Vinyl acetate, polyvinyl acetate and polyvinyl alcohol.
Explore the source record for details and available documents.
Animals↗
SEARCH · PubMed Health
Results for “Polyvinyls”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
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↗
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↗
Ocular evaluation of polyvinyl alcohol vehicle in rabbits.
The flow properties and viscosity of the vehicle into which drugs are incorporated can be determining factors in the bioavailability of topically applied ophthalmic drugs. It is shown, in rabbits, that when polyvinyl alcohol and methylcellulose are compared on a viscosity basis, there is essentially no difference in the two vehicles with regard to their influence on ocular drug bioavailability. Moreover, the rate of drainage loss for polyvinyl alcohol solutions, as determined by the radioactive technetium technique, compares favorably to methylcellulose solutions of similar viscosity. The relationship between viscosity and contact time or drainage loss of a drug is not a direct one, but an optimum viscosity range exists for polyvinyl alcohol solutions. This optimum range of 12-15 cps in rabbits is identical to that found for methylcellulose and differs considerably from the commonly employed viscosity in commercial preparations. Based on the methylcellulose-polyvinyl alcohol comparison, it appears that vehicles exhibiting or approximating Newtonian flow properties show comparable effects as ophthalmic vehicles. Finally, a discussion of non-Newtonian vehicles and their expected behavior in the eye is presented.
Animals↗
Microparticles of polyvinyl alcohol for nasal delivery. I. Generation by spray-drying and spray-desolvation.
Spray-drying and spray-desolvation are described for the generation of polyvinyl alcohol microparticles intended for nasal administration. The spray-dried microparticles of polyvinyl alcohol were of an appropriate size distribution but consisted of hollow spheres, which made them unsuitable for nasal delivery, as rapid clearance and a varied deposition pattern would be expected. Microparticles were also produced by spraying polyvinyl alcohol (average molecular weight of 14,000) solution (12.5%, w/v) at 0.332 ml/min onto the surface of acetone (spray-desolvation). These microparticles were solid collapsed spheres with the desired size for nasal deposition (10-200 microns). This method can be applied to encapsulation of drugs that are heat labile such as peptides and proteins.
Administration, Intranasal↗
In situ colonization of polyvinyl chloride, brass, and copper by Legionella pneumophila.
A sampling device (Robbins device) was used to expose brass, copper, and polyvinyl chloride plugs to potable water contaminated by Legionella pneumophila serogroup 1. Plugs were removed at approximately 1-week intervals and cultured. The colonization rates were polyvinyl chloride, 70; copper, 31; and brass, 25%. Quantitative cultures revealed that polyvinyl chloride was most heavily colonized, whereas brass was least colonized. We conclude that materials used in plumbing systems are readily colonized by Legionella and that the Robbins device provides a means for testing such materials in an in situ setting.
Bacterial Adhesion↗
Acute lower gastrointestinal hemorrhage: treatment by superselective embolization with polyvinyl alcohol particles.
OBJECTIVE: The major risk of transcatheter embolotherapy for acute hemorrhage in the lower gastrointestinal tract is irreversible intestinal ischemia. The authors studied the efficacy and safety of superselective transcatheter embolization with polyvinyl alcohol particles in arresting acute hemorrhage in the lower gastrointestinal tract. SUBJECTS AND METHODS: All patients with clinical or scintigraphic evidence of acute hemorrhage in the lower gastrointestinal tract were considered for superselective embolization. The nine patients with angiograms that showed active hemorrhage in the lower gastrointestinal tract underwent the procedure. Superselective embolization was done through a 3-French catheter and was accomplished by using 100- to 590-microns polyvinyl alcohol particles. The segments of the intestinal tracts involved in the embolizations were examined for the presence of ischemia by endoscopy (n = 7) or histologic evaluation of a surgical specimen (n = 2) 2-44 days (mean, 11 days) after embolization or by clinical evaluation (n = 1). RESULTS: The lesions treated by this method were located in the colon (n = 8) and jejunum (n = 1). Immediate hemostasis was achieved in every case. Three patients had recurrent lower gastrointestinal hemorrhage 1-24 days (mean, 9 days) after initial embolization. Two of these patients had surgery, while one had a successful second embolization. Two asymptomatic patients were found endoscopically to have small areas of ischemia involving only the mucosa. Only one patient was shown to have severe mucosal ischemia; this involved the colon in a distribution that suggested it was not caused by the embolization. CONCLUSION: Ten superselective embolization procedures that used polyvinyl alcohol particles successfully controlled hemorrhage in the lower gastrointestinal tract in nine patients. In no case was intestinal infarction induced by the procedure, and only two endoscopically proved cases of asymptomatic mucosal ischemia occurred.
