Didymin protects against polystyrene nanoplastic-induced hepatic damage in male albino rats by modulation of Nrf-2/Keap-1 pathway

Polystyrene nanoplastics (PS-NPs) are ubiquitous environmental pollutants that can cause oxidative stress in various organs, including the liver. Didymin is a dietary flavanone that displays multiple pharmacological activities. Therefore, the present study evaluated the palliative role of didymin against PS-NPs-induced hepatic damage in rats. Albino rats (n=48) were randomly distributed into 4 groups: control, PS-NPs treated group, PS-NPs + didymin co-administered group, and didymin supplemented group. After 30 days, PS-NPs intoxication lowered the expression of Nrf-2 and anti-oxidant genes [catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GSR), glutathione-S-transferase (GST), and heme oxygenase-1 (HO-1)], whereas the expression of KEAP1 kelch like ECH associated protein 1 (Keap-1) was increased. PS-NPs exposure also reduced the activities of anti-oxidants enzymes (CAT, SOD, GPx, GSR, GST, GSH, and OH-1), while malondialdehyde (MDA) and reactive oxygen species (ROS) levels were increased. The levels of alanine transaminase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were increased in PS-NPs-exposed rats. Moreover, inflammatory indices [interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), nuclear factor-kappa B (NF-κB), and cyclooxygenase-2 (COX-2)] were increased in PS-NPs-exposed rats. Furthermore, PS-NPs intoxication increased the expressions of apoptotic markers including Bax and Caspase-3, as well as reducing Bcl-2 expression. The histopathological analysis showed significant damage in PS-NPs-treated rats. However, didymin supplementation ameliorated all the PS-NPs-induced damage in the liver of rats. Therefore, it was concluded that didymin can act as a remedy against PS-NPs-induced liver toxicity due to its anti-apoptotic, anti-oxidant, and anti-inflammatory activities.

Biological effects and toxicity mechanisms of polystyrene nanoplastics: A review / 环境与职业医学

Polystyrene nanoplastics (PS-NPs) are widely used in industry, pharmaceutical and consumer packaging materials, and medical products. The biological health impacts of PS-NPs are receiving increasing attention. Therefore, it is necessary to conduct a literature review of in vitro and in vivo experimental studies from a biological mechanism perspective. Based on the latest research results at home and abroad, this review introduced the characteristics and cell internalization of PS-NPs in cytotoxicity experiments, and summarized the effects of PS-NPs on cytotoxic targets such as mitochondria, lysosomes, proteins, and DNA. In addition, the influencing factors of the health effects of PS-NPs were analyzed from the aspects of physical and chemical properties and cell types. Finally, by discussing the current research hotspots of cytotoxicity mechanism and biological effects, it was anticipated to provide a reference for the health risk management and biological safety assessment of PS-NPs.

Formation and characteristics of polystyrene nanoplastic-plant protein corona / 生物工程学报

To investigate the formation of polystyrene nanoplastic-plant protein corona and its potential impact on plants, three differently modified polystyrene nanoplastics with an average particle size of 200 nm were taken to interact with the leaf proteins of Impatiens hawkeri for 2 h, 4 h, 8 h, 16 h, 24 h, and 36 h, respectively. The morphological changes were observed by scanning electron microscopy (SEM), the surface roughness was determined by atomic force microscopy (AFM), the hydrated particle size and zeta potential were determined by nanoparticle size and zeta potential analyzer, and the protein composition of the protein corona was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The proteins were classified in terms of biological processes, cellular components, and molecular functions to study the adsorption selection of nanoplastics to proteins, investigate the formation and characteristics of polystyrene nanoplastic-plant protein corona and predict the potential impact of protein corona on plants. The results showed that the morphological changes of the nanoplastics became clearer as the reaction time extends, as evidenced by the increase in size and roughness and the enhancement of stability, thus demonstrating the formation of protein corona. In addition, the transformation rate from soft to hard protein corona was basically the same for the three polystyrene nanoplastics in the formation of protein corona with leaf proteins under the same protein concentration conditions. Moreover, in the reaction with leaf proteins, the selective adsorption of the three nanoplastics to proteins with different isoelectric points and molecular weights differed, and the particle size and stability of the final formed protein corona also differed. Since a large portion of the protein fraction in protein corona is involved in photosynthesis, it is hypothesized that the formation of the protein corona may affect photosynthesis in I. hawkeri.

