Characterization and mechanism of simultaneous degradation of aflatoxin B1 and zearalenone by an edible fungus of Agrocybe cylindracea GC-Ac2.

Contamination with multiple mycotoxins is a major issue for global food safety and trade. This study focused on the degradation of aflatoxin B1 (AFB1) and zearalenone (ZEN) by 8 types of edible fungi belonging to 6 species, inclulding Agaricus bisporus, Agrocybe cylindracea, Cyclocybe cylindracea, Cyclocybe aegerita, Hypsizygus marmoreus and Lentinula edodes. Among these fungi, Agrocybe cylindracea strain GC-Ac2 was shown to be the most efficient in the degradation of AFB1 and ZEN. Under optimal degradation conditions (pH 6.0 and 37.4°C for 37.9 h), the degradation rate of both AFB1 and ZEN reached over 96%. Through the analysis of functional detoxification components, it was found that the removal of AFB1 and ZEN was primarily degraded by the culture supernatant of the fungus. The culture supernatant exhibited a maximum manganese peroxidase (MnP) activity of 2.37 U/mL. Interestingly, Agrocybe cylindracea strain GC-Ac2 also showed the capability to degrade other mycotoxins in laboratory-scale mushroom substrates, including 15A-deoxynivalenol, fumonisin B1, B2, B3, T-2 toxin, ochratoxin A, and sterigmatocystin. The mechanism of degradation of these mycotoxins was speculated to be catalyzed by a complex enzyme system, which include MnP and other ligninolytic enzymes. It is worth noting that Agrocybe cylindracea can degrade multiple mycotoxins and produce MnP, which is a novel and significant discovery. These results suggest that this candidate strain and its enzyme system are expected to become valuable biomaterials for the simultaneous degradation of multiple mycotoxins.

Identification of two galectin-4 proteins (PcGal4-L and PcGal4-L-CRD) and their function in AMP expression in Procambarus clarkii.

Galectins, a family of lectins that bind to ß-galactoside, possess conserved carbohydrate recognition domains (CRDs) and play a crucial role in recognizing and eliminating pathogens in invertebrates. Two galectin-4 genes (PcGal4) isoforms, named PcGal4-L and PcGal4-L-CRD, were cloned from the cDNA library of Procambarus clarkia in our study. PcGal4-L contains an open reading frame (ORF, 1089 bp), which encodes a protein consisting of 362 amino acids including a single CRD and six low complexity regions. The full-length cDNA of PcGal4-L-CRD contains a 483 bp ORF that encodes a protein of 160 amino acids, with a single CRD and a low-complexity region. The difference between the two PcGal4 isoforms is that PcGal4-L has 202 additional amino acids after the CRD compared to the PcGal4-L-CRD. These two isoforms are grouped together with other galectins from crustaceans through phylogenetic analysis. Further study revealed that total PcGal4 (including PcGal4-L and PcGal4-L-CRD) was primarily expressed in the muscle, gills and intestine. The mRNA levels of total PcGal4 in gills and hemocytes were significantly induced after challenge with Aeromonas hydrophila. Both recombinant PcGal4-L and its spliced isoform, PcGal4-L-CRD, could directly bind to lipopolysaccharides, peptidoglycan and five tested microorganisms, inducing a wide spectrum of microbial agglutination. The spliced isoform PcGal4-L-CRD showed a stronger binding ability than PcGal4-L. In addition, when the PcGal4 was knockdown, transcriptions of seven antimicrobial peptides (AMPs) genes (ALF5, ALF6, ALF8, CRU1, CRU2, CRU3 and CRU4) in gills and seven AMPs genes (ALF5, ALF6, ALF8, ALF9, CRU1, CRU3 and CRU4) in hemocytes were significantly decreased. Meanwhile, the survival rate of P. clarkii decreased in the PcGal4-dsRNA group. In summary, these results indicate that PcGal4 can mediate the innate immunity in P. clarkii by bacterial recognition and agglutination, as well as regulating AMP expression, thus recognition and understanding of the functions of galectin in crustaceans in immune resistance.

Antibacterial and anti-inflammatory activities of chitosan/copper complex coating on medical catheters: In vitro and in vivo.

