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Results for “Polypropylenes”

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At least 19 recordsLinked to original sources

PubMed1992

Polypropylene small-diameter vascular grafts.

Polypropylene's physical properties (e.g., high tensile strength) and relatively inert behavior suggest that fabrication into an arterial substitute may result in an efficacious prosthesis. Grafts were woven from polypropylene yarn into conduits 4 mm I.D. x 50 mm in length. Control grafts were Dacron and ePTFE. Baseline platelet aggregometry on all dogs was performed with 10(-5) M ADP. Aspirin and dipyridamole were given for three days preoperatively and maintained for 2 weeks after surgery. Fifty-four grafts were placed into the aortoiliac position, two different graft materials per dog. The grafts were explanted at intervals of 2 weeks through 16 months; photographed for thrombus-free surface area determinations; and preserved for light, scanning, and transmission electron microscopy. Late (4-16 month) patency was 81% (13/16) for polypropylene, 69% (9/13) for Dacron, and 20% (1/5) for ePTFE. These data include one year patencies of 11/12 (92%) for polypropylene and 7/10 (70%) for Dacron. Late patency for polypropylene grafts was better than for PTFE (p less than 0.05). Platelet aggregation status did not predict graft patency. Light microscopy of 2-week polypropylene explants showed inner capsules composed of myofibroblasts and macrophages, with patchy areas of endothelial cells lining the lumen. By 1 month, a confluent endothelialized surface was seen in all polypropylene explants. Progressive thickening of inner capsules with myofibroblasts and collagen continued through 4 months, reaching a mean thickness of 142 +/- 50 microns (compared to 150 +/- 30 microns for Dacron). These findings suggest potential clinical efficacy for polypropylene as an arterial substitute.

Adenosine Diphosphate↗

PubMedDate not supplied

Replacement of the medial collateral ligament with polypropylene mesh or a polyester suture in dogs.

The medial collateral ligament of one stifle in 20 adult dogs was excised and replaced with polypropylene mesh or a polyester suture. After 26 weeks, the fibrous tissue-prosthesis composites were evaluated clinically, morphologically, and biomechanically. Clinical lameness was not significantly different after 10 days. The polypropylene mesh reconstructions consistently had more fibrous tissue and greater collagenous ingrowth than the polyester suture reconstructions. There were four complications related to fixation of the polypropylene mesh prosthesis and one to the polyester suture. The polypropylene mesh reconstructions had greater stability and were biomechanically more similar to the natural ligaments than the polyester suture reconstructions. Although the results with polypropylene mesh were favorable, more challenging biomechanical testing and alternative anchoring techniques are required before polypropylene mesh can be recommended as a collateral ligament replacement in dogs.

Animals↗

PubMed1976

Subcutaneous implants of polypropylene filaments.

Extruded filaments of unmodified polypropylene (PP) with and without antioxidant were implanted subcutaneously in hamsters in order to determine their rate of degradation. Specimens were removed periodically during a 5 month test period and analyzed by infrared spectroscopy and dynamic mechanical testing. The analyses show that degradation beigns to occur after only a few days. Although the reaction sequence is not known, several factors suggest that the in vivo degradation process is similar to autoxidation which occurs in air or oxygen. The infrared data indicate that the hydroxyl content of the implants increases at a rate of 0.061 mg/g polypropylene per day during the initiation phase of the reaction. An induction time of 108 days was extablished. Carbonyl bonds appear after an implantation time of 50--90 days and increase therafter. Mechanical tests indicate a decrease in the dynamic loss tangent, tan delta, during the first month of implantation for unmodified polypropylene. No change in the infrared spectra or tan delta was observed, however, for implants containing an antioxidant. Thus, it is apparent that polypropylene filaments implanted subcutaneously in hamsters degrade by an oxidation process which is retarded effectively by using an antioxidant. While the findings reported are specific to subcutaneous polypropylene implants, they suggest that degradation of other systems may involve similar processes. This notion suggests directions for further research on increasing the in vivo stability of synthetic polymers. Long-term effects of polymer implantation upon tissue were not studied in this work.

