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At least 19 recordsLinked to original sources
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↗
PubMedDate not supplied

[Papain immobilization on a fibrous polymer of polyvinyl alcohol].

The paper discusses papain immobilization on modified polyvinyl alcohol fibers by the ion fixation technique. The effect of the chemical structure of polyvinyl alcohol fibers on the basic properties of the bound enzyme has been examined. The level of activity and tolerance to pH changes of the resultant immobilized enzymes have been shown to depend on the papain arrangement in the polymer molecule.

Enzymes, Immobilized↗
PubMed1975

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↗
PubMed1978

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↗
PubMed1977

Hemangiopericytoma of the bladder after polyvinyl alcohol exposure.

A patient with hemangiopericytoma of the bladder following intensive exposure to polyvinyl alcohol is reported. Some early studies on polymer carcinogenesis are reviewed and recent work on vinyl chloride as a mutagen and potent carcinogen is cited. The need for epidemiologic and animal studies of other monomers is presented.

Adult↗
PubMed1975

[Prophylaxis of influenza with a clathrate of polyvinyl alcohol with iodine and boric acid].

Taking advantage of the viricdal and antimicrobial properties of the clathrate of polyvinyl alcohol with iodine and boric acid (PVAIB) and taking into account successful results obtained during the action in 1969, it was used again as a preventive measure during the epidemy of influenza in Poznań at the turn of 1971/1972. In this period, the prophylactic action included 1477 persons who recieved the drug as nasal drops in 30 gram bottles. After the extinction of influenza we checked 459 persons who had taken the drug regularly, according to medical prescription. Out of this group, only 23 persons or 5% fell ill with influenza. If compared with general morbidity, this rate proved to be four times smaller.

Administration, Intranasal↗
PubMed1977

Comparison of immediate polyvinyl alcohol (PVA) fixation with delayed Schaudinn's fixation for the demonstration of protozoa in stool specimens.

Immediate fixation of stool specimens in polyvinyl alcohol fixative (PVA) was compared with Schaudinn's fixation delayed until the specimens were received in the laboratory, in a series of 100 consecutive positive stool specimens. More specimens were found positive following PVA fixation, and the numbers of organisms present on the slides were greater in specimens processed by this technique than after Schaudinn's fixation. It is concluded that immediate fixation results in the preservation of larger numbers of organisms in a recognizable state. The routine use of PVA fixation prior to transportation of the specimen to the laboratory is recommended.

Amebiasis↗
PubMed1979

Linear dichroism of light harvesting bacteriochlorophyll proteins from Rhodopseudomonas sphaeroides in stretched polyvinyl alcohol films.

Light-harvesting bacteriochlorophyll-protein complexes from Rhodopseudomonas sphaeroides 2.4.1 and R-26 mutant are solubilized in sodium dodecyl sulfate and imbedded in polyvinyl alcohol. Stretching induces orientation, and the linear dichroism of visible and near infrared absorption is analyzed. Based on a simple model, angles between the particle axis and the transition dipole moments are found. In the near infrared absorption band of the R-26 light-harvesting protein the dichroic ratio varies from 1.30 to 1.57. Using the absorption curves the band is resolved into two exciton components. In the visible absorption band the dichroic ratio has a constant value of 0.43 for the R-26 protein but varies with wavelength for the wild type light-harvesting protein. This variation is attributed to an additional bacteriochlorophyll not present in the R-26 protein.

Bacterial Proteins↗
PubMed1977

Treatment of keratoconjunctivitis sicca with liquid paraffin or polyvinyl alcohol in double-blind trial.

Twenty-two eyes affected with keratoconjunctivitis sicca have been subjected to double trials using the double-blind randomized cross-over technique. Polyvinyl alcohol in a 5% concentration improved the condition whereas liquid paraffin aggravated it, as estimated subjectively, and by the measurement of the break up time of the corneal film, and, finally, by the scoring of rose bengal vital staining of exposed cornea and conjunctiva. The conclusion is drawn that oil is contraindicated in keratoconjunctivitis sicca, and that rose bengal scoring (modified Bijsterveld method) is a valuable aid in control of the sicca syndrome.

Adult↗
PubMed1991

Polyvinyl alcohol and polyethylene glycol as protectants against fluid-mechanical injury of freely-suspended animal cells (CRL 8018).

Two identical bioreactors run in parallel were used to examine the phenomenological characteristics of two additives, polyethylene glycol (PEG) and polyvinyl alcohol (PVA), used as protectants against fluid-mechanical cell damage. Cell-protecting ability was evaluated by comparing apparent cell growth rates of freely suspended CRL-8018 hybridoma cells cultured in serum-free medium under surface aerated conditions whereby cell damage is due to bubble entrainment and breakup. PEG of various molecular weights was used to determine whether the size of the polymer has significant effects on PEG's cell-protecting capabilities. All the PEG's with molecular weights larger than 1400 showed similar protective effects. The effect of PEG concentration was then evaluated and results showed that concentrations greater than 0.05% w/v did not significantly improve the cell-protecting properties. Direct comparisons made between the PVA, PEG, and pluronic F68 as cell protectants showed that PEG protected cells better than F68 and that PVA provided even better protection than PEG. The mechanism of protection, fluid-mechanical or biological in nature, was examined by growing the cells in additive from the beginning of the experiment (long-term exposure), or adding the additive after the cells had been agitated at rates detrimental to the cells (short-term exposure). In agreement with results reported previously on PEG and F68, fast-acting protection was seen. This implies a fluid-mechanical rather than a biological protection mechanism. In an attempt to correlate interfacial properties of the resulting media with shear protection, interfacial tension and viscosity measurements of all the media were made. On the basis of these measurements, we find no definitive correlations for evaluating these additives' cell-protecting capabilities.

Animals↗