Polyethylene Gycol Research Articles

Polyethylene Gycol (PEG) Induced Water Stress in Four Different Genotypes of Pea Seedlings and Evaluation of The Induced Defense Mechanism

The present work was undertaken on artificially induced water stress on pea seedlings under in vitro conditions in order to select the drought tolerant line. Artificial water stress was induced with PEG-6000 on 15-day old seedlings of four varieties for 4, 8 and 12 days. The activities of antioxidative enzymes like peroxidase, catalase, ascorbate peroxidase, glutathione reductase and superoxide dismutase were assayed in the stressed and control plants. POX activity was increased in the initial stages of stress, but its activity was decreased significantly on the 12th day in all the varieties. APOX also showed a similar trend but the maximum activity was noted in Var 3 on the 8th day. CAT activity decreased in var 1 and var 2 when compared with the control, which, however, increased significantly in var 3 and var 4. A slight increase in the GR activity was observed in var 1 and var 2 at the initial stages of the drought stress but its activity decreased significantly on the 12th day in both these varieties when compared with control plants. However, its activity also increased steadily in var 3 and var 4. Maximum SOD activities were noted on the 4th day of drought stress in all four varieties but its activities decreased steadily on the subsequent 8th and 12th days when compared with control. When antioxidative activities were compared among the four varieties, var 3 and var 4 showed maximum increase in antioxidant activity during the period of drought stress. Among the four varieties, var 3 and var 4 showed greater accumulation of H2O2 during the stress days and were maximum at 12th day. Lipid peroxidation also increased in the same varieties. Maximum proline content was noted in both the root and leaf of var 3, followed by var 4. It was further noted that the chlorophyll content decreased significantly in all four varieties in subsequent longer drought stresses. The accumulation of proline content was steadily higher with an increase in the stress length in all the four varieties. During the drought stress, all the varieties showed an increase in ascorbate content but, it was maximum in var 4 followed by var 3 and the least ascorbate was noted in var 1. The present findings indicate that water stress induces oxidative stress in all the four varieties. However, antioxidative mechanisms were found to be more pronounced in var 4 which, therefore, may be considered as the most tolerant to drought stress.

Effect of Dimethyl Sulfoxide (DMSO) as a Green Solvent and the Addition of Polyethylene Glycol (PEG) in Cellulose Acetate/Polybutylene Succinate (CA/PBS) Membrane’s Performance

In this study, performance of CA/PBS membranes, prepared with the non-toxic solvent dimethyl sulfoxide (DMSO) compared to Dimethylformamide (DMF), was investigated. The membranes were prepared using immersion precipitation technique at coagulation bath at temperatures of 25°C. Ternary diagram was used to show the interaction between polymer (CA/PBS), solvents (DMF or DMSO) and isopropanol as non-solvent by measuring the cloud point instead of Hansen solubility parameter differences. The effect of Polyethylene Gycol (PEG) to the membrane performance was also investigated. Morphology and tensile strength were analyzed by using Scanning Electron Microscopy (SEM) and Dynamic Mechanical Analysis (DMA), respectively. Experimental results proved that DMSO could be used to replace (DMF) as solvent, as the membranes had a higher value of salt rejection (84.9%). With the addition of PEG, salt rejection, mechanical property, and porosity of CA/PBS membrane also increases. The best result shows that PEG with concentration of 7% wt of polymer, the salt rejection is 88.89%; Permeate Flux is 29.036 L/m2.hr; tensile strength is 68.366 kPa; porosity is 75.16 % and the morphology is sponge-like with the pore size diameter in average is 0.262 µm

Crystallinity and surface morphology of the Poly Ethylene Glycol-added cholesteryl acrylate-ITO composites

Composite of cholesteryl acrylate-ITO nanoparticle was synthesized with the addition of polyethylenegycol (PEG). The crystallinity and surface morphology of the composites were investigated. XRD pattern of that product showed peaks in 2θ at 21° and confirmed a nematic phase. Therefore, added PEG could be changed the structures liquid crystal of cholesteryl acrylate. Percent crystallinity of the composites with different PEG variations of 0.001, 0.002, 0.003, 0.004, and 0.005 are0.001 is 8.14%, 12.41%, 14.85%, 7.11, and 8.66%, respectively. SEM image of the composite with PEG 0,003 indicated showed the formation of rods and chains crosslinking indicating successful photopolymerizations process. Those conditions made polymer to be micelle that affect their conductivity due to aggregation.

PVB/PEG-Based Feedstocks for Injection Molding of Alumina Microreactor Components.

