A review on in vitro corrosion performance test of biodegradable metallic materials

Extensive in vitro corrosion test systems have been carried out to simulate the in vivo corrosion behavior of biodegradable metallic materials. Various methods have their own unique benefits and limitations. The corrosion mechanism of biodegradable alloys and in vitro corrosion test systems on biodegradable metallic materials are reviewed, to build a reasonable simulated in vitro test system for mimicking the in vivo animal test from the aspects of electrolyte solution selection, surface roughness influence, test methods and evaluation methodology of corrosion rate. Buffered simulated body fluid containing similar components to human blood plasma should be applied as electrolyte solution, such as simulated body fluid （SBF） and culture medium with serum. Surface roughness of samples and ratio of solution volume to sample surface area should be adopted based on the real implant situation, and the dynamic corrosion is preferred. As to the evaluation methodology of corrosion rate, different methods may complement one another.

In vitro corrosion behavior and cytotoxicity property of magnesium matrix composite with chitosan coating

Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope(SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low p H values in simulated body fluid(SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.

Cosmetic Safety Evaluation Based on In Vitro Three-dimensional Reconstructed Human Epidermis(3D-RHE) Models

Cosmetic safety evaluation employs a series of toxicological tests, on both qualitative and quantitative levels, to assess the potential risks for the daily use of selected cosmetic ingredients and final products. Traditionally, safety evaluation of cosmetics uses animal tests. With the development of in vitro science and the 3R （Reduction, Replacement and Refinement） principle, three-dimensional reconstructed human epidermis （3D-RHE） models have been developed and widely applied in cosmetic safety evaluation. Reconstructed human skin models possess anatomy and metabolism biology similar to real human tissue. This paper reviews the current application of 3D-RHE models in the safety evaluation of skin irritation, eye irritation, phototoxicity and genotoxicity potential of cosmetic ingredients/formulas. The advantages and disadvantages of using skin models are also discussed, and comments and suggestions are given for its future development.

Study on the Efficacy Claim and Evaluation Method of Lip Cosmetics

To study the efficacy of lip moisturizing cosmetics and explore the methods for evaluating their efficacy.The claimed efficacy and number of claimed efficacy of 44 lip moisturizing cosmetics were investigated,and a combination of in vitro and human testing was used to evaluate the efficacy of the lip moisturizing cosmetics.The efficacy claims of lip cosmetics mainly included 4 categories of moisturizing,repairing,soothing and anti-wrinkle,with 79.55%of the products claiming 3~4 categories of efficacy.In the in vitro test,the cell morphology of the skin damage model improved and the secretion of pro-inflammatory factors decreased significantly.In the human trial,the water content,skin softness and brightness L value of the cuticle of the lips increased significantly in 31 subjects,and the transepidermal water loss,redness a value,and the area and volume of lip wrinkles decreased significantly;the dryness of the lip skin and the uniformity of the skin texture improved significantly.The dryness of lip skin and the uniformity of skin texture were significantly improved.The results show that the moisture content of the stratum corneum can be used to evaluate the moisturizing efficacy of lip products.The transepidermal water loss,skin color,skin softness and expert assessment can be used to evaluate the repairing efficacy.The observation of cell morphology of skin damage models and the detection of pro-inflammatory factor content can be used to evaluate the soothing efficacy.The area and volume of lip wrinkles can be used to evaluate the anti-wrinkle efficacy of products.

Effect of Air Plasma Processing on the Adsorption Behaviour of Bovine Serum Albumin on Spin-Coated PMMA Surfaces

This paper reports the adsorption of Bovine Serum Albumin （BSA） onto Dielectric Barrier Discharge （DBD） processed Poly（methyl methacrylate） （PMMA） surfaces by a Quartz Crystal Microbalance with Dissipation monitoring （QCM-D） technique. The purpose is to study the influence of DBD processing on the nature and scale of BSA adsorption on PMMA surface in vitro. It was observed that DBD processing improves the surface wettability of PMMA film, a fact attributable to the changes in surface chemistry and topography. Exposure of the PMMA to Phosphate Buffed Saline （PBS） solution in the QCM-D system resulted in surface adsorption which reaches an equilibrium after about 30 minutes for pristine PMMA, and 90 minutes for processed PMMA surface. Subsequent injection of BSA in PBS indicated that the protein is immediately adsorbed onto the PMMA surface. It was revealed that adsorption behaviour of BSA on pristine PMMA differs from that on processed PMMA surface. A slower adsorption kinetics was observed for pristine PMMA surface, whilst a quick adsorption kinetics for processed PMMA. Moreover, the dissipation shift of protein adsorption suggested that BSA forms a more rigid structure on pristine PMMA surface that on processed surface. These data suggest that changes in wettability and attendant chemical properties and surface texture of the PMMA surface may play a significant role in BSA adsorption process.

