Histopathological indices and inflammatory response in the digestive gland of the mussel Mytilus galloprovincialis as biomarker of immunotoxicity to silver nanoparticles

Background: Histopathological assessments approaches in bivalves have become an important tool in environmental toxicology. This study seeks to develop a quantitative histopathological index (Ih) and inflammation score as biomarkers in the aim to assess the health status of nanoparticles exposed mussels.

Methods: Digestive gland hematoxylin and eosin (H&;E) stained sections from Mytilus galloprovincialis were assessed after in vivo exposure (for 3, 6 and 12?h) to silver nanoparticles (Ag-NPs?Results: Silver nanoparticles clearly induced histopathological alterations in digestive gland (maximum inflammation 2.75 with AgNP?p?Ih with AgNP?p?Ih were recorded after uptake routes were blockade: AgNP?p?Conclusions: Histopathological assessments showed to be promising tool in nanotoxicity which seems to depend on nanoparticles size, exposure time and interestingly to uptake routes. It was not clear: is it the length of exposure or the size of particles is more impactful.     

The Inhibition Effect of Lactobacilli Against Growth and Biofilm Formation of <Emphasis Type="BoldItalic">Pseudomonas aeruginosa</Emphasis>

The emergence of antibiotic-resistant and food-spoilage microorganisms has renewed efforts to identify safe and natural alternative agents of antibiotics such as probiotics. The aim of this study was the isolation of lactobacilli as potential probiotics from local dairy products with broad antibacterial and anti-biofilm activities against antibiotic-resistant strains of Pseudomonas aeruginosa and determination of their inhibition mechanism. Antibiotic susceptibility and classification of acquired resistance profiles of 80 P. aeruginosa strains were determined based on Centers for Disease Control and Prevention (CDC) new definition as multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan-drug-resistant (PDR) followed by antibacterial assessment of lactobacilli against them by different methods. Among the 80 P. aeruginosa strains, 1 (1.3%), 50 (62.5%), and 78 (97.5%) were PDR, XDR, and MDR, respectively, and effective antibiotics against them were fosfomycin and polymyxins. Among 57 isolated lactobacillus strains, two strains which were identified as Lactobacillus fermentum using biochemical and 16S rDNA methods showed broad inhibition/killing and anti-biofilm effects against all P. aeruginosa strains. They formed strong biofilms and had bile salts and low pH tolerance. Although investigation of inhibition mechanism of these strains showed no bacteriocin production, results obtained by high-performance liquid chromatography (HPLC) analysis indicated that their inhibitory effect was the result of production of three main organic acids including lactic acid, acetic acid, and formic acid. Considering the broad activity of these two L. fermentum strains, they can potentially be used in bio-control of drug-resistant strains of P. aeruginosa.     

Synergistic efficacy of botanical blends with and without synthetic insecticides against Aedes aegypti and Culex annulirostris mosquitoes.

Increasing insecticide resistance requires strategies to prolong the use of highly effective vector control compounds. The use of combinations of insecticides with other insecticides and phytochemicals is one such strategy that is suitable for mosquito control. In bioassays with Aedes aegypti and Culex annulirostris mosquitoes, binary mixtures of phytochemicals with or without synthetic insecticides produced promising results when each was applied at a LC25 dose. All mixtures resulted in 100% mortality against Cx. annulirostris larvae within 24 h rather than the expected mortality of 50%. All mixtures acted synergistically against Ae. aegypti larvae within the first 24 h except for one mixture that showed an additive effect. We conclude that mixtures are more effective than insecticides or phytochemicals alone and that they enable a reduced dose to be applied for vector control potentially leading to improved resistance management and reduced costs.     

In Silico Sub-unit Hexavalent Peptide Vaccine Against an <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> Biofilm-Related Infection

Staphylococcus aureus is responsible for significant and increasing number of hospital-and community-acquired infections worldwide. A pool of pathogenesis factors helps the bacterium to cause the range of mild to severe infections leading the high mortality and morbidity. Staphylococcus aureus and Candida albicans can be co-isolated from all human mucosal sites and are responsible for diverse infections. Vaccine design for related polymicrobial infections should consider the consortia of microorganisms responsible for the disease. In this study we considered biofilm mode of growth and polymicrobial nature of the infections caused by S. aureus. In the first phase of study the prediction of putative antigenic targets of S. aureus and C. albicans was conducted based on data mining and bioinformatic characterization of their proteins. Various properties of proteins were evaluated such as subcellular localization, hydrophilicity, repeat containing modules, beta turns, surface accessibility and number of antigenic determinants. The second phase includes various immunoinformatics analyses on six proteins include ALS, ClfA, FtmB, SdrE, Spa and Bap leading to design a novel sub-unit hexavalent vaccine. Several potential T cell and B-cell epitopes are present in our vaccine. Also the vaccine is expected to strongly induce IFN-gamma production. The amino acid sequence introduced here is expected to enhance cell-mediated and humoral responses against S. aureus biofilm-related infections to clear biofilm communities of S. aureus and intracellular colonies of pathogen as well as planktonic cells and thus reduces colonization and persistence.     

