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At least 361 records · Page 20Linked to original sources
PubMed2001

Migration of 4-nonylphenol from polyvinyl chloride food packaging films into food simulants and foods.

Migration of 4-nonylphenol (NP) from polyvinyl chloride (PVC) films for food packaging into food simulants and foods has been studied in domestic applications such as wrapping of food and reheating in a microwave oven. The migration of NP from the PVC films was determined by high-performance liquid chromatography with electrochemical coulometric-array detection (LC/ED). Twelve PVC films intended for commercial use and ten for domestic applications (total: 22 samples) were analysed. Some of the PVC films (two home-use and ten retail-use) contained NP at concentrations of between 500 and 3300 microg/g. Migration of NP from the films was influenced by the test conditions (n-heptane at 25 degrees C for 60 min, distilled water at 60 degrees C for 30 min and 4% acetic acid at 60 degrees C for 30 min). The amount of NP migrating from the PVC films into n-heptane (0.33-1.6 microg/cm2) was higher than the amount migrating into distilled water or 4% acetic acid (up to 9.7 ng/cm2) for the 11 films in which NP was detected. Up to 0.23% of the NP migrated into distilled water and 4% acetic acid and up to 62.5% into n-heptane. In addition, we investigated NP migration into cooked rice samples wrapped in PVC film. Using spiked samples the method gave an average recovery of 83.7% (n = 5) with a standard deviation of 2.5%. Migration of NP ranged from not detectable (< 1.0 ng/g) to 410.0 ng/g by reheating samples in a microwave oven for 1 min and from not detectable to 76.5 ng/g by keeping samples at room temperature for 30 min.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Fatty acid substituted polyvinyl alcohol as a supporting material for microsphere preparation.

Polyvinyl alcohol, substituted with lauric, myristic, palmitic, and stearic acids at different substitution degrees was employed for the preparation of biodegradable microspheres containing progesterone or indomethacin. A solvent extraction/method was followed, starting from an oil-in-water dispersion containing the polymer and drug in the inner phase. Microspheres were obtained with high loading efficiency, whose release properties were dependent on the nature of the acyl substituent and the substitution degree. Kinetics approaching zero-order were obtained for the most hydrophile microspheres such as those based on the least substituted polymers and lowest molecular weight substituents. The hydrophilicity of these systems hindered protein absorption on their surface, suggesting their suitability for parenteral use.

Adsorption↗
PubMed2006

Assessment of control strategies for reducing volatile organic compound emissions from the polyvinyl chloride wallpaper production industry in Taiwan.

This study attempts to assess the effectiveness of control strategies for reducing volatile organic compound (VOC) emission from the polyvinyl chloride (PVC) wallpaper production industry. In Taiwan, methyl ethyl ketone, TOL, and cyclohexanone have comprised the major content of solvents, accounting for approximately 113,000 t/yr to avoid excessive viscosity of plasticizer dioctyl phthalate (DOP) and to increase facility in working. Emissions of these VOCs from solvents have caused serious odor and worse air quality problems. In this study, 80 stacks in five factories were tested to evaluate emission characteristics at each VOC source. After examining the VOC concentrations in the flue gases and contents, the VOC emission rate before treatment and from fugitive sources was 93,000 and 800 t/yr, respectively. In this study, the semiwet electrostatic precipitator is recommended for use as cost-effective control equipment.

Air Pollutants↗
PubMedDate not supplied

Evaluation of polyvinyl acetate dispersion as a sustained release polymer for tablets.

Kollicoat SR 30D is a unique 30% aqueous dispersion of polyvinvyl acetate stabilized by polyvinyl-pyrrolidone intended for preparation of sustained release products. Detailed evaluation of this polymer dispersion as a sustained release coating for active pharmaceutical ingredients of two diverse classes of drugs was studied. A water insoluble drug (ibuprofen) and a water soluble drug (ascorbic acid) were selected as model active drugs. Ibuprofen was granulated using a GPCG-1 fluid bed processor prior to tableting, to improve the particle size and particle flow properties. In this process a 2(3) factorial design was implemented to evaluate the optimum process parameters such as spray rate, inlet air temperature and the inlet air velocity. The statistical model selected was Y(ijkl) = mu + tau(i) + beta(j) + theta(k) + (taubeta)ij + (betatheta)jk + (tautheta)ik + (taubetatheta)ijk + epsilon(ijkl). The factorial design showed that the spray rate, inlet air temperature, and inlet air velocity had a significant effect (p value <0.05) on the particle size. Significant improvement was observed in the flow properties of the granules. The granules were coated with Kollicoat SR30D dispersion using top spray method in the fluid bed processor. The dissolution studies showed that the release of ibuprofen decreased with an increase in the coating levels of Kollicoat SR 30 D. In the case of ascorbic acid, preparation of sustained release coated commercial granules was not possible due to the difficulty in coating a highly soluble drug particle. However, the coated granules when compressed into tablets showed some sustainability. Ibuprofen tablets manufactured with coated granules with a 15 g polymer for 300 g batch showed dissolution parameters of t50 and t90 at 4.2 hr and 7.5 hr, respectively. An approximate zero-type of release was observed when the polymer content was increased to 45 g for 300 g batch. Ascorbic acid tablets made with coated commercial granules having a total polymer content of 45 g per a 500 g batch showed an average dissolution t50 and t90 at 1.0 hr and 4.55 hr, respectively. When the total polymer content was increased to 60 g, per 500 g, the average dissolution t50 and t90 delayed to 1.40 hr and 7.20 hr, respectively.

