucose release and glycogenolysis rate and stimulated the glycolytic pathway in DM/PDT. In addition, there was a reduction in hepatic oxidative stress, noticeable by decreased lipoperoxidation, reactive oxygen species, and carbonylated proteins in livers of chlorophyll-treated T1DM rats. These are indicators of the potential capacity of chlorophyll-a in improving the status of the diabetic liver.

Electronic and optical properties of B x C y N z hybrid α-graphynes.

Hybrid two-dimensional (2D) materials composed of carbon, boron, and nitrogen constitute a hot topic of research, as their flexible composition allows for tunable properties. However, while graphene-like hybrid lattices have been well characterized, systematic investigations are lacking for various 2D materials. Hence, in the present contribution, we employ first-principles calculations to investigate the structural, electronic and optical properties of what we call B x C y N z hybrid α-graphynes. We considered eleven structures with stoichiometry BC2N and varied atomic arrangements. We calculated the formation energy for each arrangement, and determined that it is low (high) when the number of boron-carbon and nitrogen-carbon bonds is low (high). We found that the formation energy of many our structures compared favorably with a previous literature proposal. Regarding the electronic properties, we found that the investigated structures are semiconducting, with band gaps ranging from 0.02 to 2.00 eV. Moreover, we determined that most of the B x C y N z hybrid α-graphynes proposed here strongly absorb infrared light, and so could potentially find applications in optoelectronic devices such as heat sensors and infrared filters.

High frequency of genital carriers of Leptospira sp. in sheep slaughtered in the semi-arid region of northeastern Brazil.

Although some studies in sheep have indicated leptospire colonization of the genital tract, further studies are needed to clarify the role of genital carriers in this species. Thus, this study aimed to evaluate the colonization of pathogenic leptospires in the genital and urinary tract of slaughtered sheep. Fifty-seven adult, female woolless sheep destined for slaughter were used. Renal (n = 57), bladder (n = 57), ovary (n = 34), uterine tube (n = 44), and uterus (n = 33) samples were collected for molecular detection of Leptospira sp. DNA, and blood samples (n = 57) for serological testing. The molecular testing was performed using polymerase chain reaction (PCR), and the serological testing was performed using microscopic serum agglutination test (MAT). Samples with amplifying DNA were subjected to genetic sequencing. In total, leptospiral DNA was found in the tissues of 44 (77.2%) sheep, whereas only nine animals were positive on both PCR and MAT; there was slight agreement between PCR and MAT techniques (k = 0.0268; p = 0.684). In 61 (54.9%) genital tract and in five (4.4%) urinary tract samples, the leptospiral DNA was detected, with significant difference (p < 0.001). The genes of one sample from the uterine tube and another from the bladder were sequenced and demonstrated 99% similarity to Leptospira interrogans. Anti-Leptospira antibodies were detected in 11 (19.3%) of the tested animals. The results reinforce the importance of the genital tract as an extra-renal site of colonization, suggesting the possibility of venereal transmission in sheep.

Characterization of dog serum virome from Northeastern Brazil.

Domestic dogs share habitats with human, a fact that makes them a potential source of zoonotic viruses. Moreover, knowledge regarding possible bloodborne pathogens is important due to the increasing application of blood transfusion in dogs. In the present study, we evaluated the serum virome of 520 dogs using throughput sequencing (HTS). The serum samples were pooled and sequenced using an Illumina MiSeq platform. Our unbiased method identified prevalent canine pathogens as canine protoparvovirus 1 (canine parvovirus 2), undersearched agents as canine bocaparvovirus 1 (minute virus of canines) and canine circovirus, circular viruses closely related to viruses recently found in human samples, and new parvovirus and anelloviruses. The dog virome described in the present work furthers the knowledge concerning the viral population in domestic animals. The present data includes information regarding viral agents that are potentially transmitted through blood transfusion among dogs.

B x C y N z hybrid graphenylene: stability and electronic properties.

Interest in hybrid monolayers with arrangements that differ from that of the honeycomb lattice has been growing. However, systematic investigations on the properties of these structures are still lacking. In this work, we combined density functional theory (DFT) and molecular dynamics (MD) simulations to study the stability and electronic properties of nanosheets composed of B, C, and N atoms arranged in the pattern of the carbon allotrope graphenylene. We considered twenty structures with varied atomic arrangements and stoichiometries, which we call B x C y N z hybrid graphenylenes. We calculated the formation energy for each arrangement, and found that it decreases as the number of B-C and N-C bonds decreases. We also found that the structure with minimum energy has stoichiometry B2CN and an atomic arrangement with BN and C stripes connected along the zigzag direction. Regarding the electronic properties, we found that all investigated structures are semiconductors, with band gaps ranging from 0.14 to 1.65 eV. Finally, we found that the optimized hybrid lattices presented pores of varied sizes and shapes. This diversity in pore geometry suggests that these structures might be particularly suited for molecular sieve applications.

