Characterizing the Chemical Profile of Incidental Ultrafine Particles for Toxicity Assessment Using an Aerosol Concentrator.

Incidental ultrafine particles (UFPs) constitute a key pollutant in industrial workplaces. However, characterizing their chemical properties for exposure and toxicity assessments still remains a challenge. In this work, the performance of an aerosol concentrator (Versatile Aerosol Concentration Enrichment System, VACES) was assessed to simultaneously sample UFPs on filter substrates (for chemical analysis) and as liquid suspensions (for toxicity assessment), in a high UFP concentration scenario. An industrial case study was selected where metal-containing UFPs were emitted during thermal spraying of ceramic coatings. Results evidenced the comparability of the VACES system with online monitors in terms of UFP particle mass (for concentrations up to 95 µg UFP/m3) and between filters and liquid suspensions, in terms of particle composition (for concentrations up to 1000 µg/m3). This supports the applicability of this tool for UFP collection in view of chemical and toxicological characterization for incidental UFPs. In the industrial setting evaluated, results showed that the spraying temperature was a driver of fractionation of metals between UF (<0.2 µm) and fine (0.2-2.5 µm) particles. Potentially health hazardous metals (Ni, Cr) were enriched in UFPs and depleted in the fine particle fraction. Metals vaporized at high temperatures and concentrated in the UF fraction through nucleation processes. Results evidenced the need to understand incidental particle formation mechanisms due to their direct implications on particle composition and, thus, exposure. It is advisable that personal exposure and subsequent risk assessments in occupational settings should include dedicated metrics to monitor UFPs (especially, incidental).

Deep learning predicts path-dependent plasticity.

Plasticity theory aims at describing the yield loci and work hardening of a material under general deformation states. Most of its complexity arises from the nontrivial dependence of the yield loci on the complete strain history of a material and its microstructure. This motivated 3 ingenious simplifications that underpinned a century of developments in this field: 1) yield criteria describing yield loci location; 2) associative or nonassociative flow rules defining the direction of plastic flow; and 3) effective stress-strain laws consistent with the plastic work equivalence principle. However, 2 key complications arise from these simplifications. First, finding equations that describe these 3 assumptions for materials with complex microstructures is not trivial. Second, yield surface evolution needs to be traced iteratively, i.e., through a return mapping algorithm. Here, we show that these assumptions are not needed in the context of sequence learning when using recurrent neural networks, diverting the above-mentioned complications. This work offers an alternative to currently established plasticity formulations by providing the foundations for finding history- and microstructure-dependent constitutive models through deep learning.

Multibiomarker toxicity characterization of uranium mine drainages to the fish Carassius auratus.

The release of acidic effluents, naturally enriched in metals and radionuclides, is the main legacy of uranium mines. Generally, metals dissolved by these acidic effluents can cause significant alterations in exposed organisms, with distinct toxicological outcomes. In this study, 72 individuals of the freshwater fish species Carassius auratus were exposed in situ for different periods (8, 16, 24, and 48 h) to water from a pond (treatment pond (TP)) with a chemically treated effluent and a reference pond (PRP), in the vicinity of the Cunha Baixa uranium mine (Portugal). Comparing the water of the two ponds, the PRP pond was characterized by higher pH and oxygen values and lower conductivity and hardness values. Regarding total metal concentrations, among others, magnesium (56,000 µg/L), sodium (17,400 µg/L), zinc (86 µg/L), manganese (6340 µg/L), and uranium (1380 µg/L) concentrations in the TP pond were above the values obtained for the PRP pond. The values of manganese and uranium exceeded the values of quality criteria established for surface waters for cyprinids and for irrigation purposes. After exposure to pond water, significant differences were recorded for several biomarkers: (i) between ponds for acetylcholinesterase (AChE) with higher activities for animals from the PRP and glutathione-S-transferase (GST) activities that were particularly enhanced in animals from the TP pond; (ii) between ponds and exposure periods for lactate dehydrogenase (LDH) activity, since organisms from PRP pond presented always higher values than those from the TP pond, and among these, organisms exposed for the longer period presented a further depression in LDH activity; and (iii) between exposure periods for erythrocyte micronucleus. GSTs and LDH were the most sensitive biomarkers within the timeframe of the in situ assay performed. Despite the alleged efficacy of the chemical treatment (evidenced by a significantly lower pH), some metals persisted in the treated effluent (TP pond), potentially contributing to the induction of oxidative stress or increased conjugation metabolic activity in fish.