Bacillus megaterium: a Potential and an Efficient Bio-Degrader of Polystyrene

Abstract This research has been conducted to investigate the biodegradation of polystyrene (PS) by isolated strain Bacillus megaterium from Zophobas morio's. The viability and metabolic activity of Bacillus megaterium utilizing emulsified PS in liquid carbon free basal medium as sole carbon source was confirmed using redox probe 2,3,5-triphenyltetrazolium chloride (TTC). Bacillus megaterium showed prominent result with TTC, which forms red colored insoluble TPF (triphenyl formazan) within four to seven days. The formation of TPF confirmed the metabolism activity of the cell using PS as source of carbon. The biodegradation activity of Bacillus megaterium on PS film was also confirmed by FTIR analysis, the result showed changes in functional groups due to microbial activities. FESEM analysis was carried out on the PS surface, revealing the formation of bacterial biofilm as well as occurrence of porosity and fragility of the bacterial deteriorate surface compared to control. Overall, the identification of plastic degrading bacteria (PDB) will become a fundamental platform promoting more in-depth research for optimal plastic waste management to switch from the conventional landfilling to enzymatic biodegradation. In the long run, it is to regulate the current global plastic waste accumulation on Earth which poses potent ecological threat.

Advances in microbial degradation of plastics / 生物工程学报

Plastics are widely used in daily life. Due to poor management and disposal, about 80% of plastic wastes were buried in landfills and eventually became land and ocean waste, causing serious environmental pollution. Recycling plastics is a desirable approach, but not applicable for most of the plastic waste. Microbial degradation offers an environmentally friendly way to degrade the plastic wastes, and this review summarizes the potential microbes, enzymes, and the underpinning mechanisms for degrading six most commonly used plastics including polyethylene terephthalate, polyethylene, polyvinyl chloride, polypropylene, polystyrene and polyurethane. The challenges and future perspectives on microbial degradation of plastics were proposed.

Hyperkalemia in chronic kidney disease

SUMMARY Hyperkalemia is a frequent finding in patients with chronic kidney disease (CKD). This increase in serum potassium levels is associated with decreased renal ion excretion, as well as the use of medications to reduce the progression of CKD or to control associated diseases such as diabetes mellitus and heart failure. Hyperkalemia increases the risk of cardiac arrhythmia episodes and sudden death. Thus, the control of potassium elevation is essential for reducing the mortality rate in this population. Initially, the management of hyperkalemia includes orientation of low potassium diets and monitoring of patients' adherence to this procedure. It is also important to know the medications in use and the presence of comorbidities to guide dose reduction or even temporary withdrawal of any of the potassium retention-related drugs. And finally, the use of potassium binders is indicated in both acute episodes and chronic hyperkalemia.

RESUMO A hiperpotassemia é um achado frequente em pacientes com doença renal crônica (DRC). Esta elevação do nível sérico de potássio está associada à diminuição da excreção renal do íon, assim como ao uso de medicações para retardar a progressão da DRC ou para controlar doenças associadas, como diabetes mellitus e insuficiência cardíaca. A hiperpotassemia aumenta o risco de episódios de arritmia cardíaca e morte súbita. Assim, o controle da elevação de potássio é essencial para a diminuição da taxa de mortalidade nessa população. O manejo da hiperpotassemia inclui, inicialmente, orientação de dietas com baixo teor de potássio e acompanhamento da aderência dos pacientes a esse procedimento. Também é importante conhecer as medicações em uso e a presença de comorbidades, a fim de orientar a redução de doses ou até mesmo a suspensão temporária de alguma das drogas relacionadas à retenção de potássio. E, finalmente, o uso de quelantes de potássio é indicado tanto em episódios agudos como nos casos de hiperpotassemia crônica.

Application of combined body position fixation in radiation therapy of lung cancer / 中华放射医学与防护杂志