Preoperative evaluation of transcatheter aortic valve replacement with assistance of 3D printing technique:Reanalysis of 4 death cases

Introduction:Transcatheter aortic valve replacement(TAVR)can have some fatal complications during and after the operation.Until recently,pre-procedural imaging with cardiac computed tomography(CT),which is required to evaluate for TAVR,had its own imperfections.We aimed to determine whether 3 D printed models can predict complications when other pre-procedural imaging techniques failed.Methods:Vascular center patients with aortic valve stenosis,who died after TAVR between June 2011 and June2016,were enrolled in this retrospective study.The CT datasets of the patients were imported into a threedimensional(3 D)construction software and then printed by flexible material.To predict complications during and after operations,we designed a release test using the non-valved stent mode that was consistent with the Edwards Sapien XT valve in size and radial support force.Result:The 3 D model predicted the coronary obstruction and annular rupture in the in vitro release process,which was consistent with what happened in the actual operation.Conclusion:Three-dimensional modeling facilitates pre-operative assessment of patients receiving TAVR,with accurate simulation of intraoperative status.

Remediation Effects of Different Concentration of Nano-Hydroxyapatite Level on Pb-Contaminated Soil

Phosphorus-containing amendments can reduce the mobility of Pb in soil. Hydroxyapatite (HAP) is one of the most commonly used phosphorus-containing amendments. With the development of nanotechnology, nano-hydroxyapatie (n-HAP) was gradually applied to remediate soil polluted by heavy metals. Considering the concentrations of HAP/n-HAP were not more than 5% in most studies, soil polluted by Pb was artificially prepared and three different concentrations of n-HAP: 5%, 7% and 10% by weight, were added into the Pb-polluted soil separately. The mixtures of soil and n-HAP were incubated for 180 d and sampled regularly. The bioaccessibility of Pb in soil was determined using simulated gastric juices of two in-vitro digestion tests: USPM (United States Pharmacopeia Methodology) and PBET (Physiologically-Based Extraction Test). The results showed that the immobilizing efficiency of 5% n-HAP to Pb in soil was the highest in PBET. The extractable Pb from soil by USPM was not affected by concentration of n-HAP. So, the least concentration of n-HAP, i.e. 5% n-HAP treatment, was the most cost-effective in USPM. Soil pH increased with concentration of n-HAP. However concentration of n-HAP had little effects on content of soil OM. According to regression analysis, more than 50% differences of the extractable Pb from soil by PBET can be explained by soil pH, while soil pH, organic matter content and incubation time together explained nearly 85% differences of extractable Pb from soil by USPM.

Determination of the Bioaccessibility of Cadmium in Golden Thread by Physiologically Based Extraction Test Digestion Using the in vitro/Caco2 Cell Model and Subsequent Risk Assessment

Background:The ingestion of golden thread contaminated with heavy metals through the food chain leads to detrimental effects to human health.During digestion,not all of the heavy metals could be released to the gastrointestinal tract and readily to be absorbed by human body.Thus,bioaccessibility is an important issue in health risk assessments.Aims and Objectives:The aims and objectives of this study were to investigate the bioaccessibility of Cd in golden thread and assess the associated health risks based on the exposure to bioaccessible Cd.Materials and Methods:Inductively coupled plasma mass spectrometry(ICP-MS)has been applied to determine the Cd content in golden thread.Physiologically based extraction test(PBET)digestion was performed in the in vitro/Caco2 cell model to investigate the bioaccessibility of Cd in golden thread.Furthermore,the target hazard quotient(THQ)was used to assess the risks of the total and the bioaccessible content of Cd in golden thread.Results:The results revealed that the total Cd content in six batches of golden thread ranged from 3.203 to 5.723 mg/kg.After uptake by Caco2 cells,the bioaccessibility of Cd ranged from 42.36%to 59.73%.The results of the risk assessment indicated that prior to uptake by Caco2 cells,the THQ values of Cd for all batches of golden thread were greater than 1.However,after uptake by Caco2 cells,the THQ values of Cd in all samples were less than 1,thus suggesting that the risks were at a safe level.Conclusion:This study was the first to perform health risk assessment with bioaccessible heavy metals present in traditional Chinese medicine by PBET digestion using an in vitro/Caco2 cell model,thus enabling us to obtain more accurate and objective results while allowing us to avoid unnecessary government intervention and to establish more reasonable limit standards for heavy metals.

