Novel THTPBA/PEG‐derived highly branched polyurethane scaffolds with improved mechanical property and biocompatibility

Highly branched polyurethane (PU) scaffolds that match mechanical properties are the preferred tissue engineering materials, which is composed of a multi‐hydroxyl‐terminated poly(butadiene‐co‐acrylonitrile) (THTPBA) prepolymer and poly(ethylene glycol) (PEG) via 1,6‐hexamethylene diisocyanate as anchor molecule. This combination is anticipated to influence or alter hydrophilicity or hydrophobicity, degradation and haemocompatibility of the PEG‐derived PUs. Hence, the surface properties, degradability, mechanical and biomedical properties of the PUs were scrutinized and assessed by FTIR, contact angles, gravimetry, stress‐strain measurement and haemolysis, platelet adhesion as well as methyl tretrazolium (MTT) assays. The experimental results indicated that the incorporation of THTPBA can mediate the degradation rate, which took place at the urethane or ester bonds in polymer chains. The haemolytic activity, platelet activation, and MTT investigations elicited that the component ratios of THTPBA to PEG had important influence on biomedical properties, including in vitro blood compatibility, cytotoxicity, and cell cycle or apoptosis of the PU scaffolds. The tensile stress‐strain investigations showed that the highly branched architecture offered high elastic modulus and mechanical strength. The novel PU scaffolds with highly branched architecture exhibited improved mechanical properties and biocompatibility as well as low toxicity by regulating proper component ratios, and are expected to be employed in tissue engineering, or as potential candidates for other blood‐contacting applications. Copyright © 2011 John Wiley & Sons, Ltd.     

In vitro and in vivo metabolism studies of dimethazine

The use of anabolic steroids is prohibited in sports. Effective control is done by monitoring their metabolites in urine samples collected from athletes. Ethical objections however restrict the use of designer steroids in human administration studies. To overcome these problems alternative in vitro and in vivo models were developed to identify metabolites and to assure a fast response by anti‐doping laboratories to evolutions on the steroid market. In this study human liver microsomes and an uPA^+/+‐SCID chimeric mouse model were used to elucidate the metabolism of a steroid product called ‘Xtreme DMZ’. This product contains the designer steroid dimethazine (DMZ), which consists of two methasterone molecules linked by an azine group. In the performed stability study, degradation from dimethazine to methasterone was observed. By a combination of LC‐High Resolution Mass Spectrometry (HRMS) and GC‐MS(/MS) analysis methasterone and six other dimethazine metabolites (M1–M6), which are all methasterone metabolites, could be detected besides the parent compound in both models. The phase II metabolism of dimethazine was also investigated in the mouse urine samples. Only metabolites M1 and M2 were exclusively detected in the glucuro‐conjugated fraction; all other compounds were also found in the free fraction. For effective control of DMZ misuse in doping control samples, screening for methasterone and methasterone metabolites should be sufficient. Copyright © 2016 John Wiley & Sons, Ltd.     

Intestinal metabolism of Polygonum cuspidatum in vitro and in vivo

Rhizoma et Radix Polygoni Cuspidati (RRPC) is commonly prescribed for the treatment of amenorrhea, arthralgia, jaundice and abscess in traditional Chinese medicine. Previous pharmacological studies have indicated that polyphenols are the main pharmacological active ingredients in RRPC. Meanwhile, the poor bioavailability of polyphenols in RRPC implies that those components are probably metabolized by intestinal bacteria before absorption. However, there is rather limited information about RRPC''s metabolites produced by intestinal bacteria and the intestinal absorbed constituents. In the present study, the metabolites were characterized after the aqueous extract of RRPC was incubated with the crude enzyme of human intestinal bacteria in vitro. The metabolic characteristics of glycosides in RRPC were figured out by comparing the metabolic profiles of emodin‐8‐O‐β‐d ‐glucopyranoside and polydatin between aqueous extract of RRPC and equivalent amounts of these two glycosides. The transitional constituents absorbed into blood were investigated in rats via intraduodental administration and portal vein intubation. A total of 38 prototype components and 43 metabolites were detected and characterized in vivo. The overall results demonstrated that the intestinal bacteria played an important role in the metabolism of RRPC, and the main metabolic pathways were hydrolysis in vitro, glucuronidation and sulfation in vivo.     

