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At least 73 records · Page 4Linked to original sources
PubMed1983

[Transcatheteral embolization with polyvinyl alcohol--technic and experimental studies].

The article presents hardened polyvinyl alcohol foam (PVA) as embolisation material. PVA is well tolerated by the tissue and produces permanent vascular sealing. It is possible to achieve peripheral embolisation of arteries having a diameter of approx. 100 microns, as well as sealing of vessels with diameter of up to 8 mm. Pressed PVA is used for occluding larger vessels. This PVA re-assumes its original shape and dimensions in liquids, depending on their osmolarity and molecular size. Depending upon the pressure exercised, compression and re-expansion can be fourfold to tenfold.

Angiography↗
PubMed2006

Preparation, characterization and microhardness study of semi interpenetrating polymer networks of polyvinyl alcohol and crosslinked polyacrylamide.

Semi-IPNs based on polyvinyl alcohol (PVA) and crosslinked polyacrylamide (PAM) were prepared and characterized. Various compositions of semi-interpenetrating polymer networks (semi-IPNs) were prepared by varying concentrations of PVA, acrylamide (AM) and crosslinker N,N'-methylene bis acrylamide (MBA) in the feed mixtures and polymerized using a suitable redox system comprising of potassium persulphate and metabisulphite. The prepared semi-IPNs were characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. The prepared semi-IPNs were also investigated for microhardness measurements.

Acrylamides↗
PubMed1993

Evaluation of PDGF-BB, PDGF-AA, bFGF, IL-1, and EGF dose responses in polyvinyl alcohol sponge implants assessed by a rapid histologic method.

Polyvinyl alcohol sponge implants were used in rats, mice, and guinea pigs to determine dose responses of growth factors. Eight differently treated sponges per rat or guinea pig (4/mouse) were injected with test material on alternate days and evaluated at day 8. Much of the observed response occurred in and around the capsule and was manifest as densely cellular granulation tissue. Including this capsular response in a single histologic slide ranking system provided a more sensitive and faster method of assessing growth factor effects than measurement of connective tissue ingrowth alone. Clear dose responsive effects were seen with recombinant human PDGF-BB, PDGF-AA, bFGF, and IL-1 beta, while EGF gave a lesser response. Lipopolysaccharide did not affect the connective tissue response, alone or in combination with PDGF-BB. PDGF-BB was tested in each species, and the dose response characteristics were qualitatively and quantitatively similar across species.

Animals↗
PubMed2000

The accelerated polyvinyl-alcohol method for GSR collection--PVAL 2.0.

The polyvinyl-alcohol collection method (PVAL) is used in forensic practice to gather topographical information about gunshot residues (GSR) from the hands to decide if the subject has made use of firearms. The results allow a distinction between suicide and homicide. The only inconvenience of PVAL was that the procedure took about 60 min because three layers of liquid PVAL had to be applied and dried. Therefore, the collection method was only applied to corpses. The improved and accelerated PVAL 2.0 uses a sandwich technique. Cotton gauze for stabilization is moistened with a 10% PVAL solution. A solid film of PVAL (Solublon) is spread on the cotton mesh. The gauze is then modeled to the hand and dried with a hair dryer. After removing the cotton gauze, the traces are embedded in the water-soluble PVAL. The procedure does not take more than 15 min. The results demonstrate the qualities and advantages of PVAL: topographical distribution of GSR, highest gain of GSR, sampling of all other traces like blood, backspatter etc., and humidity does not reduce the gain. In addition, with the new PVAL 2.0 dislocation of GSR or contamination are excluded. PVAL 2.0 can also be applied on live suspects.

Autopsy↗
PubMedDate not supplied

Polyvinyl alcohol sponge for embolotherapy: particle size and morphology.

The size and morphology of particulate polyvinyl alcohol (PVA) sponge prepared by a blender technique for embolotherapy were analyzed by light and scanning electron microscopy. Techniques for preparation and sizing of PVA sponge particles are described. Two types of particulate material, differing in both size and morphology, were found. Large particles (greater than 50 micron) had irregular shapes and sharp, jagged edges. Smaller particles (2-50 micron) were more numerous. Attempts to characterize the smaller particles were unsuccessful. Preparation of PVA sponge particles using the blender technique is a viable choice in external carotid neuroembolization procedures. However, the potential effects of small particles possibly causing cranial nerve palsies does need consideration.

