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PubMed2005

[Bronchial artery embolization with polyvinyl alcohol foam and gelatinum sponge for serious hemoptysis].

OBJECTIVE: To evaluate the effect of bronchial artery embolization (BAE) with polyvinyl alcohol (PVA) foam and gelatinum sponge (GS) for serious hemoptysis. METHOD: Of 46 patients with severe hemoptysis, BAE with only GS was performed in 21 cases and with both PVA and GS in 25 cases. RESULT: The total efficacy rate of BAE was 91.3%; and comparable between PVA+GS and GS groups (92.0%; vs 90.5%;, P>0.05). The total recurrence rate after BAE was 26.2%;, but lower in PVA+GS group than in GS group (11.3%; vs 42.1%;, P<0.05). No serious complications occurred in these patients after BAE. CONCLUSION: BAE is effective and safe for management of serious hemoptysis, and treatment with PVA+GS may effectively lower the recurrence rate.

Adolescent↗
PubMedDate not supplied

Embolization of spinal dural arteriovenous fistula with polyvinyl alcohol particles: experience in 14 patients.

PURPOSE: To assess the effectiveness, initial and long term, of embolization using polyvinyl alcohol particles (PVA) particles in patients with spinal dural arteriovenous fistulas (SDAVF). METHODS: The initial treatment in 14 patients with SDAVF was embolization with PVA particles. Postembolization occlusion of the SDAVF was documented angiographically in all cases. RESULTS: All 14 patients initially showed an improvement in clinical symptoms, but the neurologic status of 11 patients subsequently deteriorated. Of the 11 patients who had recurrence of symptoms, nine had angiographically proven recurrences of their SDAVF while two had negative follow-up of spinal angiography. PVA embolization is ineffective for the treatment of SDAVF and is not without risk. CONCLUSION: On the basis of a literature review of the other two alternative treatments (operation or liquid adhesive embolization) available for SDAVF and our preliminary experience with N-butyl cyanoacylate (NBCA) embolization, we suggest that NBCA embolization be the initial treatment of choice for SDAVF; if that procedure is not possible, or is unsuccessful, then operation is recommended.

Aged↗
PubMed2005

Development of a polyvinyl alcohol hydrogel for temperature measurement by MRI.

This paper describes the development of a Polyvinyl alcohol hydrogel (PVA-H) model for calibration and measurement of temperature using image contrast on MRI using DMSO/H_2O as a solvent to alter the freezing and melting points of PVA-H. Tissues exposed to temperature changes above 41 degrees C or below 0 degrees C exhibit increasingly extensive and irreversible damage, depending on the exposure duration. MR images can provide a map of temperature if there is sufficient tissue signal. To evaluate treatment principles using temperature changes (hyperthermia, cryotherapy), a model simulating tissue may be useful to provide a reproducible test environment. PVA-H is water soluble and can be seen on MRI. It can be used to construct complicated shapes such as vascular structure, soft tissues, and so on. Therefore, PVA-H can be useful to measure temperatures and assume the distribution of temperature under treatment. In this paper, we applied PVA-H as a temperature detector and calibrated temperature from image contrast. The results exhibit good capability as a temperature detector not only of high temperature (around 41 degrees C), but also of low temperature (as low as -23 degrees C).

Calibration↗
PubMed2005

[Pilot study on the biochemical treatment of mother liquid of polyvinyl chloride produced by suspension polymerization].

In the pilot study on the treatment of mother liquid of polyvinyl chloride produced by suspension polymerization (SPVC) by using a novel aerobic treatment system-4 cascade aerobic biofilm reactors with internal circulation, the removal efficiencies of the COD and turbidity at different HRT together with the resistance impact of the system were researched. The laws of the biological growth and the development were observed. Some primary factors (suspended solids, chironomidae larvae, nutrition) influencing the steady operation of the reactor were studied and their controlling methods were suggested. The experiment results show that the start-up period was very short and the total COD removal rate was over 75% at HRT of 14 h, the effluent less than 50 mg/L can steadily meet the requirement of wastewater discharge standard and also be reused after advanced treatment.

Animals↗
PubMed2005

[Cytotoxicity study of heparin coated polyvinyl chloride material].