Novel heart valve leaflet designs with stiff polymeric materials and biomimetic kinematics

Despite continuous efforts to improve the robustness of cardiac valve implants,neither bioprosthetic nor mechanical valves fulfill both hemodynamic and durability requirements.This study discussed novel flexible leaflet designs,focusing on polymeric materials with proven hemocompatibility,such as polyether ether ketone,of much higher stiffness than native tissue,aiming at optimal valve implants.A biomimetic valve with a single-curvature belly-curve(B-C)was used as a reference for new design variants with a double-curvature B-C with varying radii.Soft(13.2 MPa)and stiff(2.4 GPa)leaflet materials and different thicknesses were studied using lean simulations and in vitro experiments under physiologic hemodynamic conditions.The performance was assessed using opening pressure(OP)and orifice area(OA).The latter was determined by a newly developed automatized image processing tool.Experimental trends are in agreement with simulations and demonstrated that a buckling-inspired double-curvature leaflet design significantly enhances the trileaflet valve opening behavior,which is particularly advantageous for stiffer leaflet materials.Compared to the reference,the best-performing variant showed an OP improvement of 47%and 44%based on simulations and experiments,respectively.In contrast,the achieved mean pressure differential was directly comparable to state-of-the-art bioprosthetic valves.The OA was slightly reduced for new variants but still in the satisfying range.

A dual-axis chewing simulator for in vitro wear test of dental restoration materials

The wear rate of dental restoration materials on fixed, removable, and implant prostheses is important in the maintenance of cuspate form, masticatory efficiency and occlusal stability. Many permanent restoration materials such as composite, amalgam, gold, or porcelain show enough resistance to wear, but the wear rates of newly developed materials are generally unknown. To evaluate the wear rate of these dental materials, in vivo (clinic) and in vitro methods can be used. Since in vivo investigations are expensive, time consuming, and difficult to standardize, various in vitro methods have been developed. The use of a chewing machine is considered the best method, because a variety of wear mechanisms, temperature changes, and chemical effects of food and drink can be simulated simultaneously. This paper describes a dual axis chewing simulator for in vitro wear test of dental restoration materials. It consists of 8 test chambers, two stepper motors and related mechanism, a hot and cool water circle system, and a control unit. In the chambers, samples and antagonists make chewing movements vertically and Albert Ludwigs University, School of dentistry, Freiburg, Germany (Lü XY, Kern M and Strub JR) horizontally driven by the stepper motors so that the gnashing and slippage of two teeth against each other is simulated. A weighted test object is programmed to collide with a sample under precise operator control. The antagonists strike against the samples at various speeds from a slow nudge to snapping. Sample holders are designed for installation of varying samples, from single teeth to complete dentures. Two baths, six valves, and a group of pipes are used for the thermocycling. The machine can simulate various chewing modes in the mouth, including fully programmable thermal water cycling between 5℃ and 60℃ The control unit consists of a computer system with a built in specific program. Important operations such as “Start”, “Zero point”, and “Stop” are carried out by pressing the function keys on the front board of the unit. During the programming process and the simulation, several test modes and relevant test parameters are shown on the monitor. The control unit is connected via a series of interfaces to different controlled parts of the machine, such as the stepper motors and the pumps of cool and warm water.

Study of Aldo-keto Reductase 1C3 Inhibitor with Novel Framework for Treating Leukaemia Based on Virtual Screening and In vitro Biological Activity Testing

Aldo-keto reductase 1C3(AKR1C3)is a potential target for the treatment of acute myeloid leukaemia and T-cell acute lymphoblastic leukaemia.In this study,pharmacophore models,molecular docking and virtual screening of target prediction were used to find a potential AKR1C3 inhibitor.Firstly,eight bacteriocin derivatives(Z1-Z8)were selected as training sets to construct 20 pharmacophore models.The best pharmacophore model MODEL_016 was obtained by Decoy test(the enrichment degree was 21.5117,and the fitting optimisation degree was 0.9668).Secondly,MODEL_016 was used for the virtual screening of ZINC database.Thirdly,the hit 83256 molecules were docked into the AKR1C3 protein.Compared to the total scores and interactions between compounds and protein,16532 candidate compounds with higher docking scores and interactions with important residues PHE306 and TRP227 were screened.Lastly,eight compounds(A1-A8)that had good absorption,distribution,metabolism,excretion and toxicity(ADMET)properties were obtained by target prediction.Compounds A3 and A7 with high total score and good target prediction results were selected for in vitro biological activity test,whose IC_(50) values were 268.3 and 88.94µmol/L,respectively.The results provide an important foundation for the discovery of novel AKR1C3 inhibitors.The research methods used in this study can also provide important references for the research and development of new drugs.

