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PubMedDate not supplied

Comparison of coatings from reactive star shaped PEG-stat-PPG prepolymers and grafted linear PEG for biological and medical applications.

Grafting of poly(ethylene glycol) (PEG) is a common strategy for reducing nonspecific interactions of surfaces with proteins. We have used grafting at "cloud point" solution conditions that ensures maximum grafting density of linear methoxy terminated PEG-aldehyde (mPEG-ald, M(w) = 5000 and 30000). In an alternative approach, surfaces were modified with layers prepared from isocyanate terminated, star shaped poly(ethylene glycol-stat-propylene glycol) prepolymers (80% ethylene glycol, six arms, M(w) = 3000, 12,000, and 18,000; this compound will be referred to as "Star PEG" in the text). Due to the highly reactive endgroups, these molecules form a dense network on the substrate with a high polymer surface coverage. The two systems were compared regarding their ability to prevent unspecific adsorption of insulin and lysozyme. The layers were analyzed by ellipsometry, contact angle measurements, and XPS. Protein adsorption was monitored by surface MALDI-TOF MS and fluorescence microscopy. No protein adsorption could be detected on Star PEG coatings and on mPEG-ald 5000, whereas mPEG-ald 30,000 could only prevent adsorption of lysozyme but not of the smaller insulin.

Adsorption↗
PubMed2000

PEG-dichlorotriazine (PEG-DCT): A new soluble polymer-supported scavenger for alcohols, thiols, phosphines, and phosphine oxides

Trichlorotriazine was reacted with MeO-PEG-OH (M(w) 5000) to give a PEG-dichlorotriazine (PEG-DCT) that was used as a soluble electrophilic scavenger. PEG-DCT was added at the end of reactions to completely remove nucleophilic reactants or byproducts. The soluble polymer sequestered alcohols, thiols, triphenylphosphine, and triphenylphosphine oxide.

Journal Article↗
PubMed1998

Megakaryocyte progenitors derived from bone marrow or G-CSF-mobilized peripheral blood CD34 cells show a distinct phenotype and responsiveness to interleukin-3 (IL-3) and PEG-recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF).

In the present study we investigated the proliferative response of megakaryocyte progenitor cells (CFU-MK) derived from peripheral blood stem cell (PBSC) collections of patients with haematological malignancies and normal donors. Highly purified CD34+ cells and mononuclear cell fractions were assayed in the presence of recombinant interleukin-3 (IL-3) and pegylated-recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF), alone or in combination, and megakaryocyte colony formation was evaluated in the plasma clot. In comparison, steady-state bone marrow samples from normal donors were highly enriched in CD34+ cells and tested with the cytokines studied. Our results showed that IL-3 was able to stimulate CFU-MK colony formation from bone marrow and peripheral blood CD34+ cells. Similarly, PEG-rHuMGDF stimulated, in a dose-response manner, CD34+ cells from the bone marrow. However, normal mobilized peripheral blood CD34+ cells were not induced to generate CFU-MK colonies by PEG-rHuMGDE The same lack of response was observed when patients peripheral blood CD34+ cells primed with chemotherapy plus G-CSF or with G-CSF alone were assessed. In contrast, PEG-rHuMGDF stimulated CFU-MK growth when mononuclear cells, either from the bone marrow or from mobilized peripheral blood, were grown in plasma clot. Moreover, we analysed by flow cytometry the expression of Mpl receptor on the cell membrane of normal mobilized peripheral blood and normal steady-state bone marrow CD34+ cells. Our results showed a reduced expression of Mpl receptor on mobilized peripheral blood progenitor cells in comparison with bone marrow cells.

Antigens, CD34↗
PubMedDate not supplied

The effect of PEG concentration on the release rate of cisplatin from PEG-modified silica xerogels.

Cisplatin-an antineoplastic medicine-was incorporated into a polyethylene glycol (PEG)-modified silica xerogels received by the sol-gel method. The influence of PEG concentration and drying temperature on the release of cisplatin was studied. From our results we may state that addition of PEG (MW 600) and drying of silica xerogels at 80 degrees C augmented the release of cisplatin. The release of cisplatin from the matrices grows with the increase of PEG volume in xerogel (up to 74-97% within 7 days), whereas application of thermal drying resulted in both increased speed and amount of the drug released up to 91-97% within 2 days.

Antineoplastic Agents↗
PubMed1986

Gastrointestinal permeability in children with cow's milk allergy: effect of milk challenge and sodium cromoglycate as assessed with polyethyleneglycols (PEG 400 and PEG 1000).

