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At least 19 recordsLinked to original sources
PubMed1994

Sustained-release oral delivery of theophylline by use of polyvinyl alcohol and polyvinyl alcohol-methyl acrylate polymers.

Crystalline polyvinyl alcohol (PVA) polymer and low-crystallinity polyvinyl alcohol-methyl acrylate copolymer (PVA-MA) were examined as sustained-release tablet excipients with theophylline as a model drug. By blending of different proportions of the crystalline polymer and the low-crystallinity copolymer, it was possible to affect the release characteristics of the tablets. Tablets made with crystalline PVA provided instant release of theophylline in vitro. Tablets made with a larger proportion of PVA-MA relative to PVA provided a very prolonged release profile in vitro. A formulation containing PVA-MA:PVA:theophylline in a ratio of 1:9:10 provided sustained-release profiles in vitro and in vivo in dogs. The dissolution release profile of this PVA-blend tablet formulation in vitro agreed extremely well with the percentage of bioavailable dose absorbed over time in vivo. The formulation provided a plateau of levels in plasma over 16 h. The oral bioavailability of theophylline from this formulation in dogs was approximately 80% and was equivalent to that obtained after administration of Theo-Dur, a marketed extended-release theophylline tablet from Key Pharmaceuticals.

Absorption↗
PubMed2000

The gene pvaB encodes oxidized polyvinyl alcohol hydrolase of Pseudomonas sp. strain VM15C and forms an operon with the polyvinyl alcohol dehydrogenase gene pvaA.

A 5.7 kbp SphI fragment containing the polyvinyl alcohol (PVA) dehydrogenase gene pvaA and its 1.9 kbp 5'-flanking region was cloned from the PVA-degrading bacterium Pseudomonas sp. VM15C. The pvaB gene, encoding oxidized PVA hydrolase, was found in the region upstream of pvaA. Sequence data and expression studies indicated that pvaA and B constitute an operon in the order pvaBA. The pvaB gene encoded a protein of 379 amino acid residues (40610 Da), and a lipoprotein signal sequence and the lipase consensus sequence, Gly-X-Ser-X-Gly, characteristic of the active-site serine region in serine hydrolases, were detected in the deduced amino acid sequence. The pvaB product with the pvaA product constituted an enzyme system for the cleavage of PVA molecules. The pvaA product introduced beta-diketone groups into the PVA molecule, and the pvaB product hydrolysed these beta-diketone groups in oxidized PVA. The pvaB product also hydrolysed 4,6-nonanedione at a low rate, but not acetylacetone or 5-nonanone. It was completely inhibited by PMSF and was concluded to be a serine hydrolase. There were no proteins showing high similarity to the pvaB product in the databases, but minor similarity to a number of serine hydrolases including polyhydroxyalkanoate depolymerases was apparent.

Alcohol Oxidoreductases↗
PubMed1998

NTP Toxicology and Carcinogenesis Studies of Polyvinyl Alcohol (CAS No.9002-89-5) in Female B6C3F1 Mice (Intravaginal Studies).