Crescimento e tolerância à salinidade em três espécies medicinais do gênero Plectranthus expostas a diferentes níveis de radiação / Growth and salinity tolerance in three medicinal species of the genus Plectranthus exposed to different levels of solar radiation

No cultivo de plantas medicinais as condições de salinidade e de luz podem exercer influência no rendimento e na qualidade final da produção de biomassa. O objetivo deste trabalho foi avaliar o efeito de diferentes luminosidades e níveis de salinidade na água de irrigação sobre o crescimento e tolerância de três espécies de plantas do gênero Plectranthus. O ensaio foi conduzido em parcelas subsubdivididas com cinco repetições, sendo as parcelas referente ao fator ambiente (pleno sol e telado), as subparcelas aos níveis de salinidade na água de irrigação - CEa (0,7; 1,9; 3,1; 4,3 e 5,5 dS m-1), e as subsubparcelas às três espécies do gênero Plectranthus (P. amboinicus, P. barbatus e P. grandis). As variáveis de resposta foram: índice relativo de clorofila (IRC), área foliar (AF), razão de área foliar (RAF), área foliar específica (AFE), matéria seca da parte aérea (MSPA), matéria seca das raízes (MSR), matéria seca total (MST), relação MSR/MSPA, grau de tolerância à salinidade, e teor dos íons Na+ e K+. O estresse salino reduziu o crescimento das plantas, sendo as maiores reduções observadas nas plantas expostas a pleno sol. A salinidade influenciou a partição de matéria seca, sendo as raízes mais afetadas do que a parte aérea. Com o aumento da CEa houve aumento expressivo no teor foliar de Na+, enquanto o teor de K+ e o IRC foram reduzidos. Entretanto, o acúmulo de Na+ foi menor em P. grandis. Considerando-se a MST, verificou-se que as três espécies se mostraram moderadamente tolerantes à salinidade de até 3,1 dS m-1, exceto P. grandis cultivada em telado, classificada como tolerante. Em relação ao grau de redução na produção MSPA (parte de interesse comercial), poderia se recomendar o cultivo de P. grandis quando a água de irrigação contiver CEa de até 3,1 dS m-1.

In the cultivation of medicinal plants, salinity and light can affect the yield and quality of biomass. The objective of this study was to evaluate the effect of light and salinity levels of the irrigation water on the growth and salt tolerance of three medicinal plant species of the genus Plectranthus. A completely randomized split-plot design with five repetitions was used. The plots were formed by the environment of cultivation (full sunlight and greenhouse), the subplots by the salinity in the irrigation water - ECw (0.7, 1.9, 3.1, 4.3 and 5.5 dS m-1), and the subsubplots by the three plant species (P. amboinicus, P. barbatus and P. grandis). The following variables were evaluated: relative chlorophyll index (RCI), leaf area (LA), leaf area ratio (LAR), specific leaf area (SLA), shoot dry mass (SDM), root dry mass (RDM), total dry mass (TDM), RDM/SDM ratio, relative salt tolerance, and concentration of Na+ and K+ in leaves. Salinity reduced plant growth, with the greatest reductions observed in plants exposed to full sunlight. Salinity affected the dry matter partitioning, and the roots were more affected than the shoot. With increasing ECw, there was a significant increase in the concentration of Na+ in the leaves, while K+ and RCI decreased. However, the increase in Na+ accumulation was lower in P grandis. The three species were moderately tolerant to salinity up to 3.1 dS m-1, considering the total dry mass production, except the P. grandis grown in greenhouse, classified as tolerant. Regarding the relative reduction in shoot dry mass (part of commercial interest), we could recommend the cultivation of P. grandis when the available irrigation water presents values of ECw up to 3.1 dS m-1.