Analysis of Variance↗
PubMedDate not supplied

Micelles based on polyvinyl alcohol substituted with oleic acid for targeting of lipophilic drugs.

Polymeric micelles based on polyvinyl alcohol substituted with oleic acid were used as vehicles for progesterone and folic acid. The ability of this amphiphilic polymer to entrap lipophilic drugs and to generate stable micelles in aqueous neutral medium makes it a good candidate for drug delivery. The release of the loaded drugs in acidic environments represents another important property of these systems. Size of micelles, their stability, and their drug-loading capacity were evaluated, as well as the in vitro controlled-release profiles at pH 7.4 and 5.5.

Drug Delivery Systems↗
PubMed2006

Immobilization of pancreatic lipase on polyvinyl alcohol by cyanuric chloride.

Porcine pancreatic lipase (EC 3.1.1.3) was covalently immobilized onto 2,4,6-trichloro-s-triazine (cyanuric chloride) activated polyvinyl alcohol (PVA). The influence of activating agent and enzyme concentration on the immobilization process were evaluated. Hydrolytic activities of free and immobilized enzyme were determined and the immobilization yield was estimated by measuring the quantity of protein, both in free enzyme solution and in washing solutions after immobilization. After the optimization of immobilization process, the physical and chemical characterization of immobilized enzyme was performed. Additionally, the thermal, pH, storage, and operational stability of the immobilized and free enzymes were tested. Obtained data showed that the immobilized enzyme seemed better and offered some advantages in comparison with free enzyme.

Animals↗
PubMed2002

In vitro toxicity assessment of polyvinyl chloride particles and comparison of six cellular systems.

Occupational exposure to polyvinyl chloride (PVC) dust has been occasionally associated with lung disease. Our aim was to evaluate the in vitro toxicity of various types of PVC particles in relevant cell culture systems. Six samples from the normal industrial suspension process (PVC-S) and eight samples from the emulsion process (PVC-E) were studied. Cytotoxicity was assessed, using the MTT assay, after 20 h of incubation in A549 cells and in primary cultures of alveolar macrophages (AM) and type II pneumocytes (TII) obtained from rats (r-AM, r-TII) or from human surgical specimens (h-AM, h-TII). Hemolysis was assessed after 2 h of incubation with human erythrocytes (h-RBC). A positive control (crystalline SiO(2), Min-U-Sil) and relevant additives of these PVC particles were tested concurrently. No toxicity of PVC-S particles could be established up to 5 mg/ml in the hemolysis test and 2.5 mg/ml in the MTT assay. In contrast, 4 out of 8 PVC-E particles induced significant toxicity, with EC50 values ranging from 0.7 to 3.7 mg/ml in the hemolysis test and from 0.2 to 1.2 mg/ml in primary cells. The most toxic particles were those that contained the additives with the highest in vitro cytotoxicity. There was a good correlation between EC50 values obtained in relevant bioassays. The sensitivity order of the cell systems was A549 < h-RBC approximately h-TII < or = h-AM < r-TII < or = r-AM for the particles. In conclusion, PVC-E particles produced a moderate in vitro toxicity for primary rat and human pulmonary cells, probably because of the residual presence of additives.

Aged↗
PubMed2000

Investigation of the mechanical properties of two polyvinyl alcohols and their influence on drug release.

