Isolation,identification and cyfluthrin-degrading potential of a novel Lysinibacillus sphaericus strain,FLQ-11-1

Strain FLQ-11-1, isolated from sewage sludge, was able to degrade cyfluthrin and was identified as Lysinibacillus sphaericus based on its morphology, 16S rRNA sequence and fatty acid methyl ester (FAME) analyses. This strain could use cyfluthrin as its carbon or nitrogen source. Response surface methodology (RSM) analysis showed that the optimum conditions for degradation were at pH 7.0 and 35 °C, using an inoculum amount with an OD_600nm value of 1.6. Under these conditions, approximately 80.4% of cyfluthrin (50 mg l⁻¹) was degraded within five days (d) of incubation. Four metabolic compounds were detected during cyfluthrin degradation and identified as methyl-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane)-carboxylate, 4-fluoro-3-phenoxy-benzoic acid methyl ester, methyl-3-phenoxybenzoate, 3-phenoxy-benzaldehyde by gas chromatography–mass spectrometry (GC–MS) and tandem mass spectrum (MS/MS) analysis and no cyfluthrin was detected after seven days of incubation. A possible degradation pathway was proposed, and our data showed that cyfluthrin could be efficiently degraded by FLQ-11-1, indicating that this strain could potentially be used to eliminate the contamination of pyrethroid herbicides.     

The influence of 30-day-old Streptococcus mutans biofilm on the surface of esthetic restorative materials--an in vitro study

OBJECTIVE: To evaluate the effects of Streptococcus mutans biofilm/restorative materials interaction on surface roughness, hardness and morphology of materials tested. METHODS: Empress 2 (E2), Filtek Supreme (FS), Vitremer (V) and Ketac Molar Easymix (KM) were tested. Twenty-five disks of each material were made and divided into three storage groups: (1) 100% relative humidity (n=5); (2) growth medium (BHI and 1% sucrose) (n=5); (3) S. mutans biofilm-growth medium (n=15). Before storage, hardness measurements were immediately obtained from group 1 specimens. After 30 days of storage, the specimens were cleaned in order to obtain the surface roughness and hardness values, besides morphology analysis by scanning electron microscopy. RESULTS: The surface roughness and hardness values obtained from E2 and FS specimens did not present statistically significant differences among the groups 1, 2 and 3 and between immediate and 30-day-old specimens of each material. However, group 3 specimens of V and KM showed statistically significant higher surface roughness means than other groups. Group 1 specimens of V and KM also showed higher hardness values than the immediate values. Group 3 specimens of V presented decreased hardness values compared with other groups. The scanning electron micrographs showed an increase in surface degradation from group 1 to group 3 for FS, V and KM. CONCLUSIONS: Thirty-day-old biofilm promotes a negative effect on the surface morphology of FS, V and KM, on the surface roughness of V and KM and on the hardness of V.     

载rhBMP2凝胶微球控释系统的设计与合成实验

目的:设计与合成rhBMP2新型控释载体,初步探讨其载药及降解性能。方法:用右旋糖酐 (dextran,dex)与甲基丙烯酸缩水甘油酯(glycidylmethacrylate,GMA)合成甲基丙烯酸缩水甘油酯右旋糖酐 (dex GMA),测定该凝胶微球溶胀系数Q,并对其载药、降解性能进行初步研究。结果:dex GMA在一定条件下可以成球,粒径与制备工艺密切相关;该凝胶微球溶胀参数 10. 9±5. 3;载药性能良好,在葡聚糖酶的作用下 20~40d内可以完全降解。结论:右旋糖酐基凝胶微球具有良好的溶胀性能,可生物降解,其粒径可控,作为生长因子载体,有望达到控释给药的目的,其制备工艺及理化性能有待进一步研究。     

An ecotoxicological approach to microplastics on terrestrial and aquatic organisms: A systematic review in assessment,monitoring and biological impact