Polyvinyl alcohol is produced primarily for use in textile sizing, adhesives, polymerization aids, and paper coatings. It is also used in surgical drapes, towels, and gauze sponges; protective gloves; cosmetic formulations; topical ophthalmic preparations; plastic sponge implants for reconstructive surgery; and intravaginal contraceptive foam and film. In addition, polyvinyl alcohol is used with magnesium sulfate to dilate the cervix of women prior to induction of labor. It is estimated that hundreds of thousands of women in the United States use an intravaginal product containing polyvinyl alcohol each year. The Food and Drug Administration nominated low-viscosity polyvinyl alcohol for a 2-year study because of concern about the lack of information about the long-term toxic and carcinogenic effects by the intravaginal route. Female B6C3F1 mice received polyvinyl alcohol (approximately 99% pure) in deionized water by intravaginal administration for 30 days or 2 years. 30-DAY STUDY IN MICE: Three groups of 50 female B6C3F1 mice were used in this intravaginal study. The vehicle control group received only 20 &mgr;L of a deionized water vehicle. The other two groups each received 20 &mgr;L of 25% polyvinyl alcohol in deionized water. Animals in one dose group were returned to their cages after dosing; animals in the other dose group were restrained in a vertical nose-down position in restraint bags for several minutes after dosing. Animals were dosed daily for 30 consecutive days. All mice survived to the end of the study. The final mean body weights and body weight gains of dosed mice were similar to those of the vehicle control group. Abnormalities noted in the vaginal area after dosing included vaginal plugs, secretions, and swelling. These vaginal changes were minimal to mild and occurred in vehicle controls as well as in dosed mice. Restraint of mice after dosing appeared to eliminate vaginal secretions but increased both the incidence of vaginal irritation and the severity of vaginal opening swelling. At necropsy, mildly enlarged uterine horns were observed in 10 vehicle control mice, three 25% mice, and seven 25% (restrained) mice. No chemical-related lesions were observed. 2-YEAR STUDY IN MICE: Three groups of 100 female B6C3F1 mice were used in this intravaginal study: an untreated control group, a vehicle control group receiving 20 &mgr;L deionized water vehicle only, and a dosed group receiving 20 &mgr;L 25%% polyvinyl alcohol in deionized water. Animals were dosed 5 days per week, excluding holidays, for 104 to 105 weeks. Survival, Body Weights, and Clinical Findings: Survival of dosed mice was similar to that of the two control groups. The final mean body weight of vehicle control mice was less than that of the untreated control group. The mean body weights of the dosed mice were less than those of the untreated controls from week 17 until the end of the study. The only clinical finding was vaginal irritation, observed in six mice in the vehicle control group and 11 mice in the dosed group. Pathology Findings: No neoplasms or nonneoplastic lesions related to chemical treatment were observed. The incidences of reproductive tract nonneoplastic lesions in the dosed group did not differ significantly from those in the vehicle control group; similarly, the incidences of reproductive tract nonneoplastic lesions in the vehicle control group did not differ significantly from those in the untreated control group. CONCLUSIONS: Under the conditions of this 2-year study, there was no evidence of carcinogenic activity of polyvinyl alcohol (molecular weight approximately 24,000) in female B6C3F1 mice administered 20 &mgr;L of a 25%% solution intravaginally. There were no neoplasms or nonneoplastic lesions considered related to treatment with polyvinyl alcohol. Synonyms: Ethenol homopolymer, PVA Trade names: Akwa Tears, Alcotex, Alvyl, Aracet, Cipoviol, Covol, Elvanol, Ethenol, Gelvatol, Gohsenol, Ivalon, Kuralon, Kurare, Lemol, Liquifilm, Mowiol, Polydesis, Polysizer, Polyvinol, Polyviol, Poval, Resistoflex, Rhodoviol, Sno, Poval, Resistoflex, Rhodoviol, Sno Tears, Solvar, Sumitex, Vibatex, Vinacol, Vinalak, Vinarol, Vinarole, Vinavilol, Vinol, Vinylon

Journal Article↗
PubMed1978

A quantitative study of the effects of different grades of polyvinyl alcohol on the activities of certain enzymes in unfixed tissue sections.

Different grades of the colloid stabilizer, polyvinyl alcohol, used for protecting unfixed cryostat sections during cytochemical reactions, may have different effects on enzymatic activity. The influence of three grades of polyvinyl alcohol on the activities of "soluble", membrane-bound and membrane-enclosed enzymes has been investigated in unfixed sections; the activities were measured microdensitometrically. The largest molecular weight polyvinyl alcohol (G18/140, mol. wt. about 90 000) did not retain glucose-6-phosphate dehydrogenase activity in sections of rat liver even when used at the maximum convenient concentration (12%); G04/140 and M05/140 (molecular weights of 15 000 and 25 000 respectively) retained this soluble enzyme if used at concentrations of 30 and 20% respectively. At these concentrations, lactate dehydrogenase activity was apparently decreased when G04/140 and M05/140 were used; this diminished activity has been shown to be due to the need to establish optimal concentrations of reactants for each grade of polyvinyl alcohol and for each reaction. When optimal concentrations of reactants were used, the activities of this enzyme in the presence of each grade of polyvinyl alcohol were identical. The presence of any type of polyvinyl alcohol did not influence the activities of mitochondrial succinate dehydrogenase or of the smooth endoplasmic reticulum enzyme, delta5,3beta-hydroxysteroid dehydrogenase. However, the presence of polyvinyl alcohol improved the state of the section.

