Polyethylene glycol fusion repair of severed rat sciatic nerves reestablishes axonal continuity and reorganizes sensory terminal fields in the spinal cord

Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic nerves.We have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor recovery.Furthermore,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target muscles.In this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic nerve.Young adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative Control)the application of PEG.Compound action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury site.The success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days postoperatively.At 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish peroxidase.PEG-fusion repair reestablished axonal continuity.Compared to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal areas.Unexpectedly,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repair.This central reorganization may contribute to the improved behavioral recovery seen after PEG-fusion repair,supporting the use of this novel repair methodology over currently available treatments.

Polyethylene glycol has immunoprotective effects on sciatic allografts, but behavioral recovery and graft tolerance require neurorrhaphy and axonal fusion

Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripheral nerve allografts undergo immunological rejection by the host immune system.In contrast,peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks,reduced immune responses,and many axons do not undergo Wallerian degeneration.The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study.We hypothesized that polyethylene glycol might have some immune-protective effects,but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery.We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion.Ablation-type sciatic nerve injuries in outbred Sprague–Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts,but peripheral nerve allografts were loose-sutured(loose-sutured polyethylene glycol)with an intentional gap of 1–2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons.Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts,animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively.Other morphological signs of rejection,such as collapsed Schwann cell basal lamina tubes,were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively.Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts.While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts,loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively.MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts,but MHCII expression was modestly lower compared to negative control at 21 days postoperatively.We conclude that,while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts,successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts,and produce recovery of sensory/motor functions and voluntary behaviors.Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.

Effect of Silicon (Si) Application on Phoenix dactylifera L. Growth under Drought Stress Induced by Polyethylene Glycol (PEG) in Vitro

This study was carried out to investigate the effects of silicon (Si) 3.6 mM (as calcium silicate) under drought stress induced by polyethylene glycol “PEG” at 15% (MW 8000), in addition to the control treatment on growth and some biochemical constituents of date palm cv. Barhee cultured in vitro. Drought stress (15% PEG) depressed the growth of shoot and decreased protein content and chlorophyll concentration. Addition of 3.6 mM Si could improve the growth of shoot and increase the protein content and leaf chlorophyll concentrations of stressed plants. The inclusion of Si to the PEG containing medium significantly increased the catalase (CAT) and superoxide dismutase (SOD) activity in regenerated shoot, compared to other treatments. As well as drought stress 15% PEG induced significant accumulation of shoots proline, which were decreased by added silicon. Moreover, the results were also supported by the observation that PEG stress-induced decrease the response percentage of root induction and root lengths was reversed by added silicon. Addition of Si obviously significantly increased the wax content in leaves, response percentage of root induction and root lengths of plantlets under drought stress. The results of this study indicate that the application of silicon improved growth attributes, effectively mitigate the adverse effect of drought, and increase tolerance of date palm plants for drought stress during the course of date palm tissue cultures.

Effects of Drought Stress Simulated by Polyethylene Glycol on Seed Germination, Root and Seedling Growth, and Seedling Antioxidant Characteristics in Job’s Tears

Two Job’s tears cultivars, yy18-1 (high resistance to drought stress) and yy12-7 (susceptible to drought stress) were used to investigate the responses of seed germination, root and seedling growth, and seedling antioxidant characteristics to drought stress simulated by polyethylene glycol (PEG) 6000 solutions with 0, -0.05, -0.1, -0.15, and -0.2 MPa osmotic potentials. The results showed that the germination energy, germination rate, germination index, root and seedling lengths, root and seedling diameters, root and seedling fresh masses, root and seedling dry masses, and seedling relative water content (RWC) decreased with the decrease of the osmotic potential of PEG 6000 solution. The contents of hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline in seedling increased with the decrease of the osmotic potential of PEG 6000 solution. The activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in seedling increased and then decreased with the decrease of osmotic potential of PEG 6000 solution. -0.1 MPa was the optimal osmotic potential of PEG 6000 solution simulated drought stress at germination stage for Job’s tears. The proline content and activities of POD and CAT were important mechanisms for the maintenance of drought resistance in Job’s tears seedling.

