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PubMed1996

[Toxicity of chemicals produced by thermal destruction of synthetic materials based on polyvinyl chloride and used in coal mines].

The experiments on mongrel white rats studied toxicity of the products appearing during thermal destruction of conveyer tape TK-200 based on polyvinyl chloride and used in coal mines. The studies helped to define parameters of acute toxicity and the MACs for products of the conveyer tape burning, considering the main contents and the exposure intensity for 30-120 minutes; to determine jeopardy class; to calculate specific volatilization; to design recommendations for prevention of poisoning during fire in the mines.

Air Pollutants, Occupational↗
PubMed1996

Esophageal dilation with polyvinyl (American) dilators over a marked guidewire: practice and safety at one center over a 5-yr period.

OBJECTIVE: Improvements in dilator technology over the past decade have revolutionized esophageal dilation. There remains, however, a number of controversies relating to several technical aspects of wire-guided dilation, including whether or not fluoroscopy is necessary. We describe our experience with wire-guided esophageal bougienage. METHODS: We retrospectively reviewed our experience with esophageal dilation using polyvinyl (American) dilators and marked guidewires over the period 1990-1994 to assess the practice habits of our endoscopists and the safety of the technique. We did 606 wire-guided dilations on 354 adult patients. Dilations were done by six different endoscopists. RESULTS: Fluoroscopy was used in only 32/606 dilations (5.3%) and then only to pass a guidewire when the scope could not be passed through the stricture. Fluoroscopy was not used to monitor dilator passage. Peptic strictures were dilated to their maximal target size (determined by the individual endoscopist) in one session in 195 of 253 instances (77.1%). Practice differences were seen between the individual endoscopists relating to how rapidly dilation was accomplished, the number of dilators passed per session, and the maximal dilator size passed. No perforations or other serious complications occurred in our series. CONCLUSIONS: Wire-guided esophageal bougienage is a very safe procedure when careful attention to technique is observed. No perforations were seen in our series of over 600 dilations. Fluoroscopy is needed only in those cases in which a scope cannot be passed through a stricture to assist with guidewire passage. In a majority of cases, peptic strictures can be dilated to a 45-to 51-Fr size in a single session.

Dilatation↗
PubMedDate not supplied

Adsorption of recombinant human granulocyte colony stimulating factor (rhG-CSF) to polyvinyl chloride, polypropylene, and glass: effect of solvent additives.

The adsorption of recombinant-derived proteins to glass and polymeric materials used in their packaging and delivery remains a problem. Loss of these very expensive proteins to surface adsorption not only results in reduced yields during purification and scale-up, but also to decreased therapeutic efficacy. The purpose of the present investigation was to inhibit/minimize adsorption of a model protein, namely, recombinant human granulocyte colony stimulating factor (rhG-CSF) to glass, polyvinyl chloride (PVC), and polypropylene by inclusion of select solvent additives. Solvent additives used to inhibit/minimize surface adsorption included glycerin, U.S.P. (0.5%, 1%, 5%, and 25% v/v), Pluronic F-127 (0.005%, 0.05%, and 0.5% w/w), Pluronic F-68 (0.005%, 0.05%, and 0.5% w/w), Tween 80 (0.005% and 0.05% w/w) and Tween 20 (0.005%, 0.05%, and 0.5% w/w). Over the rhG-CSF concentration range of 0.0 ng/ml to 300 ng/ml, the amount of rhG-CSF bound per cm2 of PVC increased with an increase in the rhG-CSF concentration tested. At rhG-CSF equilibrium concentrations of 262 +/- 3.7 ng/ml and 136 +/- 1.9 ng/ml, the rhG-CSF bound/cm2 of PVC at 22 degrees C and 45 degrees C reached a maximum of 37.6 +/- 9.8 ng/cm2 and 165.2 +/- 11.7 ng/cm2, respectively. The adsorption isotherms determined at each temperature were described by the classic Freundlich equation. Moreover, the rate of adsorption of rhG-CSF to PVC was extremely rapid. The mean values of the percent of rhG-CSF bound to PVC after only 10 minutes of equilibration at 22 degrees C and 45 degrees C were 92.8 +/- 9.2 percent and 97.3 +/- 17.9 percent, respectively. The mean values of the percent of rhG-CSF bound to PVC at 22 degrees C and 45 degrees C after 24 hours were 52.4 +/- 10.9% and 70.0 +/- 9.7%, respectively, indicating that some desorption of rhG-CSF does occur during 24 hr. However, surface adsorption of rhG-CSF to PVC was shown to be irreversible over a 1 hr time period. Using viscometry, an estimate of the thickness of the adsorbed layer of rhG-CSF to glass was determined to be approximately 1 micron. The overall rank order of the solvent additives for minimizing adsorption of rhG-CSF to PVC was Tween 20 > Tween 80 > Pluronic F-127 > Pluronic F-68. Tween 20 was the most effective solvent additive for inhibiting surface adsorption of rhG-CSF to parenteral vials made of either glass or polypropylene.

