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At least 289 records · Page 16Linked to original sources
PubMed2004

Pulmonary toxicity of polyvinyl chloride particles after repeated intratracheal instillations in rats. Elevated CD4/CD8 lymphocyte ratio in bronchoalveolar lavage.

Occupational exposure to polyvinyl chloride (PVC) particles has been associated with interstitial lung disease. Our previous study showed that a single intratracheal instillation of emulsion PVC particles, with or without residual additives, induces acute but transient alveolitis in a dose-dependent manner in rats. The aim of the present study was to investigate the pulmonary response after the administration of the same PVC particles (PVC-E3 and PVC-W3) given in the same cumulative doses (10 and 50 mg/kg BW), but fractionated as seven intratracheal instillations (7 x 1.4 and 7 x 7.1 mg/kg BW) in the course of 3 weeks (day 0 to day 21). Pulmonary response was characterized by analysis of lung weight, bronchoalveolar lavage (BAL) fluid for lactate dehydrogenase (LDH), total protein, and cell cytology, and a microscopic evaluation of lung tissue. BAL T lymphocyte phenotypes (CD3 + CD4 +, CD3 + CD8+) were analyzed by flow cytometry. On day 28, lung weights, BAL-LDH, cell numbers in BAL, and CD4/CD8 ratios in BAL T lymphocytes were higher in rats that had received the high dose of PVC-E3 or PVC-W3 than in rats that had received the low dose of PVC particles and control rats. On day 90, the pulmonary response had partially regressed towards control values, but there were still microscopically evident lesions in the lungs and greater CD4/CD8 ratio in the high dose groups. There were significant positive correlations between the CD4/CD8 ratio and a histopathology score of the lung (r = 0.36, P = 0.038 on day 28, and r = 0.46, P = 0.006 on day 90). In conclusion, repeated intratracheal instillations of PVC particles yielded similar results as single instillations. The examined PVC particles have the potential of inducing a limited and transient acute inflammatory reaction in the lung, and possibly a more persistent alteration of pulmonary T lymphocyte subsets towards a high CD4/CD8 ratio.

Animals↗
PubMed2004

Pulmonary toxicity of polyvinyl chloride particles after a single intratracheal instillation in rats. Time course and comparison with silica.

Our previous in vitro studies indicated that emulsion polyvinyl chloride (PVC) particles (PVC-E3), with a mean diameter of 2 microm, exhibited a moderate toxicity in different pulmonary cell cultures. The in vitro cytotoxicity and pro-inflammatory potential of PVC-E3 particles were reduced when the additives had been "washed off" (PVC-W3), indicating that PVC-particle associated toxicity is probably related to the residual additives. In the present study, male Wistar rats (230 +/- 18 g) received a single intratracheal instillation of vehicle, crystalline silica particles [Min-U-Sil, 10 mg/kg body weight (BW)], PVC-E3 (10 or 50 mg/kg BW), or PVC-W3 (10 or 50 mg/kg BW). After 2, 7, 28, or 90 days, the rats were sacrificed (n = 6) and pulmonary injury and inflammation were determined by measuring lung weight, lactate dehydrogenase (LDH) activity and protein concentrations in bronchoalveolar lavage fluid (BALF), differential BALF cell count, and histopathology. Silica exposure resulted in pulmonary inflammation and damage at all time points with a progressive deterioration. Exposure to high concentrations of PVC particles caused pulmonary inflammation and damage, which were similar to the silica-exposed group at 2 days, but at 90 days, most parameters had returned to the control level, except for minor histopathological lesions. PVC-E3 did not induce more damage than PVC-W3. Two days after exposure, PVC-W3 caused less neutrophil but more eosinophil influx than PVC-E3. Although the pulmonary toxicity of both PVC-E3 and PVC-W3 appeared limited, this in vivo study has not confirmed the conclusion from the in vitro toxicity tests that removal of residual additives reduces the toxicity of PVC-E3 particles.

Animals↗
PubMed2005

In vitro study of the interaction of polyalkilimide and polyvinyl alcohol hydrogels with cells.