Effects of NaCl and Iso-Osmotic Polyethylene Glycol Stress on Na^+/H^+Antiport Activity of Three Malus species with Different Salt Tolerance

Salt stress contains osmotic and ionic stress, while iso-osmotic polyethylene glycol （PEG） has only osmotic stress. This study aimed to compare the different effects on the activity of H＋-ATPase, proton pump and Na＋/H＋antiport in Malus seedlings between osmotic and ionic stress. Species of salt tolerant Malus zumi, middle salt tolerant Malus xiaojinensis and salt sensitive Malus baccata were used as experimental materials. Malus seedlings were treated with NaCl and iso-osmotic PEG stress. The activity of H＋-ATPase, proton pump and Na＋/H＋antiport of plasmolemma and tonoplast in Malus seedlings were obviously increased under salt stress, and those in salt-tolerant species increased more. Under the same NaCl concentration, the activity of H＋-ATPase, proton pump and Na＋/H＋antiport of plasmolemma and tonoplast in salt-tolerant species were all obviously higher than those in salt-sensitive one. Higher Na＋/H＋antiport activity of plasmolemma and tonoplast in salt-tolerant species could help to extrude and compartmentalize sodium in roots under salt stress. The ascent rate of activity of H＋-ATPase, proton pump and Na＋/H＋antiport in Malus seedlings under the three salt concentration stress was all obviously higher than that under the iso-osmotic PEG stress. It indicated that the sodium ion effect had more stimulation on the activity of H＋-ATPase, proton pump and Na＋/H＋antiport in salt-tolerant species, and salt-tolerant species has higher capability of sodium extrusion and compartmentalization in roots and is therefore more salt tolerant.

Effect of Free Cells and Additional Supporting Material on Performance of Polyethylene Glycol (PEG)-Pellet Reactor to Treat NH4-N Contaminated Groundwater

To study the effect of free cells (suspended bacteria) on performance of entrapped bacteria system (i.e. polyethylene glycol (PEG)-pellet reactor) to treat NH4-N contaminated groundwater, two PEG-pellet reactors with a lot of free cells - Reactor A containing PEG-pellet and Reactor B containing PEG-pellet and supporting material - and the another control reactor without free cells (Reactor C) were set-up. Three reactors were operated under various NH4-N concentrations (40-60 mg/L) and various temperatures (5-25oC). The results show that the free cells effected on the NH4-N removal efficiency significantly. The free cells developed to be a biofilm layer on the pellet surface for Reactor A, the biofilm layer caused the decreasing NH4-N diffusion and incomplete nitrification eventually. On the other hand, most free cells attached to the supporting material for Reactor B. Although the NH4-N could diffuse properly, the free cells consuming acetate caused the added acetate was insufficient for complete denitrification. However, the results suggest that the supporting material could reduce the effect of free cells on the reactor performance at low temperature as indicated by 1) higher efficiency and 2) lower activation energy (Ea) for nitrification and denitrification in Reactor B than Reactor A.

Synthesis and Characterization of Storage Energy Materials Prepared from Nano-crystalline Cellulose/Polyethylene Glycol

This paper gives a brief report of the synthesis of a new kind of solid-solid phase change materials （SSPCMs）, nano-crystalline cellulose/polyethylene glycol （NCC/PEG）. These PCMs have very high ability for energy storage, and their enthalpies reach 103.8 J/g. They are composed of two parts, PEG as functional branches for energy storage, and NCC as skeleton. The flexible polymer PEG was grafted onto the surface of rigid powder of NCC by covalent bonds. The results of DSC, FT-IR were briefly introduced, and some comments were also given.