Benefícios da condroitinase abc associada a células-tronco mesenquimais na lesão espinhal aguda em ratos / Benefits of chondroitinase abc associated with mesenchymal stem cells in acute spinal cord injury in rats

Com o objetivo de estudar o efeito da condroitinase associada às células-tronco mesenquimais na lesão aguda da medula espinhal, utilizaram-se 50 ratos Lewis, distribuídos igualmente nos grupos: controle negativo (CN), tratamento com placebo (PLA), condroitinase (CDN), células-tronco mesenquimais (CTM) e condroitinase mais células-tronco mesenquimais (CDN+CTM). Todos os animais tiveram a medula espinhal exposta por laminectomia, e os grupos PLA, CDT, CTM e CDT+CTM sofreram também trauma medular compressivo. Após sete dias, procedeu-se à reexposição da medula espinhal, quando os grupos PLA e CTM receberam 4µL de líquido cefalorraquidiano artificial via intralesional, e os grupos CDT e CDT+CTM receberam o mesmo líquido contendo 2,2U de condroitinase. Após 14 dias da cirurgia inicial, todos os animais receberam 0,2mL de PBS via endovenosa, contudo, nos grupos CTM e CDT+CTM, esse líquido continha 1x106 CTM. Avaliou-se a capacidade motora até o 28o dia pós-trauma e, posteriormente, as medulas espinhais foram analisadas por RT-PCR, para quantificação da expressão gênica para BDNF, NT-3, VEGF, KDR e PECAM-1, e por imunoistoquímica, para detecção das células-tronco GFP injetadas (anti-GFP), quantificação dos neurônios (anti-NeuN) e da GFAP e vimentina, para avaliação da cicatriz glial. As análises estatísticas foram realizadas com o auxílio do Prism 5 for Windows, com o nível de significância de 5%. Não houve diferença entre os grupos quanto à capacidade motora. O grupo CDT+CTM apresentou maior imunoexpressão de neurônios viáveis do que o placebo. No CTM, houve maior expressão dos fatores neurotróficos BDNF e VEGF. E no CDT, houve menor imunoexpressão de vimentina. Concluiu-se que a associação CDT+CTM favorece a viabilidade neuronal após o trauma, que o tratamento com CTM promove aumento na expressão dos fatores tróficos BDNF e VEGF e que o tratamento com condroitinase é efetivo na redução da cicatriz glial.(AU)

The aim of this work was to study the effect of chondroitinase associated with mesenchymal stem cells in acute spinal cord injury. Therefore, 50 Lewis rats were distributed in the following groups: negative control (NC), treatment with placebo (PLA), chondroitinase (CDT), mesenchymal stem cells (MSC), and chondroitinase associated with mesenchymal stem cells (CDT + MSC). All animals had their spinal cord exposed by laminectomy, and the groups named PLA, CDT, MSC and CDT + MSC also suffered compressive spinal cord trauma. After seven days, the spinal cord was re-exposed, when the PLA and MSCs groups received 4uL of artificial cerebrospinal fluid through the lesion, and the CDT group and CDT + MSC received the same fluid containing 2,2U of chondroitinase. 14 days after the first surgery, all animals received 0.2ml of PBS intravenously; however, the MSC and CDT + MSC groups received the same liquid also containing 1x106 MSCs. The motor skills were evaluated up to 28 days post-injury and, subsequently, the spinal cords were analyzed by RT-PCR for BDNF, NT-3, VEGF, PECAM-1 and KDR gene expression quantification, immunohistochemistry to detect injected stem cells GFP (anti-GFP), to quantify neurons (anti-NeuN), GFAP and detect vimentin in order to evaluate the glial scar. Statistical analyzes were performed by Prism 5 for Windows using a 5% level of significance. There was no difference between groups with regarding motor capacity. The CDT + MSC group showed increased immunoreactivity of viable neurons than placebo. In MSC, there was a greater expression of neurotrophic factors BDNF and VEGF. Also, there was less vimentin immunostaining in group CDT. It was concluded that CDT + MSC association promotes neuronal viability after trauma, in which treatment with MSC promotes increased expression of BDNF and VEGF trophic factors, and also that treatment with chondroitinase is effective in reducing the glial scar.(AU)

Nasal airflow simulations suggest convergent adaptation in Neanderthals and modern humans.

