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At least 19 recordsLinked to original sources

PubMed2004

Structure-property correlations in polypropylene from metallocene catalysts: stereodefective, regioregular isotactic polypropylene.

A series of MAO-activated C(1)-symmetric indenyl-ansa-dithienocyclopentadienyl-based zirconocenes have been used to produce isotactic polypropylenes of medium to high molecular weights, of different degrees of stereoregularity, and free from regioerrors. The effect of the presence of rr defects on the polymorphic behavior and mechanical properties of polypropylene is analyzed. The presence of rr defects induces crystallization of gamma form and of disordered modifications intermediate between alpha and gamma forms. A linear relationship between the amount of gamma form and the average length of isotactic sequences has been found. Samples with low concentration of rr defects, up to 3-4%, present high melting temperatures, in the range 160-130 degrees C, and behave as stiff-plastic materials; sample with higher rr content, in the range 4-6% and melting temperatures around 115-120 degrees C are highly flexible thermoplastic materials, and, finally, samples with concentration of rr defects in the range 7-11% and melting temperatures in the range 80-110 degrees C are thermoplastic elastomers with high strength. The fine-tuning of the chain microstructure, achieved by a tailored design of new metallocene catalysts, has allowed production of new polypropylenes having desired properties, intermediate between those of stiff plastic and elastomeric materials.

Journal Article↗

PubMed1988

Some mechanical properties of polypropylene sutures: relationship to the use of polypropylene in vascular surgery.

This study was performed to examine some mechanical properties of Polypropylene sutures. Fifty segments of 3-0, 4-0, 5-0, 6-0, and 7-0 sutures were mounted in clamps and were subjected to stepwise elongation. Results showed that suture stiffness (elastic modulus) and breaking stress (tensile strength) correlated directly and linearly with the circumference or "skin" of the filaments and inversely with the cross-sectional area or "core" of the filaments. These data suggest that the strength of the suture may reside in the outer skin. These findings are related to the handling of Polypropylene in surgery, and to suture motion in grafts in patients.

Humans↗

PubMed2005

Comparison of safety and efficacy between silicone and polypropylene Ahmed glaucoma valves in refractory glaucoma.

OBJECTIVE: To compare the safety and efficacy of polypropylene and silicone Ahmed glaucoma valves (AGVs) over 1 year of follow-up. DESIGN: Retrospective comparative study. PARTICIPANTS: Fifty consecutive patients with polypropylene and 49 consecutive patients with silicone AGV implantation. METHODS: Our hospital instituted a formulary conversion of the glaucoma aqueous drainage device from polypropylene to silicone AGVs in January 2003. We reviewed the polypropylene AGVs within 7 months before and the silicone AGVs within 7 months after the date of conversion performed on patients with glaucoma refractory to medical treatment and filtering procedures, without previous drainage devices or cyclodestructive procedures, and with a minimum of 12 months' follow-up. Surgical success was defined as an intraocular pressure (IOP) reduction of > or =20% and a final IOP of >5 and <22 mmHg, without additional surgical intervention for IOP control, loss of light perception, or serious complications. MAIN OUTCOME MEASURES: The 2 groups were compared for IOP control, visual outcome, complication rate, and surgical success rate. RESULTS: Significant IOP reductions occurred after polypropylene AGV implantation (from 32.4+/-11.3 mmHg to 16.5+/-6.9 mmHg, P<0.0001) and silicone AGV implantation (from 32.6+/-12.6 mmHg to 14.7+/-6.9 mmHg, P<0.0001). The silicone group had a lower mean IOP than the polypropylene group at all postoperative visits, but the differences were significant only at 3 months postoperatively (P = 0.014). In addition, the silicone group was associated with a rate of insufficient IOP control as the reason of failure (IOP of > or =22 mmHg or IOP reduction of <20%) lower (4.1%) than that of the polypropylene group (20.0%, P = 0.015), but a rate of non-tube related serious complications (16.3%) higher than that of the polypropylene AGV (4.0%, P = 0.042). CONCLUSION: After 1 year of follow-up, the silicone AGV is at least as effective as the polypropylene AGV in IOP reduction but may be associated with a higher rate of complications. These differences are important for surgeons converting to use of the silicone AGV in patients with glaucoma refractory to other forms of treatment.