Optimization of an in vitro method to measure the bioaccessibility of polybrominated diphenyl ethers in dust using response surface methodology

To more reasonably evaluate human intake of PBDEs via dust ingestion, bioaccessibility should be taken into account. Previously, we developed an in vitro method to determine the bioaccessibility of PBDEs in food. Here, this method was adapted to determine the bioaccessibility of PBDEs in dust and the digestion conditions that influenced the bioaccessibility of PBDEs were optimized. The digestion conditions included the incubation time of dust in the intestinal digestion solution （T）, the bile concentration in the intestinal digestion solution （Chile）, and the ratio of the volume of the intestinal digestion solution to dust （R）. The influence of the concentrations of individual PBDE congeners （CpBDE） on the bioaccessibility of PBDEs was also investigated. Cetral composite design was used to build an experimental model and set experimental parameters, and response surface methodology was used to analyze the obtained data. The results showed that the bioaccessibility of PBDEs increased with the increases of Chile and R, and was independent of T and CpSDE. Under the digestion conditions with Chile and R being at 4.0-7.0 g/L and 150-250, respectively, the bioaccessibility of PBDEs in the method-dust varied from 39.2% to 72.8%, which were comparable with the bioaccessibility or bioavailability of PBDEs in dust/soil in the literature. Thus, the in vitro method to measure the bioaccessibility of PBDEs in dust was established and validated. Finally, the bioaccessibility of PBDEs in four natural dust samples, which ranged from 36.1% to 43.3%, were determined using the adapted method.

In Vivo and In Vitro Degradation Behavior of Magnesium Alloys as Biomaterials

The corrosion behavior of pure Mg,AZ31,and AZ91D were evaluated in various in vitro and in vivo environments to investigate the potential application of these metals as biodegradable implant materials.DC polarization tests and immersion tests were performed in different simulated body solutions,such as distilled（DI） water,simulated body fluid（SBF） and phosphate buffered solution（PBS）.Mg/Mg alloys were also implanted in different places in a mouse for in vivo weight loss and biocompatibility investigations.The in vivo subcutis bio-corrosion rate was lower than the corrosion rate for all of the in vitro simulated corrosive environments.The Mg/Mg alloys were biocompatible based on histology results for the liver,heart,kidney,skin and lung of the mouse during the two months implantation.Optical microscopy and scanning electron microscopy were carried out to investigate the morphology and topography of Mg/Mg alloys after immersion testing and implantation to understand the corrosion mechanisms.

Comparison of dissolution profile characteristics of 11 berberine hydrochloride tablet brands in different dissolution media

Berberine hydrochloride is commonly used to treat bacterial dysentery,gastroenteritis and other diseases.Many manufacturers are available on the market today,while the production process and formulation are quite different,which may directly affect the therapeutic effect of the drug.To this end,11 different production producers of berberine hydrochloride tablets were collected according to the pharmacopeia berberine hydrochloride dissolution method(basket method).In addition the dissolution process was carried out in four elution media with different pH,and the difference was similar(f2).Factors were calculated to evaluate in vitro dissolution requirements,and in vitro dissolution of different manufacturers of berberine hydrochloride tablets was determined by high performance liquid chromatography(HPLC).The method was verified by linearity,precision,stability and robustness.Based on the f2 value,there was a significant difference in the dissolution behavior of the formulations of most berberine hydrochloride tablet brands.This research provided the basis for further in-depth research in the later period.Although the drug specifications(0.1 g)were the same,the dissolution curve was different.This phenomenon may be attributed to the fact that the excipients and crystal form of the tablets affected the release and dissolution of the tablets in vitro.

