Mussel-inspired HA@TA-CS/SA biomimetic 3D printed scaffolds with antibacterial activity for bone repair

Bacterial infection is a major challenge that could threaten the patient’s life in repairing bone defects with implant materials. Developing functional scaffolds with an intelligent antibacterial function that can be used for bone repair is very important. We constructed a drug delivery (HA@TA-CS/SA) scaffold with curcumin-loaded dendritic mesoporous organic silica nanoparticles (DMON@Cur) via 3D printing for antibacterial bone repair. Inspired by the adhesion mechanism of mussels, the HA@TA-CS/SA scaffold of hydroxyapatite (HA) and chitosan (CS) is bridged by tannic acid (TA), which in turn binds sodium alginate (SA) using electrostatic interactions. The results showed that the HA@TA-CS/SA composite scaffold had better mechanical properties compared with recent literature data, reaching 68.09 MPa. It displayed excellent degradation and mineralization capabilities with strong biocompatibility in vitro. Furthermore, the antibacterial test results indicated that the curcumin-loaded scaffold inhibited S.aureus and E.coli with 99.99% and 96.56% effectiveness, respectively. These findings show that 3D printed curcumin-loaded HA@TA-CS/SA scaffold has considerable promise for bone tissue engineering

Interaction of OKL38 and p53 in Regulating Mitochondrial Structure and Function

<div><p>The tumor suppressor p53 is a well-known transcription factor controlling the expression of its target genes involved in cell cycle and apoptosis. In addition, p53 also plays a direct proapoptotic role in mitochondria by regulating cytochrome <em>c</em> release. Recently, we identified a novel downstream target of p53, OKL38, which relocalizes from nucleus to mitochondria upon forced expression to induce apoptosis. However, the mechanism underlying OKL38 targeting to mitochondria and apoptosis induction remains unclear. Here, we found that OKL38 interacts with p53 to regulate mitochondria function. After DNA damage, OKL38 colocalizes with p53 to mitochondria in U2OS cells. Further, p53 and OKL38 are targeted to mitochondria in synergy: forced expression of OKL38 leads to p53 localization to mitochondria while the expression of a mitochondria enriched p53 polymorphic variant, p53^R72, leads to OKL38 enrichment in mitochondria. Biochemical analyses found that OKL38 and p53 interact <em>in vivo</em> and <em>in vitro</em> via multiple domains. In cell biological assays, multiple regions of OKL38 mediate its mitochondria localization and induce mitochondria morphology changes. OKL38 induces formation of megamitochondria and increases cellular levels of reactive oxygen species. Furthermore, OKL38 induces cytochrome <em>c</em> release upon incubation with mitochondria. Taken together, our studies suggest that OKL38 regulates mitochondria morphology and functions during apoptosis together with p53.</p> </div

Aerobic Exercise Prevents Chronic Inflammation and Insulin Resistance in Skeletal Muscle of High-Fat Diet Mice

Obesity is commonly accompanied by chronic tissue inflammation and leads to insulin resistance. Aerobic exercise is an essential treatment for insulin resistance and has anti-inflammatory effects. However, the molecular mechanisms of exercise on obesity-associated inflammation and insulin resistance remain largely unknown. Here, we evaluated the effects of aerobic exercise on inflammation and insulin resistance in skeletal muscles of high-fat diet (HFD) mice. Male C57BL/6J mice were fed a high-fat diet or a normal diet for 12 weeks, and then aerobic training was performed on a treadmill for 8 weeks. Body weight, fasting blood glucose, food intake levels, and glucose and insulin tolerance were evaluated. The levels of cytokines, skeletal muscle insulin resistance, and inflammation were also analyzed. Eight weeks of aerobic exercise attenuated HFD-induced weight gain and glucose intolerance, and improved insulin sensitivity. This was accompanied by enhanced insulin signaling. Exercise directly resulted in a significant reduction of lipid content, inflammation, and macrophage infiltration in skeletal muscles. Moreover, exercise alleviated HFD-mediated inflammation by suppressing the activation of the NF-κB pathway within skeletal muscles. These results revealed that aerobic exercise could lead to an anti-inflammatory phenotype with protection from skeletal muscle insulin resistance in HFD-induced mice

OKL38 and p53 induced cytochrome <i>c</i> release from purified mitochondria <i>in vitro</i>.

<p>(A) Biochemical scheme used to analyze the effect of p53 and OKL38 on cytochrome <i>c</i> release from mitochondria. (B) Effects of p53 and OKL38 on cytochrome <i>c</i> release (top 2 panels), and the detection of p53 (middle 2 panels) and OKL38 (bottom 2 panels) in both soluble and pellet fractions by Western blot. Arrow denotes low levels of endogenous OKL38 in mouse liver mitochondria. (C) Western blot analyses of OKL38 digestion by trypsin without (upper panel) or with prior incubation with mitochondria (Lower panel). COX IV protein was monitored to show that mitochondrial protein is protected from trypsin digestion. The amount of trypsin in the reaction was detected by Ponceau S staining. (D) Western blot analyses of the amount of cytochrome <i>c</i> in the supernatant and pellet fractions after mitochondria were incubated with p53 and/or OKL38 at various concentrations. (E) A model of the function of OKL38 and its cooperation with p53 during DNA damage to regulate mitochondria-mediated cell death. Our data favor a model that after DNA damage, p53 activates the expression of OKL38. On the other hand, OKL38 protein can interact with p53 in cytoplasm and target each other to mitochondria to regulate mitochondrial morphology, function, and cell death.</p

Subcellular localization of OKL38 truncation derivatives.

