High Molecular Weight Polyethylene Glycol Research Articles

Modulating the rheological response of shear thickening fluids by variation in molecular weight of carrier fluid and its correlation with impact resistance of treated p-aramid fabrics

The present study deals with the effect of molecular weight of carrier fluid on the rheological behaviour of shear thickening fluid (STF) and impact energy absorption by treated p-aramid fabrics. High molecular weight polyethylene glycols (HMW-PEG: 1000, 3000 and 6000 g mol−1) were individually added to a mixture of PEG 200 and PEG 600 to prepare ternary mixtures of carrier fluids. Increase in average molecular weight of the carrier fluid via addition of PEG 1000 and PEG 3000 enhanced the dilatant behaviour of STF. On the other hand, addition of PEG 6000 led to a rheological response inferior to that obtained via addition of PEG 3000 owing to solidification of the former at room temperature resulting in fusion of silica particles. However, an inverse relation was observed between the rheological behaviour of HMW-PEG based STFs and impact resistance of p-aramid fabrics treated with them. The diminution in impact energy absorption occurred due to lubrication effect caused by long polymer chains of HMW-PEG. On the other hand, fusion of solidified PEG 6000 and silica particles created rough microstructures over the yarn surface, which enhanced inter-yarn friction, resulting in improved impact energy absorption.

Synthesis and characterization of high molecular weight polyethylene glycol glycidyl ether

Synthesis and characterization of high molecular weight polyethylene glycol glycidyl ether

Tunable Control of the Hydrophilicity and Wettability of Conjugated Polymers by a Postpolymerization Modification Approach.

A facile method to prepare hydrophilic polymers by a postpolymerization nucleophillic aromatic substitution reaction of fluoride on an emissive conjugated polymer (CP) backbone is reported. Quantitative functionalization by a series of monofunctionalized ethylene glycol oligomers, from dimer to hexamer, as well as with high molecular weight polyethylene glycol is demonstrated. The length of the ethylene glycol sidechains is shown to have a direct impact on the surface wettability of the polymer, as well as its solubility in polar solvents. However, the energetics and band gap of the CPs remain essentially constant. This method therefore allows an easy way to modulate the wettability and solubility of CP materials for a diverse series of applications.

Sucrose-Assisted Solution Combustion Synthesis of Doped Strontium Ferrate Perovskite-Type Electrocatalysts: Primary Role of the Secondary Fuel

The methodologies and experimental conditions used for the synthesis of cathode materials for electrochemical devices strongly influence their electrocatalytic performance. In particular, solution combustion synthesis is a convenient and versatile methodology allowing a fine-tuning of the properties of the material. In this work, we used for the first time a sucrose assisted-solution combustion synthesis for the preparation of Cerium and Cobalt-doped SrFeO3–δ electrocatalysts and we investigated the effect of polyethylene glycol (PEG) addition as a secondary fuel on their structural, microstructural, redox and electrochemical properties. The perovskite-type powders were characterized by X-ray diffraction coupled with Rietveld refinement, scanning, and high-resolution transmission electron microscopies, thermogravimetric analysis, nitrogen adsorption measurements, and temperature-programmed reduction. Electrical conductivity and overpotential measurements were performed after the deposition of the powders onto a Gd-doped ceria electrolyte pellet. Stable high-valence B-site cations were detected in the powders prepared from sucrose-PEG fuel mixtures, although a substantial improvement of the conductivity and a decrease of the overpotential values were obtained only with high molecular weight PEG. The superior electrochemical performance obtained using PEG with high molecular weight has been ascribed to a faster interaction of the powder with the oxygen gas phase favored by the nanometer-sized crystalline domains.

