Genomic analysis and assessment of pathogenic (toxicogenic) potential of Staphylococcus haemolyticus and Bacillus paranthracis consortia isolated from bovine mastitis in Russia

Three stable microbial consortia, each composed of Bacillus paranthracis and Staphylococcus haemolyticus strains, were isolated from milk of cows diagnosed with mastitis in three geographically remote regions of Russia. The composition of these consortia remained stable following multiple passages on culture media. Apparently, this stability is due to the structure of the microbial biofilms formed by the communities. The virulence of the consortia depended on the B. paranthracis strains. It seems plausible that the ability of the consortia to cause mastitis in cattle was affected by mutations of the cytK gene of B. paranthracis.

A Study on the Planarian Model Confirms the Antioxidant Properties of Tameron against X-ray- and Menadione-Induced Oxidative Stress

Ionizing radiation and radiation-related oxidative stress are two important factors responsible for the death of actively proliferating cells, thus drastically reducing the regeneration capacity of living organisms. Planarian flatworms are freshwater invertebrates that are rich in stem cells called neoblasts and, therefore, present a well-established model for studies on regeneration and the testing of novel antioxidant and radioprotective substances. In this work, we tested an antiviral and antioxidant drug Tameron (Monosodium α-Luminol or 5-amino-2,3-dihydro-1,4-phthalazinedione sodium salt) for its ability to reduce the harm of X-ray- and chemically induced oxidative stress on a planarian model. Our study has revealed the ability of Tameron to effectively protect planarians from oxidative stress while enhancing their regenerative capacity by modulating the expression of neoblast marker genes and NRF-2-controlled oxidative stress response genes.

Morphogenic Effect of Exogenous Glucocorticoid Hormones in the Girardia tigrina Planarian (Turbellaria, Tricladida)

We have studied the effect of two glucocorticoid hormones: hydrocortisone and its synthetic analogue methylprednisolone on the regeneration activity of head and tail blastema of the Girardia tigrina planarian. The regeneration activity was studied in head and tail blastema formed after resection by means of lifetime computer morphometry and immunohistochemical labeling of neoblasts. The search for orthologous proteins-glucocorticoid receptors (hydrocortisone) was performed using the SmedGD database of the Schmidtea mediterranea planarian. The results indicate that both hormones influence the recovery rate of the regenerating head and tail blastema. The worms with regenerating tail blastema have less sensitivity to the hormones' treatment compared to the ones with regenerating head blastema. Hydrocortisone at a high concentration (10-3 M) suppressed the regeneration rate, while stimulating it at lower concentrations (10-4-10-6 M). The same concentrations of methylprednisolone inhibited the regeneration of head blastema, but did not affect the tail blastema regeneration. The two hormones acted differently: while hydrocortisone stimulated the proliferation of neoblasts in the periwound region, methylprednisolone reduced the mitotic activity, mainly on the tail zone furthest from the wound surface. We suggest that exogenous glucocorticoids can influence endogenous mechanisms of hormone-dependent regeneration.

The first inorganic mitogens: Cerium oxide and cerium fluoride nanoparticles stimulate planarian regeneration via neoblastic activation

We report the first experimental evidence for the mitogenic action of cerium(IV) oxide and cerium(III) fluoride nanoparticles (CONs and CFNs) on the regeneration of a whole organism - freshwater flatworms Schmidtea mediterranea (planarian). Both types of cerium-containing nanoparticles are shown to be a highly potent mitogen for planaria. Both CONs and CFNs, in micro- and nanomolar concentrations, markedly accelerate planarian blastema growth, due to the enhancement of cellular proliferation, causing an increase in the mitotic index and in the quantity of blastema cells in regenerating planaria. CONs provided maximum activity at concentrations which were two orders of magnitude lower than those for CeF₃. The valence state of cerium in cerium-containing nanoparticles plays a significant role in the planarian regeneration mechanism: CeO₂ nanoparticles containing predominantly Ce⁴⁺ species presumably scavenge wound induced reactive oxygen species and moderately activate gene expression processes, while the regenerative action of CeF₃ nanoparticles containing only Ce³⁺ species is manifested in the pronounced expression of the genes involved in cell division, differentiation and migration. This is the first report on the effect of cerium-containing nanoparticles on tissue regeneration in vivo, further revealing the mechanisms of their biological action, which enhances the possibility of their use in cellular technologies.

Surface bioactivation of PEEK by neutral atom beam technology

Polyetheretherketone (PEEK) is an alternative to metallic implants and a material of choice in many applications, including orthopedic, spinal, trauma, and dental. While titanium (Ti) and Ti-alloys are widely used in many intraosseous implants due to its biocompatibility and ability to osseointegrate, negatives include stiffness which contributes to shear stress, radio-opacity, and Ti-sensitivity. Many surgeons prefer to use PEEK due to its biocompatibility, similar elasticity to bone, and radiolucency, however, due to its inert properties, it fails to fully integrate with bone. Accelerated Neutral Atom Beam (ANAB) technology has been successfully employed to demonstrate enhanced bioactivity of PEEK both in vitro and in vivo. In this study, we further characterize surfaces of PEEK modified by ANAB as well as elucidate attachment and genetic effects of dental pulp stem cells (DPSC) exposed to these surfaces. ANAB modification resulted in decreased contact angle at 72.9 ± 4.5° as compared to 92.4 ± 8.5° for control (p < 0.01) and a decreased average surface roughness, however with a nano-textured surface profile. ANAB treatment also increased the ability of DPSC attachment and proliferation with considerable genetic differences showing earlier progression towards osteogenic differentiation. This surface modification is achieved without adding a coating or changing the chemical composition of the PEEK material. Taken together, we show that ANAB processing of PEEK surface enhances the bioactivity of implantable medical devices without an additive or a coating.

