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Infection often causes disastrous consequences in all fields of clinical medicine, especially orthopedics. Hence, critical efforts are being made to engineer novel nanomaterials for the treatment of orthopedic infections due to the high biocompatibility and antibacterial properties they possess. The purpose of this study was to investigate the antibacterial effects of magnesium hydroxide (Mg(OH)2) nanoparticles (NPs) in vitro and determine their possible mechanisms of action. In this study, Escherichia coli was selected as the pathogenic bacteria and it was found that Mg(OH)2 NPs significantly inhibited the growth of E. coli by promoting nucleic acid leakage, inhibiting protein synthesis, and suppressing the metabolic activity. The minimum inhibitory concentration for these bacteria was determined to be 4.4 μg/ml. In vitro flow cytometry and immunofluorescence tests indicated that Mg(OH)2 NPs induced the macrophages to generate reactive oxygen species to kill the bacteria. To understand the mechanisms involved in this process, western blotting was performed and it was found that Mg(OH)2 NPs activated the phosphatidylinositol‐3‐kinase/serine–threonine kinase (PI3K/Akt) signaling pathway of macrophages to enhance their phagocytosis with no obvious cytotoxicity. Thus, Mg(OH)2 NPs are a suitable choice to develop promising agents or coating materials for the treatment of clinically widespread infections in view of their safety, biocompatibility, and powerful antibacterial properties. [ABSTRACT FROM AUTHOR]

Sufu is a type of fermented food with abundant nutrients and delicious taste. It is made from the fermentation of tofu by various microorganisms. In this study, three types of sufu were prepared through natural fermentation: (NF), single‐strain fermentation (SF), and mixed‐strain fermentation (MF). Microbial species, amino acids, and fatty acids were identified to investigate dynamic changes in nutritional quality and microbial flora in sufu. The results showed that the number of microbial species in NF sufu was the highest (n = 284), whereas that in SF sufu was the lowest (n = 194). Overall, 153 microbial species were found in all three types of sufu. Relative abundance analysis also revealed that Tetragonococcus, Bacillus, Acinetobacter, and Staphylococcus were the main bacteria in sufu. However, there was a large number of harmful bacteria such as Enterococcaceae in NF sufu. The levels of various nutrients were low in SF sufu, whereas the contents of protein and soy isoflavones were higher in NF and MF sufu. Seventeen kinds of amino acids were detected, comprising seven essential amino acids and ten other amino acids. The contents of essential amino acids and essential fatty acids were higher in MF sufu than the other two types, resulting in its high nutritional value. The sufu produced through the three fermentation methods differed significantly (p <.05) in terms of microbial flora and nutritional quality. [ABSTRACT FROM AUTHOR]

Intramedullary stabilization is frequently used to treat long bone fractures. Since implant removal can become technically very challenging with the potential to cause further tissue damage, biodegradable materials are emerging as alternative options. Magnesium (Mg)‐based biodegradable implants have a controllable degradation rate and good tissue compatibility, which makes them attractive for musculoskeletal research. Herein, the degradation of Mg and steel implants, the pathological characteristics and osteoblast differentiation in mice femora were examined. To investigate the molecular mechanism, we analyzed the differentially expressed long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) in Mg‐implanted or stain‐steel‐implanted callus tissues. lncRNA LOC103691336 was upregulated in Mg‐implanted tissues and most relevant to BMPR2, a kinase receptor of BMPs with an established role in osteogenesis. The knockdown of LOC103691336 attenuated Mg‐mediated osteogenic differentiation. Furthermore, miR‐138‐5p, previously reported to inhibit osteogenic differentiation, could bind to LOC103691336 and BMPR2 in bone marrow stromal cells (BMSCs). LOC103691336 competed with BMPR2 for miR‐138‐5p binding in BMSCs to attenuate the inhibitory effect of miR‐138‐5p on BMPR2 expression. Finally, the effect of LOC103691336 knockdown on Mg‐mediated osteogenic differentiation could be attenuated by miR‐138‐5p inhibition. In conclusion, we provided a novel mechanism of Mg implants mediating the osteogenesis differentiation and demonstrated that Mg implants may be promising for improving fracture healing. [ABSTRACT FROM AUTHOR]