Animals↗

PubMed1992

Pulmonary toxicity of inhaled polypropylene fibers in rats.

This study was initiated to assess the pulmonary toxicity of a polyolefin fiber composed of polypropylene in male Fischer 344 rats after 90 days of inhalation exposure. To increase fiber respirability in the rodent, polypropylene fibers were size-selected before aerosolization to have a geometric mean diameter of 1.6 microns (46% < 1 micron) and a geometric mean length of 30.3 microns. Three groups of animals were exposed in nose-only inhalation chambers, 6 hr/day, 5 days/week, for 90 days to 15, 30, or 60 mg/m3 of polypropylene, or filtered air (negative control). Microscopic examination of the polypropylene fiber-exposed lungs revealed that, at all time points examined in the study, there was a dose-dependent increase in pulmonary macrophages. These minimal or mild increases in cellularity appeared to be reversible, especially at the lower doses 30 days post exposure. No fibrosis was observed in any of the groups. A strong correlation was found between the external exposure concentration, the time of exposure, and the lung fiber burden. The number of partially degraded (segmented) fibers within the lung increased with the exposure concentration and period of exposure, as well as with the period of recovery after termination of exposure at 90 days. Fibers were recovered from exposed lungs using a hypochlorite digestion technique.

Administration, Inhalation↗

PubMed1976

Testing the effects of fluids on rat skin using disposable polypropylene chambers.

Inexpensive, disposable polypropylene chambers for testing fluids on rat skin were made by removing the wings from polypropylene wing nuts and by cutting into the top of each nut a seat for an O-ring. Polypropylene screws with black heads were fabricated as seals for the chambers. After attachment to the backs of rats, these chambers provided a satisfactory means of keeping fluid in contact with the skin for 3 days.

Animals↗

PubMed1992

A highly specific heterologous enzyme-linked immunosorbent assay for measuring testosterone in plasma using antibody-coated immunoassay plates or polypropylene tubes.

A highly specific and sensitive enzyme-linked immunosorbent assay, using a heterologous combination of antiserum raised against testosterone-3-(O-carboxymethyl) oxime-bovine serum albumin and penicillinase-labeled testosterone-11 beta-carboxymethyl ether, was developed for measuring testosterone in human plasma. Immunoassay plates (96 wells) provided a sensitivity of 2.5 pg/well. This was achieved by maintaining the molar ratios of steroid to enzyme between 10 and 20. The assay was very specific for testosterone and did not show any cross-reaction with the related C19 steroids tested. Replacement of immunoassay plates with the locally available polypropylene tubes raised the detection limits to 25 pg/tube, but improved the range of doses of testosterone that could be measured up to 10,000 pg. The antiserum to testosterone derivative was linked to both immunoassay plates and polypropylene tubes through immunochemical bridges. Comparison of testosterone values of 52 plasma specimens obtained by both solid phase methods with those of radioimmunoassay showed good correlation.

Antibodies↗

PubMed1978

Splinted vasovasostomy. Comparison of polyglycolic acid and polypropylene sutures.

An experimental study was performed comparing 6-0 polypropylene and 6-0 polyglycolic acid sutures in vasovasostomy. An indwelling entirely intraluminal splint of PE-10 tubing was used which was surgically removed three weeks postoperatively. Three months after vasovasostomy patency was determined by vasography. Eighty-five per cent patency was achieved with polyglycolic acid compared with 58 per cent patency when polypropylene was used.

Animals↗

PubMed1979

Stone formation on polypropylene suture.

Polypropylene is a relatively new suture material with many advantages, which has been demonstrated in experimental studies to be a safe material for urologic operations. However, recently, 2 patients had polypropylene suture at the matrix of urinary calculi. Symptoms from the calculi developed in both patients in the late postoperative period and both had large amounts of fibrosis around the sutured urothelium.

Adult↗

PubMed1975

Comparison of polypropylene and polyglycolic acid suture in experimental vasovasostomy.