Aged↗

PubMed2004

[Study on the interface of human hepatocyte L-02 polypropylene:simple culture method of human hepatocyte with spheroidal aggregate culture].

OBJECTIVE: To found new interface of human hepatocyte/poly propylene with good cytocompatibility for made polypropylene hollow fibers bioreactor of bioartificial liver in future. METHODS: Using the macromolecular hydroperoxide groups on the polypropylene membrane surface as initiators, acrylamides were polymerized on the polypropylene membranes, under induction by both UV irradiation and Fe2+ reduction. Growth characteristics of human hepatocyte L-02 were detected when it was cultured on polystyrene, polypropylene and modified polypropylene membrane surface. RESULTS: Water contact angle measurement of the polypropylene and the modified polypropylene membranes decreased from (72 +/- 5) degrees to (30 +/- 4) degrees , which indicated that the hydrophilicity of the membrane was improved obviously after the grafting modification. Human hepatocyte L-02 could not adhere and spread on modified polypropylene membrane surface, and grown in spheroidal aggregate with higher density and higher proliferation ratio measured by MTT method. CONCLUSIONS: Acrylamide polymerized on the polypropylene membranes is a good method which not only improved human hepatocytes cytocompatibility but also found a new simple culture method with spheroidal aggregate culture of human hepatocyte.

Cell Culture Techniques↗

PubMed1980

Adverse effects caused by polypropylene and polyvinyl feline urinary catheters.

Effects of 3 days of open dwelling urethral catheterization were evaluated in normal male cats. Commercially manufactured polypropylene and polyvinyl feline urinary catheters of sufficient length to permit constant urine drainage were compared. Catheters were similar in length, diameter, and design. Hematuria occurred in 6 of 6 cats with polypropylene catheters and in 4 of 6 cats with polyvinyl catheters. For cats with polypropylene catheters, hematuria began within 24 hours of catheter insertion. Hematuria induced by polypropylene catheters was usually more severe in final urinalyses than that induced by polyvinyl catheters. Catheter-induced bacteriuria was found in 5 of 6 cats with polypropylene catheters and in 3 of 6 cats with polyvinyl catheters. Staphylococci and streptococci were the most common bacterial isolates. Microscopic lesions in urethras and bladders were significantly less severe in cats with polyvinyl catheters than cats with polypropylene catheters. With few exceptions, urethras of cats with polyvinyl catheters were microscopically indistinguishable from urethras of noncatheterized cats. Polypropylene catheters consistently induced urethritis which was most severe in some bacteriuric cats. Severe lesions were found in the bladders of all cats with polypropylene catheters. Bladder lesions were common in cats with polyvinyl catheters, but were usually less severe in cats with polypropylene catheters. There was no apparent relation between bacteriuria and bladder lesions.

Animals↗

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↗

PubMed2006

Comparison of polypropylene and silicone Ahmed Glaucoma Valves.

PURPOSE: To evaluate and compare the clinical outcomes after implantation of the silicone plate and the polypropylene plate Ahmed Glaucoma Valves. DESIGN: Prospective, multicenter, comparative series. METHODS: A total of 132 patients with uncontrolled glaucoma were treated with either the silicone or polypropylene Ahmed Glaucoma Valve implant. MAIN OUTCOME MEASURES: Success was defined according to 2 criteria: (1) intraocular pressure (IOP) of 6 mmHg or more or 21 mmHg or less, and (2) IOP reduction of at least 30% relative to preoperative values. Eyes requiring further glaucoma surgery, including cyclophotocoagulation, or showing loss of light perception were classified as failures. RESULTS: Average follow-up was 12.8 months (range, 6-30 months) for the silicone plate group and 14.5 months (range, 6-30 months) for the polypropylene plate group (P = 0.063). At the last follow-up examination, the mean IOP was 13.8+/-3.9 mmHg and 17.3+/-6.5 mmHg (P<0.0001) and the mean number of antiglaucoma medications was 1.9+/-1.3 and 2.1+/-1.4 (P = 0.48) in the silicone plate and polypropylene plate groups, respectively. The life-table success rates for the silicone plate and polypropylene plate groups were 94.2% and 83.2% at 12 months and 82.4% and 56.7% at 24 months by definition 1, respectively (P = 0.035). When an IOP reduction of at least 30% was used for success criterion (definition 2), probabilities of success were 89.5% and 71.7% at 12 months and 78.3% and 68.5% at 24 months in the silicone and the polypropylene plate groups, respectively (P = 0.012). Visual outcomes were comparable between the 2 groups. However, complications including Tenon's cyst were observed more frequently in the polypropylene plate than in the silicone plate group (P<0.05). CONCLUSIONS: The silicone Ahmed Glaucoma Valve (model FP7) showed improved IOP reduction compared with the polypropylene (model S2) implant. Differences observed in mean IOP, success rate, and complications suggest that plate material may influence clinical outcome.