The ceramic injection molding (CIM) process is a cost-effective powder-based near net shape manufacturing process for large-scale production of complex-shaped ceramic functional components. This paper presents the rheological analysis of environmentally friendly CIM feedstock formulations based on the binder components polyvinyl butyral (PVB) and polyethylene gycol (PEG). The prepared PVB/PEG-based alumina molding compounds were investigated with respect to their PVB:PEG ratios as well as to their powder filling degrees in the range between 50 and 64 vol.%. Corresponding viscosities and shear stresses were determined for increasing shear rates to show the effects of increased PEG content and solid loadings on them. Two single reactor components were injection molded and subsequently joined in their green state for fabrication of an alumina microreactor. The intended purpose of the alumina microreactors is their potential application as wear-resistant and hydrothermal stable multifunctional devices (µ-mixer, µ-reactor, µ-analyzer) for continuous hydrothermal synthesis (CHTS) of metal oxide nanoparticles in supercritical water (sc-H2O) as the reaction medium.

A GROMOS Parameter Set for Vicinal Diether Functions: Properties of Polyethyleneoxide and Polyethyleneglycol.

An extension 53A6OXY+D to the GROMOS 53A6OXY force field is reported that includes an accurate description of the vicinal diether function. The calibration is based on the model compound 1,2-dimethoxyethane (DXE) and involves a fitting of the relevant torsional-energy parameters against quantum-mechanical (QM) rotational energy profiles for the OCCO and CCOC dihedral angles in vacuum, followed by a validation against experimental conformer populations in the pure liquid and in aqueous mixtures. A systematic comparison between the 53A6, 56A6CARBO, 53A6OXY, and 53A6OXY+D parameter sets is also performed in terms of these properties, as well as in terms of the thermodynamic properties of dimethylether (DME), diethylether (DEE), 1-methoxypropane (MPH), and DXE. Finally, the new parameter set is further validated in the context of polyethers, namely polyethyleneoxide (PEO) and polyethylenegycol (PEG). The 53A6OXY+D set reproduces well the QM rotational profiles of DXE in vacuum (by calibration), the conformational populations of DXE in the pure liquid and in aqueous mixtures, and the experimental thermodynamic pure-liquid and (polar and nonpolar) solvation properties of DME, DEE, MPH, and DXE. In particular, it accounts appropriately for the gauche-effect, both in its solvent-independent stereoelectronic component and in its solvent-dependent dielectric-screening component. In contrast to 53A6OXY, it also suggests a higher affinity of DXE for water compared to octanol, in agreement with the experimental partition coefficient. In the context of aqueous polyethers, the calculated size (Flory) exponent (νg = 0.61) for the molecular-weight dependence of the radius of gyration and persistence length (Lp = 0.39 ± 0.04 nm) agree well with estimates based on experiment or previous simulations with other force fields. The simulations also suggest a picture of aqueous polyethers as "water sponges", in which the diether function "adsorbs" an essentially constant number of water molecules corresponding to first-shell hydrogen-bonded saturation of its oxygen atoms, with a tendency to include other ether oxygen atoms along the chain in the second shell, resulting in "water bridging".

Integrin αvβ3–Targeted Dynamic Contrast–Enhanced Magnetic Resonance Imaging Using a Gadolinium-Loaded Polyethylene Gycol–Dendrimer–Cyclic RGD Conjugate to Evaluate Tumor Angiogenesis and to Assess Early Antiangiogenic Treatment Response in a Mouse Xenograft Tumor Model

The purpose of this study was to validate an integrin αvβ3-targeted magnetic resonance contrast agent, PEG-G3-(Gd-DTPA)6-(cRGD-DTPA)2, for its ability to detect tumor angiogenesis and assess early response to antiangiogenic therapy using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). Integrin αvβ3-positive U87 cells and control groups were incubated with fluorescein-labeled cRGD-conjugated dendrimer, and the cellular attachment of the dendrimer was observed. DCE MRI was performed on mice bearing KB xenograft tumors using either PEG-G3-(Gd-DTPA)6-(cRGD-DTPA)2 or PEG-G3-(Gd-DTPA)6-(cRAD-DTPA)2. DCE MRI was also performed 2 hours after anti-integrin αvβ3 monoclonal antibody treatment and after bevacizumab treatment on days 3 and 6t. Using DCE MRI, the 30-minute contrast washout percentage was significantly lower in the cRGD-conjugate injection groups. The enhancement patterns were different between the two contrast injection groups. In the antiangiogenic therapy groups, a rapid increase in 30-minute contrast washout percentage was observed in both the LM609 and bevacizumab treatment groups, and this occurred before there was an observable decrease in tumor size. The integrin αvβ3 targeting ability of PEG-G3-(Gd-DTPA)6-(cRGD-DTPA)2 in vitro and in vivo was demonstrated. The 30-minute contrast washout percentage is a useful parameter for examining tumor angiogenesis and for the early assessment of antiangiogenic treatment response.