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PEEK is a material of choice for biomaterials except that it is inert and does not integrate with bone.

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Neutral atom beam technology (ANAB) is a surface modification technique that modifies the surface at a nano-scale level and makes the surface more hydrophilic.

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Increased cell attachment and proliferation is seen on ANAB-treated PEEK.

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Dental pulp stem cells differentiate towards osteoblast when grown on ANAB-treated PEEK.

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ANAB makes PEEK bioactive.

Dawn arrives at Ceres: Exploration of a small, volatile-rich world

On 6 March 2015, Dawn arrived at Ceres to find a dark, desiccated surface punctuated by small, bright areas. Parts of Ceres' surface are heavily cratered, but the largest expected craters are absent. Ceres appears gravitationally relaxed at only the longest wavelengths, implying a mechanically strong lithosphere with a weaker deep interior. Ceres' dry exterior displays hydroxylated silicates, including ammoniated clays of endogenous origin. The possibility of abundant volatiles at depth is supported by geomorphologic features such as flat crater floors with pits, lobate flows of materials, and a singular mountain that appears to be an extrusive cryovolcanic dome. On one occasion, Ceres temporarily interacted with the solar wind, producing a bow shock accelerating electrons to energies of tens of kilovolts.

On a distributed clustering process of Coffman, Courtois, Gilbert and Piret

Coffman, Courtois, Gilbert and Piret (1991) have introduced a flow process in graphs, where each vertex gets an initial random resource, and where at each time vertices with large resources tend to attract resources from neighbours. The initial resources are assumed to be i.i.d., with a continuous distribution.

We are mainly interested in the following question: does, with probability 1, the resource of each vertex change only finitely many times?

Coffman et al. concentrate mainly on the case where the graph corresponds with the integer points on the line, in which case it is easily seen that the answer to the above question is positive. For higher-dimensional lattices they make general remarks which suggest that the answer to the above question is still positive. However, no proof seems to be known.

We restrict to the case of the square lattice, and, by a percolation approach, we reduce the question above to the question whether a certain quantity, which can be obtained from a finite computation, is sufficiently small. This computation is, however, still too long to be executed in an acceptable time. We therefore apply Monte Carlo simulation for this finite problem, which gives overwhelming evidence that, for the square lattice, the answer to the main question is positive.

New data on transuranium elements in the ecosystem of the Yenisei river floodplain

The aim of the study is to investigate levels of transuranium elements in the ecosystem of the Yenisei river floodplain in the vicinity of the Mining-and-Chemical Combine of Rosatom. For the first time, the transuranium isotopes 243,244Cm have been detected in sediment, floodplain soil, and a berry shrub (Ribes nigrum – the blackcurrant) in the floodplain of the Yenisei river. The highest level of curium isotopes registered in the sediment of the Yenisei river is 21.4Bq/kg (dry), which is more than twice higher than maximum curium levels reported for soils sampled not far from the Chernobyl Nuclear Plant. Blackcurrant plants growing on radioactively contaminated soils contain the same transuranium elements as the soil (plutonium isotopes, americium, and curium). The highest activity concentrations of all transuranic elements have been found in ashed roots of the blackcurrant plants: 239,240Pu – 9.3Bq/kg, 241Am – 6.9Bq/kg, and 243,244Cm – 1.8Bq/kg. The highest soil-plant transfer factor (TF) for 243,244Cm is determined for roots – 0.073; the TF of 243,244Cm in berries is 0.027. The TF for 239,240Pu in berries is 0.006, which is several times lower than the TF for 243,244Cm. Analysis of our results and the literature data suggests that TFs for 243,244Cm are higher than those for 239,240Pu and 241Am.

Application of molluscs for radioecological monitoring of the Chernobyl outburst

Accumulation of radionuclides was studied in molluscs from the territories polluted by the Chernobyl outburst. In addition to radiochemical evaluation of (90)Sr, a simple method of beta-radiometry of shells was applied which allowed processing of extensive samples and mapping of contamination of large territories: the Dnieper drainage area and the Kiev administrative region. Pre-Hiroshima and pre-Chernobyl radioactivity was investigated in museum collections. Differences in (90)Sr accumulation in molluscs of different genera were demonstrated for freshwater and terrestrial snails, an especially high accumulation factor was found in Helix. Indices of relative accumulation were calculated treating Lymnaea stagnalis as a standard. All the measurements were recalculated to this standard in order to provide comparisons between sampling sites disregarding collected species and to reduce variance before mapping. Based on shell beta-activity measurements, the average accumulation factor for (90)Sr in Lymnaea compared to its concentration in the river water was about 5000, its transfer factor compared to the soil contamination was about 0.1 m(2) kg(-1), figures for (137)Cs were smaller by an order of magnitude. Inverse dependence between free calcium content in the environment and the transfer factor was demonstrated, as well as a difference in (90)Sr/(137)Cs ratio in molluscs collected on different tracks of Chernobyl pollution. Monitoring the biologically accessible and biologically active fraction of (90)Sr contamination, the shell beta-activity above 15 kBq kg(-1) indicates a dangerous level of contamination for the human population.