Adult↗

PubMed1995

Iohexol in patients undergoing urography: a comparison of polypropylene containers (Unique Soft Pack) and glass vials.

The purpose of the present phase IV multicentre trial was to evaluate general patient tolerance to Omnipaque 350 mgI/ml (iohexol) supplied in polypropylene containers compared to that of the same product supplied in routinely used glass vials, with emphasis on allergy-like adverse events. Polypropylene is a pure plastic material with practically no additives, and has been tested in vitro as a contrast medium packaging material for several years. Handling of these containers is easier and safer than handling of glass vials. Iohexol was administered to 1481 patients undergoing urography (741 patients in the glass vial group, 740 in the polypropylene container group), all of whom successfully participated in the trial. Six centres, representing four European countries, participated. Patients were randomized to receive iohexol from either polypropylene containers or traditional glass vials according to a double blind, parallel design. Pre-established inclusion and pre-admission exclusion criteria were followed, as well as routine procedures for preparation of the patients and conduct of the urography examinations at each hospital. Patient tolerance was assessed by recording all adverse events experienced over a period of up to 1 h after the procedure. Allergy-like events were defined as coughing, sneezing, nausea, vomiting, urticaria or itching. No adverse events were experienced by 56.5% of the patients in the glass vial group, nor by 58.0% of those in the polypropylene group. Discomfort (mainly a sensation of warmth) was reported by 39.4% and 38.6% of the patients, and adverse events other than discomfort by 7.4% and 5.9% of the patients, respectively. There seemed to be a correlation between the speed of injection and the frequency of discomfort (an increase with increasing speed), both of which varied a lot between centres. There was no significant difference in the incidence of allergy-like events between the two groups. Such reactions were seen in 2.0% of patients in the glass vial group and 1.9% of those in the polypropylene container group. There was no significant difference between the patients' tolerance to iohexol supplied in traditional glass vials or in polypropylene containers. Therefore, the new polypropylene container can be recommended as a container for Iohexol.

Adolescent↗

PubMed2001

Comparison of video urodynamic results after the pubovaginal sling procedure using rectus fascia and polypropylene mesh for stress urinary incontinence.