Synthesis of iron oxide nanoparticles for DNA purification

Sonochemistry in combination with a combustion procedure was used to prepare superparamagnetic iron oxide nanoparticles. Two different iron precursors, ferrocene and iron(II)-acetate were dispersed in polyethylene-glycol (PEG) with different molecular weight (200–1000) by using a high efficiency ultrasonic technique. The sonochemical treatment initiated the precipitation of iron-hydroxide particles, then the PEG based colloids were burnt to create the iron oxide nanoparticles. Three phases were observed in the samples, magnetite (Fe3O4), hematite (α-Fe2O3), and maghemite (γ-Fe2O3) and their ratio can be modified by changing the iron precursor and the type of PEG. Elektrokinetic (Zeta) potential and the particle size of the synthesized iron oxide nanoparticle samples were measured and the one (A1) based on iron(II)-acetate and PEG200 have been selected to test in DNA purification, because it has negative and small size distribution. The synthesized superparamagnetic nanoparticles have been used successfully in biological isolation (DNA, deoxyribonucleic acid purification), and thus, the developed synthetic procedure is more than suitable for such applications. Highlights Sonochemical-combustion method was used to synthesize superparamagnetic nanoparticles. Magnetite, hematite and maghemite nanoparticles were synthesized. The ratio of the iron oxide phases can be tuned by changing the precursors. High molecular weight PEG promote the formation of maghemite and hematite. High molecular weight PEG inhibits the formation of magnetite. The prepared nanoparticles are applicable for DNA purification.

Tertiary blends of PAMAM/PEG/PEG tissue bioadhesives

Lack of wet adhesion and biomechanical mismatch at tissue interfaces are the major challenges related to surgical adhesive formulations. Carbene-based bioadhesives seek to address those limitations, due to their ability to covalently bond to wet tissue surfaces. Herein, diazirine-grafted polyamidoamine (PAMAM) dendrimers (PDz) dissolved in various liquid polyethylene glycols (PEG) are reported. Non-aqueous liquid PEG 400 reinforced with high molecular weight PEGs (2 kDa, 6 kDA and 10 kDa) dissolved PDz to form tertiary blends for optimization of viscosity and shear storage modulus. Dynamic photorheometry correlated PEG molar mass and tertiary ratios to adhesion strength, swelling-in-water profile and potential weight loss in aqueous medium. Tertiary blended adhesives demonstrate an improvement in elongation and adhesion strength compared to the binary blends used as control.

Preclinical evaluation of topically-administered PEGylated Fab’ lung toxicity

PEGylation is a promising approach to increase the residence time of antibody fragments in the lungs and sustain their therapeutic effects. However, concerns arise as to the potential pulmonary toxicity of antibody fragments conjugated to high molecular weight (HMW) polyethylene glycol (PEG), notably after repeated administrations, and the possibility of PEG accumulation in the lungs. The purpose of this proof-of-concept study is to give insights about the safety of lung administration of a Fab’ anti-IL17A antibody fragment conjugated to two-armed 40 kDa PEG (PEG40). The presence of the PEG40 moiety inside alveolar macrophages remained stable for at least 24 h after intratracheal administration of PEG40-Fab’ to mice. PEG40 was then progressively cleared from alveolar macrophages. Incubation of PEG40 alone with macrophages in vitro did not significantly harm macrophages and did not affect phagocytosis or the production of inflammatory markers. After acute or chronic administration of PEG40-Fab’ to mice, no signs of significant pulmonary toxicity or inflammatory cell accumulation were observed. A vacuolization of alveolar macrophages not associated with any inflammation was noticed when PEG40, PEG40-Fab’, or unPEGylated Fab’ were administered. To conclude this preliminary proof of concept study, acute or repeated pulmonary administrations of PEGylated Fab’ appear safe in rodents.

Effect of polyethylene glycol on mechanical properties of bamboo fiber‐reinforced polylactic acid composites

ABSTRACTThe bamboo fiber (BF)‐reinforced polylactic acid (PLA) composites were prepared using the twin‐screw extruder and injection molding. Thermal gravimetric analyzer results indicated the thermal stability of BF/PLA composites decreased with increasing BF content. Differential scanning calorimeter and X‐ray diffraction curves showed that BF played a role as a nucleating agent, but the crystallinity of composite materials decreased with the increasing BF content. The melt flow rate of composites reduced with the increase in BF content, resulting in a poorer processing property. The processability of the composites was improved with the addition of high molecular polyethylene glycol (PEG). Mechanics performance test showed that tensile strength and bending strength of composites increased at low loading with the BF content increased then decreased when the loading continued to increase. The tensile strength of the composite materials reached 65.46 MPa when alkali‐treated BF (ABF) content was 20 wt %. The flexural strength of the composites reached 97.94 MPa when ABF content was 10 wt %. Impact performance has also been improved. PEG‐20000 was the best plasticizer among the PEG‐6000，PEG‐10000, and PEG‐20000. When the component of PEG was 10 wt %, the elongation increased by 56%. The scanning electron microscopy (SEM) result showed that the fracture of the composites was smooth, most ABF were wrapped in matrix and distribution of ABF in PLA matrix was more uniform. It means that interfacial compatibility of bamboo fiber and PLA improved after BF modified by alkali. High molecular weight PEG enhance melt flow ability of polymer, result in fibers were further enclosed in the PLA matrix and increase properties of composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47709.