Objective To explore the CTV to PTV external expansion boundary and the effect of the dose of normal lung tissue under different fixed modes by a comparative analysis of combined body position and thermoplastic film fixed set-up error of radiation therapy for lung cancer. Methods From October 2016 to March 2018, the patients who received chest radiology at the Tangshan people's hospital were enrolled as subjects retrospectively divided into two groups, including 50 patients with lung cancer radiotherapy with combined body position fixation, and 40 patients with lung cancer with thermoplastic film fixation. The two groups of patients drew the target areas in accordance with the unified standard, and the set-up error of left and right, up and down, front and rear ( x, y, z axis) were recorded respectively after 1 time/week cone CT( CBCT) matched with the planned CT image and analyzed by t test. According to the MPTV =2. 5Σ+0. 7δ, CTV to PTV external expansion boundary in the combined body position group were calculated. And the V5、V20 and V30 of two groups of patients were calculated and analyzed by TPS system. Results The set-up error of the combined body position group and thermoplastic film group were respectively (1. 00 ± 0. 58) mm and (3. 28 ± 0. 43) mm on the x axis, (1. 42 ± 0. 28) mm on the y axis and (4. 03 ± 0. 41) mm, (1. 06 ± 0. 44) mm and (3. 18 ± 0. 34) mm on the z axis. The set-up errors of the two groups were statistically significant on x, y and z axis( t= -20. 740, -35. 596, -25. 015,P<0. 05). There was no significant difference in set-up errors between the central and peripheral lung cancer patients and between left and right lung cancer patients(P>0. 05). Through the MPTV =2. 5Σ+0. 7δ, CTV to PTV external expansion boundary in the combined body position fixation group was 2. 906 , 3. 746 and 2. 958 mm on x, y and z axis respectively. The comparison between group A and B showed that the mean values of V5 , V20 and V30 in group B were reduced by 1. 5％, 3. 1％ and 4. 8％ respectively compared with group A. Conclusions The combined body position technique can improve the accuracy of lung cancer patients after radiation therapy,and further reduce the boundary of CTV to PTV, which is of certain value to reduce the occurrence of radiation pneumonitis.

Water-equivalence of ZrO2doped polystyrene by Monte Carlo simulation / 中华放射医学与防护杂志

Objective To design water-equivalent plastic scintillator detector for the measurement of absorbed dose in tumor radiotherapy.Methods The concentration of ZrO2to be doped in polystyrene was estimated according to the empirical formula,and then the Monte Carlo program Geant 4(GEometry And Tracking 4)was used to simulate the energy deposition and transport process of X-rays with different energies in water,solid water RW34(composed of 2.1 wt％TiO2doping polystyrene)and different concentrations of ZrO2particles doped in polystyrene.The dose and attenuation coefficients were compared among different materials at different depths of water.Results The doses at different depths and the attenuation coefficient of polystyrene(doped with about 0.4 wt％ZrO2nanoparticles)were much more consistent with those of water and even exhibit much better water-equivalence than RW34.Conclusions The simulation results provide the basis for the development of water-equivalent scintillator.

Biofilm forming ability of intermediate and saprophytic Leptospira on abiotic and biotic surfaces

Aims@#Leptospira spp. has the ability to develop biofilm communities and this attribute is an essential factor to leptospiral pathogenesis. This study aims to assess and quantify the biofilm forming ability of intermediate and saprophytic Leptospira strains.@*Methodology and results@#The biofilm assay was quantified on microtitre polystyrene plates (abiotic) and wood chips (Jelutong Paya hardwood) over a duration of 11 days. Phase contrast light microscope was used to assess the structure of the on the surface. The biofilm production on wood chips surface were approximately one times higher than on polystyrene plate surface indicating Leptospira strains were capable of forming higher quantity of biofilm on biotic surface compared to abiotic surface by both intermediate and saprophytic Leptospira. A significant difference (p<0.05) exists in biofilms produced by Leptospira on wood surface which formed more biofilm than on polystyrene surface. The strongest biofilm producer is intermediate strain G14 with OD600 of 2.283±0.180 and OD600 of 2.333±0.037, on polystyrene and wood surface, respectively. Visualisation of biofilm by phase-contrast microscopy of two representative strains correlated with the OD values and the colour intensity of stained microtitre plates and wood surfaces. The biofilm formed comprises of a three-step process are adherence (1 th to 24 th h), maturation (6t h to 7 th day) and detachment (9 th to 11 th day) of biofilms.@*Conclusion, significance and impact of study@#The contact time of intermediate pathogenic strains was faster compared to saprophytic strain, indicating the biofilm forming ability is related to the level of pathogenicity of Leptospira strains.