Adsorption↗
PubMedDate not supplied

Orotic acid in clinical urine specimens by capillary zone electrophoresis using polyvinyl alcohol coated capillaries.

Orotic acid is an important compound in the investigation of several inherited metabolic diseases, and capillary zone electrophoresis provides an effective assay method for this analyte in the clinical laboratory setting. Capillaries with a polyvinyl alcohol (PVA) coating performed well in this application. However, it was necessary to employ several specimen preparation steps to achieve good assay precision.

Electrophoresis, Capillary↗
PubMed1998

Thalidomide reduces vascular density in granulation tissue of subcutaneously implanted polyvinyl alcohol sponges in guinea pigs.

The efficacy of thalidomide in the treatment of erythema nodosum leprosum is a well established fact; there is also accumulating evidence of its therapeutic value in a number of other inflammatory and immune-mediated conditions. In addition, thalidomide has been shown to be an inhibitor of angiogenesis induced by basic fibroblast growth factor (bFGF). Nevertheless, its mechanism of action remains speculative. Using guinea pigs, orally administered thalidomide significantly enhanced the response of multinucleated foreign body giant cells (p<0.05) in subcutaneously implanted polyvinyl alcohol sponges. Furthermore, the drug exerted a dual effect in that it reduced vascular density (p<0.05), which was not abolished by recombinant human bFGF, and at the same time amplified the granulomatous response with and without bFGF (p<0.05 and p<0.01, respectively). The results of our experiments represent a further step toward understanding the mechanism of action of thalidomide, with implications for its potential use in wound healing and scar formation as well as in the control of tumorigenesis.

Animals↗
PubMed1999

DNA-PCR analysis of bloodstains sampled by the polyvinyl-alcohol method.

Among the usual techniques of sampling gunshot residues (GSR), the polyvinyl-alcohol method (PVAL) includes the advantage of embedding all particles, foreign bodies and stains on the surface of the shooter's hand in exact and reproducible topographic localization. The aim of the present study on ten persons killed by firearms was to check the possibility of DNA-PCR typing of blood traces embedded in the PVAL gloves in a second step following GSR analysis. The results of these examinations verify that the PVAL technique does not include factors that inhibit successful PCR typing. Thus the PVAL method can be recommended as a combination technique to secure and preserve inorganic and biological traces at the same time.

Blood Stains↗
PubMed2001

Effect of chitosan-polyvinyl pyrrolidone hydrogel on proliferation and cytokine expression of endothelial cells: implications in islet immunoisolation.

Earlier we have shown the suitability of chitosan-polyvinyl pyrrolidone (PVP) hydrogel for islet immunoisolation and its inability to activate macrophages. Biomaterials that support vascularization without activating immune competent endothelial cells are desirous in islet immunoisolation. The aim of the present study was to evaluate effect of chitosan-PVP hydrogel on proliferation and activation of endothelial cells. Hydrogel did not allow the majority of cells to adhere well but maintained their viability. Hydrogel leachouts were nontoxic to the cells, as confirmed by tetrazolium reduction (MTT) and Neutral red uptake assays. Exposure to leachouts also did not alter their functionality as seen from normal expression of von Willebrand factor. 3H-thymidine incorporation revealed that hydrogel leachouts did not induce endothelial cell proliferation. Cells cultured on hydrogel and polystyrene control showed comparable expression of interleukin (IL) 6, IL-10, and transforming growth factor beta, with higher expression of tumor necrosis factor alpha as determined by reverse transcription-polymerase chain reaction. Taken together these results point out that hydrogel is compatible with endothelial cells and maintains their nonactivated status and hence is suitable as immunoisolation matrix.

Biocompatible Materials↗
PubMed2001

Rapid single nucleotide polymorphism analysis by primer extension and capillary electrophoresis using polyvinyl pyrrolidone matrix.

