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At least 847 records · Page 47Linked to original sources
PubMed1997

Advances in polyvinyl alcohol hydrogel keratoprostheses: protection against ultraviolet light and fabrication by a molding process.

Our goal was to: 1) modify poly(vinyl alcohol) hydrogels intended for use in a synthetic cornea to absorb ultraviolet light and 2) develop molding procedures for the fabrication of the device. Two ultraviolet light-absorbing monomers were incorporated by copolymerization. The resulting hydrogels protected against ultraviolet light, were not toxic to corneal fibroblasts, and the protection did not diminish during prolonged aqueous exposure. A novel keratoprosthesis molding procedure was developed that made use of the phase transition properties of mixtures of poly(vinyl-trifluoroacetate) and acetonitrile. In this procedure the keratoprosthesis was shaped and a fibrous skirt was bonded to it in a single operation. Composite keratoprostheses were designed and prepared for in vivo testing.

Animals↗
PubMed1984

The long-term results of polyvinyl alcohol (Ivalon) sponge for rectal prolapse in young patients.

The long-term outcome of Ivalon sponge rectopexy for rectal prolapse in a group of young patients was reviewed. Thirty-two patients under the age of 40 underwent Ivalon sponge rectopexy between 1961 and 1975 with no mortality and one early complication. Twenty-five patients (9 men; 16 women) aged 13-39 years (median 28 years) at the time of operation were interviewed and examined in the Out-Patient Department between 5 and 20 years (median 10 years) after the operation. Five (20 per cent) had developed recurrence which occurred at 1, 1, 5, 6 and 9 years. There was no significant change in bowel habit postoperatively, with the exception of 3 patients with diarrhoea who reverted to normal. There was some disturbance in faecal continence pre-operatively in 20 patients, of whom 15 (75 per cent) were improved by rectopexy. All patients had normal urinary and sexual function, and there was no disturbance of menstruation in females following rectopexy. Three men who wished to have children were successful. Three of six women who attempted to conceive post-operatively had normal pregnancies and deliveries. The three women who failed to do so had already been investigated for infertility before the operation. No patient developed pelvic malignancy.

Adolescent↗
PubMedDate not supplied

Nitrocellulose and polyvinyl coatings prevent sperm adhesion to glass without affecting the motility of intact and demembranated human spermatozoa.

The effectiveness of several glass coating agents in preventing sperm adherence to glass surfaces for both intact and demembranated human spermatozoa was investigated. These agents included bovine serum albumin (BSA), Sigmacote, poly glu-lys, Collodion and Formvar. The presence of at least 5% of seminal plasma in sperm suspensions prevented sperm adhesion to glass surfaces. On the other hand, 56% of washed spermatozoa resuspended in an isoosmotic buffer containing 1 mg/ml of BSA attached to glass. Collodion, Formvar and Sigmacote reduced sperm attachment to glass to 2, 5 and 7%, respectively. BSA was partially effective, with 20% sperm adherence to glass, and poly glu-lys was totally ineffective. Whereas Sigmacote and BSA coatings lacked transparency, Collodion always achieved the best light transmission. Demembranated reactivated spermatozoa were all attached to glass within 90 seconds of contact. This adhesion was prevented by Collodion and Formvar. Other agents were less effective or interfered with motility. In contrast to intact spermatozoa, demembranated spermatozoa have a very low progressiveness ratio (vector speed/track speed), a wide beating amplitude and because of their whiplash flagellar movement, their motility resembles that of hamster capacitated spermatozoa.

Cell Adhesion↗
PubMed1989

In vitro platelet interactions with a heparin-polyvinyl alcohol hydrogel.

No difference in in vitro platelet reactivity was found between an immobilized heparin containing hydrogel (heparin-PVA) and the hydrogel without heparin (PVA), in a variety of experimental assays. There was no significant difference between the heparin-PVA and PVA coated polyethylene tubing in the number of 51Cr-labeled platelets, the extent of 14C serotonin release by the adherent platelets or in the degree of platelet count decrease after 1 h exposure to citrated canine whole blood in a Chandler loop system. Furthermore, adhesion and release values were lower than those observed with the uncoated polyethylene tubing (e.g., 9.3 +/- 4.3 plt/10(3) microns 2 on PVA; 18.3 +/- 4.6 plt/10(3) microns 2 on polyethylene). There was also no significant difference between heparin-PVA and PVA in bead column retention values with canine blood and with the previously reported washed human platelet adhesion/release values. Thus there appears to be no effect of the immobilized heparin by itself on the in vitro interactions of PVA with platelets, with the reactivity towards platelets dominated by that of the underlying substrate (i.e., PVA).

Animals↗
PubMed2005

Role of granulocytes and monocytes in the polyvinyl chloride-induced synthesis of interleukin 8, monocyte chemoattractant protein 1, and leukotriene B4.

In an in vitro whole blood model of artificial surface-induced inflammation, we have studied the contribution of leukocyte populations in the synthesis of inflammatory mediators. This was done by depleting the blood of specific cell types using magnetic beads coated with monoclonal antibodies against leukocyte surface antigens. Synthesis of interleukin 8 (IL-8) was highly dependent on CD15+ cells and was reduced by 80% when these cells were removed from the blood. Correspondingly, IL-8 production showed a high correlation with the concentration of granulocytes (r = 0.77, p < 0.0001). Synthesis of monocyte chemoattractant protein 1 (MCP-1) was dependent on CD14+ cells and was reduced by 35% when these cells were removed from the blood. Correspondingly, MCP-1 production correlated with the concentration of monocytes (r = 0.39, p < 0.0001). Synthesis of leukotriene B4 (LTB4) was highly dependent on CD15+ cells and was reduced by 75% when these cells were removed from the blood. Correspondingly, LTB4 production correlated strongly with the granulocyte concentration (r = 0.54, p < 0.0001). As expected, complement activation was not affected by cell depletion and did not correlate with the concentration of any of the cell types. Thus, artificial surface-induced IL-8 and LTB4 synthesis was almost exclusively granulocyte dependent. However, MCP-1 synthesis was mainly a product of monocytes, although granulocytes and other subpopulations may partly contribute. (c) 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005.

Chemokine CCL2↗