Matrix stiffness regulates cell uptake of nanoparticles in 2D and 3D cultures of breast cancer cells / 药学学报

Fluorescent polystyrene nanospheres (PS) were used to explore the impact of substrate stiffness on cell uptake of nanoparticles in the breast cancer cells. Polyacrylamide (PAA) gels with varying stiffness were prepared by photopolymerization, and type I rat tail collagen was covalently conjugated on the surface of PAA gels to facilitate cell adhesion. Type I rat tail collagen was also used to fabricate collagen gels for 3D cell culture. Cells of human breast cancer cell line MCF-7 were incubated in the 2D culture on PAA gels and 3D culture within collagen gels. Next, nanospheres of 20 nm and 50 nm polystyrene were applied to MCF-7 cells in the 2D or 3D cultures. Cell morphology and uptake efficiency were observed with confocal microscopy. Our study demonstrates that substrate stiffness differentially regulated the cell morphology as well as the cell uptake behavior of polystyrene nanospheres in MCF-7 cells under 2D or 3D culture conditions.

Síntesis y caracterización de la mezcla polipropileno-poliestireno expandido (icopor) reciclado como alternativa para el proceso de producción de autopartes / Synthesis and characterization of expanded mixed polystyrene - polypropylene (styrofoam) recycled as an alternative for production process of autoparts

En el proceso de fabricación de autopartes se incluye el polipropileno (PP) como materia prima principal y la fibra de vidrio como insumo para la producción de ventiladores utilizados en los sistemas de refrigeración de los automotores. Los estándares de fabricación deben garantizar la resistencia de los productos en condiciones a las que estarán sometidos dentro del motor. Para lograrlo, el polipropileno es mezclado con fibra de vidrio en el proceso de inyección para aumentar la resistencia y la dureza del producto final, debido a que está expuesto a cambios de temperatura, choques con otras piezas, desgaste e impactos inesperados en el vehículo. Este estudio sintetizó y caracterizó un material obtenido a partir de la mezcla polipropileno puro-poliestireno expandido (EPS) (icopor) reciclado como una alternativa de aprovechamiento para el icopor dentro del proceso de fabricación de autopartes a modo de sustituto de la fibra de vidrio en el proceso de producción, siguiendo pasos como el tamizaje de los tamaños de material, la mezcla de los mismos, la obtención de probetas y la realización de ensayos mecánicos y térmicos. El objetivo fue comparar las propiedades mecánicas y térmicas del material obtenido (PP-EPS) con el material actualmente utilizado (PP-fibra de vidrio) para el que no se tenían estudios previos y de esta forma determinar la viabilidad de incorporación de un residuo a un proceso productivo y evitar su disposición directa favoreciendo el reciclaje del mismo. Las mezclas se caracterizaron mediante ensayos de tensión-deformación, dureza Shore A y análisis termogravimétrico (TGA) de los cuales se obtuvo favorecimiento en las propiedades térmicas y reducción de la resistencia mecánica en el uso de icopor, resaltando por supuesto el ahorro significativo en el cambio de insumos del proceso productivo.

Polypropylene (PP) as main raw material and fiberglass as input for the production of fans used in the cooling systems of motor is included in the process of manufacturing parts. Manufacturing standards must guarantee the resistance of the product in conditions that will be subject within the engine. To achieve this, the polypropylene is mixed with fiberglass in the injection process to increase the strength and hardness of the final product, as it is exposed to temperature changes, impacts with other parts, wear and unexpected impacts on the vehicle. This study synthesized and characterized a material obtained from the pure-polypropylene blend expanded polystyrene (EPS) (polystyrene) recycling as an alternative use for polystyrene in the auto parts manufacturing process as a substitute for fiberglass production process, following steps as screening media sizes, the mixture thereof, and obtaining specimens performing mechanical and thermal tests. The aim was to compare the mechanical and thermal properties of the material obtained (PP-EPS) with the material currently used (PP-fiberglass) for which they had no previous studies and thus determine the feasibility of incorporating a waste to a production in order to avoid direct disposal and thus promote the recycling process itself. The blends were characterized by stress-strain tests, Shore A hardness and thermogravimetric analysis (TGA) of which was obtained favoring the thermal properties and mechanical strength reduction in the use of polystyrene, of course emphasizing the significant savings in change of inputs in the production process.