Overall Blastocyst Quality, Trophectoderm Grade, and Inner Cell Mass Grade Predict Pregnancy Outcome in Euploid Blastocyst Transfer Cycles

Background： Despite recent advances that have improved the pregnancy success rates that can be achieved via in vitro fertilization （IVF） therapy, it is not yet clear which blastocyst morphological paralneters best predict the outcomes of single blastocyst transfer. In addition. most of the previous studies did not exclude the effect of embryo aneuploidy on blastocysts transfer. Thus, the present study investigated the predictive value of various parameters on the pregnancy outcomes achieved via the transfer of frozcn euploid blastocysts. Methods： The study retrospectively analyzed 914 single euploid blastocyst transfer cycles that were performed at the Peking U laivcrsity Third Hospital Reproductive Medical Center between June 2011 and May 2016. The expansion, trophectoderm （TE）. and inner cell mass （ICM） quality of the blastocysts were assessed based on blastocyst parameters, and used to differentiate between ＂excellent＂, ＂good＂, ＂average＂, and ＂poor＂-quality embryos. The relationship between these embryo grades and the achieved pregnancy outcomes was then analyzed via the Chi-square and logistic regression tests. Results： For embryo grades of excellent, good, average and poor, the clinical pregnancy rates were 65.0%. 50.3%, 50.3% and 33.3%. respectively; and the live-birth rates were 50.0%, 49.7%, 42.3% and 25.0%, respectively. Both the clinical pregnancy ratc （x2= 21.28. P = 0.001） and live-birth rate （x2 = 13.50, P 〈 0.001） increased with the overall blastocyst grade. Both rates were significanlly higher after the transfer era blastocyst that exhibited either an A-grade or B-grade TE, and similarly, an A-grade ICM. than after the transfer el a blastocyst that exhibited a C-grade TE and/or ICM. The degree of blastocysl expansion had no apparent effect on the clinical pregnancy or live-birth rate. All odds ratio were adjusted for patient age, body mass index, length （years） of infertility history, and infertility type. Conclusions： A higher overall euploid blastocyst quality is shown to correlate most strongly with optimal pregnancy outcomes. The study thus supports the use of the described TE and ICM morphological grades to augment current embryo selection criteria.

Clinical Observations on 206 Cases with Lower Limb Deep Venous Thrombosis Treated by Integrated Traditional Chinese and Western Medicine

Objective: To study the pathogenetic mechanism of integrated traditional Chinese and Western medicine in treating lower limb deep venous thrombosis (DVT). Methods: Thrombosis test in vitro of 206 cases with lower limb DVT was measured. All of them were treated by integrated traditional Chinese and Western medicine. Results: The indexes of thrombosis test in vitro of patients were much higher than those of normal subjects (P < 0. 001 ). The relevent indexes were different in type distribution according to differentiation of symptoms and signs (P < 0. 01 - 0. 001 ) and between pre-treatment and post-treatment (P < 0. 001 ). It showed that hypercoagulability of blood occurred even after DVT took place. Changes of indexes, when after treatment they got lower along with improvement in the state of illness, might be objective parameters for Syndrome Differentiation in traditional Chinese medicine. Conclusions: The therapy of traditional Chinese and Western medicine has good efficacy for DVT.

A review on food oral tribology

Food entering the oral cavity undergoes a series of complex processing behaviors.It is subjected to compression and shearing by the teeth,tongue,and palate to reduce its size and mix with saliva until it is swallowed.The oral processing behaviors are thought to be closely related to both food and oral frictional properties.Much effort has been made in recent decades about food oral tribology to explore this complicated lubrication behavior.Understanding the lubrication mechanism of food in the mouth is important for improving the consumption experience and developing the novel food.This paper provides a new perspective on the effects of composition,texture,structure,and saliva-food component interactions on lubrication properties of different foods,the relationship between sensory perception and oral frictional behavior,and the mechanism and pattern of lubrication categorized by common food types.The roles of tribology in the improvement of food taste,the search for healthier ingredient substitutes,functional foods,and the development of green foods are analyzed.Conceptual and numerical prediction models among physical properties,sensory perception,and frictional behavior of food are discussed.Studies of simulating oral processing,such as the selection of friction pair materials,physical modification of contact surfaces,addition of saliva,different modes of motion,and contact forms are concluded and classified.The progress of commercial friction apparatus as well as customized friction devices applied to the food sector in recent years are described.The characteristics,performances,and applications of these tribological instruments are analyzed and compared.In addition,the results achieved by oral tribology in identifying adulterated foods and ensuring food safety are presented.Finally,some suggestions are put forward for the current challenges and future development of food oral tribology.