Rapid molecular diagnosis of 21-hydroxylase deficiency by detecting the most common mutation in the 21-hydroxylase gene is presented using primer extension and capillary electrophoresis with a polyvinyl pyrrolidone matrix. DNA samples were subjected to polymerase chain reaction (PCR) in order to amplify a 422 bp fragment of the CYP21 gene containing the single nucleotide polymorphism (SNP) site. This product served as a template in the primer extension reaction using a fluorescently labeled primer in close proximity to the SNP. ddGTP was used to block the extension if the mutation was present and the other three dNTPs to enable elongation of the primer. Fast analysis of the resulting fragments was performed by capillary electrophoresis using 10% polyvinylpyrrolidone as sieving and wall coating matrix. The Cy5-labeled primer and the two possible primer extension products (mutant and wild type) were completely separated in 90 s.

Adrenal Hyperplasia, Congenital↗
PubMed1990

Mortality and cancer morbidity in workers exposed to low levels of vinyl chloride monomer at a polyvinyl chloride processing plant.

To study whether exposure to low levels of vinyl chloride monomer (VCM) causes increased risk for cancer morbidity and death from ischemic heart disease, a cohort study was performed among 2,031 male workers at a polyvinyl chloride (PVC) processing plant who had been employed for at least 3 months during the period 1945-1980. An almost significantly increased total mortality (SMR = 116, 95% CI 99-136) was found. Deaths caused by violence or intoxication were significantly increased (SMR = 153, 95% CI 109-213), but not deaths from ischemic heart disease (SMR = 100, 95% CI 73-135). A significant increase in total cancer morbidity was observed (SMR = 128, 95% CI 101-161). Respiratory cancers were significantly increased (SMR = 213, 95% CI 127-346). Furthermore, six brain tumors (vs. 2.6 expected) were observed. This increase, however, was not significant (SMR = 229, 95% CI 84-498). No liver hemangiosarcoma was observed. Applying a latency period of greater than or equal to 10 years from start of employment did not change the risk patterns. There were no significant exposure-response associations between exposure estimates for VCM, asbestos, and plasticizers and cancer morbidity.

Adult↗
PubMed1999

Molecular design of conjugated tumor necrosis factor-alpha: synthesis and characteristics of polyvinyl pyrrolidone modified tumor necrosis factor-alpha.

We conjugated tumor necrosis factor-alpha (TNF-alpha) with the synthetic polymeric modifier polyvinyl pyrrolidone (PVP) to facilitate its clinical use for anti-tumor therapy. TNF-alpha was chemically conjugated with the terminal carboxyl-bearing PVP at one end of its main chain, which was radically polymerized via the formation of an amide bond between the lysine amino groups of TNF-alpha and carboxyl group of PVP. In vitro specific bioactivity of PVP-conjugated TNF-alpha (PVP-TNF-alpha) relative to that of native TNF-alpha gradually decreased with increases in the degree of PVP attachment. In contrast, PVP-TNF-alpha in which 40% of TNF-alpha lysine residues were coupled with PVP (MPVP-TNF-alpha) exhibited the highest anti-tumor activity among the conjugated derivatives examined. MPVP-TNF-alpha had more than 200-fold higher anti-tumor efficacy than native TNF-alpha, and the anti-tumor activity of MPVP- TNF-alpha was more than 5-fold stronger than that MPEG- TNF-alpha which had the highest anti-tumor activity among PEG-conjugated TNF-alphas examined. Additionally, a high dose of native TNF-alpha induced toxic side-effects such as body weight reduction, piloerection and tissue inflammation, while no side effects were observed following i.v. administration of MPVP-TNF-alpha. The plasma half-life of MPVP-TNF-alpha (360 min) was about 80 and 3-fold longer than those of native TNF-alpha (4.6 min) and MPEG-TNF-alpha (122 min), respectively. These results suggested that PVP is a useful polymeric modifier for increasing the anti-tumor activity of PVP.

Animals↗
PubMed1999

Bioconjugation of laminin-related peptide YIGSR with polyvinyl pyrrolidone increases its antimetastatic effect due to a longer plasma half-life.

