Investigating heavy metal resistance, bioaccumulation and metabolic profile of a metallophile microbial consortium native to an abandoned mine

Contaminated sites represent new ecological niches where historical pollution has originated an unusual microbial biodiversity. The knowledge of these microorganisms contributes to the discovery of new pathways and metabolic networks and may offer potential solutions for damaged areas. In the present work seven microbial consortia have been isolated from an abandoned mine of blend and galena (Ingurtosu, Italy) through a selection for resistance to zinc (tested up to 40 mM in solution). All the consortia were able to accumulate zinc and the best accumulator, named Ing5, has been studied for the following characteristics: resistance and accumulation of Zn, Cd, Hg, bioaccumulation mechanisms of Zn, and influence of Zn and Cd on the metabolic profile. The results indicate that the consortium Ing5 bears resistance systems for Cd and Hg as well as Zn and that, for some of the 5 isolates belonging to Ing5, the resistance thresholds are higher in consortium than in pure culture. The prevalent mechanism for zinc accumulation can be reasonably considered to be metabolism-dependent, inducible and regulated by metal concentrations. The study on the metabolic profile, carried out by the Biolog system, shows that Zn exerts a very low influence on the metabolic profile and that this influence can also be positive; Cd has a stronger negative influence but that, despite this, the consortium is able to maintain a wide metabolic potential in the presence of heavy metals. These features of Ing5 make it a good candidate for biotechnological applications and for further investigation of the degradation of organic pollutants in the presence of metals.     

Effects of Y-TZP blank manufacturing control and addition of TiO2 nanotubes on structural reliability of dental materials

Titanium dioxide (TiO₂) nanotubes have been applied to enhance the mechanical and biological properties of dental materials. Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) have been increasingly used in dentistry as a substructure for crowns and fixed partial prostheses. Aside from its optimal clinical results, Y-TZP is prone to failures due to microstructure-related defects introduced in the manufacturing process that may lower its structural and clinical reliability. The purpose of this study was to evaluate the role of the manufacturing process of blanks as well as their original composition modification by addition of TiO₂ nanotubes (0%, 1%, 2% and 5% in volume) while controlling all manufacturing steps. Materials were subjected to a biaxial flexural strength test, a fractographic qualitative analysis by scanning electron microscopy (SEM), a microstructure evaluation in field emission-SEM and X-ray diffraction. Values of flexural strength were subjected to ANOVA, Tukey (α = 0.05) and Weibull statistics. Grain size values were subjected to Kruskal-Wallis and Dunn tests (α = 0.05). Highlights of the results include that for experimental Y-TZP added 2% vol TiO₂ nanotube ceramics presented flexural strength values at 577 MPa and Weibull modulus (m) at 8.1. The addition of TiO₂ nanotubes in different blends influenced experimental Y-TZP properties, leading to lower flexural strength, although they presented higher m than the commercial Y-TZP. Nanotubes also led to bigger grain sizes, more pores and a slight increase in the monoclinic phase, influencing the microstructure of Y-TZP. Y-TZP blank manufacturing control as well as addition of TiO₂ nanotubes led to higher m values and, hence, greater structural reliability.     

The Osteoporosis/Microbiota Linkage: The Role of miRNA

Hundreds of trillions of bacteria are present in the human body in a mutually beneficial symbiotic relationship with the host. A stable dynamic equilibrium exists in healthy individuals between the microbiota, host organism, and environment. Imbalances of the intestinal microbiota contribute to the determinism of various diseases. Recent research suggests that the microbiota is also involved in the regulation of the bone metabolism, and its alteration may induce osteoporosis. Due to modern molecular biotechnology, various mechanisms regulating the relationship between bone and microbiota are emerging. Understanding the role of microbiota imbalances in the development of osteoporosis is essential for the development of potential osteoporosis prevention and treatment strategies through microbiota targeting. A relevant complementary mechanism could be also constituted by the permanent relationships occurring between microbiota and microRNAs (miRNAs). miRNAs are a set of small non-coding RNAs able to regulate gene expression. In this review, we recapitulate the physiological and pathological meanings of the microbiota on osteoporosis onset by governing miRNA production. An improved comprehension of the relations between microbiota and miRNAs could furnish novel markers for the identification and monitoring of osteoporosis, and this appears to be an encouraging method for antagomir-guided tactics as therapeutic agents.     