Fibers and 3D mesh scaffolds from biodegradable starch-based blends: production and characterization

The aim of this work is the production of fibers from biodegradable polymers to obtain 3D scaffolds for tissue engineering of hard tissues. The scaffolds required for this highly demanding application need to have, as well as the biological and mechanical characteristics, a high degree of porosity with suitable dimensions for cell seeding and proliferation. Furthermore, the open cell porosity should have adequate interconnectivity for a continuous flow of nutrients and outflow of cell metabolic residues as well as to allow cell growth into confluent layers. Blends of corn starch, a natural biodegradable polymer, with other synthetic polymers (poly(ethylene vinyl alcohol), poly(epsilon-caprolactone), poly(lactic acid)) were selected for this work because of their good balance of properties, namely biocompatibility, processability and mechanical properties. Melt spinning was used to produce fibers from all the blends and 3D meshes from one of the starch-poly(lactic acid) blends. The experimental characterization included the evaluation of the tensile mechanical properties and thermal properties of the fibers and the compression stiffness, porosity and degradation behavior of the 3D meshes. Light microscopy picture of 3D meshes.     

体内和体外生物测定在环境监测中的应用

生物测定在环境毒物学研究中普遍用于检测人为污染物对个别生物体和生态系统的影响.这些测定适用于个别化学品或复杂的混合物(如废水)对有代表性的生物系统或整个生物体所引起的影响,并普遍应用于环境监测项目.生物测定可在生物体外或生物体内进行,前者是在实验室内利用细胞培养技术,后者除可在实验室内进行还可应用在真实的环境中.体外生物测定往往是用来研究环境样品中的污染物对生物机制的具体影响,如受体结合特性.而体内活性生物测定则提供了一个更加具体化的综合生物反应.然而,这两种类型的生物测定法可以测量许多不同的生物指标,如对生物生长及发育的影响、内分泌功能和DNA损伤.无论是在体内和体外生物测定都分别有其特有的优点和缺点,其中一些测定法可以使用于毒性鉴定和评价程序.本文简要介绍了体内和体外生物测定方法的基本特点及其在环境监测中的应用实例,指出化学物质如何影响有机体及生态系统的结构和功能,认为广泛发展更能充分反映生态系统生物多样性的生物测定方法,将有助于更准确地了解环境污染物对环境的潜在影响.     

Identification and characterization of in vitro and in vivo fidarestat metabolites: Toxicity and efficacy evaluation of metabolites

The progression of diabetic complications can be prevented by inhibition of aldose reductase and fidarestat considered to be highly potent. To date, metabolites of the fidarestat, toxicity, and efficacy are unknown. Therefore, the present study on characterization of hitherto unknown in vitro and in vivo metabolites of fidarestat using liquid chromatography–electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS) is undertaken. In vitro and in vivo metabolites of fidarestat have been identified and characterized by using LC/ESI/MS/MS and accurate mass measurements. To identify in vivo metabolites, plasma, urine, and feces samples were collected after oral administration of fidarestat to Sprague–Dawley rats, whereas for in vitro metabolites, fidarestat was incubated in human S9 fraction, human liver microsomes, and rat liver microsomes. Furthermore, in silico toxicity and efficacy of the identified metabolites were evaluated. Eighteen metabolites have been identified. The main in vitro phase I metabolites of fidarestat are oxidative deamination, oxidative deamination and hydroxylation, reductive defluroniation, and trihydroxylation. Phase II metabolites are methylation, acetylation, glycosylation, cysteamination, and glucuronidation. Docking studies suggest that oxidative deaminated metabolite has better docking energy and conformation that keeps consensus with fidarestat whereas the rest of the metabolites do not give satisfactory results. Aldose reductase activity has been determined for oxidative deaminated metabolite (F‐1), and it shows an IC50 value of 0.44 μM. The major metabolite, oxidative deaminated, did not show any cytotoxicity in H9C2, HEK, HEPG2, and Panc1 cell lines. However, in silico toxicity, the predication result showed toxicity in skin irritation and ocular irritancy SEV/MOD versus MLD/NON (v5.1) model for fidarestat and its all metabolites. In drug discovery and development research, it is distinctly the case that the potential for pharmacologically active metabolites must be considered. Thus, the active metabolites of fidarestat may have an advantage as drug candidates as many drugs were initially observed as metabolites.     