In this study, heparin ionically coated polyvinyl chloride (PVC) material was prepared by heparin-benzalkonium chloride complex (Group A), heparin-benzalkonium bromide complex (Group B) and heparin-polyethyleneimine compound (Group C). Cytotoxicity evaluation was conducted by direct cell contact evaluation and MTT colorimetry method. The results showed Group A and Group B caused L-929 cells to die out while Group C showed good compatibility with cells. The OD levels of Group A and B were lower than that of the Group C in MTT test. Method A and method B of heparin coating had remarkable cytotoxicity, while method C had little cytotoxicity and could be further studied for clinical use.

Animals↗
PubMedDate not supplied

The effect of an expandable polyvinyl acetate (Merocel) pack on the healing of the nasal mucosa of sheep.

BACKGROUND: There is a lack of knowledge about the healing of the nasal respiratory mucosa after endoscopic sinus surgery (ESS). Nasal packs often are placed after ESS in an attempt to improve hemostasis and reduce adhesion formation. Most nasal packs need to be removed in the postoperative period. This is uncomfortable for the patient and the affect of these packs on the healing process is unknown. METHODS: We have standardized the sheep as a suitable animal model to examine the healing of the nasal epithelium after ESS. The nasal mucosa of sheep was wounded under endoscopic guidance and either packed with expandable polyvinyl acetate-based pack (Merocel), which was removed at the 5th postoperative day, or left unpacked to serve as control. Serial biopsies of the wounded area were taken every 28 days, up to 112 days postwounding, for examination using light and scanning electron microscopy. RESULTS: There was no significant difference in the rate of reepithelialization between the packed and control sides of the sheep (p > 0.05). There was no significant difference in the total amount of surface cilia coverage between the packed and control sides at any time points (p > 0.05). There was no significant difference in the maturity of the cilia between the packed and control sides at any time points (p > 0.05). CONCLUSION: The use of Merocel packing postoperatively neither impairs nor promotes wound healing in the postoperative period.

Animals↗
PubMed1995

Amount of polyvinyl alcohol (pva) polymer adsorbed on the oil globules in liquid paraffinemulsions prepared by pva.

A modified method for estimating polyvinyl alcohol (PVA) in solution has been developed based on the principle of formation of PVA-iodine complex which has a characteristic absorption maxima. The amount of PVA adsorbed on the oil globules in liquid paraffin oil-water emulsions prepared by the polymer was determined. This was found to be dependent on the concentration of the polymer in the continuous phase of the emulsion until it reached a saturation point. Beyond that concentration, the amount of adsorption remained steady.

Adsorption↗
PubMed2006

Embolization of experimental wide-necked aneurysms with iodine-containing polyvinyl alcohol solubilized in a low-angiotoxicity solvent.

BACKGROUND AND PURPOSE: To evaluate the ready-to-use iodine-containing polyvinyl alcohol (I-PVA) dissolved in the low angiotoxic solvent N-methyl pyrrolidone (NMP) for embolization of porcine wide-necked aneurysms. METHODS: Fourteen broad-based carotid sidewall aneurysms were surgically constructed in 7 swine. I-PVA (40%) in NMP was injected under temporary balloon occlusion bridging the aneurysm neck. After 4 weeks, follow-up angiography, multisection CT angiography (MSCTA), and 3T MR imaging including MR angiography (MRA) sequences were performed. Afterward, harvested aneurysms were investigated histopathologically. RESULTS: The liquid embolic was well visible under fluoroscopy and displayed a favorable precipitation pattern, allowing for controlled polymer delivery. Ten aneurysms (71%) were initially completely occluded, whereas in 1 aneurysm, a minimal polymer leakage was observed. The other 4 aneurysms (29%) were almost completely occluded. One animal suffered a lethal rebleeding from the anastomosis after uneventful embolization. Aneurysms embolized with I-PVA could be discriminated well from the parent artery without beam-hardening artifacts on MSCTA, and no susceptibility artifacts were encountered on MR imaging. Histologic examination revealed all aneurysms covered with a membrane of fibroblasts and an endothelial cell layer while a moderate intraaneurysmal inflammatory response to the polymer was observed. CONCLUSION: I-PVA dissolved in NMP has proved its effectiveness for the embolization of experimental wide-necked aneurysms. This precipitating liquid embolic offers several interesting features in that it needs no preparation before use and no radiopaque admixtures, the latter allowing for artifact-free evaluation of treated aneurysms with MSCTA and MRA. Moreover, it uses NMP as a solvent, which has only a low angiotoxicity.