Animals↗
PubMed2002

Laccase stabilization by covalent binding immobilization on activated polyvinyl alcohol carrier.

AIMS: Attempts were made to immobilize laccase from Panus conchatus. METHODS AND RESULTS: The laccase was immobilized on carboxylated polyvinyl alcohol (PVA) activated by N-hydroxysuccinimide (N-HSI) in aqueous solution at different pHs, temperatures, and with different reaction times. An optimum condition for laccase immobilization is at pH 3.2, 40 degrees C and 12 h, respectively. Immobilization of laccase increased optimal pH for reaction with 2, 2'-azinobis (3-ethylbenzthiazoline-6-solfonate) (ABTS) and pH stability. Immobilized laccase proved to be reacted consecutively 17 times with only a 50% decrease on activity and be used in removal of 2,4,6-trichlorophenol (TCP). CONCLUSIONS: It was possible to immobilize the laccase on carboxylated polyvinyl alcohol by activation with N-hydroxysuccinimide in HAc-NaAc buffer. The immobilized laccase is both stable and reusable. SIGNIFICANCE IMPACT OF THE STUDY: The results indicate that this immobilized laccase can be used in the removal of poisonous effluent from pulp bleaching mills.

Basidiomycota↗
PubMed2002

Uterine artery embolization in sheep: comparison of acute effects with polyvinyl alcohol particles and calibrated microspheres.

PURPOSE: To compare the effects on the myometrium of polyvinyl alcohol (PVA) particles and calibrated microspheres (MS) in embolization of the uterine arteries in sheep. MATERIALS AND METHODS: Superselective and bilateral embolization of the uterine arteries was performed with PVA particles and calibrated MS within 24 hours after artificial ovulation in 26 adult nonpregnant sheep. PVA particles of four diameters, 150-250, 250-400, 400-600, and 600-1,000 microm, were compared with calibrated MS of similar diameters, 100-300, 300-500, 500-700, and 700-900 microm, in eight groups of sheep. Evaluation was based on histopathologic study of uterus, ovaries, and vascular pedicles after sacrifice 5 days after embolization. The scores of necrosis, the diameter of occluded arteries, and the number of particles were determined. The scores of uterine necrosis were compared by using nonparametric tests (Mann-Whitney U and Kruskal-Wallis). Spearman rank test was used for correlations. RESULTS: PVA particles clumped more readily than did MS. Small particles had a higher score (P =.02) of uterine necrosis than did large particles. PVA particles produced more necrosis than did MS. Size of MS and diameter of occluded arteries showed significant correlation (rho = 0.762, P <.001). Size of PVA particles and diameter of occluded arteries showed no correlation. PVA particles occluded vessels of a wider range of size than did calibrated MS. CONCLUSION: PVA particles are associated with intense uterine necrosis and extensive arterial occlusion regardless of size. Calibrated MS, which are associated with less uterine necrosis, permit a segmental arterial occlusion correlated with size.

Angiography↗
PubMed1988

Immobilization of a primary amine-containing drug, adriamycin. Coupling to crosslinked polyvinyl alcohol and mechanistic comparison of hydrolytic stability.

Literature reports have described the covalent coupling of the primary amine-containing anticancer drug, adriamycin, to polymeric supports through the amine group on the drug. These reports also have described drug mechanism studies with the immobilized adriamycin, where the release of the drug would undermine the validity of the conclusions. In the present paper, detailed experimental conditions are given for preparation of nonwater-soluble particles of polyvinyl alcohol by crosslinking water-soluble polyvinyl alcohol with 1,4-benzenedicarboxaldehyde, and for activation with cyanuric chloride and covalent attachment of adriamycin. The expected stability of this drug-support linkage against hydrolytic cleavage is compared mechanistically to that expected for less stable coupling through a carbamate linkage or for less stable coupling via an azomethine link.

Doxorubicin↗
PubMed1983

Comparison of polyvinyl alcohol- and formalin-preserved fecal specimens in the formalin-ether sedimentation technique for parasitological examination.

