Bacterial microbiota in different types of processed meat products: diversity, adaptation, and co-occurrence.

As a double-edged sword, some bacterial microbes can improve the quality and shelf life of meat products, but others mainly responsible for deterioration of the safety and quality of meat products. This review aims to present a landscape of the bacterial microbiota in different types of processed meat products. After demonstrating a panoramic view of the bacterial genera in meat products, the diversity of bacterial microbiota was evaluated in two dimensions, namely different types of processed meat products and different meats. Then, the influence of environmental factors on bacterial communities was evaluated according to the storage temperature, packaging conditions, and sterilization methods. Furthermore, microbes are not independent. To explore interactions among those genera, co-occurrence patterns were examined. In these respects, this review highlighted the recent advances in fundamental principles that underlie the environmental adaption tricks and why some species tend to occur together frequently, such as metabolic cross-feeding, co-aggregate at microscale, and the intercellular signaling system. Further investigations are required to unveil the underlying molecular mechanisms that govern microbial community systems, ultimately contributing to developing new strategies to harness beneficial microorganisms and control harmful microorganisms.

Synergistic hepatoprotective effect of combined administration of Lachnum polysaccharide with silymarin.

In recent years, combination therapy has gradually become one of the hot spots. As a new therapy strategy, we investigated the combination treatment of polysaccharide from Lachnum sp. (LEP-2b) with silymarin and compared the effects with mono-therapy. In this study, combining high-dose LEP-2b with silymarin (CH) significantly reduced serum biochemistry indexes (ALT, AST, AKP, LDH), hepatic inflammation (TNF-α, IL-6 and IL-1ß) and improved the antioxidant status (SOD, CAT, GSH-Px, GSH, MDA and T-AOC), in which its effect on TNF-α was very significant (P < 0.001). Therefore, the expressions of related proteins in the JNK/p38 signaling pathway associated with TNF-α were examined. The result showed that CH treatment markedly increased the expression of p-p38 and inhibited the JNK phosphorylation. TUNEL staining, immunohistochemical staining and western blot assays demonstrated that the hepatoprotective effect of CH treatment was probably related with inhibiting hepatocyte apoptosis. In summary, combination of high dose LEP-2b with silymarin would be a more effective method to protect liver injury than mono-therapy.

Mechanism of bioactive polysaccharide from Lachnum sp. acts synergistically with 5-fluorouracil against human hepatocellular carcinoma.

The antimetabolite 5-fluorouracil (5-FU) is a widely used antitumor agent, however the overall response rate to 5-FU as a single agent is usually limited. Herein, how Lachnum expolysaccharide (LEP-2a), a type of active polysaccharide isolated from Lachnum sp., acted synergistically with 5-FU on HepG2 cells was investigated. It was found that LEP-2a notably enhanced 5-FU sensitivity in HepG2 cells in a synergistic manner. After combination treatment of 5-FU and LEP-2a, Ras/Raf/MEK/ERK and PI3K/AKT/mTOR pathway were inactivated. In addition, combination treatment induced generation of reactive oxygen species, decreased the levels of intracellular antioxidant enzymes and triggered mitochondrial apoptosis pathway. Furthermore, 5-FU combined with LEP-2a also resulted in p53 activation and NF-κB inhibition, and cell cycle arrest in the S phase as well as cell metastasis stagnation. Interestingly, LEP-2a treatment also blocked the DNA damage repair procedure. These findings demonstrate that LEP-2a enhanced 5-FU sensitivity and combination of 5-FU and LEP-2a exerts synergistic antitumor efficiency through multiple approaches.

Immunoregulatory effect assessment of a novel melanin and its carboxymethyl derivative.

A novel melanin with low molecular weight (LIM205, 522Da) was isolated from the fermentation broth of Lachnum sp. and its carboxymethyl derivative (CLIM205) was prepared. The immunoregulatory effects of LIM205 and CLIM205 in immuno-compromised mice induced by cyclophosphamide were investigated. The results demonstrated that both LIM205 and CLIM205 could significantly increase the thymus and spleen indices, specific and nonspecific (including carbon clearance ability) immunity, humoral and cellular immunity of mice. Treatment with LIM205 and CLIM205 could increase activities of SOD, GSH-PX, CAT and decrease content of MDA in the mice. Furthermore, for all animal tests, the immunoregulatory activities of CLIM205 were more prominent than that of LIM205. In conclusion, our findings suggested that the natural products LIM205, as well as its carboxymethyl derivative CLIM205, had significant immunoregulatory activities, which might be a promising source of immunoregulator in healthcare field.