Influence of calcination on the sol–gel synthesis of lanthanum oxide nanoparticles

A facile sol–gel technique was employed to synthesize lanthanum oxide nanoparticles (hereafter La2O3 NPs) using micro-sized La2O3 powders, 20% nitric acid, and high-molecular weight polyethylene glycol (PEG) as raw materials. The synthesized La2O3 NPs were calcined at 750, 900, and 1000 °C in air for 2 h. The calcined products were characterised using numerous experimental techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and photoluminescence (PL) spectroscopy. The experimental results indicated that the calcination temperatures have remarkable effects on the crystallinity, particle size, and lattice strains of the La2O3 NPs. The XRD patterns confirmed the hexagonal phase of the La2O3 NPs with lattice constants: a = b = 0.3973, nm and c = 0.6129 nm. The average crystallite size of the La2O3 NPs estimated by electron miscroscopy was in good agreement with the XRD results. The degree of crystallinity, and the average crystallite size of the NPs were increased, while the lattice strains were decreased with the calcination temperatures. The photoluminescence spectra of nanoparticles illustrated a strong emission band at the vicinity of 364 nm, which is typically known to be the green band for La2O3 NPs.

Polyethylene glycol assisted facile sol-gel synthesis of lanthanum oxide nanoparticles: Structural characterizations and photoluminescence studies

In this study, lanthanum oxide nanoparticles (La2O3 NPs) synthesised via the facile sol-gel method, using a solution of micro-sized lanthanum oxide powders containing 20% nitric acid and high molecular weight polyethylene glycol (PEG). The as synthesised La2O3 NPs were then characterized using X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), energy-dispersive X-ray (EDS) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and photoluminescence (PL) spectroscopy. Our findings indicated that the concentration of PEG strongly influences the particle size and the lattice strain of the La2O3 NPs. A single phase hexagonal crystal structure was confirmed via XRD studies with lattice constants, a = b = 0.3973 nm and c = 0.6129 nm. The average crystallite size and lattice strains estimated were in the range of approximately 25–28 nm and 0.0050–0.0055 respectively. The incremental nature of the crystallinity and lattice strains of the NPs was observed with the subsequent enhancement of PEG-contents, while the average particle size was reduced. The average particle size of La2O3 NPs estimated from ESEM imaging was consistent with that obtained from the XRD data. The photoluminescence spectra revealed a strong emission band located at a wavelength of 365 nm (typical green band) for all La2O3NPsamples. This is ascribed to the recombination of delocalized electrons around the conduction band with a single charged state of a surface oxygen vacancy.

Hyaluronic-Acid Based Hydrogels for 3-Dimensional Culture of Patient-Derived Glioblastoma Cells.

Glioblastoma (GBM) is the most common, yet most lethal, central nervous system cancer. In recent years, many studies have focused on how the extracellular matrix (ECM) of the unique brain environment, such as hyaluronic acid (HA), facilitates GBM progression and invasion. However, most in vitro culture models include GBM cells outside of the context of an ECM. Murine xenografts of GBM cells are used commonly as well. However, in vivo models make it difficult to isolate the contributions of individual features of the complex tumor microenvironment to tumor behavior. Here, we describe an HA hydrogel-based, three-dimensional (3D) culture platform that allows researchers to independently alter HA concentration and stiffness. High molecular weight HA and polyethylene glycol (PEG) comprise hydrogels, which are crosslinked via Michael-type addition in the presence of live cells. 3D hydrogel cultures of patient-derived GBM cells exhibit viability and proliferation rates as good as, or better than, when cultured as standard gliomaspheres. The hydrogel system also enables incorporation of ECM-mimetic peptides to isolate effects of specific cell-ECM interactions. Hydrogels are optically transparent so that live cells can be imaged in 3D culture. Finally, HA hydrogel cultures are compatible with standard techniques for molecular and cellular analyses, including PCR, Western blotting and cryosectioning followed by immunofluorescence staining.

