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At least 343 records · Page 19Linked to original sources

Rhamnolipid production by Pseudomonas aeruginosa immobilised in polyvinyl alcohol beads.

A marine bacterium, Pseudomonas aeruginosa BYK-2 (KCTC 18012P), was immobilised by entrapment in 10% (w/v) polyvinyl alcohol beads and optimized for the continuous production of rhamnolipid. The relative activity of rhamnolipid production was maintained at 80 approximately 90% of the initial production during 15 cycles in a repeated batch culture. Continuous culture was performed in a 1.8 1 airlift bioreactor, yielding 0.1 g rhamnolipid h(-1) at a dilution rate of 0.0 18 h(-1), 25 degrees C, initial pH 7, and 0.5 vvm aeration rate with a 1.21 working volume.

Bioreactors↗

Development of tissue scaffolds using selective laser sintering of polyvinyl alcohol/hydroxyapatite biocomposite for craniofacial and joint defects.

The growing interest in scaffold-guided tissue engineering (TE) to guide and support cell proliferation in the repair and replacement of craniofacial and joint defects gave rise to the quest for a precise technique to create such scaffolds. Conventional manual-based fabrication techniques have several limitations such as the lack of reproducibility and precision. Rapid prototyping (RP) has been identified as a promising technique capable of building complex objects with pre-defined macro- and microstructures. The research focussed on the viability of using the selective laser sintering (SLS) RP technique for creating TE scaffolds. A biocomposite blend comprising of polyvinyl alcohol (PVA) and hydroxyapatite (HA) was used in SLS to study the feasibility of the blend to develop scaffolds. The biocomposite blends obtained via spray-drying technique and physical blending were subjected to laser-sintering to produce test specimens. The SLS-fabricated test specimens were characterized using scanning electron microscopy and X-ray diffraction. The test specimens were also tested for bioactivity by immersing the samples in simulated body fluid environment. The results obtained ascertained that SLS-fabricated scaffolds have good potential for TE applications.

Biocompatible Materials↗

Effects of mesangial localization of polyvinyl alcohols on glomerular basement membrane thickness.

We studied the effects of mesangial localization of polyvinyl alcohols (PVA) on glomerular basement membrane (GBM) thickness in inbred Lewis rats. To avoid possible influences of PVA redistribution after localization in liver, lung, and other organs, the kidneys of rats given PVA were transplanted into uninephrectomized normal rats. Normal kidneys transplanted into normal rats served as a control. GBM thickness at the time of transplantation was the same in PVA kidneys as in normal kidneys. However, by 18 weeks post-transplant GBM thickness was greater in PVA kidneys, and this increase was sustained at 30 weeks. Within the glomeruli of PVA kidneys, lobules with marked mesangial PVA accumulation had more marked GBM thickening than lobules with little or no PVA accumulation. It is concluded that changes within the mesangium can influence GBM thickness. Whether this represents a direct effect of mesangial architectural distortion, a consequence of local phlogistic activities such as the influx of macrophages into the mesangium of glomeruli with PVA localization, or the result of intraglomerular hemodynamic perturbations is unclear.

Animals↗

A randomised, crossover, multicentre study to compare the performance of 0.1% (w/v) sodium hyaluronate with 1.4% (w/v) polyvinyl alcohol in the alleviation of symptoms associated with dry eye syndrome.

AIMS: To assess the safety and performance of a 0.1% (w/v) solution of sodium hyaluronate (HA, Fermavisc, in the alleviation of symptoms of severe dry eye in comparison with a 1.4% (w/v) solution of polyvinyl alcohol. METHODS: A randomised, crossover, multicentre study carried out at eight centres in the UK. Eligible patients giving written informed consent were randomised to the order in which they would receive the two study products. Each treatment period lasted for 4 weeks, then the patient crossed over to the other study product. Symptoms of burning and grittiness were assessed by visual analogue scale (VAS) at each study visit and other objective clinical assessments of ocular structure and function were carried out at baseline and the end of each treatment period. RESULTS: Thirty-nine patients were entered into the study and 32 completed both treatment periods and were included in the statistical analyses. A significant improvement in the patients' VAS assessment of burning was seen after treatment with HA (P = 0.03, 95% Confidence Interval: -23.5 to -1.1). This treatment also resulted in a significantly lower rose bengal staining score (P = 0.04, 95% Confidence Interval: -1.62 to -0.05 for the right eye). CONCLUSION: The results show a significant clinical benefit in terms of relief of the symptom of burning when HA is applied topically to the eye three or four times per day or as required. HA also appears to have a protective effect on the corneal epithelium, as shown by a reduction in the level of staining of corneal epithelial cells by rose bengal. This study confirms that Fermavisc is a safe and effective product for use in the alleviation of symptoms of severe dry eye syndrome.

