Selenium and mercury levels in rat liver slices co-treated with diphenyl diselenide and methylmercury

Organoseleno-compounds have been investigated for its beneficial effects against methylmercury toxicity. In this way, diphenyl diselenide (PhSe)₂ was demonstrated to decrease Hg accumulation in mice, protect against MeHg-induced mitochondrial dysfunction, and protect against the overall toxicity of this metal. In the present study we aimed to investigate if co-treatment with (PhSe)₂ and MeHg could decrease accumulation of Hg in liver slices of rats. Rat liver slices were co-treated with (PhSe)₂ (0.5; 5 µM) and/or MeHg (25 µM) for 30 min at 37 °C and Se and Hg levels were measured by inductively coupled plasma mass spectrometry (ICP-MS) in the slices homogenate, P1 fraction, mitochondria and incubation medium. Co-treatment with (PhSe)₂ and MeHg did not significantly alter Se levels in any of the samples when compared with compounds alone. In addition, co-treatment with (PhSe)₂ and MeHg did not decrease Hg levels in any of the samples tested, although, co-incubation significantly increased Hg levels in homogenate. We suggest here that (PhSe)₂ could exert its previously demonstrated protective effects not by reducing MeHg levels, but forming a complex with MeHg avoiding it to bind to critical molecules in cell.     

Different outcomes of a cardiac rehabilitation programme in functional parameters among myocardial infarction survivors according to ejection fraction

Introduction

Exercise-based cardiac rehabilitation (EBCR) is part of the management of patients who have suffered an acute myocardial infarction (AMI). Patients with a reduced ejection fraction (EF) comprise a higher-risk subgroup and are referred less often for these programmes. This study aimed at assessing the impact of the baseline EF on the functional benefits, as assessed by peak oxygen uptake (pVO₂) and exercise duration, of an EBCR programme in AMI survivors.

Methods

Observational, retrospective cohort study including all patients admitted to a tertiary centre due to an AMI who completed a phase II EBCR programme after discharge, between November 2012 and April 2017. Functional parameters were assessed by a symptom-limited cardiopulmonary exercise test.

Results

A total of 379 patients were included [40.9% with reduced EF (<50%) at discharge]. After the programme, pVO₂ and exercise duration increased significantly (p < 0.001). Patients with a reduced EF had a lower pVO₂ and completed a shorter duration of exercise at the beginning and end of the programme. This group presented a higher increase in pVO₂ (p = 0.001) and exercise duration (p = 0.007). This was maintained after adjusting for age, gender, history of coronary artery disease, number of sessions, Killip classification, arterial hypertension, dyslipidaemia, diabetes mellitus, smoking status and baseline pVO₂.

Conclusion

A phase II EBCR programme was associated with significant improvements in pVO₂ and exercise duration among AMI survivors, irrespective of baseline EF classification. Those with a reduced baseline EF derived an even greater improvement, highlighting the importance of EBCR in this subgroup of patients.

     

Origin of Fish Biomass in a Diverse Subtropical River: An Allochthonic-Supported Biomass Increase Following Flood Pulses

Ecosystems - The origin of resources supporting metazoan biomass in rivers has long been a subject of debate. The river wave concept (RWC) postulates that the energetic basis of food webs varies...     

Analysis of a new flavodiiron core structural arrangement in Flv1-ΔFlR protein from Synechocystis sp. PCC6803