Platelet-rich Fibrin Formation was delayed in Plastic Tubes.

ntroduction: Platelet-rich fibrin (PRF) is used in many regenerative treatments. Preparing PRF in glass tubes requires quick handling and generates biohazard concerns about silica contamination and glass breakage. Using plastic tubes may be an alternative to glass tubes. Objectives: This study investigated the formation of PRF prepared in polypropylene (PP) and polystyrene (PS) tubes compared with glass tubes. Methodology: PRF was prepared from human blood (n=20) in PP, PS, and glass tubes. The time required for PRF clot formation and retraction from the tube wall were observed. The PDGF-AB, TGF-β1 levels, and the gross/SEM appearance of the PRF clots were also evaluated. Results: The PRF clots in PP and PS tubes formed and retracted significantly slower compared with those in glass tubes. The PDGF-AB levels in the PRF from PP, PS, and glass tubes were not significantly different. Although the TGF-β1 levels in the PRF from PP and glass tubes were not different, that from the PRF from PS tubes was significantly higher. The gross structure and SEM appearance of PRF from the three tube types were similar. Conclusion: The slow clot formation in PP and PS tubes can extend PRF handling time while retaining PDGF-AB level and fibrin appearance. Owing to this delay in clot formation, we could obtain the plasma without adding any anticoagulant chemical agents. The plasma can be used for accelerating bone regeneration as platelet-rich plasma.

Evaluación sanitaria de factores de riesgos físicos en viviendas Petrocasas bajo un cambio de cubierta / Health evaluation of physical risk factors in petrohouses after roof replacement

Introducción: el problema de la vivienda tiene un alcance mundial. La solución del déficit cualitativo y cuantitativo de la vivienda en Cuba transita a través de diferentes soluciones. Varios asentamientos del país se han erigido con vivienda industrial prefabricada de cloruro de polivinil ­PVC- conocidas por Petrocasas. Algunos estudios reportan estrés térmico en estas viviendas, vinculado a débil ventilación y calentamiento de cierres expuestos al sol. Objetivo: realizar una evaluación de salud ambiental en factores de riesgos físicos en el ambiente interior de las viviendas relativo a la intemperie, tras un cambio del material de cubierta. Método: se plantea un estudio experimental evaluativo de factores de riesgos físicos en el ambiente interior de las viviendas petrocasas a partir de una propuesta de modificación del material de la cubierta con la intención de reducir el estrés térmico de las mismas. Fueron edificadas con este propósito dos viviendas petrocasas con igual orientación de fachada principal y diferente cubierta; ;una fue sustituida por poliestireno expandido y la otra mantiene cubierta original (aluminio y papel de asfalto).Se evaluaron comparativamente factores de riesgos físicos: ruido, componente magnético del campo electromagnético de baja frecuencia, iluminación natural, artificial, ventilación y, principalmente, microclima para valorar la eficacia del cambio introducido. La evaluación estadística se efectuó por descriptores, modelos de regresión y espectro de potencia bivariado con los paquetes estadísticos SPSS v. 17.0 y Statistica 8.0. Resultados: la vivienda Petrocasa con cubierta de aluminio ­ asfalto presenta un clima interior algo más desfavorable al bienestar térmico que aquella de poliestireno; la ventilación en ambas resulta deficiente. Conclusiones: el cambio de material de la cubierta ligera de la vivienda Petrocasa proporciona un clima interior algo más favorable al bienestar de sus residentes(AU)

Introduction: the housing problem is global in scope. Solution to qualitative and quantitative housing deficit in Cuba has been addressed from various different perspectives. Several settlements in the country have been built with prefabricated industrial houses made of polyvinyl chloride (PVC). These are known as petrohouses. Some studies have reported thermal stress inside these houses, resulting from insufficient ventilation and the heating of roofs exposed to the sun. Objective: carry out an environmental health evaluation of physical risk factors present in the indoor environment of petrohouses as compared with the outside environment after roof replacement. Method: an experimental evaluative study was conducted of physical risk factors present in the indoor environment of petrohouses based on a proposal of modification of the roof material with the purpose of reducing thermal stress. For this purpose, two petrohouses were built with the same orientation of their main facade, but different roof material. One was roofed with expanded polystyrene, while the other retained its original roof (aluminum sheets and asphalt paper). The following physical risk factors were evaluated comparatively: noise, magnetic component of the low frequency electromagnetic field, natural and artificial lighting, ventilation, and mainly microclimate, to evaluate the efficacy of the change made. Statistical evaluation was conducted with descriptors, regression models and bivariate power spectrum, using the statistical software packages SPSS v. 17.0 and Statistica v. 8.0. Results: indoor environment in the petrohouse with an aluminum-asphalt roof is somewhat more unfavorable in terms of thermal welfare than in the polystyrene-roofed house. Ventilation is deficient in both. Conclusions: roof replacement in petrohouses provides an indoor environment somewhat more favorable to the welfare of dwellers(AU)