BSRD: a repository for bacterial small regulatory RNA.

In bacteria, small regulatory non-coding RNAs (sRNAs) are the most abundant class of post-transcriptional regulators. They are involved in diverse processes including quorum sensing, stress response, virulence and carbon metabolism. Recent developments in high-throughput techniques, such as genomic tiling arrays and RNA-Seq, have allowed efficient detection and characterization of bacterial sRNAs. However, a comprehensive repository to host sRNAs and their annotations is not available. Existing databases suffer from a limited number of bacterial species or sRNAs included. In addition, these databases do not have tools to integrate or analyse high-throughput sequencing data. Here, we have developed BSRD (http://kwanlab.bio.cuhk.edu.hk/BSRD), a comprehensive bacterial sRNAs database, as a repository for published bacterial sRNA sequences with annotations and expression profiles. BSRD contains over nine times more experimentally validated sRNAs than any other available databases. BSRD also provides combinatorial regulatory networks of transcription factors and sRNAs with their common targets. We have built and implemented in BSRD a novel RNA-Seq analysis platform, sRNADeep, to characterize sRNAs in large-scale transcriptome sequencing projects. We will update BSRD regularly.

Human proteins with target sites of multiple post-translational modification types are more prone to be involved in disease.

Many proteins can be modified by multiple types of post-translational modifications (Mtp-proteins). Although some post-translational modifications (PTMs) have recently been found to be associated with life-threatening diseases like cancers and neurodegenerative disorders, the underlying mechanisms remain enigmatic to date. In this study, we examined the relationship of human Mtp-proteins and disease and systematically characterized features of these proteins. Our results indicated that Mtp-proteins are significantly more inclined to participate in disease than proteins carrying no known PTM sites. Mtp-proteins were found significantly enriched in protein complexes, having more protein partners and preferred to act as hubs/superhubs in protein-protein interaction (PPI) networks. They possess a distinct functional focus, such as chromatin assembly or disassembly, and reside in biased, multiple subcellular localizations. Moreover, most Mtp-proteins harbor more intrinsically disordered regions than the others. Mtp-proteins carrying PTM types biased toward locating in the ordered regions were mainly related to protein-DNA complex assembly. Examination of the energetic effects of PTMs on the stability of PPI revealed that only a small fraction of single PTM events influence the binding energy of >2 kcal/mol, whereas the binding energy can change dramatically by combinations of multiple PTM types. Our work not only expands the understanding of Mtp-proteins but also discloses the potential ability of Mtp-proteins to act as key elements in disease development.

Insight into the autochthonous bacterial strains as starter cultures for improving the flavor profiles of dry-cured duck: Changes in microbial diversity and metabolic profiles.

The purpose of this study was to reveal the effect of inoculating autochthonous bacterial strains (Lactobacillus and Staphylococcus simulans) on the flavor profiles, microbial community, and metabolites, and to elucidate the potential mechanism of flavor formation in dry-cured duck. The results indicated that the inoculation of bacterial strains could improve the amount of lactic acid bacteria and Staphylococcus and reduce the counts of Enterobacteria. There was a significant difference in flavor profiles between samples inoculated with different strains. Hexanal-D, acetone, 3-methyl-1-butanol-D, thiophene, hexanal-M, propanal, pentanal, (Z)-2-penten-1-ol and ethanol-D were the potential biomarkers. A total of 70 differential metabolites were screened and identified. Amino acid metabolism and lipid metabolism were the key pathways for the production of flavor and metabolites in dry-cured duck. The results of this study will improve our understanding of the mechanism of flavor formation regarding the inoculation of autochthonous starter cultures.

Characterization and interactions of spoilage of Pseudomonas fragi C6 and Brochothrix thermosphacta S5 in chilled pork based on LC-MS/MS and screening of potential spoilage biomarkers.