Animals↗
PubMed1992

Embolization of hepatic arteriovenous malformations using radiolabeled and nonradiolabeled polyvinyl alcohol sponge in a patient with hereditary hemorrhagic telangiectasia: case report.

Polyvinyl alcohol sponge (PVA) radiolabeled with 99mTc-sulfur colloid was used to evaluate a large hepatic arteriovenous malformation (AVM) in a 71-yr-old white female prior to embolization. The patient had hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu) with severe left-to-right shunting through the hepatic AVM which resulted in high-output congestive heart failure. The patient also had severe pulmonary hypertension. Scintigraphic imaging of the embolized radiolabeled PVA particles allowed us to be certain that the particles did not flow through the liver and inadvertently embolize the lungs; with the patient's already poor pulmonary status, embolization could have been fatal.

Aged↗
PubMedDate not supplied

Polyvinyl chloride matrix membrane electrodes for manual and flow injection analysis of chloroquine in pharmaceutical preparations.

Two types of polyvinyl chloride (PVC) matrix membrane electrodes responsive to the antimalarial drug chloroquine have been constructed, electrochemically evaluated, compared and used in pharmaceutical analysis. Type 1 is the classic PVC model with chloroquine-tetraphenylborate (TPB) sensor; Type 2 is a coated silver disk without internal filling solution. Both electrode types exhibited rapid linear potentiometric response to the logarithmic concentration of diprotonated chloroquine cation in the 10(-1) - 10(-6)M range with calibration slopes 28-30 mV/concentration decade over the pH range 1.8-6.2. These electrodes were sensitive enough to permit determination of chloroquine phosphate at concentrations as low as 5 microgram/mL with good accuracy and precision. Determination of chloroquine in various pharmaceutical preparations using direct potentiometry and potentiometric titration with NaTPB gave an average recovery of 98.8% of the nominal values (SD 0.5%). The Type 2 electrode was also assessed in a flow-through sandwich cell for flow injection analysis. Results were compared with data obtained by the U.S. Pharmacopeia method.

Chloroquine↗
PubMed1991

Surface detail reproduction of Type IV dental stones with selected polyvinyl siloxane impression materials.

Four polyvinyl siloxane impression materials and 14 modified Type IV dental stones were evaluated for their abilities to reproduce surface detail. Each combination of impression material and dental stone was used to duplicate a 20-microns-wide line. Surface detail reproduction was observed by two paired-rater groups. The line was reproduced in all impression material specimens, but in only 32% of the stone cast specimens. Some combinations of impression material/dental stone reproduced the line all or most of the time, but 12 combinations did not reproduce the line at all.

Calcium Sulfate↗
PubMed1991

[Loss of intravenous nitroglycerin administered with polyvinyl chloride infusion systems].

To evaluate the consequences of the interaction between intravenous nitroglycerin (NTG) and infusion systems made of polyvinyl chloride (PVC), 20 dilutions of NTG were prepared in glass bottles with an initial concentration of 200 micrograms/ml, which were infused through 20 infusion systems at a rate of 20 ml/hour during 12 hours. NTG concentrations collected at the terminal part of the infusion systems were evaluated after 5 minutes, 6 hours and 12 hours. The results showed a substantial loss of NTG through PVC systems. The loss was 20% after 5 minutes and up to 32% after 12 hours. These results, obtained with a preparation similar to that used in clinical practice, may be helpful to estimate the real dose of the infused drug.

Infusion Pumps↗
PubMed1990

The mechanism of particulate contamination in soft polyvinyl chloride infusion fluid bags.

In the seventies, it was shown that particles were generated in soft polyvinyl chloride (PVC) infusion fluid bags when they were shaken. In this investigation an exponentially modified log-normal distribution (EMLN) is fitted to the particle data. Using the formula for the volume of a sphere, the number-density distribution is converted into a volume-density distribution. The total particle load in the samples is estimated by integration for total particle volume. The results are expressed as volume concentration in plain SI-units (microliters/l). A four-factor analysis of variance demonstrates that the mechanism of the contamination process is most probably an emulsification of low molecular weight additives in the PVC plastic, i.e. di(2-ethylhexyl) phthalate (DEHP), epoxidized vegetable oils (EVO), and others.