Hydrogels are a class of polymers that in the last decade have had a great development and application for soft tissue augmentation, due to their similarity to this tissue for their high water content. The in vitro effects of polyalkylmide hydrogel (pAI) and polyvinyl alcohol hydrogel (pVOH) on human lymphocytes and U937 cells viability, apoptosis and cell shape were investigated. Cell viability was always higher than 70%, thus showing the hydrogels were not cytotoxic for both cell lines. Some differences were, however, found. At short time, lymphocytes were very sensitive to the hydrogels incubation, while at long time, U937 cells were the most sensitive cells. Other differences on cell viability were related to the time of incubation, to the type of hydrogel and to the polymers concentration. Cell viability decreased only at the longest time of incubation and with the highest hydrogel concentration. Accordingly, cell death by apoptosis increased; necrosis was never observed in the cultures. Concentration- and hydrogel-dependent modifications of cell shape (bigger cell volume, elongations of cells) were observed in a few percentage of viable cells. In conclusion, the very high in vitro degree of biocompatibility shown by both hydrogels encourages their use as dermal fillers.

Acrylic Resins↗
PubMed2004

Radiation-induced degradation of polyvinyl alcohol in aqueous solutions.

The degradation of polyvinyl alcohol (PVA) by gamma-ray irradiation was investigated. Degradation efficiency of PVA was influenced by several factors, such as initial PVA concentration, dose rate, pH, and the addition of H2O2. The degradation kinetics depended on initial PVA concentration and dose rate. At a relatively lower PVA concentration, e.g., 180 mg/L, and a higher dose rate, e.g., 55.7 Gy/min, the degradation followed pseudo-first-order kinetics. On the contrary, at a higher PVA concentration, e.g., 500 mg/L, but a lower dose rate, e.g., 12.1 Gy/min, a pseudo-zero-order reaction occurred. The removal of PVA was more effective under acidic or alkaline conditions than that under neutral conditions. At a certain dose rate there was an optimal dosage of H2O2 to facilitate the degradation of PVA. For instance, at a dose rate of 17.2 Gy/min, the optimal H2O2 dosage was found to be about 2.5 mmol/L. Radical scavenging experiments, total organic carbon determination, and FTIR analysis on the degradation products demonstrated that PVA radiolysis was initiated by *OH and H*, leading to chain scission and formation of ketones/enols. Ultimately, complete mineralization of PVA was achieved.

Gamma Rays↗
PubMed1983

Advantages of a new polyvinyl chloride double-lumen tube in thoracic surgery.

Double-lumen endobronchial tubes offer many advantages during thoracic operations. However, technical problems with tube placement and potentially life-threatening complications have discouraged widespread use of standard double-lumen tubes. Some of these problems may be reduced with a new polyvinyl chloride (PVC) double-lumen tube. A total of 214 intubations were undertaken in 204 patients using one of three endobronchial tubes. The cases of these patients were reviewed to determine differences in the complications associated with the Carlens, Robertshaw, and PVC tubes. Complications included unsuccessful or difficult intubation, tube dislodgment, unsatisfactory lung deflation, tube malposition, and hypoxemia. In 8 of 16 intubations with the Carlens tube and in 14 of 62 intubations with the Robertshaw tube, there were complications. In all, 22 of 78 intubations (28%) using conventional double-lumen tubes were complicated compared with 5 of 136 (4%) using the PVC tube. The technical problems and risks of endobronchial intubation were reduced significantly with the PVC double-lumen tube.

Adolescent↗
PubMed2002

Characterization of estrogenic compounds in medical polyvinyl chloride tubing by gas chromatography-mass spectrometry and estrogen receptor binding assay.

BACKGROUND: In 2001, the U.S. Food and Drug Administration (FDA) convened to conduct a safety assessment of a plasticizer, di(2-ethylhexyl) phthalate (DEHP), released from polyvinyl chloride (PVC) medical devices. Hospitalized patients may be exposed to high concentrations of plasticizers, antioxidants, and chemical contaminants in PVC medical devices during blood transfusion or hemodialysis, thus, making them vulnerable to more potentially adverse effects of these chemicals than healthy people. At the same time, recently, the effect of endocrine-disrupting chemicals on hospitalized patients has attracted a great deal of attention. This study aims to investigate the harmful effects of estrogenic compounds in medical PVC tubing by two approaches of gas chromatography-mass spectrometry (GC-MS) and estrogen receptor (ER) binding assay. METHODS: Residual plasticizers, antioxidants, and chemical contaminants in PVC tubing were subjected to GC-MS in the full-scan mode with an original library for plastic additives. Such residual compounds in PVC tubing were screened at very low concentrations (10(-2)-10(5) nmol/l) to determine whether they competed with fluorescein-labeled estradiol for ER (alpha). RESULTS: DEHP, 2-ethylhexanol, butylated hydroxytoluene, and 4-nonylphenol (NP) were detected in medical PVC tubing. In addition, only NP in PVC tubing was found to bind with ER. CONCLUSIONS: The current study proves that the main residual chemical for estrogenic effect was NP in medical PVC tubing.