Adult↗

Micropatterning polyvinyl alcohol as a biomimetic material through soft lithography with cell culture.

Integrating inorganic materials with specific biological systems requires a complex set of properties that can mimic physiological function to create microchip devices. Several factors in the material including the spatial location of the cellular attachment heavily influence the control of this functionality and must be dictated to parallel in vivo characteristics. In this work, we demonstrate polyvinyl alcohol (PVA) for use in emulating these properties to produce a highly robust and functional biomaterial as a microchip. We show the utility of PVA for cellular patterning using soft lithography. Based on these results, PVA can be applied in a diversity of areas including tissue engineering, biomimetics, and cellular micropatterning.

Animals↗

Leaching of diethylhexyl phthalate from polyvinyl chloride bags into intravenous etoposide solution.

OBJECTIVE: To compare the release of diethylhexyl phthalate (DEHP) from polyvinyl chloride (PVC) bags from four different manufacturers into intravenous etoposide solutions. METHOD: Etoposide solutions, 0.4 mg/mL, containing the vehicle polysorbate 80 were prepared in 5% dextrose or 0.9% sodium chloride injection PVC bags and stored at room temperature for 24 h. DEHP content was analysed by high-performance liquid chromatography. RESULTS: Substantial amounts of DEHP (up to 20 microg/mL at room temperature) leached into the etoposide solutions. However, no significant differences were found in the amounts of DEHP leached into the etoposide infusion solutions prepared using either 5% dextrose or 0.9% sodium chloride injection and stored in the four different containers. CONCLUSION: To minimize patient exposure o DEHP, etoposide solutions should ideally be stored in a glass or polyolefin container.

Antineoplastic Agents, Phytogenic↗

Effect of wash bulk on the accuracy of polyvinyl siloxane putty-wash impressions.

Variations in the bulk of wash in a putty-wash impression technique can result in dimensional changes proportional to the thickness of the wash material during setting. The purpose of the study was to determine the amount of wash necessary to achieve accurate stone models while using a two-step putty-wash impression technique with polyvinyl siloxane (PVS) impression material. A total of 45 impressions were made of a stainless steel master model, 15 impressions for each wash thickness (1, 2 and 3 mm). The model contained three full-crown abutment preparations, which were used as the positive control. Accuracy was assessed by measuring six dimensions (occlusogingival and interabutments) on stone dies poured from impressions of the master model. One-way analysis of variance (ANOVA) showed statistically significant differences amongst the three wash bulk groups, for all occlusogingival and interabutment measurements (P < 0.001). The overall discrepancies of the groups using wash thickness of 1 and 2 mm were smaller than the group with 3 mm wash thickness. Therefore, wash bulks of 1 and 2 mm were most accurate for fabricating stone dies, using PVS impression materials. This can be achieved by using the temporary crown to create the desired wash space in the preliminary putty impression. Wash thickness > 2 mm was inadequate to obtain accurate stone dies.

Analysis of Variance↗

The effects of polyvinyl chloride and polyolefin blood bags on red blood cells stored in a new additive solution.

BACKGROUND AND OBJECTIVES: Red blood cells (RBCs) must be stored in polyvinyl chloride (PVC) bags plasticized with di-2-ethylhexyl phthalate or a similar plasticizer to achieve their full storage life with conventional storage solutions. Improved storage solutions might remove this requirement and allow blood storage in other plastics. Experimental Additive Solution-61 (EAS-61), which maintains RBCs for 9 weeks with reduced haemolysis and satisfactory 51Cr 24-h recovery, is an appropriate candidate improved RBC storage solution. MATERIALS AND METHODS: Twenty-four units of packed RBCs were pooled in groups of four units, each pool was realiquoted into four units and stored, six pooled units per arm, in one of the following: 100 ml of EAS-61 in PVC; 200 ml of EAS-61 in PVC; 100 ml of EAS-61 in polyolefin (PO); and 200 ml of EAS-61 in PO. Haemolysis, RBC morphology indices, RBC ATP concentrations, and other measures of RBC metabolism and function were measured weekly. RESULTS: RBC haemolysis exceeded 1% by 7 weeks in PO bags containing 100 ml or 200 ml of EAS-61. In PVC bags, haemolysis was less than 1% at 11 weeks. RBC ATP concentrations were 1 mol/g of haemoglobin (Hb) higher at 2 weeks in the PVC-stored units. CONCLUSIONS: RBCs stored in PVC had markedly less haemolysis and higher RBC ATP concentrations than those stored in PO. Haemolysis would limit RBC storage in PO bags to a duration of 6 weeks, even with EAS-61.