A preliminary study upon seven dogs comparing vasovasostomy using polypropylene suture to vasovasostomy using polyglycolic acid suture was carried out. Five of the seven vasa anastomosed with polyglycolic acid sutures were patent wherease none of the seven vasa anastomosed with polypropylene sutures were patent. There appeared to be less vasal inflammatory reaction where vasovasostomy had been accomplished with polyglycolic acid. This study indicates that further investigation comparing these and other suture materials in vasovasostomy is justified. It also suggests that improved results in vasovasostomy might be obtained by the use of polyglycolic acid suture.

Animals↗

PubMedDate not supplied

[Stability of dilute solutions of ganciclovir sodium (Cymevan) in polypropylene syringes and PVC perfusion bags].

The stability of ganciclovir sodium solutions stored in polypropylene syringes and PVC bags was tested in 0.9% sodium chloride at three concentrations 70, 200 and 350 mg/50 ml for polypropylene syringes, and two concentrations (70 and 350 mg/250 ml) for PVC bags and at three temperatures (-20 degrees C, + 4 degrees C, room temperature). The solutions, which had been initially frozen, were thawed by exposure to microwave radiations. The stability of each sample was determined by high-performance liquid chromatography. The results of this study indicate that admixtures of ganciclovir sodium at the concentration rates tested can be frozen for at least one year and are stable for at least 80 days at + 4 degrees C and 7 days at room temperature.

Chromatography, High Pressure Liquid↗

PubMed1977

Polypropylene suture in esophageal and gastrointestinal operations.

A comparison was made of the gross and microscopic wound healing and tissue reactivity between stainless steel wire, polypropylene and silk in anastomoses in the u-prepared colon of the dog. While all anastomoses healed irrespective of the suture material used, wire was associated with the least inflammatory response, silk the most and polypropylene intermediate, its low reactivity approaching that of wire. A clinical trial of Prolene for 71 varied anastomoses between pharynx, esophagus, stomach and colon in 47 patients undergoing esophageal resection and reconstruction or bypass was done. In four of the seven anastomotic disruptions which occurred, causative factors unrelated to the suture material could factorily in the remainder of these patients. Monotive suture which works well in esophageal and gastrointestinal anastomoses.

Animals↗

PubMed1992

Repair of parastomal hernias using polypropylene mesh.

Parastomal hernias are a common complication of ostomy construction. We have developed a method of repair that uses two strips of polypropylene prosthetic mesh through a midline incision. The medical records of 19 patients who underwent parastomal hernia repair were retrospectively reviewed. All nine patients operated on for this condition by the senior author (R.G.P.) (group 1) underwent repairs with this technique. All ten patients operated on by other surgeons in our center (group 2) underwent repairs in which the stoma was moved, the fascia was directly repaired through a parastomal incision, or the fascia was repaired via a midline incision. No patients in group 1 had recurrences while five patients in group 2 had recurrences. Neither group developed strictures or stomal prolapse. Our method of repair is technically easy and has excellent results. It is especially suitable in very large hernias in which incisional hernia is likely in the original stoma site if the stoma is moved.

Abdominal Muscles↗

PubMed1975

Bone growth into porous carbon, polyethylene, and polypropylene prostheses.

Using rats as a model, porous discs of RPG carbon and polypropylene and polyethylene were localized subperiosteally and supraperiosteally in the skull. Bone and blood vessels grew into the discs, which had adequate pore size, when placed in direct contact with bone. No bone was generated from the periosteum. Both plastic materials were estimated to be better than carbon for use in osseous reconstructive work. More long term material-tissue stability and reaction studies should be performed.

Animals↗

PubMed1977

Vasovasostomy. Experimental comparative study of polyglycolic acid and polypropylene sutures in the dog.

Experimental vasovasostomy in dogs using polyethylene tubing for splints and comparing polyglycolic acid to polypropylene sutures demonstrates the following: Polyglycolic acid sutures result in a higher vasovasostomy patency rate. Grossly and microscopically, polyglycolic acid sutures are associated with less vasal and perivasal fibrosis. Postoperative use of very small polyethylene tubing for splints appears feasible. Leaving splints entirely intraluminally at the time of surgery may be advantageous. It would necessitate vasotomy for removal of the splint postoperatively, but this is easily accomplished and not associated with increased morbidity. A transscrotal approach is associated with a much higher vasal patency rate than is an inguinal approach.