A total of 965 paired fecal specimens preserved in polyvinyl alcohol fixative and Formalin were processed by the Formalin-ether sedimentation technique. The effectiveness of the concentration procedures with material from each preservative was determined by comparing both diagnostic efficiency (percent identified) and quantitative egg and semiquantitative cyst counts. Of the 319 infections, 69.5% were detected in concentrates from both preservatives, 6.9% from polyvinyl alcohol only, and 23.5% from Formalin only. The egg and cyst counts were consistently higher from the specimens preserved in Formalin for most of the species of organisms recovered. These findings strongly support the use of Formalin-fixed specimens for the Formalin-ether concentration technique.

Ether↗
PubMed2005

Percutaneous right portal vein embolization with polyvinyl alcohol particles in gastric cancer metastasis: report of a case.

Polyvinyl alcohol (PVA) particles are used for the embolization of various vascular tumors. They are also used before hepatic resection to embolize the ipsilateral portal vein, causing hypertrophy of the remaining liver. We report our first experience with portal vein embolization (PVE) with PVA particles to treat gastric cancer metastasis to the liver. PVE with PVA is a safe interventional radiologic procedure, which does not cause problems during surgery and can improve the outcome of hepatic resection.

Embolization, Therapeutic↗
PubMed1998

Spectroscopic manifestations of flavomononucleotide dimers in polyvinyl alcohol films.

Absorption and fluorescence spectra of flavomononucleotide (FMN) in polyvinyl alcohol films (PVA) over a very wide concentration range are investigated. The dimerization constant as well as the pure monomer and dimer spectra are calculated and the structural parameters of FMN dimer are established. Excitation wavelength and temperature dependencies of FMN/PVA fluorescence spectra for different FMN concentrations were carried out. These measurements together with those of absorption reveal that dimers are imperfect traps for excitation energy and that the energy transfer can occur both in forward and in reverse direction. Moreover, it was shown that the observed temperature changes in fluorescence spectra may be qualitatively explained by the effect of inhomogeneous broadening of FMN energy levels and by the presence of fluorescent dimers.

Dimerization↗
PubMed2004

[Applications of polyvinyl alcohol in modern preparations of TCM].

As a drug additive, polyvinyl alcohol(PVA) has merits of solubility, easy forming, strong conglutination, high thermal stability, low toxicity and no irritation. In these years, PVA has been applied wider and wider in medicine industry. In the study of modem preparations of TCM PVA, as film material of membrane and pellicles, is very promising owing to its easy forming and excellent toughness. PVA is good polymer matrix for suppositories and gel, because it can not only carry drug but also improve the properties of preparations on application and technology. It can be said that PVA is an excellent carrier. At the present, PVA is mainly applied in vitro preparations of TCM, but its applications will be spread with further research. The prospective applications of PVA in osmotic pump controlled release preparations, drug carried microspheres and swelling controlled release system are foreseen.

Delayed-Action Preparations↗
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↗
PubMed2004

Ester synthesis catalyzed by Mucor miehei lipase immobilized on magnetic polysiloxane-polyvinyl alcohol particles.

Mucor miehei lipase was immobilized on magnetic polysiloxane-polyvinyl alcohol particles by covalent binding with high activity recovered. The performance of the resulting immobilized biocatalyst was evaluated in the synthesis of flavor esters using heptane as solvent. The impact on reaction rate was determined for enzyme concentration, molar ratio of the reactants, carbon chain length of the reactants, and alcohol structure. Ester synthesis was maximized for substrates containing excess acyl donor and lipase loading of 25 mg/mL. The biocatalyst selectivity for the carbon chain length was found to be different concerning the organic acids and alcohols. High reaction rates were achieved for organic acids with 8 or 10 carbons, whereas increasing the alcohol carbon chain length from 4 to 8 carbons gave much lower esterification yields. Optimal reaction rate was determined for the synthesis of butyl caprylate (12 carbons). Esterification performance was also dependent on the alcohol structure, with maximum activity occurring for primary alcohol. Secondary and tertiary alcohols decreased the reaction rates by more than 40%.

Alcohols↗
PubMed1990

[A polyvinyl alcohol (PVA) hydrogel as a soft contact lens material].

A transparent polyvinyl alcohol (PVA) hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water miscible organic solvent by cooling. The physical properties were evaluated in comparison with commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methyl methacrylate (MMA) and N-vinyl pyrrolidone (VP). The PVA hydrogel showed higher tensile strength and elongation at break than the other materials, while it had high water content and oxygen permeability the latter being comparable to those of PMMA/VP copolymers. The protein adsorption of the PVA hydrogel was much less than those of the other materials. The PVA hydrogel soft contact lenses were applied on rabbit eyes for 12 weeks. The influence on the cornea was studied by biomicroscopy, ultrasonic corneal pachymetry and histopathological examination. These examinations revealed no abnormal findings in the cornea. These results suggest that the PVA hydrogel may be promising as a new soft contact lens material.