3-Hydroxysteroid Dehydrogenases↗
PubMed1995

Application of polyvinyl alcohol hydrogel membrane as anti-adhesive interposition after spinal surgery.

STUDY DESIGN: Three inflammatory and adhesive changes inside the spinal canal were analyzed histopathologically in cats. OBJECTIVE: To investigate the usefulness of a polyvinyl alcohol hydrogel sheet as an interposition over the dura to prevent inflammatory and adhesive reaction after laminectomy. SUMMARY OF BACKGROUND DATA: A major concern after laminectomy is scar tissue formation that may result in extradural compression or make subsequent surgery to the same area difficult and hazardous. METHODS: Wide laminectomy was performed at L5 in 30 adult cats. The dura was covered with a polyvinyl alcohol hydrogel sheet, free fat graft, or without interposition as a control. Animals were killed at 3 or 12 weeks. RESULTS: In the control group, adhesion of the exposed dura was apparent. Thick, fibrous connective tissue was observed between the dura and the paravertebral muscles. In the fat graft group, the dura was separated from the scar tissue by living grafted fat. However, the dura was adherent to the grafted fat and fibroblasts migrated into the interstitial space. In the polyvinyl alcohol hydrogel group, only a thin synovium-like layer was formed around the polyvinyl alcohol hydrogel sheet. CONCLUSIONS: Polyvinyl alcohol hydrogel is made of water and alcohol, and has been shown to be nontoxic to tissues. This is permeable to low molecular weight, but impermeable to large cells such as fibroblasts. Thus, the polyvinyl alcohol hydrogel sheet prevents migration of inflammatory cells and subsequently reduces intraspinal canal scar tissue formation and adhesive reaction. Other beneficial properties are extreme elasticity and low friction, which eliminate mechanical reaction to the spinal cord. The polyvinyl alcohol hydrogel sheet is believed to be useful in eliminating scar tissue formation and does not interfere with the dynamic gliding movement of the spinal cord and nerve roots.

Adipose Tissue↗
PubMed1980

Adverse effects caused by polypropylene and polyvinyl feline urinary catheters.

Effects of 3 days of open dwelling urethral catheterization were evaluated in normal male cats. Commercially manufactured polypropylene and polyvinyl feline urinary catheters of sufficient length to permit constant urine drainage were compared. Catheters were similar in length, diameter, and design. Hematuria occurred in 6 of 6 cats with polypropylene catheters and in 4 of 6 cats with polyvinyl catheters. For cats with polypropylene catheters, hematuria began within 24 hours of catheter insertion. Hematuria induced by polypropylene catheters was usually more severe in final urinalyses than that induced by polyvinyl catheters. Catheter-induced bacteriuria was found in 5 of 6 cats with polypropylene catheters and in 3 of 6 cats with polyvinyl catheters. Staphylococci and streptococci were the most common bacterial isolates. Microscopic lesions in urethras and bladders were significantly less severe in cats with polyvinyl catheters than cats with polypropylene catheters. With few exceptions, urethras of cats with polyvinyl catheters were microscopically indistinguishable from urethras of noncatheterized cats. Polypropylene catheters consistently induced urethritis which was most severe in some bacteriuric cats. Severe lesions were found in the bladders of all cats with polypropylene catheters. Bladder lesions were common in cats with polyvinyl catheters, but were usually less severe in cats with polypropylene catheters. There was no apparent relation between bacteriuria and bladder lesions.

Animals↗
PubMed1999

Influence on blood of plasticized polyvinyl chloride: significance of the plasticizer.

An investigation has been made of the significance of the level of the plasticizer di-(2-ethylhexyl)phthalate at the surface of plasticized polyvinyl chloride for interactions with blood components. Plasticized polyvinyl chloride before and after treatment with methanol to reduce the plasticizer surface level was assessed in terms of fibrinogen and albumin adsorption with unplasticized polyvinyl chloride acting as a control. As the plasticizer surface level decreased, fibrinogen adsorption decreased almost linearly while albumin adsorption increased initially before decreasing slightly. The investigation indicates that reduction in the amount of plasticizer at the surface improves the blood compatibility of plasticized polyvinyl chloride, and the influence on blood is due primarily to the plasticizer rather than the polyvinyl chloride itself.

Adsorption↗
PubMed1992

Experimental hybrid islet transplantation: application of polyvinyl alcohol membrane for entrapment of islets.