Pseudomonas and Brochothrix are the main spoilage organisms in pork, and each of these plays an essential role in the spoilage process. However, the effect of co-contamination of these two organisms in pork has not been elucidated. The changing bacterial communities during spontaneous spoilage of pork at 4 °C were evaluated using high-throughput sequencing. The dominant spoilage bacteria were isolated and these were identified as Pseudomonas fragi C6 and Brochothrix thermosphacta S5. Chilled pork was then experimentally contaminated with these strains, individually and in combination, and the progression of spoilage was assessed by analyzing various physicochemical indicators. These included total viable counts (TVC), pH, color, total volatile basic nitrogen (TVB-N), and detection of microbial metabolites. After 7 days of chilled storage, co-contaminated pork produced higher TVC and TVB-N values than mono-contaminated samples. Metabolomic analysis identified a total of 8,084 metabolites in all three groups combined. Differential metabolites were identified, which were involved in 38 metabolic pathways. Among these pathways, the biosynthesis of alkaloids derived from purine and histidine was identified as an important pathway related to spoilage. Specifically, histidine, histamine, AMP, IMP, GMP, succinic acid, and oxoglutaric acid were identified as potential spoilage biomarkers. The study showed that the combined presence of P. fragi C6 and B. thermosphacta S5 bacteria makes chilled pork more prone to spoilage, compared to their individual presence. This study provides insights that can assist in applying appropriate techniques to maintain quality and safety changes in meat during storage and further the assessment of freshness.

Flavor profile of "Dao Ban Xiang" (a traditional dry-cured meat product in Chinese Huizhou cuisine) at different processing stages in winter and summer.

"Dao Ban Xiang" is a famous traditional Chinese dry-cured meat product. This study aimed to comparatively analyze the difference in the volatile flavor information of "Dao Ban Xiang" produced in winter and summer. In this study, we determine the physical and chemical properties, free amino acids (FAAs), free fatty acids (FFAs), and volatile compounds in the four processing stages of samples in winter and summer. The content of FAAs decreased significantly during the curing period in winter while increasing steadily in summer. The content of total FFAs increased in both winter and summer, and polyunsaturated fatty acids (PUFAs) decreased significantly in summer. The characteristic compound in winter samples is hexanal, nonanal, and (E)-2-octenal, which may mainly come from the degradation of FAAs, while the characteristic compound in winter samples is hexanal, nonanal, and (E)-2-nonenal, which may mainly be derived from the oxidation of FFAs. This study extends our knowledge on flavor from traditional cured meat products at different processing stages in different seasons and could be useful for the standardization of the traditional and regional meat products.

Sequential activation of M1 and M2 phenotypes in macrophages by Mg degradation from Ti-Mg alloy for enhanced osteogenesis.

BACKGROUND: Even though the modulatory effects of Magnisum (Mg) and its alloys on bone-healing cells have been widely investigated during the last two decades, relatively limited attention has been paid on their inflammation-modulatory properties. Understanding the activation process of macrophages in response to the dynamic degradation process of Mg as well as the relationship between macrophage phenotypes and their osteogenic potential is critical for the design and development of advanced Mg-based or Mg-incorporated biomaterials. METHODS: In this work, a Ti-0.625 Mg (wt.%) alloy fabricated by mechanical alloying (MA) and subsequent spark plasma sintering (SPS) was employed as a material model to explore the inflammatory response and osteogenic performance in vitro and in vivo by taking pure Ti as the control. The data analysis was performed following Student's t-test. RESULTS: The results revealed that the macrophages grown on the Ti-0.625 Mg alloy underwent sequential activation of M1 and M2 phenotypes during a culture period of 5 days. The initially increased environmental pH (~ 8.03) was responsible for the activation of M1 macrophages, while accumulated Mg2+ within cells contributed to the lateral M2 phenotype activation. Both M1 and M2 macrophages promoted osteoblast-like SaOS-2 cell maturation. In vivo experiment further showed the better anti-inflammatory response, regenerative potentiality and thinner fibrous tissue layer for the Ti-0.625 Mg alloy than pure Ti. CONCLUSION: The results highlighted the roles of Mg degradation in the Ti-0.625 Mg alloy on the sequential activation of macrophage phenotypes and the importance of modulating M1-to-M2 transition in macrophage phenotypes for the design and development of inflammation-modulatory biomaterials.