Polyvinyl pyrrolidone (PVP) which can be radically synthesized and have a long blood residency was used to modify the laminin-related peptide YIGSR, and its inhibitory effect on experimental lung metastasis of B16-BL6 melanoma cells was examined. The antimetastatic effect of PVP-conjugated YIGSR (PVP-YIGSR) was more than 100-fold greater than that of native YIGSR. When injected intravenously, PVP-YIGSR showed more than a 15-fold longer plasma half-life relative to native YIGSR. In addition, the stability of YIGSR in plasma was increased by conjugation with PVP. These findings suggest that PVP is a useful polymeric modifier for increasing the antimetastatic activity of YIGSR.

Animals↗
PubMed1997

Fractal Dimensionality of Vinyl Chloride Monomer Adsorption on Polyvinyl Chloride Particles

The extent of adsorption of vinyl chloride monomer (VCM) on polyvinyl chloride (PVC) beads of various size was examined using the inverse gas chromatography technique at 288, 295, 303, and 313 K. The sizes of the PVC beads were 60-80, 100-120, and 150-200 mesh. On them the specific retention volume Vg (ml/g) of the injected gaseous monomer was determined. Vg depends on the mean particle size &dmacr; of PVC beads according to the relationship log Vg = (D - 3)log &dmacr;, from which the mass fractal D values were determined between 2.95 and 2.63 depending on the temperature and the dilution of monomer. Higher temperatures (313 K) are associated with lower D values (2.63-2.67), whereas lower temperatures (288 K) are associated with higher D values (2.87-2.95). These results suggest that the PVC behaves more as a two-dimensional material in relation to VCM adsorption at higher temperatures, whereas at lower temperatures it looks more like a three-dimensional Euclidean solid.

Journal Article↗
PubMed1999

1H NMR Self-Diffusion Study of Morphology and Structure of Polyvinyl Alcohol Cryogels.

The multicomponent self-diffusion of the polyvinyl alcohol (PVA) cryogels prepared by a freezing-thawing treatment of aqueous and water-DMSO solutions of PVA has been studied with the NMR FT-PGSE method. The temperature dependencies of the self-diffusion coefficients, Ds, for the PVA chains have a maximum at 45 degrees C due to the syneresis of cryogels. They are quite different from the monotonous increase of Ds for the aqueous solutions of PVA. Evaluated apparent activation energies, Ea, of the self-diffusion for the PVA chains in the PVA solutions and cryogels in D2O are practically the same and equal 22-24 kJ/mol below the crucial point. The proton spin-lattice relaxation times, T1, of the PVA chain also coincide with one another for solutions and cryogels. This means that molecular packing in cryogels depends mainly on the dimensions of the ice and polymer microcrystallites formed by freezing the solution. Above the crucial point polymer compartments become firmer, and the chain mobility somewhat reduces. The strength of cryogels also increases along with growing the DMSO contents and decreases by the BSA addition. For estimation of the cryogel morphology, effects of the restricted diffusion of both the water and PVA in a q-space have been taken into account. By the introduction of DMSO to cryogels the solvent filled pores become smaller, and channels become much shorter. The diameter of the PVA filaments is similar to those for all the cryogels, but the length of filaments with D2O is twice that for cryogels with a mixed solvent. Entrapment of BSA in the cryogel matrix by preparation leads to the increase of an average diameter of the water filled pores and destroys molecular packing the cryogel. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

The Use of Thermodynamics for the Indirect Determination of Neutral Surfactants Activities in Mixtures of Potassium Polyvinyl Sulfate (PVSK), Dodecyltrimethylammonium Bromide (DTABr), and N-Dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB12).

Mixtures of zwitterionic and cationic surfactants were studied in the presence of an anionic polyelectrolyte. We used N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB12), dodecyltrimethyl ammonium bromide (DTA+Br-), and polyvinyl sulfate (potassium salt) (PVS-K+). The composition of the system was determined by measuring the activity of DTABr with an ion-selective electrode, and deducing the activity of SB12 from thermodynamic equations. This method provides information about the distribution of all species (activities of both surfactants and composition of the micelles), by experimental determination of only one quantity. SB12 affected the adsorption of DTABr onto PVSK. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Effect of Polyvinyl Pyrrolidone on the Thermal Phase Transition of 1,2 Dipalmitoyl-sn-glycero-3-phosphocholine Bilayer.