The aim of this work was the investigation of the elastic behavior and the internal stress of two different polyvinyl alcohols (PVAs) and how their swelling behavior and drug release are influenced through internal stress. We used thermal mechanical analysis (TMA 202/1/F Netzsch-Germany) to make a qualitative evaluation of the internal stress and the elastic behavior of PVA 55/12 and 55/03. These two PVAs have the same molecular weight and different acetyl contents. The tablets were compressed with an instrumented eccentric tablet machine. Tablets from different PVAs showed different elastic behavior. The measured internal stress of PVA 55/12 was higher than that of PVA 55/03. By increasing the compaction force, the internal stress increased. The internal stress decreased as the humidity increased for both kinds of PVA. The expansion behavior in the diametrical and axial direction was significantly different due to the predominant orientation of the PVA crystals. PVA tablets that were thermal analyzed showed different swelling behavior from those that were not thermal analyzed. This can be caused by the released internal stress of thermal-analyzed tablets. The compaction behaviors of both PVAs were also investigated using different methods. PVA 55/03 had better compactibility and compressibility behavior. The drug release behavior was also investigated and showed that the drug release rate of PVA 55/12 was higher than that of PVA 55/03. This can be due to the different solubilities and elastic behaviors of the PVAs. TMA can be used to predict and evaluate elastic behavior and internal stress. Humidity can influence the internal stress of the tablet. The measured swelling of PVA was a combination of real swelling and the released internal stress. TMA also allowed prediction of the binding mechanism in tablets.

Chemistry, Pharmaceutical↗
PubMed2002

Biodegradation of polyvinyl alcohol by Phanerochaete chrysosporium after pretreatment with Fenton's reagent.

Polyvinyl alcohol (PVA) solutions (BP05 and BF17; 5.0%, wt v(-1)) were degraded by a combination of chemical (Fenton's reagent) and fungal (Phanerochaete chrysosporium) treatments. The overall degradations of BP05 and BF17 were 74.4 and 72.8%, respectively, as determined by chemical oxygen demand (COD) analysis, and 63.7% and 57.7%, respectively, as determined by total organic carbon (TOC) analysis. Increased retention times and changes in the intensity of the PVA peaks on gel permeation chromatograms indicated that PVA molecules of greater molecular weights were degraded to lower molecular weights by both the chemical and fungal treatments. The predominant enzyme secreted by P. chrysosporium in medium containing 2% (wt v(-1)) ground cereal bran in 60 mM phosphate buffer (pH 6.0) was manganese peroxidase. Neither laccase nor lignin peroxidase activity was detected. Manganese peroxidase was probably involved in the biodegradation of the PVA solutions.

Biodegradation, Environmental↗
PubMed2002

Studies on fixed-bed biosorption and elution of copper using polyvinyl alcohol-immobilized seaweed biomass.

Biosorption of copper by inactivated biomass of the brown marine alga Sargassum baccularia immobilized in polyvinyl alcohol (PVA) beads was investigated. PVA-immobilized biomass beads were packed in a laboratory-scale fixed-bed column and subjected to three consecutive cycles of copper loading and elution. Bound copper was eluted with solutions containing a range of ethylenediaminetetraacetic acid (EDTA) concentrations. Up to 100% of the bound copper was consistently recovered from immobilized biomass using an aqueous solution containing 4mM EDTA in repeated loading/elution cycles. The PVA-immobilized biomass beads were shown to be robust and stable with little decrease in the copper uptake capacity under dynamic flow conditions. The excellent reusability of the new biosorbent could lead to the development of a viable metal removal technology.

Adsorption↗
PubMed2004

Polyvinyl alcohol--trypsin as a catalyst for amino acid ester synthesis in organic media.

The bovine trypsin-catalyzed synthesis of N-alpha-benzoyl-DL-arginine esters from N-benzoyl-DL-arginine were studied in various organic solvents. Trypsin was immobilized to polyvinyl alcohol (PVA) by adsorption from its aqueous solutions. Immobilized enzyme showed higher catalytic activities than free enzyme for amino acid esterification in ethanol. The yield of ester is strongly dependent upon the PVA/trypsin ratio and water content in the reaction medium. The rate and equilibrium constant of the ester formation reaction are also dependent on water content.

Adsorption↗
PubMed2001

Interpolymer complexation. II. Entrapment of ibuprofen by in-situ complexation between polyvinyl acetate phthalate (PVAP) and polyvinylpyrrolidone (PVP) and development of a chewable tablet formulation.