FTIR spectroscopic study of conformational equilibria of substituted ethane in polyethylene glycols

In this paper, we considered the conformational behaviour of 1,2-dichloroethane in polyethylene glycols with molecular weight equaled to 200, 400 and 600. We determined the enthalpy differences of conformations of this compound in polyethylene glycols by FTIR spectra. The obtained values were compared with that for high molecular weight polyethylene glycol PEG 10,000.

Inhibition of Postinfarction Ventricular Remodeling by High Molecular Weight Polyethylene Glycol

BackgroundMyocardial infarction (MI) is a major etiology for the development of heart failure. We have previously shown that high molecular weight polyethylene glycol (PEG) can protect cardiac myocytes from hypoxia-reoxygenation injury in vitro. In this study, we investigated the potential protective effects of 15-20 kD PEG postinfarction without reperfusion. MethodsOne milliliter of PEG 15-20 was delivered intravenously following permanent left anterior descending ligation in adult male rats with phosphate buffer saline (PBS) as control (n = 9 in each group). Echocardiography was performed at baseline and at 8 wk post-MI. Left ventricles (LVs) were harvested to quantify fibrosis, apoptosis, cell survival signaling, regulation of β-adrenergic signaling, and caveolin (Cav) expression. ResultsThe PEG group had significant recovery of LV function at 8 wk compared with the PBS group. There was less LV fibrosis in both the infarct and remote territory. Cell survival signaling was upregulated in the PEG group with increased Akt and ERK phosphorylation. PEG inhibited apoptosis as measured by terminal deoxynucleotidyl transferase [TdT]-mediated dUTP nick-end labeling positive nuclei and caspase-3 activity. There was maintenance of Cav-1, Cav-2, and Cav-3 expression following PEG treatment versus a decline in the PBS group. Negative regulators of β-adrenergic signaling, G protein-coupled receptor kinase-2, and β-arrestin 1 and 2 were all upregulated in PBS-treated samples compared to normal control; however, PEG treatment led to decreased expression. ConclusionsThese data suggest that PEG 15-20 may have significant protective effects post-MI even in the setting of no acute reperfusion. Upregulation of Cav expression appears to be a key mechanism for the beneficial effects of PEG on ventricular remodeling and function.

Singlet Oxygen Plays an Essential Role in the Root's Response to Osmotic Stress.

The high osmotic potentials in plants subjected to drought stress can be mimicked by the application of high molecular weight polyethylene glycol. Here, we quantified the effects of exposure to polyethylene glycol on the growth of the main and lateral roots of Arabidopsis (Arabidopsis thaliana) seedlings. The effects on root growth were highly correlated with the appearance of singlet oxygen, as visualized using the singlet oxygen-specific probe singlet oxygen sensor green. The production of singlet oxygen was followed by cell death, as indicated by the intracellular accumulation of propidium iodide due to the loss of membrane integrity. Cell death began in the epidermal region of the root tip and spread in a dynamic manner to meristematic sections. In parallel, gene expression changes specific to the presence of singlet oxygen were observed. The accumulation of other reactive oxygen species, namely hydrogen, peroxide, nitric oxide, and superoxide, did not correlate with cell death. In addition, both the singlet oxygen scavenger His and the lipoxygenase inhibitor salicylhydroxamic acid specifically inhibited singlet oxygen accumulation and cell death. These results suggest a light-independent, type-I source of singlet oxygen production. Serpin-protease interactions were used as a model to assess the possibility of vacuolar-type cell death. Osmotic stress induced the accumulation of complexes between the cytoplasmic serpin AtSERPIN1 and its cognate vacuolar proteases, indicating that vacuolar integrity was compromised. These findings imply that singlet oxygen plays an essential role in conveying the root response to osmotic stress.