<p>(<b>A</b>) Schematic drawing of the OKL38 domain structure and FLAG-OKL38 truncations used to analyze subcellular distribution. (B–C) Preferential mitochondrial localization of FLAG-OKL38^1–240 (B) and FLAG-OKL38^1–300 (C). (D–E) Nuclear and mitochondrial localization of FLAG-OKL38^241–477 (D, arrows denote mitochondria) and FLAG-OKL38^301–477 (E). Also see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0043362#pone.0043362.s004" target="_blank">figure S4</a> for more examples of subcellular localization of FLAG-OKL38 truncations. (F–G) The morphology of mitochondria in live cells was detected using a GFP-mito reporter protein in control U2OS cells (F) or in cells co-transfected with the full length FLAG-OKL38 construct (G). Also see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0043362#pone.0043362.s005" target="_blank">figure S5</a> for more examples of mitochondria changes in cells co-transfected with FLAG-OKL38 and GFP-mito.</p

Interaction of OKL38 and p53 proteins.

<p>(A) p53 was co-immunoprecipitated by the M2 agarose beads together with the FLAG-OKL38 expressed in p53^+/+ HCT116 cells, but not from the control cells without FLAG-OKL38 expression. (B) Nuclear extracts of U2OS cells were precipitated with normal mouse IgG or anti-p53 antibody and blotted with anti-p53 and anti-OKL38 antibodies. (C) Nuclear extracts of U2OS cells were precipitated with normal rabbit IgG or anti-OKL38 antibody and blotted with the anti-OKL38 and anti-p53 antibodies. Arrow denotes the position of p53. (D) GST-pull down experiments showed that GST-OKL38 beads retained p53 from nuclear extracts. (E) Similarly, GST-p53 beads retained FLAG-OKL38 expressed in Hela cells. (F) Illustration of OKL38 domain structures (TrkA and Pyr_Redox_2 domains) and the GST-truncation OKL38 constructs used to analyze OKL38 and p53 interaction. (G) Interaction of p53 with GST-OKL38 full length (residues 1–477) or its truncation derivatives in GST-pull down assays. Different percentages of input were loaded to serve as a control. (H) Illustration of p53 domain structures and its derivatives used in studying p53 and OKL38 interaction. (I) GST-pull down assays to detect interaction of FLAG-OKL38 with GST-p53 and its truncation derivatives.</p

OKL38 expression induced formation of megamitochondria and ROS production.

<p>(A) Ultrastructure analyses of mitochondria (M) using TEM in U2OS cells. (B–D) Ultrastructure analyses of mitochondria (M) in U2OS cells after OKL38 expression. Note the enlargement of mitochondria and the alteration of cristae structures. (E) The surface mitochondria areas in TEM images were analyzed by NIH image J program. The occurrence of megamitochondria was only observed in U2OS cells after OKL38 expression. (F) Flow cytometry analyses of cellular ROS levels in U2OS cells after H₂O₂ treatment. (G) Flow cytometry analyses of cellular ROS levels after FLAG-OKL38 expression. The DCF fluorescence signals were increased after H₂O₂ treatment or FLAG-OKL38 expression.</p

Tailoring the tribology property and corrosion resistance of selective laser melted CoCrMo alloys by varying copper content

In this study, the cobalt-chromium-molybdenum (CoCrMo) alloys containing varying Cu contents (CCM-xCu, x  = 0, 2, 3, 4 wt%) were fabricated via the selected laser melting (SLM) method. The influences of Cu content on tribological performance and corrosion resistance were investigated. The 2 and 3 wt% Cu contributed to inhibiting the generation of the HCP phase, whereas the inhibitory effect was quite limited at 4 wt% Cu. Notably, 4 wt% Cu led to the formation of Cr-enrich precipitates in the matrix, which was partially coherent with the Cu nanoparticle. The corrosion resistance of the CCM alloy was enhanced as the 2 and 3 wt% Cu added into the CCM alloy, contrarily, which deteriorated when Cu content reached 4 wt%. For the CCM-2Cu and CCM-3Cu, Cr-precipitates played a major role in enhancing the wear resistance, while the Cu lubrication effect working in coordination with Cr-precipitates determined that for the CCM-4Cu. This study was expected to achieve better tribology and corrosion properties of SLM-produced CCM alloys by tailoring microstructure through the Cu element