Butylated Hydroxytoluene↗
PubMed1995

Prospective randomized comparison of polyvinyl bougies and through-the-scope balloons for dilation of peptic strictures of the esophagus.

We prospectively compared the efficacy of polyvinyl bougies (Savary type) passed over a guide wire and through-the-scope balloons for the dilation of peptic esophageal strictures in a randomized study. Thirty-four patients, 17 in each treatment arm, were studied. At entry, dysphagia was assessed according to a six-point scale (0, unable to swallow; 5, normal). The end-point for dilation was to size 45F or 15 mm. Discomfort during the procedure was graded on a four-point scale (0, no discomfort; 1, mild; 2, moderate; 3, severe discomfort). Follow-up visits were at 1 week, 1 month, 3 months, and every 3 months thereafter for 2 years. At the 1-week visit, the size of esophageal lumen was measured by 8-, 10-, and 12-mm pills. Both devices effectively relieved dysphagia. By life-table analysis, stricture recurrence during the first year of follow-up was similar in both groups, but during the second year, the risk of recurrence was significantly lower in patients whose strictures were dilated with balloons. Other advantages of balloons included the need for fewer treatment sessions to achieve the defined end-diameter for dilation (1.1 + 0.1 versus 1.7 + 0.2, p < .05), and less procedural discomfort (p < .05). The differences in luminal size after dilation, measured by the barium pill test, were not significant. Ability to pass the 12-mm pill and absence of dysphagia were correlated. Our results indicate that both devices are effective in relieving dysphagia, but balloons may have a long-term advantage.

Adult↗
PubMed1975

Analysis of Dns-amino acids by liquid chromatography. I. Selection of optimum mobile phase composition for separation of Dns-amino acids on polyvinyl acetate gel.

The separation of a mixture of ten Dns-amino acids (Gns-Gly, -Ala, -Val, -Leu, -Pro, -Hypro, -Met, -Ser, -Asn and -Gln) was carried out by liquid chromatography by using macroreticular polyvinyl acetate gel as a packing material. Different mobile phase systems were investigated, based mainly on mixtures of n-hexane with ethanol, methanol, chloroform, acetone, methyl ethyl ketone, ethyl acetate, dioxane and tetrahydrofuran. The solvent composition was fixed so as to elute all of the components of the sample mixture in a practical period of 2 h. Satisfactory separation of the ten components was obtained with the n-hexane-ethanol (90:10) system. The presence of methanol as a modifier in the n-hexane was effective in reducing the elution time, but the separation was not as satisfactory. Chloroform or dioxane was useful only for the separation of Ser, Asn and Gln. Acetone, methyl ethyl ketone, ethyl acetate and tetrahydrofuran were not suitable for practical separations of Dns-amino acids.

Amino Acids↗
PubMed2003

Gas chromatography-mass spectrometry determination of the migration of phthalate plasticisers from polyvinyl chloride toys and childcare articles.

Two laboratory-based linear horizontal agitation methods for determining a range of phthalate esters from soft polyvinyl chloride (PVC) toys are presented in compliance with EU legislation. Both of these methods were validated through interlaboratory trials using a PVC reference disc and four soft PVC toy/childcare articles intended or likely to be mouthed. Two of these commercial samples contained diisononyl phthalate (DINP), one diisodecyl phthalate (DIDP) and one bis(2-ethylhexyl) phthalate (DEHP). Acceptable repeatability (r, within-laboratory) and reproducibility (R, between-laboratory) data were demonstrated for both the analytical detection technique (GC-MS) (r = 9.8% and R = 8.1%) and agitation/extraction procedure (r=21.9% and R = 35.3% at 37 degrees C; r = 22.7% and R = 31.1% at 65 degrees C) for DINP. This was achieved through the participation of six laboratories. The remaining three phthalates from the EU Scientific Committee for Toxicity, Ecotoxicity and the Environment (CSTEE) list--dibutyl phthalate (DBP), benzyl butyl phthalate (BBP) and di-n-octyl phthalate (DnOP)--were not tested due to the unavailability of suitable materials.

Gas Chromatography-Mass Spectrometry↗
PubMed1995

Tensile bond strength of polyvinyl siloxane impressions bonded to a custom tray as a function of drying time: Part I.