Multi-scale nacre-inspired lamella-structured Ti-Ta composites with high strength and low modulus for load-bearing orthopedic and dental applications.

Mimicking the hierarchical structure of nacre in artificial materials is a promising approach to obtain high mechanical performance. In this work, nacre-inspired lamella-structured Ti-Ta composites were fabricated by successive spark plasma sintering, mechanical processing and annealing. The specimen sintered at 1200 °C and then hot rolled with 60% height reduction exhibited multi-scale lamellar microstructure. At micro-scale, the composite was composed of alternate Ti-enriched and Ta-enriched micro-bands. At nano-scale, highly-ordered lamellar structures consisted of Ti-enriched and Ta-enriched nano-lamellae were found near Ti/Ta micro-bands. The biomimetic-structured Ti-Ta composite possessed appropriate combination of strength (1030 MPa ultimate tensile strength) and ductility (10.2% elongation), which is much stronger than pure Ti and comparably strong as Ti-6Al-4 V. Moreover, the biomimetic-structured Ti-Ta composite possessed low modulus (80.6 GPa). In vitro cell culture experiment revealed that the biomimetic-structured Ti-Ta composite was cytocompatible, evidenced by the well-spread morphology and favorable growth of human bone mesenchymal stem cells (hBMSCs) on material surface. A rat femoral fracture model was employed to evaluate the therapeutic performance of biomimetic-structured Ti-Ta composite implant on fracture healing compared to that of pure Ti. In vivo results showed that the composite implant enhanced fracture healing in rats. Together, the findings obtained in the current work suggest that mimicking the hierarchical structure of nacre in Ti-Ta composite is an effective way for material strengthening. Moreover, the biomimetic-structured Ti-Ta composite with high strength, good ductility, low modulus and favorable biocompatibility is promising for load-bearing applications in orthopedic and dental area.

The response of macrophages and their osteogenic potential modulated by micro/nano-structured Ti surfaces.

Current understanding on the interactions between micro/nano-structured Ti surfaces and macrophages is still limited. In this work, TiO2 nano-structures were introduced onto acid-etched Ti surfaces by alkali-heat treatment, ion exchange and subsequent heat treatment. By adjusting the concentration of NaOH during alkali-heat treatment, nano-flakes, nano-flakes mixed with nano-wires or nano-wires could formed on acid-etched Ti surfaces. The micro- and micro/nano-structured Ti surfaces possessed similar surface chemical and phase compositions. In vitro results indicate that the morphology of macrophages was highly dependent on the morphological features of nano-structures. Nano-flakes and nano-wires were favorable to induce the formation of lamellipodia and filopodia, respectively. Compared to micro-structured Ti surface, micro/nano-structured Ti surfaces polarized macrophages to their M2 phenotype and enhanced the gene expressions of osteogenic growth factors in macrophages. The M2 polarized macrophages promoted the maturation of osteoblasts. Compared to that with nano-flakes or nano-wires, the surface with mixed features of nano-flakes and nano-wires exhibited stronger anti-inflammatory and osteo-immunomodulatory effects. The findings presented in the current work suggest that introducing micro/nano-topographies onto Ti-based implant surfaces is a promising strategy to modulate the inflammatory response and mediate osteogenesis.

Facile synthesis of multi-functional nano-composites by precise loading of Cu2+ onto MgO nano-particles for enhanced osteoblast differentiation, inhibited osteoclast formation and effective bacterial killing.