AFM protein–protein interactions within the EcoR124I molecular motor

Dynamic Force Spectroscopy (DFS), an Atomic Force Microscopy (AFM) technique, has been used to investigate the interaction between the HsdR subunit and the core methylase (MTase) of the Type I Restriction-Modification (R-M) enzyme EcoR124I. Such systems are of interest in bionanotechnology owing to their ability to translocate DNA, thus acting as molecular motors. Forces between a glutathione S-transferase (GST)-HsdR(PrrI) motor subunit attached to an AFM tip using a polyethylene gycol linker and the core MTase on poly-L-lysine pre-treated mica were measured at different loading rates. In the absence of an applied force, the position of energy barrier xdiss, bond dissociation rate kdiss(0) and lifetime of the bond τ(0) were calculated to be 1.35 ± 0.17 nm, 0.16 s−1 and 6.3 s, respectively. The kdiss(0) value was a little lower than that obtained from magnetic tweezers (0.4 s−1), suggesting that the thermodynamic equilibrium may be affected by the presence of DNA. This work demonstrates that kinetic data concerning protein–protein interactions between subunits within Type I R-M enzymes are accessible via AFM. Such information is important for structure elucidation and the development of nanodevices.

Targeted Systemic Radiotherapy with scVEGF/177Lu Leads to Sustained Disruption of the Tumor Vasculature and Intratumoral Apoptosis

Tumor vessels abundantly express receptors for vascular endothelial growth factor (VEGF), despite treatment with conventional or antiangiogenic drugs. We wished to determine whether the high levels of VEGF receptor (VEGFR) within the tumor vasculature could be leveraged for intracellular delivery of therapeutically significant doses of scVEGF/(177)Lu, a novel radiopharmaceutical based on a recombinant single-chain (sc) derivative of VEGF, in orthotopic breast cancer models. scVEGF-PEG (polyethylene gycol)-DOTA conjugates containing 2.0-, 3.4-, or 5.0-kDa PEG linkers site-specifically conjugated to a cysteine-containing tag (Cys-tag) in scVEGF were radiolabeled with (177)Lu (scVEGF/(177)Lu) for in vivo studies. Human MDA231luc and mouse 4T1luc cell lines were injected orthotopically to establish breast carcinoma tumors in immunodeficient and immunocompetent hosts, respectively. The effects of scVEGF/(177)Lu were defined by analysis of changes in tumor growth and immunohistochemical staining for the endothelial markers CD31 and VEGFR-2 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining for intratumoral apoptosis. Biodistribution assays and dosimetric calculations established that scVEGF/(177)Lu with a 3.4-kDa PEG linker delivered the highest dose of radiation to tumors (69.9 cGy/MBq/g of tissue) and the lowest dose to the kidneys (33.3 cGy/MBq/organ). Total doses below 40 MBq/mouse of scVEGF/(177)Lu did not affect renal function, and 3 divided doses of 6.3 MBq/mouse or a bolus dose of 18.9 MBq/mouse induced only transient lymphopenia and weight loss (<10% baseline weight). In mice with orthotopic mammary breast carcinoma, intravenous injections of well-tolerated bolus and fractionated doses of scVEGF/(177)Lu in the range from 6.3 to 18.9 MBq/mouse (25-76 MBq/m(2)) resulted in dose-dependent tumor growth inhibition. Immunohistochemical analysis of tumors at 4-5 wk after single injections of scVEGF/(177)Lu indicated dose-dependent regression of tumor vasculature and widespread intratumoral apoptosis. A single dose of 7.4 MBq/mouse of scVEGF/(177)Lu given before a course of bevacizumab or sunitinib treatment enhanced the antiangiogenic effects of both drugs. Selective targeting of VEGFR in tumor vasculature with well-tolerated doses of scVEGF/(177)Lu is effective in orthotopic breast cancer models. As high levels of VEGFR expression in the tumor vasculature are a common feature in a variety of cancers, targeting tumor angiogenesis with scVEGF/(177)Lu warrants further exploration.