BIOCHEMICAL AND PHYSIOLOGICAL CHANGES OF CALLUS GROWTH AND LYCOPENE PIGMENT PRODUCTION FROM TOMATO (Lycopersicon esculentum Mill.) UNDER DROUGHT STRESS

This experiment was conducted in faculty of Science labs, Kufa University, carried out during 2015 to applied methods for extraction, purification and Quantitative of Lycopene red pigments, from callus tissue and tomato fruits mother plant (Lycopersicon esculentum Mill).This study include of three parts, Firstly; Tomato seeds(Supper queen) hybrid were germinated in free MS medium and callus induction from shoot tip (3cmpieces) by using MS medium supplemented with Dichlorophenoxiactic acid (2,4-D) at different concentration (0.5,1, 1.5mg/l)with benzyl adenine (BA) at concentration of (0.3 mg/l). Secondly; identically callus fresh weight re-cultured in the same MS medium supplemented with high molecular weight polyethylene glycol (PEG) was used as selective agent at level of (5,10,15 and 25%). Thirdly; comparisons study were made between in vitro and in vivo grown plant. Powder of control lycopene used as standard solution. The content of lycopene was done by using high performance liquid chromatography (HPLC), and compare of the quantitatively of lycopene with these content in fruits of mother plant, and callus tissue. Also, include alcohol extraction of Lycopene from tomato fruit by using acetone and hexane mixture. The result showed significant increased (P< 0.05) of lycopene production and the superiority of lycopene content in callus than the content in fruits of mother plant. Antioxidant enzymes activity like Catalase (CAT),Guaiacol peroxidise (POX) and Superoxide dismutase(SOD) were high in callus under drought stress than in fruit of mother plant. However, Proline and total sugar content were at higher levels in callus under drought stress than in fruit of mother plant.

NMR Study of Elastin's Elasticity Mechanism

Elastin is the most abundant elastomer in nature. The recoil mechanism is believed to be entropically driven for which there re two molecular level theories. Recoil in one theory is a rubber-like mechanism in which the decrease in entropy with stretch is due to a decrease in conformational entropy from backbone ordering. The alternative is a decrease in solvent entropy with stretch from solvent ordering, i.e., the hydrophobic effect. Using a novel double quantum (2Q) pulse sequence in solid state NMR; water ordering at elastin fiber surface was studied quantitatively. We find that water is weakly oriented at the Elastin-water surface when the fiber is relaxed and stretching the fiber or increasing the temperature significantly increases the 2Q signal, i.e., increases the ordered water fraction. Furthermore, the 2Q signal decreases with the addition of high molecular weight polyethylene glycol (20kDa or 6kDa PEG) that is known to precipitate proteins and decrease their hydration in solution. We believe PEG causes less water to be available on the fibers surface and thus less ordered water. Also, this is likely the reason why the fibers become less flexible. Our preliminary results in both water and high molecular weight PEG experiments directly correlate the recoil mechanism with the hydrophobic effect.

Modulatory effect of high molecular weight polyethylene glycols on drug release from ibuprofen matrix tablets

The work aim at investigating the channeling or modulatory effects of polyethylene glycol (PEG) (MW 4000 and 6000) on drug release from ibuprofen sustained release formulation. Different batches of ibuprofen matrix granules and tablet were prepared by melt granulation using different concentrations of carnauba wax and PEG at different ratios. The granule flow properties and various tablets parameters were evaluated using standard procedures. Drug release kinetics and mechanisms from the tablets were investigated as well as DSC and FTIR drug-excipients compatibility. The granules showed increasingly close packing with increase in the amounts of PEG incorporated. All the tablets did not meet compendial specifications with regard to crushing strength and friability. The release rate and extent of release were found to be influenced by the amount of PEG used as well as the carnauba wax concentration. PEG combination of equal amounts produced the highest release of 91 % in the formulation prepared with 12.20 %w/w of carnauba wax while a 1:2 combination in tablets prepared with 24.40 %w/w of carnauba wax gave a maximum drug release of 83 %. Drug release kinetic and mechanism were most consistent with the Higuchi model hence the release was diffusion mediated. DSC and FTIR studies showed no interactions between ibuprofen and the excipients. Carnauba wax-PEG system can be used successfully as a matrix former to sustain the release of ibuprofen for over 6 h. The studies indicate that the proper balance between a matrix former and a channeling agent can produce a desired drug dissolution profile.Keywords: carnauba wax, PEG, granulation, release modifier, ibuprofen, tablets