Mechanical and dielectric properties of segmented polyurethane elastomers containing chemical crosslinks in the hard segment

Mechanical and dielectric properties of two series of segmented polyurethanes having soft segment concentration of 50 and 70% and a varying degree of crosslinking through the hard segment were studied. The degree of crosslinking in each series was varied by varying the butane diol/trimethylol propane ratio in the chain extender mixture. Tensile strength, elongation at break decrease, but elastic recovery increases monotonically with increasing crosslinking. The plateau modulus in the dynamic mechanical test decreases and then increases with increasing TMP content. Crosslinking causes broadening of the soft segment glass transition as seen by permittivity and loss factor measurements. It also affects high temperature behavior (above the glass transition of the hard segment); it lowers permittivity, loss factor, and ionic conductivity. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 237–251, 1998     

In vitro metabolism studies of desoxy‐methyltestosterone (DMT) and its five analogues,and in vivo metabolism of desoxy‐vinyltestosterone (DVT) in horses

The positive findings of norbolethone in 2002 and tetrahydrogestrinone in 2003 in human athlete samples confirmed that designer steroids were indeed being abused in human sports. In 2005, an addition to the family of designer steroids called ‘Madol’ [also known as desoxy‐methyltestosterone ( DMT )] was seized by government officials at the US–Canadian border. Two years later, a positive finding of DMT was reported in a mixed martial arts athlete's sample. It is not uncommon that doping agents used in human sports would likewise be abused in equine sports. Designer steroids would, therefore, pose a similar threat to the horseracing and equestrian communities. This paper describes the in vitro metabolism studies of DMT and five of its structural analogues with different substituents at the 17α position (R ? H, ethyl, vinyl, ethynyl and ²H₃‐methyl). In addition, the in vivo metabolism of desoxy‐vinyltestosterone ( DVT ) in horses will be presented. The in vitro studies revealed that the metabolic pathways of DMT and its analogues occurred predominantly in the A‐ring by way of a combination of enone formation, hydroxylation and reduction. Additional biotransformation involving hydroxylation of the 17α‐alkyl group was also observed for DMT and some of its analogues. The oral administration experiment revealed that DVT was extensively metabolised and the parent drug was not detected in urine. Two in vivo metabolites, derived respectively from (1) hydroxylation of the A‐ring and (2) di‐hydroxylation together with A‐ring double‐bond reduction, could be detected in urine up to a maximum of 46 h after administration. Another in vivo metabolite, derived from hydroxylation of the A‐ring with additional double‐bond reduction and di‐hydroxylation of the 17α‐vinyl group, could be detected in urine up to a maximum of 70 h post‐administration. All in vivo metabolites were excreted mainly as glucuronides and were also detected in the in vitro studies. Copyright © 2015 John Wiley & Sons, Ltd.     

In vitro and in vivo degradation behavior of aqueous-derived electrospun silk fibroin scaffolds

We investigated the in vitro degradation behavior of the electrospun silk fibroin (SF) scaffolds by protease XIV. Phosphate-buffered saline (PBS) without enzyme was used as a control. About 65% of the electrospun SF scaffolds were degraded within 24 d in protease XIV, while almost no scaffolds were degraded in PBS. A great deal of fragments was visible in protease XIV solution. SEM indicated surface erosion of the scaffolds increased during protease degradation with increasing exposure time. FTIR and XRD indicated the crystalline structure of the scaffolds decreased after protease degradation for 24 d, and a degradation mechanism was proposed. Furthermore, the results of the in vivo degradation by implantation in rats showed that the scaffolds were completely degraded in vivo after implantation for 8 weeks and well tolerated by the host animals. The insights gained in this study can serve as a guide to match desired degradation behavior with specific applications for the electrospun SF scaffolds, such as tissue engineering and drug delivery.     