Drug Contamination↗
PubMed1990

The covariation of chemical contamination, particulate matter and turbidity in soft polyvinyl chloride infusion fluid bags.

About 200 samples of normal saline, isotonic glucose and Ringer acetate infusions in soft polyvinyl chloride (PVC) bags obtained from three manufacturers have been analyzed by conductometric particle counting, turbidimetry and gas liquid chromatography (GLC). The particle counts were fitted to an exponentially modified log-normal model and integrated for total particle-volume. Di(2-ethylhexyl) phthalate (DEHP) and epoxidized vegetable oils (EVO), which are the main water insoluble contaminants in PVC fluid bags, were determined by GLC. There was a strong linear correlation between turbidity and GLC results. The correlation between particle-volume concentration and the DEHP and EVO concentrations was fairly good. The results seem to verify that an emulsion of plastic additives is formed when soft PVC infusion fluid bags are shaken.

Chromatography, Gas↗
PubMed1990

Meatal strictures after transurethral prostatectomy using latex or polyvinyl chloride three-way catheters.

Because latex rubber catheters have been implicated in urethral stricture formation, the incidence of urethral strictures following transurethral prostatectomy (TUP) and subsequent catheterisation with latex rubber or polyvinyl chloride catheters was compared. A total of 84 patients with benign prostatic hyperplasia (n = 71) or prostatic carcinoma (n = 13) underwent assessment of urethral diameter and subsequent internal urethrotomy prior to TUP. Following resection, 42 patients received three-way self-retaining latex rubber catheters and 42 received similar catheters made of PVC. Catheters were removed when the urine was clear (mean time = 3 days), and no patient required recatheterisation. Urinary flow was assessed in all patients at 6, 12 and 24 weeks after surgery, and diminution of flow with submeatal stricture formation was noted in one patient who had received a latex rubber catheter, and in one who had received a PVC catheter. In this study, the composition of the catheter had no bearing on subsequent stricture formation following TUP.

Aged↗
PubMed1990

[A polyvinyl alcohol (PVA) hydrogel as a soft contact lens material].

A transparent polyvinyl alcohol (PVA) hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water miscible organic solvent by cooling. The physical properties were evaluated in comparison with commercially available soft contact lens materials, such as polyhydroxyethyl methacrylate (PHEMA) and copolymers of methyl methacrylate (MMA) and N-vinyl pyrrolidone (VP). The PVA hydrogel showed higher tensile strength and elongation at break than the other materials, while it had high water content and oxygen permeability the latter being comparable to those of PMMA/VP copolymers. The protein adsorption of the PVA hydrogel was much less than those of the other materials. The PVA hydrogel soft contact lenses were applied on rabbit eyes for 12 weeks. The influence on the cornea was studied by biomicroscopy, ultrasonic corneal pachymetry and histopathological examination. These examinations revealed no abnormal findings in the cornea. These results suggest that the PVA hydrogel may be promising as a new soft contact lens material.

Adsorption↗
PubMedDate not supplied

A high density culture of hepatocytes using a reticulated polyvinyl formol resin.

To enable high density culture of hepatocytes to be used as a hybrid artificial liver support or bioreactor system, collagen coated reticulated polyvinyl formal (PVF) resin (a filter material with a porosity of more than 80%) was used for the primary culture of hepatocytes. Stationary and perfusion culture experiments using PVF resin and monolayer culture were performed as control experiments. Due to the porous structure of the substrate material, hepatocytes were able to penetrate the reticulated pores of the PVF resin, and adhere to and spread on its surface. The densities of hepatocytes attained with PVF were about 10 times as high as those in the monolayer culture using conventional collagen coated Petri dishes. Hepatocytes immobilized in the PVF resin showed viability, as assessed by glutamic pyruvic transaminase (GPT) activity in the medium. Perfusion culture with PVF resin showed stable, high level metabolism, ammonium removal, and urea secretion comparable to the monolayer culture. It is concluded that perfusion culture with PVF resin is useful in attaining a high density culture of hepatocytes.

Animals↗