Multi-heme Cytochromes in Shewanella oneidensis MR-1:Structures, functions and opportunities

Multi-heme cytochromes are employed by a range of microorganisms to transport electrons over distances of up to tens of nanometers. Perhaps the most spectacular utilization of these proteins is in the reduction of extracellular solid substrates, including electrodes and insoluble mineral oxides of Fe(III) and Mn(III/IV), by species of Shewanella and Geobacter. However, multi-heme cytochromes are found in numerous and phylogenetically diverse prokaryotes where they participate in electron transfer and redox catalysis that contributes to biogeochemical cycling of N, S and Fe on the global scale. These properties of multi-heme cytochromes have attracted much interest and contributed to advances in bioenergy applications and bioremediation of contaminated soils. Looking forward there are opportunities to engage multi-heme cytochromes for biological photovoltaic cells, microbial electrosynthesis and developing bespoke molecular devices. As a consequence it is timely to review our present understanding of these proteins and we do this here with a focus on the multitude of functionally diverse multi-heme cytochromes in Shewanella oneidensis MR-1. We draw on findings from experimental and computational approaches which ideally complement each other in the study of these systems: computational methods can interpret experimentally determined properties in terms of molecular structure to cast light on the relation between structure and function. We show how this synergy has contributed to our understanding of multi-heme cytochromes and can be expected to continue to do so for greater insight into natural processes and their informed exploitation in biotechnologies

Triple POCUS: A New Approach to an Old Problem

Pulmonary embolism (PE) is the most serious and life-threatening clinical presentation of venous thromboembolism, and difficult to diagnose. Triple point-of-care-ultrasonography (POCUS) of the lung, heart and leg veins is a multiorgan approach that may help to evaluate patients suspected of having PE, in combination with existing protocols and computed tomographic pulmonary angiography (CTPA). We present the case of a 26-year-old man with sudden onset of dyspnoea and swelling of the leg with a Well's score of 9. With CTPA unavailable at the time of presentation, triple POCUS showed subpleural consolidations and a venous thrombus in a popliteal vein. A diagnosis of deep vein thrombosis with PE was made and the appropriate treatment was started immediately. Although triple POCUS has less sensitivity and specificity than CTPA, it could be very useful in some clinical settings.info:eu-repo/semantics/publishedVersio

Neonatal pyruvate dehydrogenase deficiency due to a R302H mutation in the PDHA1 gene: MRI findings

Pyruvate dehydrogenase (PDH) deficiency is one of the most common causes of congenital lactic acidosis. Correlations between the genetic defect and neuroimaging findings are lacking. We present conventional and diffusion-weighted MRI findings in a 7-day-old male neonate with PDH deficiency due to a mosaicism for the R302H mutation in the PDHA1 gene. Corpus callosum dysgenesis, widespread increased diffusion in the white matter, and bilateral subependymal cysts were the main features. Although confirmation of PDH deficiency depends on specialized biochemical analyses, neonatal MRI plays a role in evaluating the pattern and extent of brain damage, and potentially in early diagnosis and clinical decision making

Multiparametric in vitro genotoxicity assessment of different variants of amorphous silica nanomaterials in rat alveolar epithelial cells

The hazard posed to human health by inhaled amorphous silica nanomaterials (aSiO2 NM) remains uncertain. Herein, we assessed the cyto- and genotoxicity of aSiO2 NM variants covering different sizes (7, 15, and 40 nm) and surface modifications (unmodified, phosphonate-, amino- and trimethylsilyl-modified) on rat alveolar epithelial (RLE-6TN) cells. Cytotoxicity was evaluated at 24 h after exposure to the aSiO2 NM variants by the lactate dehydrogenase (LDH) release and WST-1 reduction assays, while genotoxicity was assessed using different endpoints: DNA damage (single- and double-strand breaks [SSB and DSB]) by the comet assay for all aSiO2 NM variants; cell cycle progression and γ-H2AX levels (DSB) by flow cytometry for those variants that presented higher cytotoxic and DNA damaging potential. The variants with higher surface area demonstrated a higher cytotoxic potential (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_15_Phospho). SiO2_40 was the only variant that induced significant DNA damage on RLE-6TN cells. On the other hand, all tested variants (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_40) significantly increased total γ-H2AX levels. At high concentrations (28 µg/cm2), a decrease in G0/G1 subpopulation was accompanied by a significant increase in S and G2/M sub-populations after exposure to all tested materials except for SiO2_40 which did not affect cell cycle progression. Based on the obtained data, the tested variants can be ranked for its genotoxic DNA damage potential as follows: SiO2_7 = SiO2_40 = SiO2_15_Unmod > SiO2_15_Amino. Our study supports the usefulness of multiparametric approaches to improve the understanding on NM mechanisms of action and hazard prediction