The purpose of this study was to investigate the interaction of polyvinyl pyrrolidone (PVP) with phospholipid bilayers in an effort to add a new dimension to our understanding of polymer interaction with lipids. For the preparation of lipid-polymer dispersions, measured amounts of DPPC (1,2 dipalmitoyl-sn-glycero-3-phosphocholine) and PVP were mixed in chloroform. After complete elimination of organic solvent, the dry mixtures were hydrated at 50-55 degrees C. Interactions between DPPC and PVP were assessed by differential scanning calorimetry (DSC) and photon correlation spectroscopy (PS). Separation of liposomes and micelles was performed by centrifugation. Liquid scintillation counting and a UV spectrophotometer were used for their analysis. PVP added as dry powder or added as aqueous solution to dry lipid or preformed liposomes failed to interact. Only PVP previously dissolved in chloroform interacted with DPPC. The DPPC main phase transition moved to lower temperatures with increasing PVP concentrations. This reduction of the phase transition temperature was accompanied by an increase of the DPPC phase transition enthalpy. Analysis of solubilization indicated that the amount of PVP present in the bilayer is dependent on the PVP bulk concentration. The data suggest interaction of PVP previously dissolved in chloroform with the acyl chains of the phospholipid deep into the bilayer. Copyright 1999 Academic Press.

Journal Article↗
PubMed2000

Magnetic and Mössbauer Studies of Magnetite-Loaded Polyvinyl Alcohol Hydrogels.

Materials producing strain in a magnetic field are known as magnetoelastic or magnetostrictive materials. A new type of material that is able to produce giant strain in a nonhomogeneous magnetic field has been developed. In these magnetic-field-sensitive gels (ferrogels) fine colloidal particles having superparamagnetic behavior are incorporated into a highly swollen elastic polymer network. Magnetic properties of ferrogels have been investigated using electron microscopy, static magnetization measurements, and Mössbauer spectroscopy. Analysis of the data yielded information on the superparamagnetic behavior of ferrogels and made it possible to estimate the size distribution of the magnetic cores of magnetite particles made by chemical precipitation and built into a chemically cross-linked polyvinyl alcohol matrix. The results are interpreted on the basis of a core-shell model. Copyright 2000 Academic Press.

Journal Article↗
PubMed2002

Preparation and characterization of polyvinyl alcohol-capped CdSe nanoparticles at room temperature.

Polyvinyl alcohol (PVA)-capped CdSe nanoparticles were successfully prepared by a one-step solution growth technique at room temperature and ambient pressure. X-ray diffraction, transmission electron microscopy, infrared spectra, and X-ray photoelectron spectra were used to characterize the final product. The as-prepared CdSe nanocrystals were well dispersed and uniform in shape and the diameter of the particles was confined within 8 nm. Ultraviolet-visible absorption spectra were used to study the confined growth process of PVA-capped CdSe nanoparticles. Photoluminescence measurement showed the near band-edge luminescence of the final product.

Journal Article↗
PubMed2000

Growth modulation of fibroblasts by chitosan-polyvinyl pyrrolidone hydrogel: implications for wound management?

Wounds in adults and fetuses differ in their healing ability with respect to scar formation. In adults, wounds lacking the epidermis exhibit excess collagen production and scar formation. Fibroblasts synthesize and deposit a collagen rich extracellular matrix. The early migration and proliferation of fibroblasts in the wound area is implicated in wound scarring. We have synthesized a hydrogel from chitosan-polyvinyl pyrrolidone (PVP) and examined its effect on fibroblast growth modulation in vitro. The hydrogel was found to be hydrophilic as seen from its octane contact angle (141.2+/-0.37 degrees). The hydrogel was non-toxic and biocompatible with fibroblasts and epithelial cells as confirmed by the 3(4,5-dimethylthiazolyl-2)-2, 5-diphenyl tetrazolium bromide (MTT) as-say. It showed dual properties by supporting growth of epithelial cells (SiHa) and selectively inhibiting fibro-blast (NIH3T3) growth. Growth inhibition of fibroblasts resulted from their inability to attach on to the hydrogel. These findings are supported by image analysis, which revealed a significant difference (P<0.05) between the number of fibroblasts attached to the hydrogel in tissue culture as compared to tissue culture treated polystyrene (TCPS) controls. However, no significant difference was observed (P>0.05) in the number of epithelial (SiHa) cells attached on to the hydrogel as compared to the TCPS control. Although in vivo experiments are awaited, these findings point to the possible use of chitosan-PVP hydrogels in wound-management.

3T3 Cells↗