Both modern humans (MHs) and Neanderthals successfully settled across western Eurasian cold-climate landscapes. Among the many adaptations considered as essential to survival in such landscapes, changes in the nasal morphology and/or function aimed to humidify and warm the air before it reaches the lungs are of key importance. Unfortunately, the lack of soft-tissue evidence in the fossil record turns difficult any comparative study of respiratory performance. Here, we reconstruct the internal nasal cavity of a Neanderthal plus two representatives of climatically divergent MH populations (southwestern Europeans and northeastern Asians). The reconstruction includes mucosa distribution enabling a realistic simulation of the breathing cycle in different climatic conditions via computational fluid dynamics. Striking across-specimens differences in fluid residence times affecting humidification and warming performance at the anterior tract were found under cold/dry climate simulations. Specifically, the Asian model achieves a rapid air conditioning, followed by the Neanderthals, whereas the European model attains a proper conditioning only around the medium-posterior tract. In addition, quantitative-genetic evolutionary analyses of nasal morphology provided signals of stabilizing selection for MH populations, with the removal of Arctic populations turning covariation patterns compatible with evolution by genetic drift. Both results indicate that, departing from important craniofacial differences existing among Neanderthals and MHs, an advantageous species-specific respiratory performance in cold climates may have occurred in both species. Fluid dynamics and evolutionary biology independently provided evidence of nasal evolution, suggesting that adaptive explanations regarding complex functional phenotypes require interdisciplinary approaches aimed to quantify both performance and evolutionary signals on covariation patterns.

Cylindrospermopsin effects on cell viability and redox milieu of Neotropical fish Hoplias malabaricus hepatocytes.

Cylindrospermopsin (CYN) is a cyanotoxin that is cytotoxic to a wide variety of cells, particularly to the hepatocytes. In this study, the toxic effects of purified CYN were investigated in primary cultured hepatocytes of Neotropical fish Hoplias malabaricus. After isolation, attachment, and recovery for 72 h, the cells were exposed for 72 h to 0, 0.1, 1.0, 10, and 100 µg l-1 of CYN. Then, cell viability and a set of oxidative stress biomarker responses were determined. Catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione S-transferase activities were not affected by exposure to CYN. Concentration-dependent decrease of glutathione reductase activity occurred for most CYN-exposed groups, whereas non-protein thiol content increased only for the highest CYN concentration. Lipid peroxidation, protein carbonylation, and DNA damage levels were not altered, but reactive oxygen species levels increased in the cells exposed to the highest concentration of CYN. Cell viability decreased in all the groups exposed to CYN. Thus, CYN may cause a slight change in redox balance, but it is not the main cause of cell death in H. malabaricus hepatocytes.

A mixture toxicity approach to predict the toxicity of Ag decorated ZnO nanomaterials.

Nanotechnology is a rising field and nanomaterials can now be found in a vast variety of products with different chemical compositions, sizes and shapes. New nanostructures combining different nanomaterials are being developed due to their enhancing characteristics when compared to nanomaterials alone. In the present study, the toxicity of a nanostructure composed by a ZnO nanomaterial with Ag nanomaterials on its surface (designated as ZnO/Ag nanostructure) was assessed using the model-organism Daphnia magna and its toxicity predicted based on the toxicity of the single components (Zn and Ag). For that ZnO and Ag nanomaterials as single components, along with its mixture prepared in the laboratory, were compared in terms of toxicity to ZnO/Ag nanostructures. Toxicity was assessed by immobilization and reproduction tests. A mixture toxicity approach was carried out using as starting point the conceptual model of Concentration Addition. The laboratory mixture of both nanomaterials showed that toxicity was dependent on the doses of ZnO and Ag used (immobilization) or presented a synergistic pattern (reproduction). The ZnO/Ag nanostructure toxicity prediction, based on the percentage of individual components, showed an increase in toxicity when compared to the expected (immobilization) and dependent on the concentration used (reproduction). This study demonstrates that the toxicity of the prepared mixture of ZnO and Ag and of the ZnO/Ag nanostructure cannot be predicted based on the toxicity of their components, highlighting the importance of taking into account the interaction between nanomaterials when assessing hazard and risk.