Ex vivo expansion of hematopoietic stem cells in a proliferation chamber with external stirred conditioning tank: Sequential optimization of growth factors

The insufficient number of hematopoietic stem cells (HSCs) extracted from various cell sources creates the need for the use of growth factors in the culture systems. Numerous types and concentrations of growth factors have been reported in the literature. In this study, we investigated the effect of three important hematopoietic growth factors thrombopoietin (TPO), stem cell factor (SCF), and Fms‐like tyrosine kinase‐3 ligand (Flt‐3) as well as cell‐seeding density on ex vivo expansion of human HSCs using a factorial design. Sequential optimization was then followed by methods of steepest ascent and central composite design. The optimum concentrations of growth factors were 50, 90, and 34 ng/mL for SCF, TPO, and Flt‐3, respectively, at an initial cell density of 2.5 × 10⁵ cells/mL. Effective expansion factor value (EEF) of HSCs increased considerably and revealed almost similar results when the cells were cultured in a 24‐well plate (EEF = 4.54 ± 0.43) and a proliferation chamber with an external stirred conditioning tank (PC‐ESCT; EEF = 5.1 ± 0.35) at seeding density of 2.5 × 10⁵ cells/mL after 7 days. The cells did not show considerable changes in proliferation when they were cultured in medium containing serum or in a commercial serum‐free medium at the optimum concentrations of the growth factors. The present study demonstrated the optimum condition of hematopoietic growth factors as well as the potential of PC‐ESCT for ex vivo expansion of HSCs.     

Bio fertilizers and zinc effects on some physiological parameters of triticale under water-limitation condition

In order to study bio fertilizers and zinc effects on some physiological parameters of triticale under a water-limitation condition, a factorial experiment was conducted based on randomized complete block design with three replications in 2014 and 2015. Experimental factors consisted of three irrigation treatments [normal irrigation (W₀); moderate water limitation (W₁) and severe water limitation (W₂)]; four bio fertilizers’ levels [(no bio fertilizer (F₀), application of mycorrhiza (F₁), plant-growth-promoting rhizobacteria (PGPR) (F₂) and both application PGPR and mycorrhiza (F₃)] and four nano zinc oxide levels [(without nano zinc oxide (Zn₀) as control, application of 0.3 (Zn₁), 0.6 (Zn₂) and 0.9 (Zn₃) g?L^?1)]. Results showed that water limitation decreased chlorophyll content, relative water content, stomatal conductance, quantum yield and grain yield of triticale, whereas electrical conductivity and the activity of catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7) and polyphenol oxidase (PPO, EC 1.14.18.1) enzymes were increased. Inoculation of plants with bio fertilizers and zinc application improved these traits (except electrical conductivity) under water-limitation condition as well as normal irrigation. Based on the results, it was concluded that bio fertilizers and nano zinc oxide application can be recommended for profitable triticale production under water-limitation condition.     

Hypoxic exposure and activation of the afterdischarge mechanism in conscious humans

After voluntary hyperventilation, normal humans do not develop a significant ventilatory depression despite low arterial CO2 tension, a phenomenon attributed to activation of a brain stem mechanism referred to as the "afterdischarge." Afterdischarge is one of the factors that promote ventilatory stability. It is not known whether physiological stimuli, such as hypoxia, are able to activate the afterdischarge in humans. To test this, breath-by-breath ventilation (VI) was measured in nine young adults during and immediately after a brief period (35-51 s) of acute hypoxia (end-tidal O2 tension 55 Torr). Hypoxia was terminated by switching to 100% O2 (end-tidal O2 tension of first posthypoxic breath greater than 100 Torr). Brief hypoxia increased VI and decreased end-tidal CO2 tension. In all subjects, termination of hypoxia was followed by a gradual ventilatory decay; hyperoxic VI remained higher than the normoxic baseline for several breaths and, despite the negative chemical stimulus of hyperoxia and hypocapnia, reached a new steady state without an apparent undershoot. We conclude that brief hypoxia is able to activate the afterdischarge mechanism in conscious humans. This contrasts sharply with the ventilatory undershoot that follows relief of sustained hypoxia, thereby suggesting that sustained hypoxia inactivates the afterdischarge mechanism. The present findings are of relevance to the pathogenesis of periodic breathing in a hypoxic environment. Furthermore, brief exposure to hypoxia might be useful for evaluation of the role of afterdischarge in other disorders associated with unstable breathing.     

Mutants of Myxococcus xanthus impaired in protein secretion: an approach to study of a secretory mechanism

Summary Bacteria able to secrete proteins efficiently into the growth medium occur relatively rarely amongst Gram-negative species. However, the increasing technological interest in protein secretion has focused attention on this process. We have demonstrated that Myxococcus xanthus actively secretes protein. The number of proteins secreted is quite large, but the total amount is strictly regulated and remains constant under conditions that change the specific activities of some of the secreted enzymes. Tn5-insertion mutants were obtained which were impaired in what seems to be the control system for protein secretion. Two of the mutants displayed increased levels of extracellular protein.