Molecular mechanism of Xiaohuoluo wan for rheumatoid arthritis by integrating in vitro and in vivo chemomics and network pharmacology

The cause of rheumatoid arthritis (RA) is unclear. Xiaohuoluo wan (XHLW) is a classical Chinese medicine that is particularly effective in the treatment of RA. Given the chemical composition of XHLW at the overall level has been little studied and the molecular mechanism for the treatment of RA is not clear, we searched for the potential active compounds of XHLW and explored their anti-inflammatory mechanism in the treatment of RA by flexibly integrating the high-resolution ultra-performance liquid chromatography–mass spectrometry (UPLC–MS)-based in vitro and in vivo chemomics, network pharmacology, and other means. The results of the study identified that the active compounds of XHLW, such as alkaloids, nucleosides, and fatty acids, may play an anti-inflammatory role by regulating key targets such as IL-2, STAT1, JAK3, and MAPK8, inducing immune response through IL-17 signaling pathway, T-cell receptor, FoxO, tumor necrosis factor (TNF), and so forth, inhibiting the release of inflammatory factors and resisting oxidative stress and other pathways to treat RA. The results of this study provide referable data for the screening of active compounds and the exploration of molecular mechanisms of XHLW in the treatment of RA.     

鼠肝星状细胞体内与体外激活的显微拉曼光谱

采用密度梯度离心法从肝组织中分离、提纯肝星状细胞, 进行常规细胞鉴定后, 通过体外培养诱导肝星状细胞体外活化, 在不同的时间点上进行原位拉曼光谱表征; 通过一次性腹腔注射CCl4诱导鼠急性肝损伤, 取不同的时间点的肝损伤组织做拉曼光谱表征, 并以肝组织的光谱变化来间接反映肝星状细胞的体内活化. 结果表明, 用拉曼光谱能快速、 灵敏地监测肝星状细胞体内和体外活化过程中的分子变化, 可为肝纤维化的早期诊断提供依据.     

Degradation behaviors of nerve guidance conduits made up of silk fibroin in vitro and in vivo

We have developed a new design of nerve guidance conduits (NGCs) made up of silk fibroin (SF), referred to as SF-NGCs, by a well-established method. The present study aimed to comprehensively investigate the degradation behaviors of SF-NGCs versus SF fibers. After they were allowed to incubate in the protease XIV solution or to be subcutaneously implanted in rabbits, SF-NGCs and SF fibers were subjected to degradation level measurement, mass loss assessment and gel electrophoresis, or light and electron microscopy and mass loss assessment for testing the dynamic course of in vitro or in vivo degradation. The results collectively indicated that SF-NGCs were able to degrade at a significantly increasing rate as compared to SF fibers, thus meeting the requirements of peripheral nerve regeneration. Furthermore, based on the possible involvement pathway in the in vivo degradation of SF-NGCs, the time-dependent changes in the mRNA level of lysosome-related genes (Hip1R, cathepsin D, and tPA) in subcutaneous implantation site within 24-week period post-implantation was determined by real-time RT-PCR, and the resulting data might contribute to our understanding of the molecular aspects that affect in vivo degradation and absorption of SF-NGCs.     

Modification of collagen-chitosan membrane by oxidation sodium alginate and in vivo/ in vitro evaluation for wound dressing application

Collagen-chitosan (COL-CS) membranes materials without a cross-linking agent have poor mechanical properties. In this paper, COL-CS membranes were modified by a novel naturally-derived crosslinker, alginate dialdehyde (ADA) with different oxidation degree, and the COL-CS-ADA films were obtained. COL-CS-ADA films were characterized by Fourier transform attenuation total reflection infrared spectroscopy (ATR-FTIR), differential calorimetric scanning (DSC), thermogravimetric analysis (TG), tensile testing, and cross-link density testing. The modification of ADA exhibited positive effects on mechanical properties, the thermal stability of COL-CS membranes. The cross-linking degree between ADA and COL-CS membranes increased significantly with an increase in the oxidation degree. COL-CS-ADA films showed no cytotoxicity toward L929 fibroblasts and had good biocompatibility. The animal experiments showed that COL-CS-ADA film could promote wound healing.     