Assessment and determinants of airborne bacterial and fungal concentrations in different indoor environments: Homes, child day-care centres, primary schools and elderly care centres

Until now the influence of risk factors resulting from exposure to biological agents in indoor air has been far less studied than outdoor pollution; therefore the uncertainty of health risks, and how to effectively prevent these, remains. This study aimed (i) to quantify airborne cultivable bacterial and fungal concentrations in four different types of indoor environment as well as to identify the recovered fungi; (ii) to assess the impact of outdoor bacterial and fungal concentrations on indoor air; (iii) to investigate the influence of carbon dioxide (CO2), temperature and relative humidity on bacterial and fungal concentrations; and (iv) to estimate bacterial and fungal dose rate for children (3–5 years old and 8–10 years old) in comparison with the elderly. Air samples were collected in 68 homes, 9 child day-care centres, 20 primary schools and 22 elderly care centres, in a total of 264 rooms with a microbiological air sampler and using tryptic soy agar and malt extract agar culture media for bacteria and fungi growth, respectively. For each building, one outdoor representative location were identified and simultaneously studied. The results showed that child day-care centres were the indoor microenvironment with the highest median bacterial and fungal concentrations (3870 CFU/m3 and 415 CFU/m3, respectively), whereas the lowest median concentrations were observed in elderly care centres (222 CFU/m3 and 180 CFU/m3, respectively). Indoor bacterial concentrations were significantly higher than outdoor concentrations (p < 0.05); whereas the indoor/outdoor ratios for the obtained fungal concentrations were approximately around the unit. Indoor CO2 levels were associated with the bacterial concentration, probably due to occupancy and insufficient ventilation. Penicillium and Cladosporium were the most frequently occurring fungi. Children's had two times higher dose rate to biological pollutants when compared to adult individuals. Thus, due to children's susceptibility, special attention should be given to educational settings in order to guarantee their healthy future development

Suitability of salivary leucocytes to assess DNA repair ability in human biomonitoring studies by the challenge-comet assay

The challenge-comet assay is a simple but effective approach that provides a quantitative and functional determination of DNA repair ability, and allows to monitor the kinetics of repair process. Peripheral blood mononuclear cells (PBMC) are the cells most frequently employed in human biomonitoring studies using the challenge-comet assay, but having a validated alternative of non-invasive biomatrix would be highly convenient for certain population groups and circumstances. The objective of this study was to validate the use of salivary leucocytes in the challenge-comet assay. Leucocytes were isolated from saliva samples and challenged (either in fresh or after cryopreservation) with three genotoxic agents acting by different action mechanisms: bleomycin, methyl methanesulfonate, and ultraviolet radiation. Comet assay was performed just after treatment and at other three additional time points, in order to study repair kinetics. The results obtained demonstrated that saliva leucocytes were as suitable as PBMC for assessing DNA damage of different nature that was efficiently repaired over the evaluated time points, even after 5 months of cryopreservation (after a 24 h stimulation with PHA). Furthermore, a new parameter to determine the efficacy of the repair process, independent of the initial amount of damage induced, is proposed, and recommendations to perform the challenge-comet assay with salivary leucocytes depending on the type of DNA repair to be assessed are suggested. Validation studies are needed to verify whether the method is reproducible and results reliable and comparable among laboratories and studies. © 2022 The AuthorsFunding text 1: This work was funded by the Spanish Ministry of Science and Innovation : MCIN/AEI/10.13039/501100011033 (Grants PID2020-113788RB-I00 and PID2020-114908 GA-I00 ), NanoBioBarriers project (PTDC/MED-TOX/31162/2017), Xunta de Galicia (ED431B 2022/16), co-financed by the Operational Program for Competitiveness and Internationalization (POCI) through European Regional Development Funds ( FEDER / FNR ), Spanish Ministry of Education, Culture and Sport [ BEAGAL18/00142 to V.V.], and Spanish Ministry of Economy and Competitiveness , co-financed by the European Social Fund [ RYC-2015-18394 to L.L,-L,]. Funding for open access charge: Universidade da Coruña/CISUG. ; Funding text 2: This work was funded by the Spanish Ministry of Science and Innovation: MCIN/AEI/10.13039/501100011033 (Grants PID2020-113788RB-I00 and PID2020-114908 GA-I00), NanoBioBarriers project (PTDC/MED-TOX/31162/2017), Xunta de Galicia (ED431B 2022/16), co-financed by the Operational Program for Competitiveness and Internationalization (POCI) through European Regional Development Funds (FEDER/FNR), Spanish Ministry of Education, Culture and Sport [BEAGAL18/00142 to V.V.], and Spanish Ministry of Economy and Competitiveness, co-financed by the European Social Fund [RYC-2015-18394 to L.L,-L,]. Funding for open access charge: Universidade da Coruña/CISUG