Acute Disease↗
Effect of addition of inorganic acids or alkalis on gelation of polyvinyl alcohol aqueous solution by gamma-ray irradiation.--Color development with iodine--.
Below the critical concentration of polyvinyl alcohol, the effect of inorganic acids or alkalis on gelation of polyvinyl alcohol aqueous solution was investigated by color development with iodine after gamma-ray irradiation. The absorbances of the polyvinyl alcohol-iodine complex decreased remarkably in the presence of nitric or perchloric acid. These acids decompose and form oxygen or hydrogen peroxide which oxidize the polymer and leads to a fading of the color. On addition of sulfuric, phosphoric and hydrochloric acids, the absorbances decrease in the order that agrees with that of the acidity of these acids at the same molarity. In the alkaline solution the absorbances decrease by the addition of sodium hydroxide and aqueous ammonia in the order that agrees with that of the basicity of these alkalis. These results indicate that the gel formation is caused by the radiolysis of water. As a result of chemical analysis, these additives are considered not to be attached to the polymer.
Acids↗
Mouse skin carcinogenicity tests of the flame retardants tris(2,3-dibromopropyl)phosphate, tetrakis(hydroxymethyl)phosphonium chloride, and polyvinyl bromide.
The flame retardants tris(2,3-dibromopropyl)phosphate, tetrakis(hydroxymethyl)phosphonium chloride, and polyvinyl bromide were tested for carcinogenic activity by skin application 3 times weekly in random-bred female ICR/Ha Swiss mice for 420 to 496 days. Tris(2,3-dibromopropyl)phosphate at two dose levels (30 mg and 10 mg/application) induced benign and malignant tumors of the skin, forestomach, and oral cavity (tongue and gingiva) in a statistically significant number of mice (30/group). A statistically significant incidence of papillary tumors of the lung was observed at both dosages, and the higher dose also resulted in one mouse with a tubular adenoma of the kidney. Tetrakis(hydroxymethyl)phosphonium chloride (2 mg/application, 60 mice) and polyvinyl bromide (0.1 ml latex suspension/application, 30 mice) were inactive. Polyvinyl bromide was also injected s.c. into another group of female ICR/Ha Swiss mice once weekly for 48 weeks, and the mice were observed for a total of 60 weeks. Liposarcomas were induced in 19 of 30 mice, which was ascribed to physical carcinogenesis. Appropriate solvent and no-treatment control groups were included.
Administration, Topical↗
The effects of corticosterone and cortisone on the uptake of polyvinyl pyrrolidone and the transmission of immunoglobulin G by the small intestine in young rats.