In this study, we first examined in vitro a polyvinyl alcohol membrane to be used to contain hybrid islet cells, and second we tested a bioartificial pancreas with entrapment of pancreatic islets in polyvinyl alcohol membrane in rats with experimentally induced diabetes. The permeability of the polyvinyl alcohol membrane to different substances was studied in a two-cell chamber system. Glucose, insulin, and nutrients passed through the membrane easily, whereas the passage of immunoglobulin G was completely prevented, indicating that this membrane could be effective in protecting the bioartificial pancreas from immunorejection. Approximately 2,000 islets collected from three Sprague-Dawley rats were enclosed in a mesh-reinforced polyvinyl alcohol tube and transplanted into the peritoneal cavity of six Wistar rats with streptozotocin-induced diabetes. Their nonfasting serum glucose levels were significantly decreased for at least 12 days. Six diabetic rats receiving intraperitoneal transplantation of free islets without the tube showed a slight but significant decrease in nonfasting serum glucose levels for only 3 days. One diabetic rat with transplantation of the bioartificial pancreas had a significant and sustained decrease in nonfasting glucose levels from pretransplanted levels of 440-500 mg/dl to a mean value of 162 +/- 13 mg/dl for over 3 months without immunosuppression. The bioartificial pancreas was then removed, and glucose levels gradually increased to over 500 mg/dl. The results of the present study suggest that a bioartificial pancreas with entrapment of islets in a polyvinyl alcohol membrane could be a promising therapeutic approach to diabetes mellitus.

Animals↗
PubMed1996

Morphologic characterization of polyvinyl sponge (Ivalon) breast prosthesis.

BACKGROUND: Although almost all breast implants are made of silicon, some implants, especially the ones used in early augmentation mammoplasty, were made of other materials, one of which is polyvinyl alcohol (commercially known as the Ivalon sponge). The morphology of this type of breast implant and its associated tissue reactions have not been characterized in detail. MATERIALS AND METHODS: A pair of polyvinyl breast prostheses implanted 40 years ago in a 66-year-old woman were removed together with their capsules to correct progressive disfiguration. The implants and capsules were radiographed. Sections from these specimens were subjected to routine histologic studies and special stains, including periodic acid-Schiff and Masson's trichrome stains. RESULTS: The breast implants were composed of crystals with a pathognomonic morphology. By hematoxylin-eosin stain, these crystals were polygonal, colorless, and refractile, but nonbirefringent, and they had a characteristic bubbling internal structure. The crystals displayed a deep-blue color with Masson's trichrome stain and were strongly periodic acid-Schiff-positive, with or without diastase digestion. These crystals appeared isolated or interconnecting and were separated from one another by spaces filled with tissue fluid. The capsules were composed of the same kind of crystals, but they were heavily calcified and associated with dense fibrosis and occasional multinucleated giant cells. CONCLUSIONS: This case serves to emphasize that breast prostheses made of materials other than silicon may be rarely encountered in the surgical pathology laboratory. Although polyvinyl breast implants were abandoned, injection of polyvinyl into various tissues for therapeutic purposes is sometimes indicated. The morphologic features of polyvinyl as detailed in this study should enable prompt and accurate recognition of this material, whether it is in breast implants or other types of tissue.

Aged↗
PubMed1985

Functional studies on in situ-like mitochondria isolated in the presence of polyvinyl pyrrolidone.

Mitochondria isolated and maintained in sucrose mannitol medium show a large intermembrane space and a condensed matrix unlike the appearance of in situ mitochondria. Mitochondria resembling in situ organelles are obtained when the isolation medium is supplemented with certain macromolecules such as polyvinyl pyrrolidone. We found that the in situ appearance was acquired also by the conventionally isolated mitochondria when they were exposed to 2% polyvinyl pyrrolidone supplemented medium. Paradoxically, however, these in situ looking mitochondria proved functionally inferior in that their brief incubation without substrates led to a marked loss of their ability to respire with subsequently added substrates such as pyruvate, acylcarnitines or glutamate. The oxidation of succinate was, however, not so affected. This phenomenon was shared by heart and skeletal muscle mitochondria of different animal species but not by rat liver mitochondria. The inhibition of respiration could not be related to the failure to oxidize NADH, to the tieing up of mitochondrial free CoASH, or to the increased matrix space of mitochondria that was observed in the presence of polyvinyl pyrrolidone. The polyvinyl pyrrolidone-exposed mitochondria regained their respiratory ability on being freed from polyvinyl pyrrolidone. The same phenomenon was seen also when the medium contained 2% albumin or 20% Ficoll.