Biomaterials with multi-functions including enhancing osteogenesis, inhibiting osteoclastogenesis and effectively removing bacteria are urgently needed in the treatment of osteoporotic bone defects. In this study, MgO nano-particles were employed as a platform for precise Cu2+ loading. By immersing MgO into CuSO4 solution with a pre-defined concentration (0.1, 1 or 10 mM), 1 mg MgO adsorbed 3.25, 32.5 or 325 µg Cu2+ from the solution. As-synthesized nano-composites were referred as MgO-0.1Cu, MgO-1Cu or MgO-10Cu depending on the concentration of employed CuSO4 solution. The results revealed that MgO-xCu (x = 0.1, 1 and 10) nano-composites were lamella-shaped and composed of amorphous Cu(OH)2, crystalline Mg(OH)2 and minor MgO. The extracellular release of Cu2+ was rather limited due the capture of Cu2+ by Mg(OH)2. In vitro results revealed that MgO-xCu (x = 0.1, 1 and 10) nano-composites modulated osteoblast, osteoclast and bacterium response in a Cu2+ loading amount-dependent manner. MgO-0.1Cu nano-composite exhibited stimulatory function on osteoblast proliferation without influencing osteoblast maturation, osteoclast formation and bacterial survival. MgO-1Cu nano-composite enhanced osteoblast proliferation and differentiation, inhibited osteoclast formation and effectively killed bacteria. When larger amount of Cu2+ was loaded, MgO-10Cu nano-composite exhibited stronger stimulatory effect on osteoblast maturation, enhanced inhibitory function on osteoclast formation and promoted bactericidal performance, although it showed a certain degree of initial cyto-toxicity. Together, the results suggest that MgO nano-particles could be employed as potential platform for precise Cu2+ loading and intracellular Cu2+ delivery. MgO-xCu (x = 1 and 10) nano-composites are promising to be employed as multi-functional fillers in bone tissue engineering scaffolds for osteoporotic bone regeneration.

Stimulation of in vitro and in vivo osteogenesis by Ti-Mg alloys with the sustained-release function of magnesium ions.

Magnesium (Mg) is well-known for its bioactivity and degradability. However, due to its low evaporation temperature and limited solubility in titanium (Ti), the fabrication of Ti-Mg alloys remains a huge challenge. In this study, Ti-xMg (x = 0.312, 0.625, 1.25 and 2.5 wt.%) alloys were fabricated by the combination of mechanical alloying (MA) and spark plasma sintering (SPS). Mg mainly existed as a solid solute element in the Ti matrix, while it also existed as second-phase particles due to its precipitation and dispersion during the SPS process. At a low content of 0.625 wt.%, Mg could increase the mechanical strength of Ti by the solid solution strengthening. However, it was detrimental to material mechanical properties when the Mg content increased to 1.25 wt.%. Being immersed in phosphate buffered solution (PBS), Ti-Mg alloys exhibited a burst Mg2+ release behavior within the first day, and then the rates of Mg2+ release gradually decreased within the following 27 days. The results suggested that the cell viability was dependent on the content of Mg in the Ti-Mg alloys. The high Mg content (2.5 wt.%) in the Ti-Mg alloys could lead to significant cytotoxicity. However, appropriate Mg content (0.312∼0.625 wt.%) could promote cell attachment, proliferation and differentiation. The Ti-0.625Mg alloy exhibited the best in vitro biological performance among all groups. In vivo results obtained by implanting the Ti-0.625Mg alloy in the femurs of rats further revealed its enhanced regenerative potential and osteointegration compared to pure Ti implants.

Using MgO nanoparticles as a potential platform to precisely load and steadily release Ag ions for enhanced osteogenesis and bacterial killing.

Bio-functional fillers including bio-ceramic, degradable metallic and composite particles are commonly introduced into bone tissue engineering (BTE) scaffolds to endow the materials with specific biological functions for enhanced bone defect therapy. In this work, MgO nanoparticles (NPs) were employed as a potential platform for precise loading and sustained release of Ag+. The results showed that MgO NPs possessed strong adsorption capacity (almost 100%) towards Ag+ in AgNO3 solutions with different concentrations (0.1, 1 and 10 mM). After the adsorption of Ag+ in AgNO3 solutions, cube-shaped MgO NPs transformed to lamella-structured nano-composites (NCs) composed of Mg(OH)2 and Ag2O, which were referred as MgO-xAg (x = 0.1, 1 or 10) NCs depending on the employed concentration of AgNO3 solution. After being suspended in distilled water, as-prepared positively charged NCs underwent a fast degradation process during the initial 4 days. From day 4 and 14, steady release behaviors of Mg2+ and/or Ag+ from the NCs were noticed. With the lowest loading amount of Ag+, MgO-0.1Ag NCs did not exhibit significant modulatory effect on SaOS-2 cell response. On the contrary, MgO-10Ag NCs loaded with the highest amount of Ag+ showed significant cyto-toxicity towards SaOS-2 cells. With appropriate amount of Ag+ loading, MgO-1Ag NCs showed significantly stimulatory effects on SaOS-2 cell proliferation and differentiation. This is evidenced by the enhanced cell viability, alkaline phosphatase (ALP) activity and collagen (COL) production as well as the gene expressions of ALP, COL and osteoprotegerin (OPG) in MgO-1Ag group. Moreover, MgO-1Ag exhibited strong bactericidal capacity against both Escherichia coli and Staphylococcus aureus. Together, the results indicate that MgO could be employed as a potential platform for precise loading and sustained release of Ag+. MgO-1Ag NCs are promising to be used as bio-functional fillers in BTE scaffolds for simultaneously promoted osteogenesis and bacterial killing.