1. The distribution of polyvinyl pyrrolidone along the intestinal lumen and in the intestinal wall, following oral administration to normal and corticosterone treated rats, was found to be extremely variable. Valid comparisons between the two groups of animals could not be made using this technique. 2. Three, 4 and 5 days after corticosterone treatment there was no significant change in the uptake of 125I-labelled polyvinyl pyrrolidone from standard doses injected into ligated segments of the distal small intestine; nor did the treatment induce precocious replacement of the absorptive cells in this region. Cortisone induced precocious cell replacement, a process which took up to 4 days to complete, and also led to a marked reduction in the uptake of 125I-labelled polyvinyl pyrrolidone from ligated segments of the distal intestine. 3. Three days after treatment with corticosterone (5 mg I.P. at 12 days) there was a marked reduction of labelled immunoglobulin G transport into the blood. Four and 5 days after treatment there was some recovery of the immunoglobulin G transport function. Three days after treatment with cortisone (5 mg I.P. at 12 days) there was closure of the gut to labelled immunoglobulin G. 4. The relevance of these results to antibody transmission and the termination of immunoglobulin transport is discussed.
Animals↗
Morbidity associated with prolonged use of polyvinyl feeding tubes.
In two newborn infants, morbidity was associated with long-term use of polyvinyl chloride feeding tubes. In one case, a hard, sharp catheter was thought to be responsible for peritonitis. In other, the polyvinyl tube hardened into a coil that could only be extricated by introduction of an intraluminal guide wire and prolonged manipulation under fluoroscopic control. The rigidity acquired by these tubes is thought to present serious potential for morbidity and mortality. Methods and materials appropriate for short-term alimentation should no be presumed appropriate for long-term use, and alternatives should be considered.
Enteral Nutrition↗
Effect of phthalate plasticizer on blood compatibility of polyvinyl chloride.
The amount of a phthalate plasticizer on the surface of a sheet of polyvinyl chloride used in the fabrication of blood storage bags was quantified using attenuated total reflectance spectroscopy, water contact angle measurement, and weight loss due to methanol extraction. Water wettability increased as the amount of surface phthalate extracted by methanol increased, which indicates that the accumulation of phthalate on the surface increases hydrophobicity. The extraction of phthalate by methanol consists of two steps: (a) methanol first dissolves surface phthalate, and (b) phthalate in the bulk then diffuses through the surface. The adsorption of plasma proteins was investigated to determine the initial events as blood contacts the surface. The composition of adsorbed proteins on the methanol-cleansed surface differs from that on the uncleansed polyvinyl chloride surface. Albumin adsorption onto phthalate-contaminated surfaces is less than on cleansed surfaces while adsorption of gamma-globulin and fibrinogen is greater on phthalate-contaminated surfaces. Protein adsorption can be related to surface thrombus formation. Increases in platelet numbers appeared on phthalate-contaminated surfaces as compared with methanol-treated surfaces. A phthalate may enhance platelet adhesion and aggregation when it exists on a polymer surface.
Adsorption↗
Polyvinyl chloride pyrolysis products. A potential cause for respiratory impairment.
A limited investigation of respiratory and other symptom prevalence, plus before and after shift ventilatory capacity was conducted among a group of 17 meat wrappers exposed to pyrolysis products of polyvinyl chloride and a group of 21 control subjects. Exposed meat wrappers showed a higher prevalence of cough, phlegm, hay fever, and asthma than did the control group. The exposed group also demonstrated relative decreases in forced expiratory volume, one second (FEV1.0) and forced expiratory flow 50% (FEF50) after one shift of work; whereas, the controls showed an opposite tendency. These findings suggest that meat wrappers exposed to pyrolysis products of polyvinyl chloride might be adversely affected. The results, while suggestive, are not totally conclusive owing to the fact that there was not ideal matching of the exposed and control groups in regard to age, height, race, sex, and smoking status.
Age Factors↗
Liver disease among polyvinyl chloride production workers.
A protocol for systematic testing of all employees of a chemical plant is presented. This factory manufactures polyvinyl chloride compounds and resins, ABS compounds and resins, and synthetic rubber. The results were reviewed, which led to the discovery of 2 additional cases of angiosarcoma and 11 cases of portal fibrosis. Two of the 11 cases were found to have developed in employees other than polyvinyl chloride production workers.