PEG模拟干旱胁迫下苗期木薯的生长生理响应

【目的】研究聚乙二醇(polyethylene glycol,PEG)模拟干旱胁迫对木薯生长生理的影响。【方法】以木薯品种NZ199为试验材料,将其根系浸入质量分数分别为0%、5%、10%、15%和20%的PEG溶液中,进行为期9 d的模拟干旱胁迫试验,并分别于第3、6、9天测量其生长、光合和生理各项指标。【结果】随着PEG质量分数的升高,同一时期NZ199的各项生长指标整体呈先升高后降低的趋势;净光合速率、气孔导度和蒸腾速率在低质量分数下被促进,而在高质量分数下受到抑制,处理前期(≤3 d)以10%PEG处理最高,后期(≥6 d)以5%PEG处理最高;可溶性蛋白含量呈先升高后降低的趋势,在10%PEG处理6和9 d时最高;15%和20%PEG处理的脯氨酸含量显著高于其他处理;过氧化物酶活性呈先升高后降低的趋势,以10%PEG处理6 d时最高;过氧化氢酶活性逐渐升高,以20%PEG处理9 d时最高;丙二醛含量逐渐增加,以20%PEG处理9 d时最高,表明木薯受到的胁迫最为严重。【结论】在NZ199苗期,适当的PEG质量分数和时间模拟干旱胁迫可以促进植株的光合作用,有利于积累同化物,但PEG质量分数过高会对植株产生反作用,叶片光合作用降低,脯氨酸含量、过氧化氢酶活性和丙二醛含量升高,即对其生长生理造成了胁迫,使其抗逆性减弱。

Polyethylene glycols: An effective strategy for limiting liver ischemia reperfusion injury

Liver ischemia-reperfusion injury(IRI) is an inherent feature of liver surgery and liver transplantation in which damage to a hypoxic organ(ischemia) is exacerbated following the return of oxygen delivery(reperfusion). IRI is a major cause of primary nonfunction after transplantation and may lead to graft rejection, regardless of immunological considerations. The immediate response involves the disruption of cellular mitochondrial oxidative phosphorylation and the accumulation of metabolic intermediates during the ischemic period, and oxidative stress during blood flow restoration. Moreover, a complex cascade of inflammatory mediators is generated during reperfusion, contributing to the extension of the damage and finally to organ failure. A variety of pharmacological interventions(antioxidants, anticytokines, etc.) have been proposed to alleviate graft injury but their usefulness is limited by the local and specific action of the drugs and by their potential undesirable toxic effects. Polyethylene glycols(PEGs), which are non-toxic water-soluble compounds approved by the FDA, have been widely used as a vehicle or a base in food, cosmetics and pharmaceuticals, and also as adjuvants for ameliorating drug pharmacokinetics. Some PEGs are also currently used as additives in organ preservation solutions prior to transplantation in order to limit the damage associated with cold ischemia reperfusion. More recently, the administration of PEGs of different molecular weights by intravenous injection has emerged as a new therapeutic tool to protect liver grafts from IRI. In this review, we summarize the current knowledge concerning the use of PEGs as a useful target for limiting liver IRI.

Isothermal Crystallization Kinetics of Microencapsulated Polyethylene Glycol Particles

The microenapsulated polyethylene glycol （PEG） with different molecular weight by a fluidized coating method has been prepared and the crystallization behaviors of PEG particles in three-dimensional confined vohume were investigated by using differential scanning calorimetry （DSC） measurement. The results showed that the width of the crystallization peak of PEG increases and its height gradually diminishes in case that the PEG particles are microencapsulated. Compared with the non-microencapsulated PEG particles, the proportion of the first crystallization peak of microencapsulated PEG particle increases, and that of the second one decreases. The reason for the difference maybe is that the crystallization process of microencapsulated PEG particles is uniform and the crystallization ends when the spherulites touch the wall, thus the opportunity of producing the second crystallization peak was relatively reduced.

Polymerization of Bisphenol A Epoxy Resin with Polyethylene glycol

The catalyst boron trifluoride etherate was used to catalyze the reaction of epoxy resin with polyethylene glycol (PEG), and the effect of the concentration of the catalyst on the reaction is studied. It is shown that there exist two competitive reactions : I, self polymerization of epoxy resin via chain growth and II, copolymerization of epoxy resin with PEG via step growth. At high concentration of the catalyst reaction I dominates and reaction II is negligible. On the contrary, at low concentration of the catalyst, reaction II dominates and block copolymers are formed In the intermediate case, the two reactions are comparable with the result that a gel structure is obtained.