5-HT2A/C receptors mediate the antipsychotic-like effects of alstonine.

The purpose of this study was to determine the effects of alstonine, an indole alkaloid with putative antipsychotic effects, on working memory by using the step-down inhibitory avoidance paradigm and MK801-induced working memory deficits in mice. Additionally, the role of serotonin 5-HT2A/C receptors in the effects of alstonine on mouse models associated with positive (MK801-induced hyperlocomotion), negative (MK801-induced social interaction deficit), and cognitive (MK801-induced working memory deficit) schizophrenia symptoms was examined. Treatment with alstonine was able to prevent MK801-induced working memory deficit, indicating its potential benefit for cognitive deficits now seen as a core symptom in the disease. Corroborating previously reported data, alstonine was also effective in counteracting MK801-induced hyperlocomotion and social interaction deficit. Ritanserin, a 5-HT2A/C receptor antagonist, prevented alstonine's effects on these three behavioral parameters. This study presents additional evidence that 5-HT2A/C receptors are central to the antipsychotic-like effects of alstonine, consistently seen in mouse models relevant to the three dimensions of schizophrenia symptoms.

Underreporting of cocaine and marijuana during the thrid trimester of gestation among pregnant adolescents

Objetive: The aim of this study is to check the validity of the self-report of drug use by pregnant adolescents, by comparing their responses to a structured interview about their use of cocaine and marijuana during the pregnancy with an analysis of their hair. Results: Hair analysis detected the use of cocaine and/or marijuana, 17 (1,7%) used only cocaine, and 3 (0,3%) used both drugs. None of the patients had reported the use of these substances in their interview with healthcare profissionals. Conclusion: Althougth the prevalence of the use of drugs during pregnancy is significant despite consistent evidence about the compromise of the neurobehavioral development of the newborns that are exposed to drugs during the prenatal period, drugs use is frequently not reported. Therefore, more sensitive methods of detection should be used so that appropriate medical and psychosocial interventions com be implemented for the mothers as well as for their children. (AU)

Salmonella enterica: isolamento e soroprevalência em suínos abatidos no Rio Grande do Sul / Salmonella enterica: isolation and seroprevalence in swines slaughtered in Rio Grande do Sul

Estudou-se a prevalência de Salmonella spp. em suínos ao abate e compararam-se os resultados obtidos no isolamento e na sorologia de modo a determinar a fase mais importante de infecção (granja ou transporte/espera pré-abate) em relação ao número de suínos portadores encontrados ao abate. Foram avaliados 40 rebanhos de três diferentes empresas do sul do Brasil, com colheitas de sangue e linfonodos mesentéricos de 20 animais por lote. O soro foi submetido ao ELISA produzido com antígeno somático de Salmonella Typhimurium. A frequência de isolamento variou de 62,5 por cento a 85,0 por cento, enquanto a soroprevalência de 73,8 por cento a 83,2 por cento nos três sistemas amostrados. Os sorovares mais prevalentes foram Agona, Typhimurium e Panama. A infecção dos animais ocorreu nas granjas produtoras de suínos nestes sistemas de produção, pois os lotes apresentaram elevada soroprevalência ao abate. Concluiu-se que o controle da infecção por Salmonella spp. no sul do Brasil deve iniciar-se pela implementação de medidas de profilaxia nas granjas de produção de suínos.

The prevalence of Salmonella in slaughtered swines was evaluated and the results of serology and Salmonella isolation were compared to determine the most important stage of the infection (on-farm or transport and pre-slaughter) in relation to the number of carrier animals found at slaughter. Forty herds from three different swine raisers of the southern region of Brazil were sampled at slaughter. Blood and mesenteric lymph nodes were collected from 20 swines of each herd. Serum samples were submitted to ELISA including somatic antigens of S. Typhimurium. Salmonella was isolated from 62.5 percent to 85.0 percent of the animals, while seroprevalence varied from 73.8 percent to 83.2 percent in the three swine raisers. Serovar Agona, Typhimurium, and Panama were the most prevalent among the Salmonella isolates. Isolation and serological results demonstrated that Salmonella infection occurred during the on-farm stage, since a high seroprevalence was detected at slaughter. It was concluded that a Salmonella control program in southern Brazil must be started with the implementation of intervention measures at farm level.