Copper ions (Cu) grafted chitosan coating was prepared using the pneumatic spraying method on the silicone rubber surface. Coating's surface properties, morphology, composition, Cu releasing behavior, antibacterial, and anti-inflammatory activities are investigated and discussed. Surface properties, composition, and morphology were investigated by scanning electron microscopy (SEM) and contact angle measurements. The antibacterial activity has been tested with Escherichia coli and Staphylococcus aureus suspensions in vitro. Besides, the morphology of the biofilm was inspected with a field emission SEM. To evaluate the anti-inflammatory activity and biosafety of the coating in vivo, the optimized coating samples and control groups were implanted subcutaneously into the back of mice. The bacterial environment model was established by injection of the bacterial suspension. The morphology and bacterial adhered on the surface of catheters and the surrounding tissues were analyzed after 5 days of implantation. As in vitro results, the number of adhered bacterial on the surface of the silicon rubber surface was decreased, and the anti-inflammatory rate was increased by the intensify of the Cu content in chitosan coating. As for in vivo results, after 5 days of implantation, there was no evident inflammation in the surrounding tissues of all catheters in all without the S. aureus injected group. In the injected chitosan/Cu coated group; the inflammation, the number of the adhered bacteria were observed less than other injected samples without Cu; no inflammation were noticeable. Results indicate that the Cu-modified chitosan coating can confer excellent antibacterial and anti-inflammatory activity as applied on medical catheters.

Biosafety and biodegradation studies of AZ31B magnesium alloy carotid artery stent in vitro and in vivo.

Biosafety of AZ31B magnesium (Mg) alloy and the effect of its degradation products on tissues, organs, and whole systems are highly needed to be evaluated before clinical application. This study serves a wide variety of safety evaluations of biodegradable AZ31B alloy on nerve cells. As a result of this in vitro study, the maximum aluminum (Al) ion and Mg ion concentrations in the medium were estimated to be 22 µmol/L and 2.75 mmol/L, respectively, during degradation. In addition, the corresponding cell mortality was observed to be 36% and lower than 5% according to the resistance curves of the cell to Mg and Al ions. Furthermore, the maximum Al ion and Mg ion concentrations in serum and cerebrospinal fluid were detected to be 26.1 µmol/L and 1.2 mmol/L, respectively, for 5 months implantation. Combining the result of in vivo dialysis with the result of ion tolerance assay experiments, the actual death rate of nerve cells is estimated between 4 and 10% in vivo, which is lower than the result of in vitro cytotoxicity evaluation. Moreover, no psychomotor disability during clinical studies is observed. Consequently, stent made of AZ31B alloy with surface treatment is feasible for carotid artery stenosis, and it is safe in terms of cell viability on the nervous system.

High nitrogen stainless steel drug-eluting stent - Assessment of pharmacokinetics and preclinical safety in vivo.

Pharmacokinetic analyses were performed using 20 pigs for 120-days implantation, while one sirolimus-eluting stent was implanted into one of their coronary artery. At different time points, the residual sirolimus on the stent, delivered locally (to artery wall), regionally (to adjacent and downstream muscle) and systemically (to plasma and visceral organs), was detected throughout 120 days. Preclinical safety evaluation was performed using 32 pigs for 180-days implantation to study the safety of metal platform material and the effectiveness of sirolimus eluting coating on the HNS stent. The neointima area, restenosis rate and inflammatory grade for HNS and control group stents were detected and analyzed. Approximately 80% sirolimus was eluted from the sirolimus-eluting stents after 30-days implantation in vivo. Additionally, there was sustained sirolimus in the artery wall, cardiac muscle and heart throughout 120-days implantation, and sirolimus accumulated to the peak at 90-days implantation. It was inferred that the sirolimus eluting stent in this study was covered by neointima before 90-days implantation, indicating that the sirolimus eluting coating on the HNS stent was safe and effective. Very little sirolimus was distributed in visceral organs after 14-days implantation. HNS sirolimus-eluting stent exhibited lower restenosis rate and lower inflammatory grade than control group, which verified that the sirolimus-eluting coating design in this study was reasonable and practical. In addition, there were no significant difference in restenosis rate and inflammatory score between HNS bare-metal stent and drug-eluting stents, illustrating that HNS has good bio-compatibility and is suitable to use as coronary artery stent material.