Multi-mode microwave assisted preparation of PEGylated polystyrene resin / 国际药学研究杂志

Objective: To study a method of microwave-assistant PEGylation of polystyrene resin. Methods: Modify the commercial Merrifield resin with PEG-200, and study the influence of the yield under different conditions. The self-prepared PEG resin was further derived to PEG-wang resin; kinds of amino acids were anchored, and the loading rates were compared with commercial wang resin. Result: A general series react conditions were preferred, which was performed with 5 g resin, 50 ml PEG-200. irradiating for 15 min×2 at 600 W, preset temperature was 170 °C. The resin was then transformed to PEGylated Wang resin and anchored with amino acids, the yields were satisfied. Conclusion: The multi-mode microwave assistant PEGylation of Merrifield resin method was first reported in this paper. This method has the advantages of simple operation, fast preparation, mild reaction conditions and good yield, which was much better than the traditional method.

Electrokinetic Separation of Polystyrene Microspheres in Conductive Media on a Microfluidic Chip / 分析化学

A polydimethylsiloxane ( PDMS )/glass microfluidic chip consisting of a three-layer sandwich structure and three-parallel micro-electrode system was fabricated for the separation of polystyrene microspheres according to the particle size in high conductive solution by electric field produced by alternating current. The principle of electrokinetics of microspheres directional movement was investigated. The results showed that, when the applied voltage was 14 V at 100 kHz, the separation efficiency of 10 and 25 μm polystyrene microspheres was the best. Similarly, with a voltage of 10 V at 2 MHz, the separation efficiency of 5 and 25 μm polystyrene microspheres could achieve the highest value. Meanwhile, the voltage of 11 V at 1 MHz was suitable for the separation of 5 , 10 and 25 μm polystyrene microspheres with the separation efficiency of over 90%. At the same time, the formation of the laminar region in the middle of the electrode gap was the key role of microsphere separation.

Preparation of Polyacrylamide Resin and Its Adsorption Properties on 2,4-Dichlorophenoxyacetic Acid / 分析化学

Polyacrylamide resin was synthesized via surface-initiated atom transfer radical polymerization ( SI-ATRP) method. Acrylic amide ( AM) was grafted onto the surface of the chloromethyl polystyrene resin via SI-ATRP in the CuBr/2, 2'-bipyridine ( Bpy) system as catalyst at room temperature. The compositions of polyacrylamide resin were determined by means of elementary analysis, FT-IR analysis and scanning electron microscopy ( SEM) . The adsorption properties, the parameters of kinetics and the thermodynamics of the resin were evaluated in details, respectively. As the results, adsorption capacity of 2,4-dichlorophenoxyacetic acid (2,4-D) increased with the initial concentrations of solution increasing at room temperature, and its highest adsorption capacity was 111. 0 mg/g with solution concentration of 8 mmol/L. Adsorption isotherm at room temperature was determined and modeled with Langmuir and Freundlich equations. The thermodynamic equilibrium functions were calculated to be ΔG0, hence, the adsorption was spontaneous, endothermic and entropy increasing. The kinetics fitted the pseudo-second-order well. The polyacrylamide-chloromethyl polystyrene (PAM-CMCPS) resin was used for the adsorption of 2,4-D in orange sample, and good results were obtained.

Multi-mode microwave assisted preparation of PEGylated polystyrene resin / 国际药学研究杂志

Objective To study a method of microwave-assistant PEGylation of polystyrene resin. Methods Modify the commercial Merrifield resin with PEG-200, and study the influence of the yield under different conditions. The self-prepared PEG resin was further derived to PEG-wang resin; kinds of amino acids were anchored, and the loading rates were compared with commercial wang resin. Result A general series react conditions were preferred, which was performed with 5 g resin, 50 ml PEG-200, irradiating for 15 min ×2 at 600 W, preset temperature was 170 ℃. The resin was then transformed to PEGylated Wang resin and anchored with amino acids, the yields were satisfied. Conclusion The multi-mode microwave assistant PEGylation of Merrifield resin method was first reported in this paper. This method has the advantages of simple operation,fast preparation, mild reaction conditions and good yield, which was much better than the traditional method.