Flavodiiron proteins (FDPs) play key roles in biological response mechanisms against oxygen and/or nitric oxide; in particular they are present in oxygenic phototrophs (including cyanobacteria and gymnosperms). Two conserved domains define the core of this family of proteins: a N-terminal metallo-β-lactamase-like domain followed by a C-terminal flavodoxin-like one, containing the catalytic diiron centre and a FMN cofactor, respectively. Members of the FDP family may present extra modules in the C-terminus, and were classified into several classes according to their distribution and composition. The cyanobacterium Synechocystis sp. PCC6803 contains four Class C FDPs (Flv1-4) that include at the C-terminus an additional NAD(P)H:flavin oxidoreductase (FlR) domain. Two of them (Flv3 and Flv4) have the canonical diiron ligands (Class C, Type 1), while the other two (Flv1 and Flv2) present different residues in that region (Class C, Type 2). Most phototrophs, either Bacterial or Eukaryal, contain at least two FDP genes, each encoding for one of those two types. Crystals of the Flv1 two core domains (Flv1-ΔFlR), without the C-terminal NAD(P)H:flavin oxidoreductase extension, were obtained and the structure was determined. Its pseudo diiron site contains non-canonical basic and neutral residues, and showed anion moieties, instead. The presented structure revealed for the first time the structure of the two-domain core of a Class C-Type 2 FDP.     

Attraction of Fruit-Eating Bats with Essential Oils of Fruits: A Potential Tool for Forest Restoration

Previous tests with essential oils from ripe chiropterochoric fruits suggested they can be used to attract and capture fruit-eating bats inside forest remnants. Here we evaluated the efficiency of these oils to attract frugivorous bats to open areas. We performed field tests with artificial fruits impregnated with essential oils of the genera Piper or Ficus that were attached to two groups of mist-nets set 50 m outside the border of a forest remnant. One group of artificial fruits received the corresponding oil isolated through hydrodistillation and the other received water only. Fruits with oils attracted significantly more fruit-eating bats, especially Artibeus lituratus that regularly crosses open habitats to reach other forest remnants. The highly significant attraction of A. lituratus by the oil of Piper was unexpected, since this bat is a specialist on Ficus fruits. We hypothesize that in habitats with no fruit available it is possible to attract frugivorous bats with the odor of several ripe fruit species. Furthermore, we verified that almost half of the individuals captured defecated seeds, indicating that the oils also attract recently fed bats, even when their preferred food is available nearby. This technique potentially may increase seed rain at specific locations, being particularly promising to restoration projects.     

Escherichia coli di-iron YtfE protein is necessary for the repair of stress-damaged iron-sulfur clusters

DNA microarray experiments showed that the expression of the Escherichia coli ytfE gene is highly increased upon exposure to nitric oxide. We also reported that deletion of ytfE significantly alters the phenotype of E. coli, generating a strain with enhanced susceptibility to nitrosative stress and defective in the activity of several iron-sulfur-containing proteins. In this work, it is shown that the E. coli ytfE confers protection against oxidative stress. Furthermore, we found that the damage of the [4Fe-4S](2+) clusters of aconitase B and fumarase A caused by exposure to hydrogen peroxide and nitric oxide stress occurs at higher rates in the absence of ytfE. The ytfE null mutation also abolished the recovery of aconitase and fumarase activities, which is observed in wild type E. coli once the stress is scavenged. Notably, upon the addition of purified holo-YtfE protein to the mutant cell extracts, the enzymatic activities of fumarase and aconitase are fully recovered and at rates similar to the wild type strain. We concluded that YtfE is critical for the repair of iron-sulfur clusters damaged by oxidative and nitrosative stress conditions.     

Regulation of autophagy as a therapy for immunosenescence-driven cancer and neurodegenerative diseases: The role of exercise

Aging is one of the risk factors for the development of low-grade inflammation morbidities, such as several types of cancer and neurodegenerative diseases, due to changes in the metabolism, hormonal secretion, and immunosenescence. The senescence of the immune system leads to improper control of infections and tissue damage increasing age-related diseases. One of the mechanisms that maintain cellular homeostasis is autophagy, a cell-survival mechanism, and it has been proposed as one of the most powerful antiaging therapies. Regular exercise can reestablish autophagy, probably through AMP-activated protein kinase activation, and help in reducing the age-related senescence diseases. Therefore, in this study, we discuss the effects of exercise training in immunosenescence and autophagy, preventing the two main age-related disease, cancer and neurodegeneration.