Facile fabrication of the zoledronate-incorporated coating on magnesium alloy for orthopaedic implants.

BACKGROUND: Bisphosphonates (BPs) are known as a group of well-established drugs which are clinically used in metabolic bone disorder-related therapies. Recently increasing interests are focused on the application of BPs in the biodegradable Mg-based implants. METHODS: In this study a facile method was applied to fabricate a zoledronate loaded coating on AZ31 Mg alloy in comparison with the previous construction strategies, such as Ca-P chelation with BPs. RESULTS: The results showed that the fluoride pretreated coating could provide better corrosion resistance. Zoledronic acid (ZA) was successfully loaded on the surface of Mg alloy detected by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) analysis, and the release profile was quantified with Ultraviolet (UV) detection. CONCLUSION: It is considered that this construction of ZA coated Mg-based orthopedic implants could be easily and efficiently used in clinic. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: Different from the traditional drug release mode, this paper used the hydrogen bond between drug molecules and drug carriers to not only realise the effective drug release in the early stage of drug release, but also meet the continuous effect of drugs in the later stage, providing a new possibility for clinical application.

Anticoagulation and antibacterial functional coating on vascular implant interventional medical catheter.

Vascular implant interventional medical catheter will contact with blood firstly after implantation. The anticoagulation and antibacterial functions of this device will determine the success or failure. Copper (Cu) has been verified to possess multi-biofunctions, but it was challenging to add the Cu metal to most materials. Take advantage of its functionality; Cu has been grafted on the material surface to improve the anticoagulation function and accelerate endothelialization. In this study, a Cu-bearing chitosan coating was prepared on the catheter to endow the anticoagulation and anti-infection functions. Besides, properties characterization and functional evaluation of the coated medical catheter were investigated. Dynamic blood clotting and platelet adhesion tests were carried out to evaluate the anticoagulation property. Besides this, the antibacterial test was used to estimate the anti-infection function. The surface energy and Cu ions release from the coating were detected and calculated by contact angles and immersion tests, respectively. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that Cu ions were grafted in the chitosan coating. Thermogravimetric analysis (TA) result showed the concentration of Cu ions in the coating. The results of dynamic blood clotting, platelet adhesion, and antibacterial tests revealed that Cu grafted in chitosan would improve the blood compatibility and anti-infection property. The surface properties and Cu ions release behavior of Cu-bearing coating revealed the reasons for multi-biofunctions. This study indicated that the Cu-bearing chitosan coating could endow the vascular implant interventional device anticoagulation and anti-infection functions, which has excellent potential for clinical application.

In vivo research on Cu-bearing ureteral stent.

Infection and encrustation limit the use of ureteral stent and to data no device can completely solve these complications. The Cu-bearing stainless steel is a novel material with properties of inhibiting infection and decreasing encrustation in vitro. In this work, ureteral stents were fabricated and implanted into the bladder of New Zealand rabbits, aiming to further investigate the effects of material on bacterial survival and growth as well as the implant related encrustation. Less adherent microbes and deposited crystals on Cu-bearing stainless steel stents were found, with significant differences in comparison with stainless steel stents, which further support the development of biofunctional ureteral stents.

Anti-fibrotic function of Cu-bearing stainless steel for reducing recurrence of urethral stricture after stent implantation.