The effect of magnesium on bioactivity,rheology and biology behaviors of injectable bioactive glass-gelatin-3-glycidyloxypropyl trimethoxysilane nanocomposite-paste for small bone defects repair

Injectable bioactive glass-based pastes represent promising biomaterials to fill small bone defects thus improving and speed up the self-healing process. Accordingly, injectable nanocomposite pastes based on bioactive glass-gelatin-3-glycidyloxypropyl trimethoxysilane (GPTMS) were here synthesized via two different glasses 64SiO₂. 27CaO. 4MgO. 5P₂O₅ (mol.%) and 64SiO₂.31CaO. 5P₂O₅ (mol.%). In particular, the effects of MgO on bioactivity, rheology, injectability, disintegration resistance, compressive strength and cellular behaviors were investigated. The results showed that the disintegration resistance and compressive strength of the composite were improved by the replacement of MgO; thus, leading to an increase in the amount of storage modulus (G′) from 26800 to 43400 Pa, equal to an increase in the viscosity of the paste from 136 × 10³ to 219 × 10³ Pa s. Since the release rate of ions became more controllable, the formation of calcite was decreased after immersion of the Mg bearing samples in the SBF solution. Specimens’ cytocompatibility was firstly verified towards human osteoblasts by metabolic assay as well as visually confirmed by the fluorescent live/dead staining; finally, the ability of human fibroblasts to penetrate within the pores of 3D composites was verified by a migration assay simulating the devices repopulation upon injection in the injured site.     

Structural Evolution During Reaction to Form Aluminum Titanate from Sol-Gel Precursors

Aluminum titanate ceramic materials have been obtained by field-activated sintering of amorphous sol-gel powder precursors. Aluminum titanate formation started at 1000°C. The structural evolution with temperature from the amorphous sol-gel state to the final fully densified ceramic product has been monitored by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and electron microscopy. The full crystallization of aluminum titanate occurred at 1200°C. The grain size of the specimen densified at 1300°C was between 150 and 500 nm.     

Specific and generalized expectancies in marital interaction.

40 married couples engaged in 2 laboratory interactions. The Marital Agendas Protocol was used to assess relational efficacy, and spouses' expectancies for partner behaviors during each interaction were elicited. Subsequent to the interactions, spouses' perceptions of their partners' actual behaviors were indicated, and spouses chose situational or dispositional attributions for each behavior. Results showed that distressed couples expect more negative and fewer positive behaviors and that spouses with high relational efficacy choose relationship-enhancing attributions more often than do low-efficacy spouses. The low-efficacy group showed strong preferences for distress-maintaining attributions. The results are interpreted as supporting the concept of sentiment override as well as the usefulness of the specific operationalization of relational efficacy utilized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

层状双金属氢氧化物/壳聚糖复合膜的制备与性能研究

用改性层状双金属氢氧化物(M-LDHs)与壳聚糖(CS)溶液共混,制得了具有阻隔性的可降解M-LDHs/CS复合膜。通过X射线衍射、红外光谱和原子力显微镜对复合膜进行结构表征,并对复合膜的气体阻隔性能、透光性能与拉伸性能进行了测试。结果表明:当w(M-LDHs)∶w(CS)为10∶100时,复合膜的氧气阻隔性能最佳,比纯CS膜提高了42%;当w(M-LDHs)∶w(CS)为15∶100时,拉伸强度最大,而断裂伸长率却有所下降。