A new method involving in situ complexation between polyvinyl acetate phthalate (PVAP) and polyvinylpyrrolidone (PVP) has been developed for the entrapment of ibuprofen, a bitter tasting anti-inflammatory drug. The procedure involved dissolving ibuprofen in a thoroughly mixed aqueous alkaline solution of PVAP and PVP, and subsequently slowly adjusting the pH of the solution to 1 with dilute HCl. The yield of the entrapped product, and the percent entrapment of ibuprofen, were 85-90%, and 90-98%, respectively. The PVAP-PVP entrapped granules showed no bitter taste due to ibuprofen. The chewable tablets, prepared by mixing the granules with a cherry-flavored directly compressible tableting excipient, exhibited a release of less than 2% of ibuprofen in pH 1.2 buffer over a period of three hours. In pH 7.4, 100% of ibuprofen was released in six hours. The results presented show that in situ complexation between PVAP and PVP may be useful to produce palatable ibuprofen granules suitable for use in the development of chewable tablets.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1955

Studies on the generalized Shwartzman reaction. VI. Production of the reaction by the synergistic action of endotoxin with three synthetic acidic polymers (sodium polyanethod sulfonate, dextran sulfate, and sodium polyvinyl alcohol sulfonate).

Lesions indistinguishable from those of the generalized Shwartzman reaction occured in rabbits when a single intravenous injection of Gram-negative bacterial endotoxin was accompanied, or followed, by an injection of one of the following synthetic, heparin-like, acidic polymers-sodium polyanethol sulfonate, dextran sulfate, or sodium polyvinyl alcohol sulfonate. These reactions were produced by doses of polymer or of endotoxin which were without demonstrable effect when given singly. Heparin, in those similar to those previously shown to protect rabbits against the lesions of the generalized Shwartzman reaction, prevented the reaction to the combined injection of endotoxin and acidic polymers. Nitrogen mustard, which was previously shown to prevent the lesions of the generalized Shwartzman reaction from occurring after two intravenous injections of endotoxin, had no protective action against the lesions produced by the combined injection of endotoxin and polymer. Cortisone did not affect the reaction to endotoxin and polymer. The role of fibrinogen in the reaction under study is discussed in the paper which follows.

Animals↗
PubMed2000

Polyvinyl alcohol-Fricke hydrogel and cryogel: two new gel dosimetry systems with low Fe3+ diffusion.

Two new Fricke dosimeter gel systems with low diffusion rates have been developed for 3D radiation dosimetry purposes. Both systems consist of a solution of 20% (by weight) polyvinyl alcohol (PVA) in a 50 mM H2SO4 solution with 0.4 mM ferrous ammonium sulphate and xylenol orange (FX). The difference in the two gels is the way that the gelation process was initiated: either by bringing the temperature to (a) +5 degrees C or (b) -20 degrees C before returning them to room temperature. These gels are termed 'hydrogel' and 'cryogel', respectively. The hydrogel is optically transparent, and can be used with either optical or MRI detection methods for dosimetric imaging. The cryogel is rubbery in texture but opaque, so its internal Fe3+ concentration can only be measured with MRI. The hydrogel's optical attenuation coefficient is linear (r2 = 0.99) with dose from 0 to 20 Gy with a sensitivity of 0.106 cm(-1) Gy(-1) (at 543 nm). In terms of MR relaxation rate, the dose response for both the hydrogel and cryogel was linear (r2 = 0.99) with a sensitivity of 0.020 s(-1) Gy(-1) (at 1.5 T). The Fe3+ diffusion coefficient (at 20 degrees C) was measured to be 0.14 mm2 h(-1), which is significantly lower than similar preparations reported for porcine gelatin or agarose. The PVA-FX gels can be stored for long periods of time before exposure to radiation, since the auto-oxidation rate was 10 times less than that of gelatin-Fricke recipes. The new gels developed in this work are a significant improvement on previous Fricke gel systems.

Calibration↗
PubMed2005

Optical and acoustic properties at 1064 nm of polyvinyl chloride-plastisol for use as a tissue phantom in biomedical optoacoustics.

A novel optoacoustic phantom made of polyvinyl chloride-plastisol (PVCP) for optoacoustic studies is described. The optical and acoustic properties of PVCP were measured. Titanium dioxide (TiO2) powder and black plastic colour (BPC) were used to introduce scattering and absorption, respectively, in the phantoms. The optical absorption coefficient (mua) at 1064 nm was determined using an optoacoustic method, while diffuse reflectance measurements were used to obtain the optical reduced scattering coefficient (mu's). These optical properties were calculated to be mua = (12.818 +/- 0.001)ABPC cm(-1) and mu's = (2.6 +/- 0.2)S(TiO2) + (1.4 +/- 0.1) cm(-1), where ABPC is the BPC per cent volume concentration, and S(TiO2) is the TiO2 volume concentration (mg mL(-1)). The speed of sound in PVCP was measured to be (1.40 +/- 0.02) x 10(3) m s(-1) using the pulse echo transmit receive method, with an acoustic attenuation of (0.56 +/- 1.01) f(1.51+/-0.06)MHz (dB cm(-1)) in the frequency range of 0.61-1.25 MHz, and a density, calculated by measuring the displacement of water, of 1.00 +/- 0.04 g cm(-3). The speed of sound and density of PVCP are similar to tissue, and together with the user-adjustable optical properties, make this material well suited for developing tissue-equivalent phantoms for biomedical optoacoustics.