Adsorption↗
PubMed2001

Long-term implantation test and tumorigenicity of polyvinyl alcohol hydrogel plates.

Two types of flat plates made from a polyvinyl alcohol (PVA) hydrogel with a water content of 80 and 20 (PVA-H80, PVA-H20), 20 x 10 x 1 mm in size, were subcutaneously implanted into each of 50 young, male Wistar rats. As a control, a sham operation was done on another set of 50 rats (Sham Op group). The shape and transparency of the PVA hydrogel were unchanged for up to 24 months. Tumors arose in 14 rats from the PVA-H80 group. In the PVA-H20 group, tumors appeared in 15 rats. The average tumor latency was 598 +/- 109 days in the PVA-H80 and 637 +/- 94 days in the PVA-H20. There was no difference in tumor incidence between the PVA-H20 and PVA-H80 groups (p < 0.05). In the Sham Op group, no malignant tumors appeared. Histopathologically, the tumors induced by hydrogel plates were malignant tumors resembling fibrosarcoma or malignant fibrous histiocytoma. This indicates that PVA hydrogel implants also induce solid state carcinogenesis at a similarly high rate to medical grade hydrophobic material reported in a previous study.

Absorbable Implants↗
PubMed2002

Effect of polyvinyl alcohol (PVA) concentration during vitrification of in vitro matured bovine oocytes.

Polyvinyl alcohol (PVA) was used as a substitute for serum in a vitrification solution for in vitro matured bovine oocytes. In vitro matured bovine oocytes were cryopreserved in various vitrification solutions (VS) supplemented with different concentrations (0.05, 0.1, 0.5, and 1%) of PVA, 20% fetal calf serum (FCS) or without macromolecule supplementation in a gel-loading tip (GL-tip). After warming, vitrified oocytes were examined for effects on survivability, fertilizability, and embryonic development in vitro. At 18 h in vitro fertilization after vitrifying and warming, the number of surviving mature oocytes vitrified in VS without macromolecule supplementation was significantly (P < 0.05) lower than those with macromolecule supplementation. For fertilizability after vitrification, there was no significant difference in the penetration rate of oocytes among fresh oocytes (98.7%); oocytes vitrified in VS supplemented with 0.1 (76.8%), 0.5 (70.2%), or 1% (80.3%) PVA; 20% (84.1%) FCS; or without supplementation (61.7%). Also, the normal fertilization rate was not significantly different in oocytes vitrified with 0.1 (56.5%), 0.5 (43.5%), or 1% (49.7%) PVA and 20% (60.6%) FCS, compared with fresh oocytes (84.0%). Subsequently, vitrified oocytes were examined for embryonic development effects in vitro. The highest proportion of cleaved oocytes after vitrification was obtained in VS supplemented with 0.1% (18.8%) PVA. Additionally, the proportion of development to morula stage (7.7%) in the oocytes vitrified in a VS supplemented with 0.1% PVA was significantly (P < 0.05) superior to that of the 0, 0.5, and 1% PVA-vitrified groups. However, the beneficial effect of PVA addition was not found in blastocyst development. Embryonic development of vitrified oocytes was significantly lower than that of fresh oocytes. In conclusion, the present results indicate that 0.1% PVA supplementation in VS results in a significantly higher rate of morula stage embryos than 0, 0.5, and 1% PVA supplementation, and could replace FCS in VS for vitrification of in vitro matured bovine oocytes.

Animals↗
PubMed1993

Pulmonary embolization and infarction. An iatrogenic complication of transcatheter embolization of a cerebral arteriovenous malformation with polyvinyl alcohol sponge.

Transcatheter embolization therapy of vascular abnormalities is a well-accepted technique. It is particularly useful in the preoperative management of cerebral arteriovenous malformations, in which the risk of significant hemorrhage at surgery would otherwise be unacceptably high. A patient developed symptomatic pulmonary emboli and infarction following an uneventful embolization using polyvinyl alcohol particles. The authors believe this to be the first reported case of this complication of embolic therapy using polyvinyl alcohol.

Adult↗