In vitro and in vivo degradation of an injectable bone repair composite

In vitro and in vivo degradation behaviors of an injectable bone regeneration composite (IBRC) which comprised of nano-hydroxyapatite/collagen (nHAC) particles in alginate hydrogel carrier were investigated. In vitro degradation quantitative testing indicated that the alginate had a faster degradation rate in simulated body fluid (SBF) than in deionized water at 37 °C. Similarly, IBRC also had a higher degradation rate in SBF than in deionized water at 37 °C, which was evaluated by alginate molecular weight measurement, mechanical properties test and degradation kinetics evaluation. But molecular weight of alginate degraded slower in IBRC than that in aqueous solution. In vitro results showed that degradation medium SBF had influence on degradation of alginate molecules. In the in vivo degradation study, surprisingly, there was no obvious decreasing of molecular weight of alginate from 0 to 8 weeks. IBRC degraded mostly after 24 weeks implantation and was replaced by connective tissue. No fibrous capsule and acute inflammatory reaction were found during the observed 24 weeks after IBRC implantation. There is only a mild short-term inflammatory response in rat dorsum muscle. These results indicated that IBRC had a controllable degradability and biocompatibility. Therefore, IBRC may be a promising degradable material for bone repair and bone tissue engineering.     

Poly(D,L-lactide)-block-poly(2-hydroxyethyl acrylate) block copolymers as potential biomaterials for peripheral nerve repair: in vitro and in vivo degradation studies

The properties of poly(D ,L ‐lactide)‐block‐poly(2‐hydroxyethyl acrylate) (PLA‐b‐PHEA) block copolymers by means of in vitro / in vivo (rat) degradation are investigated and compared to those of PLA homopolymer. Over 12 weeks, we observe mass loss and molecular weight decrease. In vitro and in vivo findings are very similar for each polymer tested. When a short PHEA block is used (PLA‐b‐PHEA 15 000–3 000 g · mol^?1, 85/15 wt%), the degradation process is found to be very similar to that of homo‐PLA, and to be typical of a bulk erosion mechanism, with no mass loss observed until week 7 and continuous decrease of molar mass within this timeframe. For a longer PHEA block length within the block copolymer (PLA‐b‐PHEA 15 000–7 500 g · mol^?1, 65/35 wt%), the degradation mechanism is modified, with a significant mass loss observed at early times and only a slight decrease in molar mass. The latter finding is related to the pronounced hydrophilicity and softness of the material induced by the PHEA block, which allow easy diffusion and rapid leakage of the degradation residues from the material towards the aqueous medium. Schwann cells are found to better adhere on spin‐coated films of PLA‐b‐PHEA (85/15 wt%) than on PLA ones. These results show the potential of such hydrophilized PLA‐based copolymers for use in peripheral nerve repair.

     

Structure and physical properties of segmented polyurethane elastomers containing chemical crosslinks in the hard segment

Two series of segmented polyurethanes, one containing 50% soft segments and the other with 70% soft segments were synthesized. Chemical crosslinks were introduced through the hard segment in a controlled way. Chemical polyurethane networks were characterized by swelling. The effect of the degree of crosslinking on properties was examined. It was found that chemical crosslinks in the hard segment reduce the mobility of the soft phase and destroy the crystallinity of the hard phase, but they improve heat stability of the hard domains. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 221–235, 1998     

Rheological and mechanical properties of epoxy/polyurethane blends initiated by N‐benzylpyrazinium hexafluoroantimonate salt