Acoustics↗
PubMed1988

Polyvinyl alcohol membrane permeability characteristics of 5-fluorouracil.

5-fluorouracil is a useful new treatment modality in the difficult glaucoma filtering patient. However, its use is attended by a high incidence of complications principally involving the corneal epithelium. The pharmacokinetics of this drug suggest that a sustained release delivery system might avoid many of these problems if it could produce therapeutic levels in the subconjunctival space while avoiding toxic levels in the cornea and other ocular structures. In vitro studies of release rates for polyvinyl alcohol membranes suggest that this material could form the basis of such a delivery system.

Delayed-Action Preparations↗
PubMed1999

Augmentation of thyroid-stimulating antibody-stimulated cyclic adenosine monophosphate response by polyethylene glycol, polyvinyl alcohol, and dextran; highly sensitive porcine thyroid cell thyroid-stimulating antibody assay.

Previously, we reported that 5% polyethylene glycol (PEG) (6000) augmented thyroid-stimulating antibody (TSAb)-stimulated cyclic adenosine monophosphate (cAMP) production in porcine thyroid cell (PTC) assay. This augmentation by PEG was specific to TSAb-stimulation. In this study we examined the effects of nonionic hydrophilic polymers such as PEG, polyvinyl alcohol (PVA), and dextran (DEX) on TSAb-stimulated cAMP production. We demonstrated that graded doses of PEG, PVA, and DEX augmented TSAb-stimulated cAMP productions; the prominent augmentations were observed with 5% PEG (20,000), 5% PEG (6000), 6% PEG (4000), 10% PVA, 14% DEX T-250, and 14% DEX T-70. PVA did not augment thyrotropin (TSH)-stimulated cAMP synthesis. Five percent PEG (20,000), 14% DEX T-250, and 14% DEX T-70 augmented TSH-stimulated cAMP synthesis very slightly. PEG, PVA, and DEX had no effects on the cAMP synthesis stimulated by GTPgammaS, forskolin, or pituitary adenylate cyclase activating polypeptide (PACAP), which stimulated adenylate cyclase. We also demonstrated that PEG, PVA, and DEX augmented the cAMP responses stimulated by small amounts (50 microL) of sera from Graves' patients; small amounts (50 microL) of sera could be used instead of purified immunoglobulin G (IgG). This may simplify the TSAb assay. We developed a highly sensitive simplified TSAb assay. PEG weakly augmented TSAb binding to isolated TSH receptor (thyrotropin-binding inhibitor immunoglobulin [TBII] increased slightly). The mechanisms of the augmentations of TSAb-stimulated cAMP productions by PEG, PVA, and DEX is not simply explained by increased binding of TSAb to the receptors. Some factors that enhance TSAb action at the receptor site are suggested.

Animals↗
PubMed1996

Loss of quinidine gluconate injection in a polyvinyl chloride infusion system.

The effect of a polyvinyl chloride (PVC) i.v. administration system on the availability of quinidine gluconate was studied. Quinidine gluconate diluted in 5% dextrose injection was administered intravenously to five healthy volunteers via conventional PVC infusion sets, and the subjects received oral quinidine sulfate two days later. The mean +/- S.D. oral bioavailability of quinidine was, unexpectedly, greater than 100% (147 +/- 44%). To test the possibility that this occurred because of reduced delivery of i.v. quinidine, the percentage of drug delivered via two systems was evaluated in simulation studies, one involving a conventional PVC administration set and the other a glass syringe attached to shorter PVC tubing and a winged i.v. catheter. Spectrophotometric analysis revealed a 5-7% reduction in absorbance associated with loss of quinidine in the PVC infusion bag and a further 34-38% reduction in absorbance attributable to quinidine loss in the PVC tubing. However, with the winged i.v. catheter system the loss was reduced to less than 3%. More than 40% of a dose of quinidine gluconate was lost when the drug was administered with a conventional PVC i.v. administration set. Drug loss was reduced by using a winged i.v. catheter and shorter tubing.

Administration, Oral↗