Systematic analysis of alternative promoters correlated with alternative splicing in human genes.

Interactions between various events are essential for complex and delicate transcriptional regulation. To delineate the features and potential roles of alternative promoters (APs) correlated with alternative splicing (AS), we have systematically analyzed 9908 putative alternative promoters (PAPs) from 3797 human genes. Our results showed that approximately 65% of AS events are associated with PAPs. Intriguingly, PAPs per human AS gene only averaged 2.6 for our dataset, which was significantly lower than previously reported. This seems to imply that the human genome contains a small pool of appropriable PAPs for AS genes. Exploration of the characteristics of PAPs such as CpG islands, TATA boxes, GC-content, transcription factor binding sites (TFBSs) and repetitive elements suggested that, respectively, 87% and 90% of PAPs of human AS genes are CpG- and TATA box-poor. The GC-content is significantly higher in the downstream of transcription start sites (TSSs) than upstream (58% vs. 53%), and there is a strong negative correlation between the GC-content and the number of PAPs. These suggested that GC-content around the TSSs plays an important role in the regulation of AS. Moreover, different APs contain distinct densities of repetitive elements and TFBSs, indicating that such sequences have an intrinsic role in the divergent regulation of PAPs and AS. Substantial difference was also found between human AS genes in terms of PAP numbers. A close connection between PAPs and AS may play a critical role in the choice of APs and regulation of AS genes. Furthermore, the distribution of AS genes on different human chromosomes also influences the numbers of PAPs and isoforms of AS genes. Our results may provide important clues for further studies on regulatory network of transcription-related events.

Comparing the regeneration potential between PLLA/Aragonite and PLLA/Vaterite pearl composite scaffolds in rabbit radius segmental bone defects.

Mussel-derived nacre and pearl, which are natural composites composed CaCO3 platelets and interplatelet organic matrix, have recently gained interest due to their osteogenic potential. The crystal form of CaCO3 could be either aragonite or vaterite depending on the characteristics of mineralization template within pearls. So far, little attention has been paid on the different osteogenic capacities between aragonite and vaterite pearl. In the current work, aragonite or vaterite pearl powders were incorporated into poly-l-lactic acid (PLLA) scaffold as bio-functional fillers for enhanced osteogenesis. In intro results revealed that PLLA/aragonite scaffold possessed stronger stimulatory effect on SaOS-2 cell proliferation and differentiation, evidenced by the enhanced cell viability, alkaline phosphatase activity, collagen synthesis and gene expressions of osteogenic markers including osteocalcin, osteopotin and bone sialoprotein. The bone regeneration potential of various scaffolds was evaluated in vivo employing a rabbit critical-sized radial bone defect model. The X-ray and micro-CT results showed that significant bone regeneration and bridging were achieved in defects implanted with composite scaffolds, while less bone formation and non-bridging were found for pure PLLA group. Histological evaluation using Masson's trichrome and hematoxylin/eosin (H&E) staining indicated a typical endochondral bone formation process conducted at defect sites treated with composite scaffolds. Through three-point bending test, the limbs implanted with PLLA/aragonite scaffold were found to bear significantly higher bending load compared to other two groups. Together, it is suggested that aragonite pearl has superior osteogenic capacity over vaterite pearl and PLLA/aragonite scaffold can be employed as a potential bone graft for bone regeneration.