Role of purines on hepatic ischemia-reperfusion lesions in rabbit.

In this work, we evaluate the effects of adenosine 5' triphosphate (ATP) on hepatic lesions caused by ischemia/reperfusion (I/R) in liver rabbit. Rabbits were pretreated with ATP (15 mg/kg IV) or saline solution 0.9% (SS), before the hepatic I/R procedure. We evaluated the effects of ATP on hepatic injury before and after I/R. The warm hepatic I/R procedure caused profound acute liver injury, as indicated by elevated serum aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase levels, as well as a high apoptotic cell count. All these changes were attenuate by ATP treatment before the hepatic I/R procedure. These results suggested that ATP exerted protective effects on hepatic I/R lesions in the rabbit. This ATP effect may be related to improved energy metabolism during reperfusion in ischemic livers protecting against functional damage of cellular and subcellular membranes during lipid peroxidation.

Inhibition of cyclin A/Cdk2 phosphorylation impairs B-Myb transactivation function without affecting interactions with DNA or the CBP coactivator.

Expression of the B-Myb transcription factor is directed by an E2F-dependent transcriptional mechanism to late G1 and S phases of the cell cycle, where its transactivation properties are enhanced post-translationally by cyclin A/Cdk2-mediated phosphorylation. Other experiments have shown that removal of the B-Myb C-terminus constitutively activates both transactivation and DNA-binding activities, suggesting that autoregulation by this inhibitory domain is counteracted by phosphorylation. We report here on further experiments to examine this hypothesis. The importance of this modification was first emphasized by showing that co-transfected dominant-negative Cdk2 (Cdk2DN) substantially reduced B-Myb transactivation activity. We then attempted to map the autoregulatory domain by analysing a series of progressively deleted C-terminal B-Myb mutants. Removal of just 29 C-terminal aa increased transactivation appreciably, however, maximal activity required removal of 143 amino acids (as in B-Myb + 561). Enhanced B-Myb + 561 function correlated with the acquisition of DNA binding activity to a single Myb binding site (MBS) oligonucleotide as determined by bandshift assays, however, further assays showed that even wt B-Myb could bind a DNA fragment containing three MBS. Although transactivation by B-Myb was severely dependent on hyperphosphorylation, neither inhibiting this activity by co-transfecting Cdk2DN nor augmenting it with cyclin A resulted in significant effects on DNA-binding. We also found that B-Myb could synergize with the CBP coactivator and that this cooperativity was cyclin A/Cdk2-dependent. Despite this, the physical association between these proteins was not influenced by the B-Myb phosphorylation status. We discuss these findings in relation to the autoregulation of B-Myb by the C-terminal domain.

Regulation of the cell cycle by B-Myb.

B-Myb is a cell-cycle-regulated member of the Myb transcription factor and, like c-Myb, has been implicated in regulation of hematopoietic cell proliferation and differentiation. In this study we have examined the mechanisms by which B-Myb regulates the cell cycle. We found that the ability of B-Myb both to promote Saos-2 cells into the S phase of the cell cycle and to overcome G1 arrest mediated by overexpression of the retinoblastoma-related p107 protein was correlated with the capacity of B-Myb to form an in vivo complex with p107, but was independent of its transactivation function. Further experiments using a B-Myb dominant-negative protein suggested that transcriptional activation of genes regulated through Myb DNA-binding sequences was required for cell proliferation. Our experiments suggest, therefore, that B-Myb influences cell cycle progression at two distinct levels: by inhibiting p107 and by inducing transcription of specific target genes.