Adenosine Triphosphate↗

Effect of albumin and polyvinyl alcohol on the vitality, motility and acrosomal integrity of canine spermatozoa incubated in vitro.

Sperm culture media used for in vitro fertilization (IVF) procedures are important factors concerning the viability, motility and acrosomal integrity of spermatozoa. The aim of this study was to investigate the effects of three different sperm diluting media, tissue culture medium (TCM-199), sperm culture medium (Sp-TALP) and human tubular fluid (HTF) supplemented with varying concentrations of bovine serum albumin (1, 4 and 6%) or polyvinyl alcohol (0.8%) on the acrosomal integrity, motility and viability of canine spermatozoa. Ejaculates collected from four dogs were diluted in all media and spermatozoa were separated from seminal plasma by the swim-up technique. Sperm progressive motility was assessed using a phase contrast microscope. Viability and acrosomal integrity were evaluated using a dual stain technique (Giemsa-Trypan blue). The results demonstrated that the number of live canine spermatozoa was similar in culture media supplemented or not supplemented with macromolecules. A minimal concentration of albumin (1%) in the three media showed similar effects on vitality, motility and acrosomal integrity, as had higher concentrations (4 and 6%). The percentage of acrosome-intact spermatozoa was markedly higher after HTF (94.1%) than after TCM-199 (70.1%) or Sp-TALP (71.0%) without supplementation. It is concluded that serum bovine albumin, irrespective of the concentration, preserved sperm viability and function, and HTF is the most suitable medium for preserving the acrosome in canine spermatozoa prepared for in vitro manipulation through short incubation.

Acrosome Reaction↗

A comparison of prelubricated hydrophilic and non-hydrophilic polyvinyl chloride catheters for urethral catheterization.

OBJECTIVE: To evaluate whether patients performing clean intermittent self-catheterization (CISC) for a short period preferred a prelubricated, hydrophilic, disposable polyvinyl chloride (PVC) catheter or a non-hydrophilic PVC catheter which could be used several times and that had to be lubricated by the patient. PATIENTS AND METHODS: In a prospective cross-over study, 32 patients used each type of catheter for 3 weeks. After each 3-week period, the patients completed a questionnaire to assess comfort and preference, and urine specimens were obtained for culture. RESULTS: There was no significant difference between the groups in the frequency of CISC, discomfort when used, opinion on handling the catheters, preference toward one of the catheters, or of infection. CONCLUSION: Non-hydrophilic PVC catheters may be used safely and with no discomfort to the patient. In addition it may be possible for the healthcare system to save money, as the non-hydrophilic PVC catheters are much cheaper.

Aged↗

Migration resistant, blood-compatible plasticized polyvinyl chloride for medical and related applications.

Plasticized polyvinyl chloride (PVC), although not a blood-compatible polymer, is the material of choice for the manufacture of blood bags and hemodialysis tubing throughout the world. PVC is usually plasticized with di-(2-ethylhexyl phthalate) (DEHP) to impart flexibility and low temperature properties to the final product. DEHP belongs to a class of agents called hypolipidemic hepatocarcinogens, and it migrates in small quantities into the storage medium such as blood, plasma, or serum, resulting in a number of toxic effects. It has been shown that the migration resistance and blood compatibility of flexible PVC could be significantly improved by grafting polyethylene glycol (PEG), the most blood-compatible polymer known today, onto the surface of flexible PVC by the classical Williamson ether synthesis reaction. The technique is simple and versatile enough to produce blood-compatible, migration resistant PVC surfaces for many medical applications. The method may also find use for preventing plasticizer migration from PVC cling films and polyvinylidene chloride films used extensively in food packaging.

Animals↗

The effect of methanol washing of plasticized polyvinyl chloride on biomaterial-contact-mediated CD11b (mac-1) expression in a rat recirculation model.