Electrochemical oxidation of polyethylene glycol in electroplating solution using paraffin composite copper hexacyanoferrate modified (PCCHM) anode

Electrochemical oxidation of polyethylene glycol(PEG) in an acidic(pH 0.18 to 0.42) and high ionic strength electroplating solution was investigated. The electroplating solution is a major source of wastewater in the printing wiring board industry. A paraffin composite copper hexacyanoferrate modified(PCCHM) electrode was used as the anode and a bare graphite electrode was used as the cathode. The changes in PEG and total organic carbon(TOC) concentrations during the course of the reaction were monitored. The efficiency of the PCCHM anode was compared with bare graphite anode and it was found that the former showed significant electrocatalytic property for PEG and TOC removal. Chlorides present in the solution were found to contribute significantly in the overall organic removal process. Short chain organic compounds like acetic acid, oxalic acid, formic acid and ethylene glycol formed during electrolysis were identified by HPLC method. Anode surface area and applied current density were found to influence the electro-oxidation process, in which the former was found to be dominating. Investigations of the kinetics for the present electrochemical reaction suggested that the two stage first-order kinetic model provides a much better representation of the overall mechanism of the process if compared to the generalized kinetic model.

Studies on the Absorption of NO_2 by Polyethylene Glycol and the Oxidizing Properties of the Resulting Absorbent Product

PEG (Polyethylene glycol average molecular weight 300) is used as absorbent of NO2. The absorption efficiency is found to reach up to 97%. The absorbing product, PEG NO2, can be used to cleave benzyl ethers mildly and selectively to benzaldehyde and corresponding fatty alcohols, showing that PEG is a valuable oxidizing agent of benzyl ethers. As a carrier of NO2.PEG can be recovered and utilized repeatedly after the oxidation.

PEG-6000模拟干旱胁迫对不同青稞发芽的影响

为了明确聚乙二醇(PEG-6000)模拟干旱胁迫对青稞苗的影响,以9个青稞品种(系)种子为试验材料,研究比较了在5%,10%,15%和20%PEG-6000模拟干旱胁迫和对照处理下(不含PEG-6000)培养8 d青稞发芽率及苗生长生理指标的变化。结果表明,从CK到20%PEG-6000,各青稞的出苗率降低,发芽时间延长,茎长随着PEG-6000浓度增加而降低,青稞的苗茎鲜重和茎干重随着PEG-6000浓度的增加而减少。随着PEG-6000浓度的增加,各青稞品种生长性降低,PEG-6000浓度的升高使青稞生长受干旱胁迫严重,在不含PEG-6000的培养基中生长最好。

Reduced Sensitivity of Campomanesia adamantium(Cambess.)O.Berg Seeds to Desiccation:Effects of Polyethylene Glycol and Abscisic Acid

The Campomanesia adamantium is a threatened species from Brazil Savannah which seeds are desiccation-sensitive and do not withstand storage. This study aimed to reduce the sensitivity of Campomanesia adamantium seeds to desiccation using polyethylene glycol (PEG) and abscisic acid (ABA). Initially, seeds were subjected to PEG (0, -1.48, and -2.04 MPa) with or without ABA (100 μM) during 120 h, followed fast drying (silica gel) or slow drying (laboratory environment), at 20%, 15%, and 10% moisture content. In the second experiment, the seeds were PEG treated (-1.48 MPa) which provided the best results in the first experiment;the seeds were then subjected to different incubation times in PEG (30, 60, 90, or 120 h) and ABA (0, 10ˉ3, 10ˉ4, and 10ˉ5 μM), following the seeds were fast dried at 15% moisture content. The slow drying should be avoided, even in seeds previously subjected to osmotic conditioning with or without ABA. Seeds submitted to PEG treatment (-1.48 MPa/120h) without ABA and PEG (-1.48 MPa) with 10ˉ3 or 10ˉ4 μM of ABA (90 h), followed by fast drying at 15% moisture content showed reduction of desiccation sensitivity and high germination and vigor when compared to the other treatments.