Animals↗

PubMed1992

Arthroscopic-assisted anterior cruciate ligament reconstruction with the semitendinosus tendon: comparison of results with and without braided polypropylene augmentation.

Fifteen chronic anterior cruciate ligament-deficient knees were arthroscopically reconstructed with a semitendinosus tendon polypropylene (STP) augmented composite graft. A comparison group of 28 reconstructions with the semitendinosus tendon (ST) but without augmentation was simultaneously reviewed. The mean follow-up in the STP group was 31 months (range of 24-42 months) and in the ST group it was 34 months (range 26-54 months). Both patient groups had similar age, sex, preinjury functional sports level, injury-to-surgery interval, and associated meniscal pathology. Good-to-excellent subjective results were reported in 86% of STP patients and 78% of ST patients, whereas 86% of the STP patients and 88% of the ST patients returned to sports activity. Objective examination revealed 73% of the STP group and 82% of the ST group to have a negative or 1+ Lachman test result. A negative pivot shift was noted at follow-up in 80% of the STP group and in 82% of the ST group. KT-1000 testing revealed 60% of the STP patients and 61% of the ST patients to have less than or equal to 3 mm of side-to-side difference. In the STP group there was no evidence of graft breakage, deep infections, or sterile effusions. Overall subjective and functional results were uniformly better than objective results in both patient groups. Analysis of subjective, objective, and functional results reveal no difference in outcome between the STP and the ST patient groups.

Adult↗

PubMed1992

In situ hybridisation of EBV DNA-DNA hybrids using wet heat in polypropylene containers.

AIMS: To explore procedures designed to optimise DNA-DNA in situ hybridisation, using cells infected with Epstein-Barr virus (EBV) and tissues and subfragments of the EBV DNA as probes. METHODS: The denaturation step occurred in a polypropylene container, using wet heat generated by a hot water container, the pressure cooker, or the microwave oven, without coverslips, reaching a temperature of 121 degrees C or more in these two last systems. Two different visualisation systems were used. RESULTS: Fixed cells and tumours harbouring a high and medium to low copy number (a few hundreds to 33 copies per cell), were clearly labelled, using a simple reiterated subfragment (BamW) of the EBV DNA, and fresh frozen cells, harbouring a very low copy number (one to two on average) labelled using BamW as well as BamH (single non-reiterated 6 kilobase subfragment). CONCLUSION: This is a valuable alternative technique for DNA-DNA ISH that can be used in fresh frozen samples as well as fixed samples.

DNA, Viral↗

PubMedDate not supplied

Multiple peptide synthesis on polypropylene membranes for rapid screening of bioactive peptides.

A new multiple peptide synthesis technique that allows several hundred peptides to be synthesized on polypropylene membranes in one working day has been developed. Peptides are assembled as spots on a membrane sheet sandwiched between two 96-reaction well templates. Activity measurements can be made either with the membrane-bound peptides, for example, using an enzyme linked immunosorbent assay (ELISA), or after cleavage from the membrane. The method is simple and economical in the use of reagents, and peptides are of high quality, making possible the synthesis of rather long (> 20 residues) peptides. This method has been used to identify antigenic determinants recognized by antisera to bovine myelin proteolipid protein.

Amino Acid Sequence↗

PubMed1976

Reaction of the urinary tract to polypropylene sutures.

Cystotomies were performed on 99 mature guinea pigs and closed with polypropylene sutures. The bladders were removed at intervals from day 4 through day 144 postoperatively. They were studied with both light and electron microscopy. A localized mild, acute, inflammatory reaction was noted transitorily; it subsided between the 7th and 14th day. Three calculi were formed, a result which compares favorably with studies of other sutures. Results indicate that the suture may have a place in urologic surgery, but further studies are necessary before clinical use.

Animals↗