PURPOSE: Video urodynamic changes were compared after the pubovaginal sling procedure using rectus fascia or polypropylene mesh in women with stress urinary incontinence. MATERIALS AND METHODS: A total of 50 women with various types of stress urinary incontinence were treated with the pubovaginal sling procedure using randomly abdominal rectus fascia in 24 or polypropylene mesh in 26. The sling was placed at the level of the bladder neck and tied with sufficient tension to prevent urinary leakage without obstructing the bladder outlet. Video urodynamics were performed preoperatively, and 7 to 14 days and 3 to 6 months postoperatively in all cases. Surgical results and urodynamic changes after the pubovaginal sling procedure were compared in the 2 groups. Long-term results were evaluated at a mean followup of 2 years. RESULTS: Complete continence was achieved in 23 patients (95.8%) in the rectus fascia group and 26 (100%) in the polypropylene mesh group, including 1 initial failure with reoperation, at a median followup of 24 and 23 months, respectively. The subjective success rate was 91.6% for rectus fascia and 92.3% for polypropylene mesh. The main cause of dissatisfaction was persistent urge incontinence and dysuria in 2 cases each. In each group video urodynamics revealed a mild but nonsignificant decrease in maximum urinary flow and a significant increase in bladder neck opening time at 7 to 14 days versus baseline. However, these parameters returned to baseline within 3 to 6 months postoperatively. Voiding pressure, cystometric capacity and post-void residual urine also showed no significant change in either group after the pubovaginal sling procedure. Patients treated with a polypropylene mesh sling had a shorter operative time and hospital stay, a higher spontaneous voiding rate after catheter removal and a lower incidence of wound pain after surgery. One patient treated with polypropylene mesh had sling margin extrusion. The incidence of new onset detrusor instability and persistent dysuria was similar in the 2 groups. Transrectal sonography of the sling showed that it was located beneath the bladder neck and proximal urethra in all patients in each group. CONCLUSIONS: The results of this study show that the pubovaginal sling procedure using rectus fascia or polypropylene mesh as the sling material had similar effectiveness for treating female stress incontinence but the polypropylene group had more rapid recovery. Postoperatively video urodynamics demonstrated that the pubovaginal sling using either sling material did not cause bladder outlet obstruction with proper surgical technique.

Fasciotomy↗

PubMed1981

Primary vascular anastomosis in growing pigs: comparison of polypropylene and polyglycolic acid sutures.

Stenosis remains a significant problem in vascular anastomoses performed in the growing patient. This study compares the growth of vascular anastomoses performed with either polypropylene or polyglycolic acid sutures. End-to-end infrarenal aortic anastomoses were performed in 18 piglets. Twelve were performed with polypropylene; in six all sutures were placed in a continuous fashion (Group 1A), and in the other six the posterior sutures were continuous and the anterior were interrupted (Group B). Six anastomoses were performed with polyglycolic acid sutures placed in a continuous fashion (Group 2). The animals were killed 6 months following operation. The abdominal aorta was removed, measured, burst tested, and subjected to histologic studies. All anastomoses were patent. There were no burst failures at 300 mm Hg mean pressure. All polypropylene sutures in Group 1A and the continuous portion in Group 1B had straightened without breaking. Straightening without polypropylene suture breakage resulted in stricture in three Group 1A anastomoses and one Group 1B anastomosis; there was intraluminal polypropylene suture material in two Group 1A and five Group 1B anastomoses. Bowstring formation of the straightened, continuous portion of the polypropylene suture in two Group 1A anastomoses and one Group 1B anastomosis resulted in adherent thrombus. Group 2 anastomoses were without stricture and were grossly indistinguishable from adjacent normal vessel. Histologic examination showed varying degrees of chronic inflammation in the polypropylene anastomoses but negligible inflammation in the polyglycolic acid anastomoses. These results suggest that continuous suture techniques with polypropylene in growing vessels may result in stenosis and/or thrombosis. Moreover, synthetic absorbable polyglycolic acid sutures will be of use in vascular anastomoses in growing patients and in cases in which exacting technique with minimal postsurgical inflammation may be crucial to patency.

Animals↗

PubMed2003

Assessment of adhesion formation to intra-abdominal polypropylene mesh and polytetrafluoroethylene mesh.