Our objective was to assess whether using a methanol wash to reduce the level of plasticizer present on the surface of medical-grade polyvinyl chloride (PVC) has a moderating effect on the expression of CD11b (mac-1) on neutrophils in rats undergoing recirculation. The study was carried out on 3 groups of 10 adult male Sprague-Dawley rats weighing between 350 and 450 g. In the 2 test groups, the animals were exposed to 48 cm(2) of di-(2-ethyl-hexyl)-phthalate (DEHP)-plasticized PVC in a parallel plate recirculating test cell through which blood was recirculated at 1.5 ml/min. In the first test group, the PVC was untreated; in the second test group, the PVC was washed in methanol to reduce the level of plasticizer on the surface. The test cell was connected to the right femoral circulation, and recirculation was established for a period of 60 min. Blood samples were taken at 0, 30, and 60 min for assessment of CD11b expression on neutrophils using flow cytometric analysis. In a third group of 10 control experiments, rats underwent the entire surgical procedure, but without recirculation through the test cell. There was statistically significant (p < 0.001) lower Cd11b expression on neutrophils in the blood of rats perfused through the cell containing methanol-washed PVC after 30 min and at 60 min. CD11b expression was significantly (p < 0.001) lower in the control group than in both test groups at both the 30 and 60 min time points and at the 60 min time point on comparison with the group where blood was perfused through methanol-washed PVC. These results demonstrate that the biomaterial-contact-mediated upregulation of CD11b may be significantly reduced by employing a methanol-washing technique on the plasticized PVC. Although this technique does not entirely eliminate the expression of CD11b on neutrophils, the difference is significant and suggests the role of the plasticizer in the development of this inappropriate inflammatory response.

Animals↗

Inflammatory response of rat and human neutrophils exposed to di-(2-ethyl-hexyl)-phthalate-plasticized polyvinyl chloride.

A series of in vitro studies were designed to determine whether di-(2-ethyl-hexyl)-phthalate (DEHP)-plasticized polyvinyl chloride (PVC) and DEHP itself initiated an inflammatory response in both human and rat blood. Additionally, the effect of methanol washing of the PVC on the inflammatory response was studied in both blood types. Blood from both species was exposed to first, no material; second, ground DEHP-plasticized PVC; third, methanol-washed ground DEHP-plasticized PVC; and fourth, known concentrations of DEHP. The expression of the integrin CD11b was employed as a marker of the inflammatory response. After 20 minutes' exposure to PVC, CD11b expression increased to 210 +/- 32% of baseline in human blood and to 238 +/- 21.7% in rodent blood. Both blood types showed an increase in CD11b expression with increasing concentrations of DEHP (214 +/- 40.8% of baseline levels in human blood and 237 +/- 14.5% in rodent blood at the highest concentration). Methanol washing resulted in a significant moderation in CD11b upregulation in both blood types; 117 +/- 27% of baseline in human and 150 +/- 14.7% in rodent. These results support the hypothesis that DEHP-plasticized PVC and DEHP itself are proinflammatory in blood from both species, and suggest that the rodent is an appropriate model for studies of this nature.

Animals↗

Allergic contact dermatitis from a pyridine derivative in polyvinyl chloride leather.

Antimicrobial coating of household products has gained wide acceptance in Japan in the past several years. Pyridine derivatives, used as antifungal or antibacterial agents in many common products, are known to cause contact dermatitis. We present a case of severe contact dermatitis caused by a pyridine derivative used as an antifungal agent in the polyvinyl chloride (PVC) leather of a chair. An open patch test was performed with each ingredient of the PVC leather. Other products were previously eliminated from consideration based on a series of negative patch tests. The PVC leather obtained from the patient's chair gave a ++ reaction with evident blistering, according to the International Contact Dermatitis Research Group standard. Fifteen ingredients of the PVC leather were open patch tested; a positive reaction was found with 2,3,5,6-tetrachloro-4 (methylsulphonyl) pyridine (1% in petrolatum). Clinicians should be aware that antifungal or antibacterial agents may be increasingly incorporated into common household products and should be suspected in cases of contact dermatitis.

Adult↗

Development of polyvinyl alcohol-hydrogel (PVA-H) shields with a high water content for tendon injury repair.

The main problem in tendon repair is adhesion formation between the tendon and surrounding tissue. To prevent this, we have developed adhesion preventive shields using polyvinyl alcohol hydrogel (PVA-H) with 90% water content. This implant experiment used the deep flexor tendon of the 3rd toe of the domestic fowl. Injured tendons shielded with PVA-H healed within about 3 weeks without adhesion to the surrounding tissues. Neither breakage of the PVA-H shield itself nor infection or degeneration in the surrounding tissue was observed. These results show that tendon is capable of intrinsic repair, and was able to regenerate using synovial nutrition through the PVA-H. The high water content of PVA-H may be clinically useful and applicable to adhesion preventive shields for tendon repair.