Time-dependent bond strength studies of two polyvinyl siloxane impression materials to acrylic resin disks with their respective adhesives were studied to determine the optimal time for maximum bond strength. Six groups were tested with varying adhesive dry times of 0, 7, 15, and 60 minutes and 8 and 24 hours before testing. The results indicated that the bond strength of the adhesive increased at least twofold from time zero to 7 minutes adhesive dry time and peaked at 60 minutes for one of the materials and at 8 hours for the other. Bond strengths increased rapidly to the 15-minute test interval and then seemed to plateau. Both materials exhibited decreased adhesive bond strengths at 24 hours.

Acrylic Resins↗
PubMed1996

Polyvinyl siloxane template aids in recontouring natural teeth opposing single dentures.

This article describes a procedure that provides proper reduction of natural teeth opposing complete dentures. By use of a polyvinyl siloxane prosthetic template, natural dentition can be reduced to a more favorable plane, which will facilitate denture construction. This procedure will eliminate the risk of arbitrary grinding and will minimize guesswork through guided intraoral reduction.

Dental Impression Materials↗
PubMed1996

The effect of various base/core materials on the setting of a polyvinyl siloxane impression material.

Five resin-modified glass ionomers and amalgam, used as a base or core buildup material, were clinically evaluated for whether they effected polymerization of a low viscosity (light body) regular set polyvinyl siloxane impression material. A total of 20 samples per group was prepared according to the manufacturer's recommendations. Ten samples from each group were handled with latex gloves during mixing and the other 10 were handled with vinyl gloves. Five of the 10 samples had the outer surface prepared with a round diamond wheel. Impressions were made of all the samples. The impression materials were visually scored inhibited or noninhibited. Inhibited impression materials met at least one following criterion: (1) an oily substance on the surface of the impression readily collected on a sterile explorer tine as it was moved across the impression surface; (2) a rippled appearance on the surface of the impression material; or (3) unpolymerized impression material adherent to the prepared sample surface. If none of the criteria were observed, the impression was scored noninhibited. The data were analyzed with the chi square analysis (level of significance p = 0.05). Total chi square analysis revealed a significant difference between brands (p = 0.0001) and between prepared and non-prepared samples (p = 0.001). Interrater reliability data were analyzed with the kappa correlation analysis. Raters were in complete agreement (kappa = +1). The prepared samples of Vitrebond material had an inhibitory effect on the polymerization of Express impression material.

Composite Resins↗
PubMed1998

The effect of temperature changes on the dimensional stability of polyvinyl siloxane and polyether impression materials.

STATEMENT OF PROBLEM: Dental impressions are commonly mailed to remote dental laboratories and can be subjected to extreme temperature changes; however, the effects of these temperature changes on the accuracy of elastomeric impression materials are unknown. PURPOSE: This study evaluated the dimensional changes of polyether and polyvinyl siloxane impression materials as a function of storage temperature. MATERIAL AND METHODS: A total of 144 impressions were made of a stainless steel die similar to ADA Specification No. 19. Half of the impressions were made in perforated custom trays and the other half in solid trays. Measurements of the vertical and horizontal lines on the impressions were made at 10 minutes, 1 hour, 24 hours, and 26 hours, and storage temperatures ranged from 4 degrees C to 40 degrees C. RESULTS: Changes in storage temperature had a statistically significant effect on the dimensional stability of the horizontal and vertical lines. However, overall dimensional changes were extremely small. CONCLUSIONS: Storing both impression materials at 4 degrees C for 24 hours and then allowing the impressions to reach room temperature resulted in a slightly expanded impression that partially compensated for the contraction that occurred from polymerization shrinkage. Similar results occurred for polyether material only, when stored at 40 degrees C.

Analysis of Variance↗
PubMedDate not supplied

Characterization of emissions of dioxins and furans from ethylene dichloride, vinyl chloride monomer and polyvinyl chloride facilities in the United States. Consolidated report.

This is the consolidated report of emissions of PCDD/F from facilities in the organic chemical manufacturing chain leading to polyvinyl chloride. Data have been gathered from facilities in the US and Canada from a number of manufacturers and at various steps in the manufacturing process. Estimates of US emissions or transfers of PCDD/F were generated on an "Upper Bound" and "Most Likely" basis. The Most Likely estimate of US emissions of PCDD/F to the open environment, that is, air, water and land surface by facilities in this chain, based on evaluation of non-detects at one-half the detection limit is about 12 g I-TEQ per year. On this same basis, an estimated 19 g is disposed of in secure landfills.