Abstract 2702: Renal cell carcinomas lack arginosuccinate synthetase expression and respond to pegylated arginine deiminase treatment

Abstract Biomarkers may be predictive of benefit from therapy. As a result, there is increasing interest in determining new biomarkers and new agents that may target specific pathways that are abnormal in a certain cancer. Normal cells produce arginine internally via the urea cycle. However, certain cancer cells lack one of the urea cycle enzymes, argininosuccinate synthetase (ASS) and become dependent upon an exogenous supply of arginine for growth and survival. For these ASS-deficient cancers, preferential killing of tumor cells induced by arginine deprivation may be effective and safe. ADI-PEG20 is a microbial enzyme, arginine deiminase conjugated with polyethylene gycol. The primary mechanism of action of ADI-PEG20 is arginine deprivation. Thus cancers that are deficient in ASS expression and require arginine could benefit from ADI-PEG20. ADI-PEG20 has been in phase 2 clinical trials for the treatment of hepatocellular carcinoma and metastatic melanoma. Patients whose cancers were deficient in ASS expression have demonstrated medical benefit from ADI-PEG20. Thus at least in these cancers, lack of ASS expression could serve as a biomarker to predict clinical benefit from ADI-PEG20. Other investigators have noted that human renal cell carcinoma (RCC) tissue specimens lack expression of ASS. To confirm these observations and investigate the extent of ASS deficiency in RCC, we analyzed biopsy samples obtained from 31 patients for ASS expression by immunohistochemistry and found all to be ASS negative. We also established three primary RCC cell lines and tested them for response to ADI-PEG20 treatment. Dose dependent growth inhibition was observed after 48 hours for all three cell lines using the MTS proliferation assay. We further tested three ATCC RCC cell lines, 786-O, ACHN and Caki-1 using the MTS assay and observed similar growth inhibition after 48 hours. Cell cycle analysis using the three primary RCC lines revealed that G1 arrest was apparent in samples treated with ADI-PEG20. After 48 hours of ADI-PEG20 treatment, the percentage of cells in G1 increased from 33% to 62%. These results suggest that ADI-PEG20 can potentially be an effective therapeutic agent for the treatment of RCC. They also suggest the potential utility of ASS expression as a biomarker in identifying patients that are most likely to benefit from the ADI-PEG20 treatment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2702.

Precipitation of bovine rotavirus by polyethylen glycol (PEG) and its application to produce polyclonal and monoclonal antibodies

Many protocols are available to produce monoclonal antibodies (MAbs) against bovine rotavirus (BRV) using purified virus particles but those methods are time-consuming and produce substantial loss of virus structure or infectivity. Polyethylene gycol (PEG) viral precipitation was investigated as a possible alternative method to obtain purified virus and viral antigen for monoclonal and polyclonal antibodies production. The antigenic mass inoculated into rabbits was sufficient to obtain a polyclonal hyperimmune serum with neutralizing activity and a wide range of humoral responses to different viral proteins with minimum cellular contamination. This antigenic mass inoculated into mice was capable of producing seven MAbs with different biochemical characteristics (Western-blot; indirect immunofluorescence and serum neutralization assays). When evaluated as diagnostic tools to detect BRV antigen in feces the MAbs were effective for detecting rotavirus in naturally infected calves. This work demonstrate that PEG precipitation could be an useful procedure for obtaining viral antigen to produce polyclonal and MAbs against BRV. The antigenic mass obtained, the viral infectivity, and the conserved protein pattern suggest that this methodology could be applied to this and to other viruses, reducing time or possible loss of antigens involved in viral purification.

Molecular thermodynamic properties of protein solutions from partial specific volumes

AbstractPartial specific volumes at 25°C are reported for α‐chymotrypsinogen in aqueous solutions containing NaCl, citrate, and/or polyethylene gycol (PEG) over a range of protein concentrations. The concentration dependence of the partial specific volume can be either positive or negative, depending on the solvent. For example, the partial specific volume increases with increasing protein concentration in NaCl/citrate solutions at high salt concentrations, and decreases with increasing protein concentration in solutions containing PEG. Kirkwood‐Buff solution theory has been applied to interpret these results, and it was found that the concentration dependence is determined by two factors: (1) the effective or solvent‐averaged interactions between protein molecules in solution, and (2) three‐body protein – protein – solvent and protein – solvent ‐ solvent interactions. An approach is proposed for the experimental determination of both contributions that involves measuring osmotic pressures and volumetric properties of dilute to concentrated protein solutions.

Liposome-mediated transformation of streptomycetes by chromosomal DNA.

Transformation is a process of unidirectional transfer of genetic information in which DNA originating from one cell is taken up by another and stably maintained1. Among the actinomycetes, probably the most interesting and important genus of bacteria, there is only one convincing description of transformation by chromosomal DNA2. It has been suggested that the absence of such transformation in streptomycetes may be due to the production of extracellular DNase3. DNA encapsulated in liposomes is resistant to the action of DNases and liposomes can be made to fuse with cells by treatment with polyethylene gycol (PEG)4. Here we describe the fusion of liposomes containing chromosomal DNA with protoplasts of streptomycetes, resulting in the formation of genetically characterized transformants.