Recurrent stenosis is the main reason inducing the failure of urethral stricture treatment. Our previous study has found that the 316L type Cu bearing stainless steel (316L-Cu SS) showed antimicrobial activity and anti-encrustation performance when it was used for relieving urethral obstructer. However, whether it can reduce the occurrence of fibrosis or not, we need further investigation to compare the cellular and molecular responses of human urethral scar fibroblast cells (USFCs) on 316L-Cu SS and medical grade 316L stainless (316L SS, as a control). [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulfophenyl)- 2H-tetrazolium (MTS) and Transwell were used to assess the cellular responses, which confirmed that 316L-Cu SS could inhibit proliferation and migration of USFCs. Molecular expressions of fibrosis were evaluated by western blot, real-time quantitative polymerase chain reaction (qPCR), and Cu/Zn superoxide dismutase (CuZnSOD) measurement. The results indicated that up-regulating of CuZnSOD attenuated the transforming growth factor-ß1 expression and phosphorylation of Smad3 after exposure to 316L-Cu SS. Besides, the content of collagen type I (COL1) and collagen type III (COL3) secreting into the culture medium measured by enzyme-linked immunosorbent assay were in accord with the results of messenger ribonucleic acids. Both of them exhibited lower levels of COL1/COL3 exposure to 316L-Cu SS, demonstrating the inhibitory performance of 316L-Cu SS against fibrosis. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2019-2028, 2018.

Evaluation of promoting effect of a novel Cu-bearing metal stent on endothelialization process from in vitro and in vivo studies.

Drug eluting stents (DES) have been extensively applied nowadays and reduce the incidence of in-stent restenosis (ISR) greatly as compared with bare metal stents (BMS). However, the development of DES is hindered by the risk of late stent thrombosis (LST) due to delayed re-endothelialization, while endothelialization is an important process related to ISR and LST after implantation. 316L is a traditional stent material without bioactivity and have a high risk of ISR. Cu is recognized for angiogenesis stimulation in these years. Hence a copper bearing 316L stainless steel (316L-Cu) was prepared and evaluated about its effect on endothelialization in this paper. Compared with traditional 316L, it was proved that 316L-Cu increased the proliferation of co-cultured human umbilical vein endothelial cells (HUVECs) at first day. Moreover, HUVECs stretched better on the surface of 316L-Cu. It also improved the expression of angiogenesis related genes and tube formation ability in vitro. 316L-Cu-BMS, DES and 316L-BMS were implanted in swine to evaluate the re-endothelialization ability in vivo. And 316L-Cu-BMS showed the best effect on endothelialization with good biosafety. Consequently, 316L-Cu is a kind of promising BMS material for coronary field.

In vitro and in vivo evaluation of MgF2 coated AZ31 magnesium alloy porous scaffolds for bone regeneration.

Porous magnesium scaffolds are attracting increasing attention because of their degradability and good mechanical property. In this work, a porous and degradable AZ31 magnesium alloy scaffold was fabricated using laser perforation technique. To enhance the corrosion resistance and cytocompatibility of the AZ31 scaffolds, a fluoride treatment was used to acquire the MgF2 coating. Enhanced corrosion resistance was confirmed by immersion and electrochemical tests. Due to the protection provided by the MgF2 coating, the magnesium release and pH increase resulting from the degradation of the FAZ31 scaffolds were controllable. Moreover, in vitro studies revealed that the MgF2 coated AZ31 (FAZ31) scaffolds enhanced the proliferation and attachment of rat bone marrow stromal cells (rBMSCs) compared with the AZ31 scaffolds. In addition, our present data indicated that the extract of the FAZ31 scaffold could enhance the osteogenic differentiation of rBMSCs. To compare the in vivo bone regenerative capacity of the AZ31 and FAZ31 scaffolds, a rabbit femoral condyle defect model was used. Micro-computed tomography (micro-CT) and histological examination were performed to evaluate the degradation of the scaffolds and bone volume changes. In addition to the enhanced the corrosion resistance, the FAZ31 scaffolds were more biocompatible and induced significantly more new bone formation in vivo. Conversely, bone resorption was observed from the AZ31 scaffolds. These promising results suggest potential clinical applications of the fluoride pretreated AZ31 scaffold for bone tissue repair and regeneration.

A novel ureteral stent material with antibacterial and reducing encrustation properties.