Adenosine Diphosphate↗
PubMed1982

Microemboli observed in deaths following cardiopulmonary bypass surgery: silicone antifoam agents and polyvinyl chloride tubing as sources of emboli.

Refractile foreign particles within clear vacuoles were observed in capillaries of 17 patients who underwent cardiopulmonary bypass surgery, died, and were autopsied at the George Washington University Hospital from December 1978 through April 1981. The postoperative survival time ranged from less than one day to more than eight months. The approximate maximal diameter of the individual particles was 10 micrometer and that of the vacuoles 60 micrometer. The particle-droplet complexes showed affinity for hydrophobic stains. In all 17 cases, the kidneys were involved in combination with several other organs. In two patients, the emboli were associated with microinfarcts in one or more organs. Scanning electron microscopy (SEM) of the polyvinyl chloride tubing used during four cardiopulmonary bypasses showed spallation and shredding of the luminal surface in the areas exposed to the roller pump heads. This suggested that fragments of polyvinyl chloride might be the particles in the emboli. Another possible source was the antifoam agent used in the bubble oxygenator. Scanning electron microscopy x-ray microprobe analysis of the foreign material within capillaries of several organs showed it to be strongly positive for silicon but not for chlorine. Therefore, it was concluded that the microemboli were droplets of antifoam agent, the refractile particles corresponding to the particulate silica component and the vacuoles corresponding to the dimethylpolysiloxane liquid component. Since x-ray microprobe analysis of the microemboli did not reveal a strong chloride peak, there is as yet no evidence that polyvinyl chloride fragments were involved in the microembolism. The morphologic findings reported here indicate that antifoam microembolization continues to complicate cardiopulmonary bypass surgery and must, therefore, be considered a potential cause of postoperative morbidity. The consequence of the fragments of polyvinyl chloride tubing released into the circulation remains to be established.

Antifoaming Agents↗
PubMed1983

Colonization of bacteria on polyvinyl chloride and Teflon intravascular catheters in hospitalized patients.

During an 8-month period all intravascular catheters were removed by sterile technique upon completion of use and submitted to the hospital microbiology laboratory. All catheters were routinely cultured by the semiquantitative culture technique, with greater than or equal to 15 colonies being defined as a positive result. Of the 687 Teflon catheters cultured, 6.9% were positive by culture, compared with 24.6% of 77 polyvinyl chloride catheters (P less than 0.001). Also, colonization of coagulase-negative staphylococci on polyvinyl chloride was more than on Teflon. These data suggest that polyvinyl chloride catheters are colonized more frequently with organisms than are Teflon catheters; additionally, there is an increased affinity of coagulase-negative staphylococci for polyvinyl chloride as compared with Teflon, substantiating our previous observations with an in vitro system. We conclude that the type of catheter material may be important in determining the incidence of catheter-related infections and in selective colonization by coagulase-negative staphylococci.

Bacterial Infections↗
PubMed1984

Permeability of latex and polyvinyl chloride gloves to carmustine.

Permeability of latex and polyvinyl chloride gloves to the antineoplastic agent carmustine was studied. The latex gloves were of two types: sterile surgical gloves and disposable utility gloves. Polyvinyl chloride gloves of two thicknesses (0.20 mm and 0.35 mm) were tested. Both single and double thicknesses of each material were exposed to carmustine 3.33 mg/ml in a 10% aqueous solution of ethanol, and to the solvent alone, for 5-90 minutes. Permeation of carmustine was tested using a mutagenicity assay and a chemical assay. A time-dependent increase in carmustine permeation was observed for all types of materials (both double and single thicknesses). Mean amounts of carmustine permeating single gloves at 90 minutes ranged from 53 to 86 micrograms for the mutagenicity assay and 49 to 78 micrograms for the chemical assay. Double thicknesses of glove material (especially of the thicker polyvinyl chloride) reduced the amount of drug permeation. These latex and polyvinyl chloride glove materials offer only limited protection against contact exposure to carmustine. Latex surgical gloves may be slightly less permeable than the other types tested.

Carmustine↗