Chemical and Drug Induced Liver Injury↗
Human red blood cells with normal or improved oxygen transport function prepared and frozen in the primary polyvinyl chloride plastic blood collection container.
This is a report a a new system for freezing human red blood cells in the same polyvinyl chloride plastic container in which the blood is collected and separated into components. This polyvinyl chloride plastic collection bag with integrally attached transfer packs for blood collection, component separation, red blood cell biochemical modification, freezing, storage, and post-thaw dilution before washing, represents a major advancement in the freeze-preservation process. The label with the donor's blood type and identification number affixed to the bag at the time of collection remains in place throughout the freezing and thawing process. The transfused red blood cells are of superior quality, and the processing cost is less than with other methods of freeze-preservation. There is a lower risk of contamination with these red blood cells because manipulation of the product is kept at a minimum. "Rejuvenation", a bioengineering process by which outdated red blood cells can be salvaged, can be incorporated into the preservation process using one of the attached transfer packs of the primary collection bag. This process has been introduced as a possible means of alleviating the dramatic blood shortages which occur periodically. Red blood cells may also be "rejuvenated" after storage in the liquid state to increase their 2,3 DPG and ATP levels to 150 to 200% of normal, and these red blood cells with improved oxygen transport function have been administered to anemic patients with and without cardiopulmonary insufficiency, patients undergoing cardiopulmonary bypass and treatment with hypothermia during cardiac surgery, and in instances where nonhemolytic transfusion reactions might be expected.
Adenosine Triphosphate↗
Surface morphology of polyvinyl chloride and silicone elastomer umbilical artery catheters by scanning electron microscopy.
The surface features of a new silicone elastomer umbilical artery catheter have been defined by scanning electron microscopy and compared with those of a standard polyvinyl chloride catheter. Little difference was noted in the surfaces of the catheter materials themselves, but the radiopaque material used to render the catheters visible by x-ray resulted in a considerable difference in the overall smoothness. The polyvinyl chloride catheter's marker was in the form of a wide, rough band extending the length of the tubing whereas the marker particles of the silicone elastomer were dispersed, more uniform in size, and resulted in less overall irregularity of the surface.
Catheterization↗
Linear drug release from laminated hydroxypropyl cellulose-polyvinyl acetate films.
Release of drug from a single-layer film containing dispersed drug follows a diffusion-controlled matrix model, where the quantity released per unit area is proportional to the square root of time. The kinetics may be made linear with time (zero order) by laminating a second film without drug to the releasing side of the film with dispersed drug. In this manner, the drug layer serves as a reservoir and controls the duration of drug release, while the nondrug layer functions as a rate-controlling membrane. Zero-order drug release was demonstrated in such laminated films using 18-45 percent pentobarbital, methapyrilene, or salicylic acid contained in hydroxypropyl cellulose as the reservoir layer and mixtures of hydroxypropyl cellulose and polyvinyl acetate as the membrane layer. Inverse relationships between the release rate and membrane thickness and between the logarithm of the rate and the percentage of polyvinyl acetate in the membrane layer were observed. Of the three drugs tested, salicylic acid gave the fastest release rates while pentobarbital gave the slowest.
Acetates↗
Polyvinyl siloxane impression materials: a review of properties and techniques.
Polyvinyl siloxane impression materials have been shown to have excellent properties as impression materials; however, they are sensitive to manipulative variables. Several methods of using very high viscosity (putty) materials to form "trays" to obtain uniform bulk of the wash impression are described, and the disadvantages of each of these techniques is pointed out. It is recommended that for best results acrylic resin custom trays should be used routinely. The interaction of polyvinyl siloxane materials with latex products is also discussed and problems that this inhibition can cause are stated. Suggestions to avoid this interaction are outlined. One of the disadvantages of the impression materials is that it has a relatively short working time. Refrigerating the material will increase working time without affecting accuracy.
Acrylic Resins↗