Establishment of chronic ocular hypertension model by anterior chamber injection of polystyrene microspheres in mouse / 中华实验眼科杂志

Background Many methods of ocular hypertension modeling have been used before,but these models remain short-duration ocular hypertension only.A new method of elevating intraocular pressure in mice by anterior chamber injection of polystyrene microspheres was reported abroad.However,this model is rarely used in China.Objective This study was to evaluate the application value of anterior chamber injection of polystyrene microspheres to establish glaucoma model in mice.Methods Forty-two SPF adult female C57BL/6L mice were divided into three groups according to random number table.Polystyrene microspheres (2 μl) were injected into the anterior chamber monocularly in the microspheres group,and the equal amount of PBS was used in the same way in the PBS group.No intervene was performed in the normal control group.The eyes of mice were examined by slit lamp microscope,and the intraocular pressure (IOP) was measured with TonoLab rebound tomometer in a 3-day interval after injection.Ocular histological sections were prepared 2 and 4 weeks after injection,and the anterior chamber angle was examined under the optical microscope.Neurons retrograde labeling was performed by 4％ fluorogold to calculate the survival number of retinal ganglion cells (RGCs) and the nerve fiber density was detected to assess the degree of RGCs and axon damage in retinal flat mounts,and the β-Ⅲ-tubulin-positive cells in the RGCs layer were examined by immnofluorescence method.The use and care of the animals complied with the instruction of Association for Research in Vision Ophthalmology (ARVO).Results IOP was significantly higher in the mice of the microspheres group than that in the normal control group or PBS group 2 and 4 weeks (all at P＜0.05).In the microspheres group,IOP reached peak in 2 weeks after injection and was significantly higher than that of 4 weeks after injection ([29.67±2.34] mmHg versus[15.71±1.23] mmHg) (all at P＜0.05).In 2 and 4 weeks after the anterior chamber injection of polystyrene,corneal edema was found under the slit lamp microscope,and under the optical microscope,microspheres accumulated at the anterior chamber angle.Additionally,in 2 and 4 weeks after injection,the number of survival RGCs was (4 542.82 ± 653.72)/mm2 and (3 623.12 ± 628.79)/mm2,respectively in the microspheres group,which showed significantly decrease in comparison with (6 979.33 ± 678.49)/mm2 and (6963.91 ±497.29)/mm2 in the normal control group (t =17.729,28.569,both at P＜0.05) and (6 843.21 ±573.42)/mm2 and (6 937.53±465.24)/mm2in the PBS group (t =16.975,29.145,both at P＜0.05).The number of RGCs was significantly less in the fourth week compared with second week after injection (t =6.951,P＜0.05).The β-Ⅲ-tubulin positive RGCs were (4 576.36± 479.64)/mm2 and (3 712.90 ± 660.31)/mm2 in 2 and 4 weeks in the microspheres group,respectively,which were significantly decreased in comparison with (6 725.94 ± 619.42)/mm2 and (6 741.90±663.60)/mm2 of the normal control group (t =18.811,22.182,both at P ＜ 0.05) or (6 757.85 ±463.59)/mm2 and (6 773.17± 471.35)/mm2 in the PBS group (t =18.953,22.605,both at P＜0.05),and in the microspheres group,β-Ⅲ-tubulin positive cells in the fourth week were decreased than those in the second week after injection (t=7.253,P＜0.05).The neural fiber density in the microspheres group in 2 and 4 weeks after injection was (193.08 ±32.75)/mm2 and (139.O0 ±38.24)/mm2,respectively,with a significant decline in comparison with (305.57±81.21)/mm2 and (297.46±52.60)/mm2(t=8.900,16.883,both at P＜0.05) of the normal control group or (312.63±70.62)/mm2 and (269.37±61.63)/mm2 of the PBS group (t=7.731,15.959,both at P＜0.05),and the neural fiber density was significantly lower in the fourth week than that in the second week after injection (t =7.442,P＜0.05).Conclusions Single injection of polystyrene microspheres into the anterior chamber can induce chronic ocular hypertension in mouse,which leads to the progressive damage of RGCs and neural fibers.This animal model shows a similar chronic pathogenic process to human glaucomatous eye.

Biofilm formation on polystyrene under different temperatures by antibiotic resistant Enterococcus faecalis and Enterococcus faecium isolated from food

The ability of antibiotic resistant E. faecalis and E. faecium isolated from food to form biofilm at different temperatures in the absence or presence of 0.75% glucose was evaluated. A synergistic effect on biofilm at 10 °C, 28 °C, 37 °C and 45 °C and glucose was observed for E. faecalis and E. faecium.