Chemical Industry↗
PubMedDate not supplied

Testicular cancer and occupational exposures with a focus on xenoestrogens in polyvinyl chloride plastics.

In a case-control study of 148 cases of testicular cancer and 314 healthy controls information was collected on lifetime working histories and specific exposures. The main finding was a six-fold increase in the risk for seminoma, one type of testicular cancer, among plastic workers exposed to polyvinyl chloride (PVC). No overrisks were observed for other plastics than PVC. There may be an aetiological link to xenoestrogens, i.e. chemicals in the environment with oestrogenic properties. Phthalates are used in PVC as plasticizer and have oestrogenic properties that could promote the growth of endocrine sensitive tumour cells. However, this "endocrine disruptors" hypothesis must be further evaluated in experimental models with regard to the causative mechanisms of the oestrogenic tumour promotion.

Adult↗
PubMed1988

Longterm histopathologic follow-up of bronchial arteries after therapeutic embolization with polyvinyl alcohol (Ivalon) in patients with cystic fibrosis.

We used light microscopy to examine, at autopsy, bronchial arteries in three patients with cystic fibrosis who died, respectively, 10, 16, and 28 months after bronchial artery embolization with barium sulfate-impregnated polyvinyl alcohol (PVA) to control hemoptysis. PVA was not identified beyond the midsegmental bronchus in any patient. Persistent focal fibrovascular occlusion was noted in two patients, and recanalized and/or partially obstructed vessels were associated with PVA in all. The histologic reaction to PVA included fibrosis, mild chronic inflammation, localized foreign body reaction, and, in two patients, focal calcification of PVA spicules. Within the inflammatory milieu were numerous macrophages containing BaSO4. Extensive vascular mural destruction and fibrosis associated with PVA were also observed. Both PVA and BaSO4 were also frequently present in the perivascular connective tissue. These findings indicate that, although longterm occlusion persists after therapeutic arterial embolization with PVA, focal recanalization also occurs. The extent of vascular mural injury following PVA embolization in humans has been previously underestimated by animal experiments. Finally, perivascular deposition of PVA represents a common reaction to diverse foreign body emboli in both systemic and pulmonary arteries.

Adolescent↗
PubMed2000

The protective action of polyvinyl alcohol during rapid-freezing of mouse embryos.

Biological products like serum and BSA are routinely used in embryo freezing solutions. These products are undefined and can potentially expose the embryos to infectious agents. Therefore, this experiment was designed to evaluate in vitro and in vivo survival of mouse embryos frozen in solutions supplemented with a chemically defined macromolecule, polyvinyl alcohol (PVA). Morula-stage embryos from superovulated mice were collected, frozen by a rapid freezing procedure, and cryoprotectant diluted out (after thawing) in media supplemented with either 10% fetal calf serum (FCS), 0.1 mg/mL PVA, or a combination of 10% FCS and 0.1 mg/mL PVA. Frozen-thawed (good to excellent quality) and nonfrozen (control, collected in FCS supplemented medium) embryos were cultured in medium M16 (32) supplemented with either 4 mg/mL BSA or 0.1 mg/mL PVA for 72 h. Embryos frozen in solutions supplemented with FCS or PVA and nonfrozen embryos were transferred to pseudopregnant recipients. Recipients were humanly killed on Day 15 after transfer, and the rate of implantation and percentage of live fetuses were recorded. The supplementation of collection, freezing and cryoprotectant dilution solutions with FCS, PVA or FCS plus PVA did not influence (P > 0.05) the rate of survival and in vitro development of embryos to hatched/hatching blastocyst-stage. However, a higher (P < 0.01) in vitro development rate to hatching/hatched-stage was recorded when frozen-thawed embryos were cultured in medium supplemented with BSA than with PVA. There was no difference (P > 0.05) in the rate of implantation (68 vs 72%) or percentage of live fetuses (62 vs 60%) between pregnant recipients with embryos frozen in medium with FCS or PVA. The rate of implantation and development of embryos frozen in medium supplemented with PVA or FCS was comparable (P > 0.05) to that of nonfrozen embryos. It may be concluded that PVA can be substituted for FCS in medium for freezing mouse embryos; however, it can not be completely substituted for BSA in the in vitro culture of embryos to the hatched blastocyst stage.

Animals↗