Animals↗

[Sequential scintigraphy of liver and spleen in patients with polyvinyl chloride disease (author's transl)].

Occurence of severe liver damage including angiosarcoma in polyvinyl chloride production workers necessitates regular control investigations of liver and spleen. Radioisotope techniques with small irradiation doses which give valid results should be used. Investigations of 15 patients with PVC-induced liver disease showed that hepatic perfusion as demonstrated by 99mTc pertechnate does not correlate with the uptake of sulphide colloid in the hepatic reticuloendothelial system. This provides evidence that in VC disease specific damage of the reticuloendothelial system of the liver occurs. Sequential scintigraphy also proved that the liver perfusion quotient can be considered as a measure of portal pressure. In practice this may be used for follow-up controls. Vascularized tumours described in VC disease can also be demonstrated by scintigraphy.

Chemical and Drug Induced Liver Injury↗

Perifusion culture system for bovine embryos: improvement of embryo development by use of bovine oviduct epithelial cells, an antioxidant and polyvinyl alcohol.

Three experiments were conducted in an attempt to improve a continuous flow-perifusion system capable of maintaining embryo development for long periods of time. Bovine embryos (8-16 cells) obtained from static co-culture with cumulus cells in a serum-free medium were perifused in an ACUSYST-S cell culture incubator. Culture chambers of the incubator consisted of a 0.2-mL unit (Chamber 1) connected to a 1.5-mL unit (Chamber 2), with the outflow from Chamber 1 routed to the inlet to Chamber 2. A bovine embryo culture medium supplemented with 3 mg mL-1 bovine serum albumin (BSA) and 25 mM HEPES was used as a perifusion culture medium (PCM). Embryos were perifused in Chamber 2 for 24, 48 and 72 h and further co-cultured in a static system up to 216 h after insemination. In Experiment 1, conditioning PCM with frozen-thawed bovine oviduct epithelial cells (BOEC) placed in Chamber 1 enhanced (P < 0.05) blastocyst formation of embryos in Chamber 2, after 24, 48 and 72 h of perifusion culture. The proportion of blastocysts was not further increased by placing BOEC in Chamber 2 along with the embryos. In Experiment 2, embryos were perifused with PCM conditioned with BOEC in Chamber 1 for 48 h or 72 h. A higher proportion of perifused embryos developed to the blastocyst stage after addition of 25 U mL-1 or 50 U mL-1 of superoxide dismutase (SOD) to PCM than in its absence. However, blastocyst formation of embryos perifused for 72 h was not increased after addition of 50 U mL-1 SOD compared with its absence. In Experiment 3, the proportions of morulae and blastocysts were not decreased by replacement of 3 mg mL-1 BSA with 1 mg mL-1 polyvinyl alcohol (PVA) in a BOEC-conditioned medium containing 50 U mL-1 SOD after perifusion for 48 h. In conclusion, PCM conditioning with BOEC and addition of an antioxidant to the perifusion medium improved the developmental capacity of perifused embryos. PVA is an adequate replacement for BSA in the perifusion medium.

Animals↗

Effects of amino acid supplements and replacement of polyvinyl alcohol with bovine serum albumin in porcine zygote medium.

The effects of glutamine, hypotaurine, taurine and premixed solutions of essential amino acids (EAA) and non-essential amino acids (NEAA) on in vitro development of porcine zygotes were evaluated. The effects of refreshing the medium and replacing polyvinyl alcohol (PVA) with bovine serum albumin (BSA) on embryonic development were also investigated. Porcine zygotes produced by in vitro maturation (IVM) and in vitro fertilisation (IVF) were cultured in porcine zygote medium (PZM), as the basal culture medium, for 5 days after IVF. The total number of cells in blastocysts was significantly increased by the addition of 2 mm glutamine to PZM, as was blastocyst yields after supplementation with 0.25 to 4 mm glutamine. Addition of 1.25 to 10 mm hypotaurine to PZM significantly increased blastocyst yields. Addition of 5 mm taurine to PZM significantly increased blastocyst yield, whereas taurine had no effect on blastocyst yield in cultures already containing 5 mm hypotaurine. Adding 1 x EAA significantly increased the rate of blastocyst formation compared with no or 2 x EAA, whereas 2 x NEAA significantly increased the total cell numbers in blastocysts compared with no NEAA. Refreshing the medium at Day 3 had no effect on blastocyst yields, whereas medium change significantly reduced the total cell numbers in blastocysts. Adjusting the amino acid concentrations of a chemically defined medium can improve the developmental competence of porcine embryo.

Amino Acids↗