In this work the cure behavior and rheological and mechanical interfacial properties of the diglycidylether of bisphenol A (DGEBA)/polyurethane (PU) blend system, initiated by 1 wt % N‐benzylpyrazinium hexafluoroantimonate as a latent thermal catalyst, were investigated. To characterize the mechanical interfacial properties of the system, the critical stress intensity factor (K_IC) was calculated with a single‐edge‐notched beam (SEN) beam fracture toughness test. And an impact test was performed at room and cryogenic temperatures to determine the performance of PU at room and low‐temperatures, respectively. As a result, the E_c of the blend system was increased with increasing PU content, showing a maximum value at 30 wt % PU, which was in good agreement with the mechanical properties of the blend system. Consequently, these results could be explained by the improvement that occurred in intermolecular hydrogen bonding between the hydroxyl group in EP and the isocyanate group in PU, resulting in increased compatibility of the components within the interpenetrating polymer networks. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3841–3848, 2004     

The in vitro and in vivo toxicity of gold nanoparticles

Gold nanoparticles,owing to their unique physicochemical and optical properties,well-established synthetic methods and easy modifications,have been widely used in biomedical science.Therefore,for their safe and efficient applications,much attention has been given to the toxicological evaluations of gold nanoparticles in biological systems.A large number of studies focusing on this problem have been carried out during the past years.However,the researches on gold nanoparticles toxicity still remain fragmentary and even contradictory with each other.This may be caused by the variety in experimental conditions.In this review,we aim to provide a better understanding about the in vitro and in vivo toxicity of gold nanoparticles by reviewing and describing the up to date literatures related to this problem and we mainly focused on these properties such as the particle size and shape,the surface charge and modification.Besides,we also summarized the adverse effect of gold nanoparticles on immune systems and analyzed the origin of the toxicity.     

低左旋度聚丙交酯的分子结构及体外降解行为研究

以辛酸亚锡为催化剂,135℃下低左旋度的l-丙交酯([a]_(Na)~(25)=—231°)开环聚合制备了低左旋度聚(l-丙交酯)[l-PLLA]([a]_(CHCl_3)~(25)=-119.7°),并用同核去偶~1H-NMR谱表征其分子链结构。用成纤模压法制备了该聚合物的棒材(φ=3.2mm)试样,研究了其在37℃的模拟体液(SBF)中的降解行为。结果表明,l-PLLA具有良好的力学性能,其初始弯曲强度(σ_b)、剪切强度(σ_s)以及弯曲模量(E_b)虽比聚(l-丙交酯)(PLLA)低,但均比聚(dl-丙交酯)(PDLLA)高得多,且材料表现出很好的韧性,呈非晶态,其分子量下降速率和失重速率都介于PLLA和PDLLA之间,可望是一种良好的骨折内固定材料。     

Fabrication of open‐porous PCL/PLA tissue engineering scaffolds and the relationship of foaming process,morphology, and mechanical behavior

Tissue engineering scaffolds should provide a suitable porous structure and proper mechanical strength, which is beneficial for the delivery of growth factor and regulation of cells. In this study, the open‐porous polycaprolactone (PCL)/poly (lactic acid) (PLA) tissue engineering scaffolds with suitable porous scale were fabricated using different ratios of PCL/PLA blends. At the same time, the relationship of foaming process, morphology, and mechanical behavior in the optimized batch microcellular foaming process were studied based on the single‐factor experiment method. The porous structures and mechanical strength of the scaffolds were optimized by adjusting foaming parameters, including the temperature, pressure, and CO₂ dissolution time. The results indicated that the foaming parameters influence the cell morphology, further determine the mechanical behavior of PCL/PLA blends. When the PCL content is high, with the increase of temperature and time, the cell diameter and the elastic modulus increased, and the tensile strength and elastic modulus increased with the increase of the average cell size, and decreased as the increase of the cell density. While when the PLA content was high, the cell diameter showed the same trend, and the tensile strength and elastic modulus were higher, and the elongation at break was lower, and tensile strength and elastic modulus decreased with the increase of the average cell size and increased with the increase of cell density. This work successfully fabricated optimized porous PCL/PLA scaffolds with excellent suitable mechanical properties, pore sizes, and high interconnectivity, indicating the effectiveness of modulating the batch foaming process parameters.