Marine and land plastic debris biodegrades at micro- and nanoscales through progressive fragmentation. Oceanographic model studies confirm the presence of up to ∼2.41 million tons of microplastics across the Atlantic, Pacific, and Indian subtropical gyres. Microplastics distribute from primary (e.g., exfoliating cleansers) and secondary (e.g., chemical deterioration) sources in the environment. This anthropogenic phenomenon poses a threat to the flora and fauna of terrestrial and aquatic ecosystems as ingestion and entanglement cases increase over time. This review focuses on the impact of microplastics across taxa at suggested environmentally relevant concentrations, and advances the groundwork for future ecotoxicological-based research on microplastics including the main points: (i) adhesion of chemical pollutants (e.g., PCBs); (ii) biological effects (e.g., bioaccumulation, biomagnification, biotransportation) in terrestrial and aquatic organisms; (iii) physico-chemical properties (e.g., polybrominated diphenyl ethers) and biodegradation pathways in the environment (e.g., chemical stress, heat stress); and (iv) an ecotoxicological prospect for optimized impact assessments.     

镁基合金生物可降解支架的国内外研究进展

近年来,镁基合金生物可降解支架在血管领域的应用取得了很大进展。镁基合金作为一种生物降解材料,比铁基合金和锌基合金具有一定的优势。然而,镁基合金的降解速度太快,无法与组织愈合的速度相匹配,而且还表现出不均匀腐蚀的特性。因此,研究者们从支架的表面改性、锻造工艺和成分配比等方面优化支架生物金属特性,并且逐步运用到动物实验及临床研究。本综述主要围绕以下3个方面展开：镁基合金生物可降解支架的国内外发展历程;镁基合金生物可降解支架的特性;镁基合金生物可降解支架的研究热点。     

The formation of an organic coat and the release of corrosion microparticles from metallic magnesium implants

Magnesium alloys have been proposed as prospective degradable implant materials. To elucidate the complex interactions between the corroding implants and the tissue, magnesium implants were analyzed in a mouse model and the response was compared to that induced by Ti and by the resorbable polymer polyglactin, respectively. One month after implantation, distinct traces of corrosion were apparent but the magnesium implants were still intact, whereas resorbable polymeric wound suture implants were already fragmented. Analysis of magnesium implants 2 weeks after implantation by energy-dispersive X-ray spectroscopy indicated that magnesium, oxygen, calcium and phosphate were present at the implant surface. One month after implantation, the element composition of the outermost layer of the implant was indicative of tissue without detectable levels of magnesium, indicating a protective barrier function of this organic layer. In agreement with this notion, gene expression patterns in the surrounding tissue were highly similar for all implant materials investigated. However, high-resolution imaging using energy-filtered transmission electron microscopy revealed magnesium-containing microparticles in the tissue in the proximity of the implant. The release of such corrosion particles may contribute to the accumulation of calcium phosphate in the nearby tissue and to bone conductive activities of magnesium implants.     

Biodegradation of Titanium Implants After Long-Time Insertion Used for the Treatment of Fractured Upper and Lower Jaws Through Osteosynthesis: Element Analysis by Electron Microscopy and EDX or EELS

Twelve patients underwent an osteosynthesis with titanium to treat upper and lower jaw fractures. Six to 12 months later, the miniplates were removed. Tissue samples were analyzed by light and electron microscopy for detection of a metallosis. The analysis showed new bone formation like callus tissue around the miniplates. In some cases small, rounded deposits and accumulation of colloid-like particles located next to bigger titanium artifacts were detected in the cytoplasm of histiocytes and in the matrix of connective tissue. The titanium was identified by elemental analysis using EDX in SEM as well as by EELS and electron diffraction in TEM. Both kinds of particles contain titanium, but they seem to be different in composition and derivation. The bigger particles seem to consist of metallic titanium and sourced by working on the metallic implants during the implantation itself. On the other hand, the colloidal-like, small, rounded particles in tissue macrophages and outside the cells in the matrix of connective tissue are presumably of other origin; for example, they could be derived from biodegradation and chemical conversion of the metallic implants. The titanium miniplates were examined before and after implantation by using ESCA technique and revealed metallic titanium and different compositions with other elements. The amount of titanium load of the tissue was very low in most cases and presumably not of biomedical relevance.