Effect of composition on in vitro degradability of Ti-Mg metal-metal composites.

In this work, Ti and Mg alloys were made into composites by using spark plasma sintering, in order to combine the high stiffness of Ti and biodegradability of Mg alloys. The effect of the content of Mg-3Zn alloy on the degradability was studied by using electrochemical corrosion, immersion in simulated body fluid and incubation of Saos-2 cells. The results show that Ti-Mg metal-metal composites (MMCs) exhibit low Young's modulus (31-48 GPa) and good yield strength (616.5-642.8 MPa). The modulus and strength both decrease with the content of Mg-3Zn alloy increasing. The electrochemical corrosion rates of Ti-Mg MMCs were much lower than that of monolithic Mg-3Zn alloys. After an immersion for 21 days, Ti matrix remained integrity and Mg phase dissolved in the solution, inducing the formation of apatite layer on the MMCs. The precipitation of apatite increased with the content of Mg-3Zn alloy increasing. In vitro study indicated that Ti-10Mg and Ti-20 Mg MMCs possessed good biocompatibility to Saos-2 cells, while the biocompatibility of Ti-30 Mg MMCs decreased slightly. In summary, Ti-Mg MMCs are promising implant materials with adjustable degradation rates and improved biocompatibility for orthopedic applications.

Changes in the phospholipid molecular species in water-boiled salted duck during processing based on shotgun lipidomics.

Knowledge of the changes in the phospholipid molecular species during processing is helpful to understanding the complicated mechanisms of lipid degradation and transformation. The shotgun lipidomics strategy was utilized to analyze the phospholipid (PL) molecular species in raw Pekin duck and the subsequent dynamic changes that occur during the processing of water-boiled salted duck (WSD). Only 110 PL molecular species have been identified in raw duck meat, while a total of 119 PL molecular species were identified during processing, including 33 phosphatidylcholines, 22 phosphatidylethanolamines, 13 phosphatidylglycerols, 18 phosphatidylinositols and 33 phosphatidylserines. Most of the content of PL molecular species gradually decreased during processing, while the content of most of the lysophospholipids (LPLs) increased. After reaching a maximum, the LPLs were obviously reduced during the 3 d of dry-ripening. The results showed that processing techniques, such as dry-curing, dry-ripening and boiling, had a significant effect on the changes in the PLs in WSD. We further screened 10 PL molecular markers, which can be used to distinguish different operating units.

Nanoparticles and their effects on differentiation of mesenchymal stem cells.

Over the past decades, advancements in nanoscience and nanotechnology have resulted in numerous nanomedicine platforms. Various nanoparticles, which exhibit many unique properties, play increasingly important roles in the field of biomedicine to realize the potential of nanomedicine. Due to the capacity of self-renewal and multilineage mesenchymal differentiation, mesenchymal stem cells (MSCs) have been widely used in the area of regenerative medicine and in clinical applications due to their potential to differentiate into various lineages. There are several factors that impact the differentiation of MSCs into different lineages. Many types of biomaterials such as polymers, ceramics, and metals are commonly applied in tissue engineering and regenerative therapies, and they are continuously refined over time. In recent years, along with the rapid development of nanotechnology and nanomedicine, nanoparticles have been playing more and more important roles in the fields of biomedicine and bioengineering. The combined use of nanoparticles and MSCs in biomedicine requires greater knowledge of the effects of nanoparticles on MSCs. This review focuses on the effects of four inorganic or metallic nanoparticles (hydroxyapatite, silica, silver, and calcium carbonate), which are widely used as biomaterials, on the osteogenic and adipogenic differentiation of MSCs. In this review, the cytotoxicity of these four nanoparticles, their effects on osteogenic/adipogenic differentiation of MSCs and the signalling pathways or transcription factors involved are summarized. In addition, the chemical composition, size, shape, surface area, surface charge and surface chemistry of nanoparticles, have been reported to impact cellular behaviours. In this review, we particularly emphasize the influence of their size on cellular responses. We envision our review will provide a theoretical basis for the combined application of MSCs and nanoparticles in biomedicine.