BACKGROUND: The development of intra-abdominal adhesions, bowel obstruction, and enterocutaneous fistulas are potentially severe complications related to the intraperitoneal placement of prosthetic biomaterials. The purpose of this study was to determine the natural history of adhesion formation to polypropylene mesh and two types of polytetrafluoroethylene (ePTFE) mesh when placed intraperitoneally in a rabbit model that simulates laparoscopic ventral hernia repair. MATERIALS AND METHODS: Thirty New Zealand white rabbits were used for this study. A 10-cm midline incision was performed for intra-abdominal access and a 2 cm x 2 cm piece of mesh (n = 60) was sewn to an intact peritoneum on each side of the midline. Two types of ePTFE mesh (Dual Mesh and modified Dual Mesh, W.L. Gore & Assoc., Flagstaff, AZ) and polypropylene mesh were compared. The rate of adhesion formation was evaluated by direct visualization using microlaparoscopy (2-mm endoscope/trocar) at 7 days, 3 weeks, 9 weeks, and 16 weeks after mesh implantation. Adhesions to the prosthetic mesh were scored for extent (%) using the Modified Diamond Scale (0 = 0%, 1 50%). At necropsy the mesh was excised en bloc with the anterior abdominal wall for histological evaluation of mesothelial layer growth. RESULTS: The mean adhesion score for the polypropylene mesh was significantly greater (P < 0.05) than Dual Mesh at 9 weeks and 16 weeks and modified Dual Mesh at 7 days, 9 weeks, and 16 weeks. Fifty-five percent (n = 11) of the polypropylene mesh had adhesions to small intestine or omentum at necropsy compared to 30% (n = 6) of the Dual Mesh and 20% (n = 4) of the modified Dual Mesh. There was a significantly greater percentage (P < 0.003) of ePTFE mesh mesothelialized at explant (modified Dual Mesh 44.2%; Dual Mesh 55.8%) compared to the polypropylene mesh (12.9%). CONCLUSIONS: Serial microlaparoscopic evaluation of intraperitoneally implanted polypropylene mesh and ePTFE mesh in a rabbit model revealed a progression of adhesions to polypropylene mesh over a 16 week period. The pore size of mesh is critical in the development and maintenance of abdominal adhesions and tissue ingrowth. The macroporous polypropylene mesh promoted adhesion formation, while the microporous nature of the visceral side of the ePTFE served as a barrier to adhesions.

Abdomen↗

PubMed2006

Textile analysis of heavy weight, mid-weight, and light weight polypropylene mesh in a porcine ventral hernia model.

BACKGROUND: The purpose of this study was to assess the burst strength and stiffness of heavy weight (HW), mid-weight (MW), and light weight (LW) polypropylene mesh pre-implantation and 5 months post-implantation in a porcine ventral hernia model. MATERIALS AND METHODS: HW (95 g/cm2), MW (45 g/cm2), and LW (28 g/cm2) polypropylene were tested as dry samples (n = 8/mesh) before implantation using a stamp strain machine. Three weeks after creating four hernia defects in each mini-pig (n = 18), the polypropylene meshes (8 x 10 cm; 24/mesh type) were implanted in the preperitoneal space, ensuring 2 cm overlap circumferentially. At 5 months, the mesh was harvested en bloc with the abdominal wall. Testing of burst strength and stiffness was repeated on the ex vivo specimens. RESULTS: After implantation in the pig for 5 months, the mean burst strength and stiffness of HW and MW meshes remains the same. LW mesh with an absorbable monofilament in its weave has significant reductions in mean burst strength (P = 0.01) and mean stiffness (P < 0.0001). The burst strength for all meshes tested was much higher than measured for the abdominal wall fascia alone. The degree of shrinkage of the various weight meshes did not differ. CONCLUSION: A reduction in mean burst strength and stiffness occurs after 5 months implantation of LW polypropylene mesh with an absorbable monofilament. All meshes exhibited burst strengths that were much greater than the burst strength of the abdominal wall fascia alone. After tissue incorporation, the LW polypropylene mesh maintains mean burst strength comparable to MW polypropylene mesh, while becoming less stiff than HW mesh. Long-term, this may contribute to more physiological abdominal wall compliance after LW polypropylene mesh implantation.

Animals↗

PubMed2007

Comparison of silicone and polypropylene Ahmed Glaucoma Valve implants.