Impact of polymer geometry on the interactions of protein-PEG conjugates

The conjugation of high molecular weight polyethylene glycol (PEG) to an active pharmaceutical ingredient (API) is an attractive strategy for the modification of biophysical and biodistribution properties of the API. Indeed, several therapeutic proteins conjugated to PEG have been safely administered in the clinic. While there have been studies on the configuration of these conjugates in solution, investigations on the impact of PEG geometry on protein-PEG conjugate interactions is limited. In this study, we use dynamic light scattering (DLS), rheology, and small-angle neutron scattering (SANS) to investigate the biophysical solution and interaction behavior of a 50kDa Fab protein attached to either a linear or tetrameric (branched) 40kDa PEG molecule. The hydrodynamic radii, diffusivity, viscosity and pair distance distribution function (PDDF) were obtained for the protein-PEG conjugates in solution. An analysis revealed that interactions between unconjugated proteins were quite attractive, however linear PEG-protein conjugates exhibited net repulsive interactions, similar to that of the unconjugated polymer. Tetramer PEG-protein conjugates on the other hand, exhibited a net weak attractive interaction, indicating a more balanced distribution of repulsive and attractive interaction states. Further analysis of the SANS data using geometric models consistent with the PDDF elucidated the conjugates' equilibrium configuration in solution. Insights gained from measurements and analysis used here can also be useful in predicting how conjugate geometries affect viscosity and aggregation behavior, which are important in determining suitable protein-polymer drug formulations.

Improving the productivity of a multidimensional chromatographic preparative system by collecting pure chemicals after each of three chromatographic dimensions

The enhanced sample collection capability of a heart-cutting three-dimensional GC-prep system is reported. In its original configuration, a highly pure component can be usually collected after the last (3D) column outlet by means of a dedicated preparative station. The latter is located after the last chromatographic column, and this poses the requirement for multiple heart cuts even for those components showing satisfactory degree of purity after the first (or second) separation dimension. The feasibility to collect pure components after each chromatographic dimension is here described, employing a three-dimension MDGC system equipped with high-temperature valves, located inside the first and second GC ovens, with the aim to improve the productivity of the collection procedure. In addition to a commercial preparative collector located at the 3D outlet, two laboratory-made collection systems were applied in the first and second dimension, reached by the effluent to be collected trough a high-temperature valve switching the heart-cut fraction between either the detector (FID), or the collector. Highly pure sesquiterpene components were collected, namely: patchouli alcohol after the first column [poly(5% diphenyl/95% dimethylsiloxane)], α-bulnesene after a second column coated with high molecular weight polyethylene glycol, and α-guaiene after an ionic-liquid based column (SLB-IL60), used as the third dimension. Purity levels ranging from 85 to 95% were achieved with an average collection recovery of 90% (n=5). The following average amounts were collected per run: 160μg for α-guaiene, 295μg for α-bulnesene, and 496μg for patchouli alcohol.

Polyethylene Glycol Preconditioning: An Effective Strategy to Prevent Liver Ischemia Reperfusion Injury.

Hepatic ischemia reperfusion injury (IRI) is an inevitable clinical problem for liver surgery. Polyethylene glycols (PEGs) are water soluble nontoxic polymers that have proven their effectiveness in various in vivo and in vitro models of tissue injury. The present study aims to investigate whether the intravenous administration of a high molecular weight PEG of 35 kDa (PEG 35) could be an effective strategy for rat liver preconditioning against IRI. PEG 35 was intravenously administered at 2 and 10 mg/kg to male Sprague Dawley rats. Then, rats were subjected to one hour of partial ischemia (70%) followed by two hours of reperfusion. The results demonstrated that PEG 35 injected intravenously at 10 mg/kg protected efficiently rat liver against the deleterious effects of IRI. This was evidenced by the significant decrease in transaminases levels and the better preservation of mitochondrial membrane polarization. Also, PEG 35 preserved hepatocyte morphology as reflected by an increased F-actin/G-actin ratio and confocal microscopy findings. In addition, PEG 35 protective mechanisms were correlated with the activation of the prosurvival kinase Akt and the cytoprotective factor AMPK and the inhibition of apoptosis. Thus, PEG may become a suitable agent to attempt pharmacological preconditioning against hepatic IRI.