Ureteral stents have been used to relieve ureterostenosis. Complications such as infection and encrustation occur in the long time of stent implantation, which is a clinical problem needs to be resolved. Indwelling ureteral stents have shown to develop microbial biofilm that may lead to recurrent infection and encrustation. This study was aiming to reduce those complications by using a novel material, Cu-bearing antibacterial stainless steel. The antibacterial performance, encrustation property, and biocompatibility were examined by SEM, image analysis, MTT and would healing. The in vitro immersion test showed that 316LCu-bearing stainless steel (316LCu-SS) not only inhibited proliferation of bacteria and formation of biofilm, but also had less encrustation deposition. Its antibacterial effectiveness against Escherichia coli reached to 92.7% in the artificial urine for 24h and 90.3% in the human urine for 6h. The encrustation surface coverage percentage was 30.2% by 12weeks, which was nearly one half of NiTi alloy. The in vitro tests showed that 316LCu-SS had no toxicity, and promoted the migration of urethral epithelial cells.

Research on the corrosion resistance and formation of double-layer calcium phosphate coating on AZ31 obtained at varied temperatures.

In this study, the effect of varied processing temperatures on the corrosion resistance and formation of dual-layer calcium phosphate coating on AZ31 was investigated. The microstructure, phase and morphology were characterized by a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD), respectively. The in vitro degradation behavior of coated AZ31 samples were evaluated by electrochemical and immersion tests in simulated body fluid. The results showed that the varied processing temperatures responded to different microstructure, phase and morphology; and a dual-layer coating was formed during the deposition process at 70°C. Meanwhile the higher processing temperature induced a faster coating formation rate and greater surface coverage. The in vitro degradation tests in simulated body fluid indicated that the corrosion rates of AZ31 alloy were effectively decreased with increasing processing temperature, which was attributed to the denser protective coating. The formation mechanism of dual-layer coating influenced by deposition temperature was proposed.

Effect of hydrion evolution by polylactic-co-glycolic acid coating on degradation rate of pure iron.

For biodegradable iron coronary stents, the major problem is the low degradation rate in body environment. In this study, a new strategy was proposed to increase the degradation rate of iron in vitro. The hydrion evolution was intended to be introduced into the degradation system to increase the degradation rate. To realize this strategy, polylactic-co-glycolic acid (PLGA) was coated onto the surface of pure iron. The degradation process and mechanism of pure iron coated with PLGA were investigated. The results showed that iron coated with PLGA exhibited higher degradation rate in the static immersion test all along. With the degradation of PLGA, the oligomers of PLGA could release abundant H(+) which could dissolve the ferrous oxide to make the electrolyte and oxygen to reach the surface of iron again and simultaneity trigger the hydrion evolution at the middle stage of the degradation. The study also revealed that the solution ions failed to permeate the PLGA coating and the deposition of calcium and phosphorus in the degradation layer was inhibited which further enhanced the degradation.

In vivo degradation and tissue compatibility of ZK60 magnesium alloy with micro-arc oxidation coating in a transcortical model.

Magnesium alloys were studied extensively as a class of biodegradable metallic materials for medical applications. In the present study, ZK60 magnesium alloy was considered as a candidate and the micro-arc oxidation (MAO) treatment was adopted in order to reduce the degradation rate of the alloy. The in vivo degradation behaviors and biological compatibilities of ZK60 alloys with and without MAO treatment were studied with a transcortical model in rabbits. The implant and the surrounding bone tissues were characterized by CT, SEM and histological methods at 2, 4 and 12 weeks after the implantation. The results demonstrated that both the bare and MAO-coated ZK60 alloys completely degraded within 12 weeks in this animal model. The MAO coating decreased the degradation rate of ZK60 alloy and enhanced the response of the surrounding tissues within the first 2 weeks. After then, an acceleration of the degradation of the MAO-coated ZK60 alloy was observed. It was found that the alloy could be degraded before the complete degradation of the MAO coating, leading to the local peeling off of the coating. An in vivo degradation mechanism of the MAO-coated ZK60 alloy was proposed based on the experimental results. The severe localized degradation caused by the peeling off of the MAO coating was the main reason for the acceleration of the degradation of the MAO-coated ZK60 alloy.

Effect of hydrion evolution by polylactic-co-glycolic acid coating on degradation rate of pure iron.