PURPOSE: To compare the efficacy and safety of silicone and polypropylene Ahmed Glaucoma Valves (AGVs) in patients with refractory glaucoma. METHODS: A retrospective chart review of 180 eyes of 166 patients who underwent AGV implantation with a minimum follow-up period of 3 months was performed. All patients who underwent implantation of either the AGV model S-2 (polypropylene) or model FP-7 (silicone) were included, unless previous laser cyclophotocoagulation had been performed. The primary outcome measures were the change in intraocular pressure (IOP) and visual acuity after surgery and the rate of postoperative complications. RESULTS: No significant differences were seen in the baseline characteristics of patients in each group. Baseline IOP was statistically equivalent in the 2 groups (silicone =33.8+/-11.9 mm Hg, polypropylene=33.0+/-10.3 mm Hg, P=0.6). A significant reduction in IOP from baseline was achieved after both silicone and polypropylene AGV implantation (silicone =-17.7+/-11.8 mm Hg, polypropylene =-17.7+/-11.3 mm Hg, both P<0.00005). However, there was no statistically significant difference in IOP decrease between the 2 groups at any follow-up visit (all P>0.09). The mean number of postoperative antiglaucoma medications was also similar in the silicone and the polypropylene AGV groups at each time point (all P>0.2). The rate of complications and the change in visual acuity did not differ between the 2 groups (P>0.6 and P>0.3, respectively). CONCLUSIONS: Silicone and polypropylene AGVs have similar results with respect to both safety and efficacy in the treatment of patients with refractory glaucoma.

Antihypertensive Agents↗

PubMed1997

Blood compatibility of polypropylene surfaces in relation to the crystalline-amorphous microstructure.

Blood-contacting properties of polypropylene surfaces with different crystalline states at the surface layer were examined in terms of plasma protein adsorption and changes in cytoplasmic free Ca2+ levels in platelets. Though the wettability of polypropylene surfaces was almost constantly independent from the surface layer crystallinity and interlamellar spacing, an increase in adhesiveness was observed with decreasing surface layer crystallinity and interlamellar spacing. It is suggested that the surface properties of the sheets varied in relation to the crystalline-amorphous microstructure. Minimum magnitudes in albumin and fibrinogen adsorption were observed on the polypropylene surface with a particular surface layer crystallinity (c. 55 wt%). A decrease in interlamellar spacing resulted in enhancing albumin adsorption and diminishing fibrinogen adsorption. Transient phenomena in plasma protein adsorption were observed on their surfaces with a plasma concentration. It is considered that the polypropylene surface with a particular crystalline-amorphous microstructure reduces the denaturation of adsorbed proteins. An increase in cytoplasmic free Ca2+ levels in platelets was prevented at the polypropylene surface with a surface layer crystallinity of 55 wt%: the particular crystalline-amorphous microstructure of such apolar surfaces as polypropylenes acts to reduce platelet activation. Thus, it is concluded that the blood compatibility of polypropylene surfaces is greatly improved by controlling a crystalline-amorphous microstructure at the surface layer.

Adhesiveness↗

PubMed2005

Effects of autoclaving on dimensional qualities and physical properties (flexural rigidity and brittleness) of newly developed root canal filling point made of polypropylene (FLEX POINT NEO).

In this study, we investigated the effects of 10 cycles of conventional autoclaving (121 degrees C, 20 min) on the dimensional integrity and physical properties (flexural rigidity and brittleness) of a newly developed root canal filling point made of polypropylene (FLEX POINT NEO). We measured the diameters of autoclave-sterilized and non-treated polypropylene points (020 through 070) and calculated the incidence of deviation from ISO specifications (6877.4.4.1, 1995). In order to ascertain physical properties, we tested autoclave-sterilized and non-treated polypropylene points (030, 050 and 070) for flexural rigidity. This was done by evaluating deflection value when a load was placed at the free tip-end of the point and brittleness in accordance with ISO specifications (6877.6.5.2). Ten cycles of autoclaving showed no significant effect on the diameters of the polypropylene points. All the polypropylene points in both the non-treated and the autoclave-sterilized groups met ISO specifications in terms of dimensional integrity of diameter. In the autoclave-sterilized group, 030 and 050 polypropylene points showed a slight decrease in flexural rigidity (3.4% in 030, 10.0% in 050). In terms of brittleness, none of polypropylene points showed any sign of fracture.

Hot Temperature↗

PubMedDate not supplied

[Complications of the management of secondary peritonitis with contained-open abdomen. Comparison of the Bogota's bag vs polypropylene mesh].