Sixteen children with immediate-type cow's milk allergy were challenged with increasing amounts of cow's milk. Gastrointestinal permeability was investigated before and after challenge by the 6-hr urinary recovery of a mixture of different-sized polyethyleneglycols (PEG 400 and PEG 1000). The results were related to clinical symptoms in the individual patients. The majority of the children displayed changed permeability characteristics after the challenge, both with respect to the maximum uptake of a small test molecule (usually 370 dalton PEG) and/or a large molecule (1074 dalton PEG), and to size-dependent exclusion of probe molecules. When corrected for the dose of milk taken, the children showing the most severe immediate-type symptoms also displayed the greatest alteration of permeability. Treatment with sodium cromoglycate (SCG) before the challenge diminished the effect on the uptake of probe molecules, usually decreased the severity of elicited symptoms, allowing about a ten-fold increase in the milk dose. Cow's milk challenge in healthy children caused only minor permeability changes, whereas challenge in the sensitized subjects significantly changed (increased or decreased) the recovery of a large test molecule. The difference between healthy and allergic subjects was most obvious when correcting for dose of milk ingested. We conclude that oral challenge with cow's milk in allergic subjects affects the mucosal barrier, and peroral treatment with SCG moderates immediate hypersensitivity reactions with respect to both tolerated antigen dose and intestinal permeability properties.

Administration, Oral↗
PubMed2002

[Primary operative gastrostomy or percutaneous endoscopic gastrostomy (PEG) in progressive oesophageal carcinomas? A case report on abdominal wall metastases following PEG].

INTRODUCTION: Percutaneous endoscopic gastrostomy (PEG) is a safe and easy procedure used to provide enteric nourishment in patients with non-operable, constricting, malignant tumors of the oropharynx or esophagus. However, as a late complication, the development of abdominal wall metastases have been described, the mechanism of which is controversially. PATIENTS AND METHODS: We describe two cases in which abdominal wall metastases developed 9 and 14 months, respectively, following PEG. Both patients suffered from an advanced esophageal carcinoma. One patient had to undergo surgery because of the size of the metastasis. This was followed by several weeks of hospital treatment. The second patient was already in a prefinal condition so that no surgical procedure was performed. Reviewing the current literature, we discuss the question of whether, in certain cases, an operative gastrostomy should be preferred to a PEG. RESULTS: As in our opinion the reason for abdominal wall metastases is direct tumor seeding, we suggest that in certain cases, in order to avoid a possible metastasis resection, an operative gastrostomy should be discussed. This is particularly relevant if the tumor is constricting with a high risk of losing tumor cells. If possible, a minimal-invasive method is to be preferred.

Abdominal Neoplasms↗
PubMed2006

Dexamethasone nano-aggregates composed of PEG-PLA-PEG triblock copolymers for anti-proliferation of smooth muscle cells.

Dexamethasone nano-aggregate was prepared for the treatment of intimal hyperplasia caused by abnormal proliferation of smooth muscle cells. Triblock copolymers composed of poly(ethylene glycol) [PEG] and poly(D,L-lactic acid) [PLA] were synthesized with different chain lengths of PEG. Triblock copolymers in organic phase were mixed with dexamethasone and dexamethasone nano-aggregates was prepared by dispersing the organic phase into water. The average diameter of the nano-aggregates ranged from 200 to 300 nm. Dexamethasone was released out from the nano-aggregates and the release profile was dependent on PEG chain lengths. The dexamethasone nano-aggregates showed superior anti-proliferation effects on smooth muscle cells compared to dexamethasone. Flow cytometry showed that smooth muscle cells treated with dexamethasone nano-aggregates was arrested at a dormant phase in a dose-dependent manner. The dexamethasone nano-aggregates are expected to be a potent candidate for anti-proliferating smooth muscle tissues after a balloon-catheter treatment.

Animals↗
PubMed1994

Degradation of O6-benzylguanine in aqueous polyethylene glycol 400 (PEG 400) solutions: concerns with formaldehyde in PEG 400.

The degradation of O6-benzylguanine (BG) in aqueous polyethylene glycol (PEG) 400 solution at room temperature had been investigated using chromatographic and spectrometric methods. The degradation of BG in this solvent appeared to arise from a reaction between BG and formaldehyde. The formaldehyde was present as an impurity in PEG 400 and probably formed through air oxidation of PEG 400. The major product of this reaction was believed to be a methylene-bridged compound containing two BG molecules. This was probably produced via an intermediate imine, a schiff base between one BG molecule and formaldehyde. This degradation reaction was the only observable reaction in the 40% PEG/water solvent (pH 8.0) i.e. degradation of the drug via hydrolysis was minimal under these conditions.

Chromatography, High Pressure Liquid↗
PubMed1977

Measurements of intestinal permeability using low molecular weight polyethylene glycols (PEG 400). I. Chemical analysis and biological properties of PEG 400.

A new approach to the measurement of intestinal permeability in man has been developed, using low molecular weight polyethylene glycol (PEG 400) as probe molecules. PEG 400 (range of molecular weight 232 to 594) is a mixture of water-soluble molecules of different sizes which can be extracted readily from biological fluids and analyzed by gas-liquid chromatography. PEG 400 is nontoxic, not degraded by intestinal bacteria, not metabolized after absorption, and rapidly excreted in urine. The different-sized molecular components cross the intestinal epithelium at different rates, allowing characterization of the passive permeability properties of the mucosa.

Animals↗
PubMed1985

Gastrointestinal permeability in atopic and non-atopic mothers, assessed with different-sized polyethyleneglycols (PEG 400 and PEG 1000).