Osteosarcoma is a malignant primary bone tumor, which often associates with pulmonary metastasis. The radical surgery of osteosarcoma often requires internal orthopedic implants. Therefore, implants with antitumor properties should be developed. Magnesium (Mg) and its alloys possess great potential as orthopedic materials, given their biodegradable properties, superior osteogenesis performance, and antitumor features. However, problems arise with their uncontrolled degradation rates and their unknown antitumor mechanisms. In our study, when compared with pure Mg, the rare element silver alloyed with yttrium (Ag–Y) could extremely enhance the corrosion resistance of these elements, giving the Ex–Mg–1Ag–1Y alloy better anticorrosion rates. Here, we implanted the Ex–Mg–1Ag–1Y alloy and pure Mg and Ti alloy in vivo around tumors in nude mice (BALB/c). Notably, the local tumor weight in Mg alloy and pure Mg groups were much smaller than that in Ti alloy group in 36 days after surgery (6.59 ± 0.70, 6.76 ± 0.62, and 8.54 ± 0.56 g), while the general scores of lung metastasis in Mg alloy and pure Mg groups were also lower than Ti alloy group (64.50 ± 7.64, 62.73 ± 7.84, and 87.60 ± 9.43). Therefore, the Mg and Ex–Mg–1Ag–1Y alloy, both demonstrated resisting effects against local tumor growth and pulmonary metastasis, which could be performed by changing the extracellular acidosis microenvironment, elevating the Mg concentration, suppressing C–X–C chemokine receptor type 4 (CXCR4) levels, and increasing prostacyclin (PGI2) synthesis. Our work revealed that the Ex–Mg–1Ag–1Y alloy may be a promising orthopedic implant for treating osteosarcoma due to its better corrosion resistance and antitumor attributes. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2537–2548, 2019. [ABSTRACT FROM AUTHOR]

Abstract: Magnesium (Mg) alloy is gaining more interest because of its degradability and osteogenic potential. Still, it has some deficiencies, such as its rapid degradation rate, insufficient mechanical property. This research aimed to design a novel biodegradable Mg‐argentum (Ag)‐yttrium (Y) alloy, and Y was added to improve degradable and mechanical property. Mg‐Ag‐Y alloys were characterized for mechanical features, practicabilities in vitro and in vivo. The mechanical features results shown that this novel component was similar to native bone tissue in elastic moduli, tensile, and compressive stress. Then mesenchymal stem cells (MSCs) were seeded in alloys to assess cell toxicity in vitro. The results showed that its aqueous extract was suitable for MSCs adhesion and proliferation. Then the alloy was evaluated for biomedical applications in nonfractured distal femora of Sprague Dawley rats for 6 weeks, compared with those of pure‐Mg and stainless steel groups. All rats survived, and hematological and histological evaluation showed no abnormal physiology 6 weeks postimplantation, and measurements of serum Mg2+ concentration were within normal levels. X‐ray scanning, microcomputed tomography, and histological examinations were performed to evaluate the degradability and osteogenic potential. The results indicated that the degradation rate of alloy was 0.91 mm per year, (range 0.77–1.22 mm), and pure‐Mg 1.80 mm per year (1.43–2.26 mm). The new bone quantity was 3.18 mm3 (1.46–4.44 mm3) in Mg‐Ag‐Y alloys group, 1.39 mm3 (0.54–2.32 mm3) in pure‐Mg group, and none in stainless steel group. These promising results suggest potential clinical application of Mg‐Ag‐Y alloys for use as resorbable bone fixation implant. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2059–2069, 2018. [ABSTRACT FROM AUTHOR]