For biodegradable iron coronary stents, the major problem is the low degradation rate in body environment. In this study, a new strategy was proposed to increase the degradation rate of iron in vitro. The hydrion evolution was intended to be introduced into the degradation system to increase the degradation rate. To realize this strategy, polylactic-co-glycolic acid (PLGA) was coated onto the surface of pure iron. The degradation process and mechanism of pure iron coated with PLGA were investigated. The results showed that iron coated with PLGA exhibited higher degradation rate in the static immersion test all along. With the degradation of PLGA, the oligomers of PLGA could release abundant H+ which could dissolve the ferrous oxide to make the electrolyte and oxygen to reach the surface of iron again and simultaneity trigger the hydrion evolution at the middle stage of the degradation. The study also revealed that the solution ions failed to permeate the PLGA coating and the deposition of calcium and phosphorus in the degradation layer was inhibited which further enhanced the degradation. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.

Research on super-hydrophobic surface of biodegradable magnesium alloys used for vascular stents.

Micro-nanometer scale structure of nubby clusters overlay was constructed on the surface of an AZ31 magnesium alloy by a wet chemical method. The super-hydrophobicity was achieved with a water contact angle of 142° and a sliding angle of about 5°. The microstructure and composition of the super-hydrophobic surface were characterized by SEM and FTIR. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion behavior, and the hemocompatibility of the super-hydrophobic surface was investigated by means of hemolytic and platelet adhesion tests. Results showed that the super-hydrophobic treatment could improve the corrosion resistance of magnesium alloys in PBS and inhibit blood platelet adhesion on the surface, which implied excellent hemocompatibility with controlled degradation.

[Design and fabrication of the nickel-free stainless steel coronary stent].

A kind of coronary stent was made from Nickel-free stainless steel, and the technological process of the stent was studied. A preferable flexible and support force stent was simulated by a commercial finite element code ANSYS with laser cutting, pickling and vacuum annealing. This kind of coronary stent has more superiority. It was also presented that a self designed automatic stent electro-polishing device, which greatly improve efficiency and quality, and the optimization electro-polishing process was put forward.

Enhanced efficacy of sirolimus-eluting bioabsorbable magnesium alloy stents in the prevention of restenosis.

PURPOSE: To determine the efficacy of sirolimus-eluting bioabsorbable magnesium alloy stents (SEBMAS) in restenosis prevention. METHODS: A balloon-expandable bioabsorbable magnesium alloy stent (BMAS) was created and coated with biodegradable poly(lactic acid-co-trimethylene carbonate) that contained the antiproliferative drug sirolimus (140 ± 40 µg/cm²). Both the uncoated BMAS and the coated SEBMAS were deployed 2 cm apart in balloon-injured infrarenal abdominal aortas of 20 New Zealand white rabbits. The stented aortic segments were removed at 30, 60, 90, and 120 days (5 rabbits per interval) after implantation. The average stent strut sectional area of each group was measured to evaluate the degree of magnesium corrosion and to forecast the biodegradation time profile of the magnesium stent. Histology and histopathology of the sectioned stented aortic segments were performed to evaluate neointima formation, endothelialization, and inflammation. RESULTS: The SEBMAS degraded gradually after being implanted into the rabbit aorta, and total biocorrosion occurred after ~120 days. In all groups, the lumen area was significantly greater, but the neointimal area was significantly smaller in SEBMAS segments compared with the uncoated BMAS segments (p < 0.05) at all time points. There was no significant difference in the injury or inflammation scores between the groups. Endothelialization was delayed at 30 days in the SEBMAS segments vs. the uncoated BMAS segments. CONCLUSION: SEBMAS further reduces intimal hyperplasia and improves the lumen area when compared to uncoated BMAS; however, it delays vascular healing and endothelialization.

Study on compression behavior of porous magnesium used as bone tissue engineering scaffolds.

In this work, porous magnesium (Mg) with a three-dimensional open-cellular structure, potentially employed as bone tissue engineering scaffolds, was fabricated by the mechanical perforation method. The influences of porosity, pore size and pore arrangement on compressive behavior and the anisotropy of new porous Mg were analyzed theoretically using orthogonal arrays and the finite element method (FEM). The results showed that the parameters of porosity, pore size and pore arrangement had different effects on the compressive properties. The compressive strength could be improved by optimizing these parameters. The anisotropy of porous Mg was also verified in this study. The theoretical results showed good agreement with the experimental ones before the strain reaches 0.038.