BACKGROUND: Surgery is the cornerstone regarding the treatment of secondary peritonitis, although the complications of the contained-open abdomen are common, and are usually severe. OBJECTIVES: To identify the complications with the use of the "Bogotá's bag" compared with polypropylene mesh in contained-open abdomen. To identify other possible morbidity and mortality risk factors, independently of the mesh type usage. METHODS: One hundred patients with secondary peritonitis were included in this retrospective cohort study. They were treated from January 2000 to March 2002. Fifty subjects were operated on with the "Bogota's bag " (50%) and 50 with the polypropylene mesh (50%). Mannheim's peritonitis severity index, complications and mortality using central tendency and dispersion means, the logistic regression analysis, prevalence and prevalence-ratios were analyzed. RESULTS: Most frequent etiologies of secondary peritonitis were intestinal anastomosis dehiscence, hollow viscera perforation, and severe pancreatitis. Observed complications were: perforation and intestinal fistula in 13 cases (13%); 10 (20%) out of these belonged to the polypropylene mesh group, and 3 (6%) to the Bogota's bag group (p = 0.036). Evisceration was observed in 8 cases (8%); 2 (4%) in the polypropylene mesh group, and 6 (12%) in the Bogota's bag group (p = 0.140). Hemorrhage was present in 30 cases (30%); 16 (32%) in the polypropylene mesh group, and 14 (28%) in the Bogota's bag group (p = 0.662). Colonization was present in 24 cases (24%); and this was mainly evident in the polypropylene mesh group (p = 0.019). Mortality reached 42% (42 cases), and was associated to postoperative bleeding (p = 0.004), peritonitis' severity (p = 0.0012), and surgical reinterventions. CONCLUSIONS: The contained-open abdomen is the best surgical option to treat infection and the compartmental abdominal syndrome in secondary peritonitis, however, complications may be relevant. These results demonstrated a direct relationship between peritonitis severity, the need for surgical re-interventions and mortality. The use of polypropylene mesh was related to an increased risk of intestinal fistulization and prothesis-associated infection.

Abdomen↗

PubMed2005

Adsorption of polypropylene from dilute solutions on a zeolite column packing.

Faujasite type zeolite CBV-780 was tested as adsorbent for isotactic polypropylene by liquid chromatography. When cyclohexane, cyclohexanol, n-decanol, n-dodecanol, diphenylmethane, or methylcyclohexane was used as mobile phase, polypropylene was fully or partially retained within the column packing. This is the first series of sorbent-solvent systems to show a pronounced retention of isotactic polypropylene. According to the hydrodynamic volumes of polypropylene in solution, macromolecules of polypropylene should be fully excluded from the pore volume of the sorbent. Sizes of polypropylene macromolecules in linear conformations, however, correlate with the pore size of the column packing used. It is presumed that the polypropylene chains partially penetrate into the pores and are retained due to the high adsorption potential in the narrow pores.

Journal Article↗

PubMed1995

Polypropylene production and colorectal cancer: a review of the epidemiological evidence.

Polypropylene has been produced for over 35 years and has a wide variety of applications including industrial uses, food packaging and many domestic uses. As a high-molecular-weight polymer, polypropylene is considered chemically inert with little or no physiological or toxicological effects. Nevertheless, early epidemiological studies of polypropylene production workers and carpet manufacturing employees who use polypropylene reported a significant excess of colorectal cancer. In one study, five of the seven cases were diagnosed within a five-month period, and in the other study, five cases were diagnosed within an 18-month period. Recent updates of these two study populations have found no continuation of the excess of colorectal cancer, thereby indicating that the earlier observations on these two groups reflected the chance nature of a time-space cluster. Moreover, investigations of polypropylene production workers in the United States, Germany, Australia and the United Kingdom found no association with colorectal cancer. When the results of all studies of polypropylene production workers are pooled, the summary risk ratio for colorectal cancer is 1.37 (95% confidence interval 0.83-2.11). Taken together, the epidemiological evidence and the absence of toxicological data do not support a causal association between polypropylene and colorectal cancer.

Adult↗