Gastrointestinal permeability was compared in seventy-one women, forty-six allergic and twenty-five non-allergic according to case history, by measuring the 6-hr urinary recovery after an oral load of different-sized polyethyleneglycols (PEG 400 and PEG 1000). Further classification, atopic and non-atopic, was obtained by skin-prick tests to inhalant and food allergens in sixty-four of the seventy-one mothers. No significant differences were observed between allergic and non-allergic women, neither regarding the maximum recovery nor the recovery ratio between a large and a small molecule. The results do not lend support to the hypothesis of a persistently increased gut permeability in atopic subjects, which in turn could possibly imply an increased risk of intrauterine sensitization of the foetus of an atopic mother.

Adult↗
PubMed1998

Preparation, characterization, and dissolution studies of ibuprofen solid dispersions using polyethylene glycol (PEG), talc, and PEG-talc as dispersion carriers.

Solid dispersions of ibuprofen (IBF) were prepared by solvent evaporation method using polyethylene glycol 10000 (PEG), talc, and PEG-talc as dispersion carriers. The drug-carrier(s) interactions in the solid state were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and x-ray diffraction analysis. Interactions in the solution were studied by performing dissolution experiments. No important and well-defined chemical interaction was found between the ingredients. The increase in the IBF dissolution rate from the solid dispersions with the carriers used in this study could be attributed to several factors such as improved wettability, local solubilization, and drug particle size reduction.

Calorimetry, Differential Scanning↗
PubMed2006

To PEG or not to PEG: a review of evidence for placing feeding tubes in advanced dementia and the decision-making process.

Percutaneous endoscopic gastrostomy (PEG) has evolved into a common low-risk procedure in current medical practice. Clinical evidence supporting the use of tube feedings in patients with advanced dementia is clearly lacking, yet PEG procedures continue to be performed in a large number of these cases. In fact, multiple studies have shown that feeding tubes seldom are effective in improving nutrition, maintaining skin integrity by increased protein intake, preventing aspiration pneumonia, minimizing suffering, improving functional status, or extending life. The decision-making process is complicated, however, and involves the clinician considering such issues as advance directives, ethical considerations, legal/financial concerns, emotional factors, cultural background, religious beliefs, and the need for a family meeting incorporating all of these principles.

Advance Directives↗
PubMed2001

Lewis acid catalysis in a supercritical carbon dioxide (scCO2)-poly(ethylene glycol) derivatives (PEGs) system: remarkable effect of PEGS as additives on reactivity of Ln(OTf)3-catalyzed Mannich and aldol reactions in scCO2.

Use of poly(ethylene glycol) derivatives (PEGs) as additives in supercritical carbon dioxide (scCO2) was found to be effective for Mannich and aldol reactions of silyl enolates with aldehydes and imines, and formation of emulsions was observed in these systems.

Journal Article↗
PubMed1982

Effect of food on the bioavailability of griseofulvin from microsize and PEG ultramicrosize (GRIS-PEG) plain tablets.

Effect of food on the bioavailability of griseofulvin from its two plain tablets, a commercial microsize product and a PEG ultramicrosize (GRIS-PEGR) one, was investigated. The drug was dissolved at a slower rate from ultramicrosize formulation than from microsize one in 18 1 of pH 7.2 buffer but at a little faster rate in 40% dimethylformamide. When administered to fasting subjects, the microsize product showed higher serum levels and peak serum level than ultramicrosize one but the extent of the bioavailability was nearly the same. A standard breakfast enhanced the rate of absorption of the drug from both the products, especially from ultramicrosize one, and those products were equivalent in the rate and extent of bioavailability after food ingestion. The peak serum level of ultramicrosize product in nonfasting was about twice higher than that in fasting subjects. The different intensities of food effect on the bioavailabilities from two dosage forms suggest that formulation factors should be considered for the evaluation of food effect.

Adult↗
PubMed2006

Optimization of preparation of DHAQ-loaded PEG-PLGA-PEG nonaparticles using central composite design.

Mitoxantrone (DHAQ)-loaded poly (ethylene glycol)-poly (lactic acid-co-glycolic acid) -poly (ethyleneglycol) (PELGE) nanoparticles (NP) were fabricated using an emulsification/solvent evaporation technique. A central composite design (CCD) was applied to evaluate the joint influence of three formulation variables: the amounts of polymer, concentration of the DHAQ, and the ratio of the organic phase (inner-phase) and the aqueous phase (outer-phase). In this study, we optimize the preparation technology on the basis of the single factor evaluation. The optimal conditions for the preparation of DHAQ-loaded nanoparticle were found to be: the concentration of PELGE was 9 mg/mL, the concentration of inner-phase of DHAQ was 27.5 mg/L, and the ratio of inner-phase/outer-phase was 8.5/1. The results showed that CCD is an ideal technique for formulation studies. The entrapment efficiency ratio (ER) was 90% and particle sizes are less than 500 nm. The nanoparticles, as examined by transmission electron microscopy (TEM), have a smooth and spherical surface. The DHAQ could be loaded into PELGE copolymers. In this study, the DHAQ nanoparticle-polymer delivery system was established by using PELGE polymers as carrier material.

Biocompatible Materials↗