BICENTRAL POLYMER SUPPORTED PHASE TRANSFER CATALYST POLYSTYRENE－SUPPORTED POLYETHYLENE GLYCOL AND PYRIDINIUM SALT

A bicentral polymer-supported Phase transfer catalyst, polystpyne-suPPorted polyethylene glycol and Pyridinium salt (PS-Py-PEG-400),synthesized with ohloromethylated polystyrene as supporter on which PEG and Pyridinium salt were immobilized successively. Its catalytic activity was tested for the reauction of solid potassium acetate and benzyl bromide by GC analysis. It was found that the bicentral catalyst performed higher activity than the monocentral PS-PEG-400 and PS-Py.

Effect of Brassinosteroids on Germination and Seedling Growth of Radish (<i>Raphanus sativus</i>L.) under PEG-6000 Induced Water Stress

Effect of 24-epibrassinolide and 28-homobrassinolide on the germination and seedling growth of radish (Raphanus sativus) subjected to water stress being imposed by 15% (w/v) polyethylene glycol (equivalent to -2.95 bars of osmotic pressure) was studied. Brassinosteroids supplementation reduced the inhibitory effect of water stress on seed germination and seedling growth. The growth stimulation in radish seedlings by brassinosteroids under desiccation stress was associated with elevated levels of nucleic acids and soluble proteins and lowered activities of RNase. The mitigation of osmotic stress imposed by PEG was associated with increased scavenging of reactive oxygen species as reflected in elevated activities of superoxide dismutase, catalase and ascorbate peroxidase. Brassinosteroids also enhanced the accumulation of the osmolyte free proline in radish seedlings challenged with drought stress. The two brassinosteroids also maintained membrane integrity under water deficiency conditions as indicated by lowered lipid peroxidation reflecting in reduced MDA content. The results of present study demonstrate the protective role of brassinosteroids against PEG imposed water stress in radish seedlings.

赤霉素处理对PEG模拟干旱条件下茄子种子萌发的影响

为了研究赤霉素浸种处理对PEG模拟干旱条件下茄子种子萌发的影响,本研究以3个品种茄子种子为试验材料,采用4种浓度(0、100、300、500 mg/L)的赤霉素浸种24 h后置于20%聚乙二醇(PEG)胁迫处理下进行种子发芽试验。试验结果表明,300 mg/L赤霉素浸种处理明显提高了3个品种茄子种子的发芽势、发芽率,并且降低了芽抑制率及根抑制率,能明显缓解干旱对茄子种子发芽率、幼苗生长的抑制作用。促进幼苗生长的最适赤霉素浓度为300 mg/L。

Effects of PVA and PEG on pH Dependent Shear Yield Stress of Concentrated Alumina Suspensions

The pH dependence of the extrapolated shear yield stress for Alcoa A16 a-Al2O3 suspensions at the powder volume fraction of 0.27 with and without addition of both polyvinyl alcohol (PVA) and polyethylene glycol (PEG) each at fixed 0.18% of the powder mass was studied. With the polymer added, the full deflocculation of the suspension shifts from about pH=4 to around pH=1.5, at which the minimum value of shear yield stress is higher than that at pH=4. The addition of both PVA and PEG was found to prevent the filter cake from cracking.

聚乙二醇基(PEG)水凝胶包埋漆酶研究

漆酶(Laccase)在有机污染物降解以及废水处理等环境治理领域有着杰出的作用,但在极端温度和pH下容易失活,限制了其应用。因此,设计具有较好保护作用的漆酶固定化载体,以扩大其在环境污染防治领域的应用具有重要的研究意义。采用紫外光照聚合法将漆酶固定在水凝胶(PEG)上,然后与戊二醛(GA)交联,得到了固定化漆酶水凝胶微球Lac/particles。以2,2′-联氮双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)为底物,对包埋后的漆酶的活性进行了考察。研究结果表明,在凝胶的保护下,Lac的pH耐受性、温度耐受性以及储存稳定性等方面均比游离漆酶有着不同程度的增强。