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PubMed1987

Characterization of Hexsyn, a polyolefin rubber.

Hexsyn is the Goodyear Tire and Rubber Company tradename for a polyolefin rubber synthesized from 1-hexene with 3-5% methylhexadiene as the source of residual double bonds for vulcanization. Under license from Goodyear, this same polymer has been manufactured by Lord Corporation for the hinge portion of finger joint prostheses using the tradename Bion. This rubber is currently licensed to the University of Akron and to the Cleveland Clinic Foundation for use in biomedical applications, and is being used primarily for biocompatible and highly fatigue resistant rubber components in ventricular assist and artificial heart systems. Results are presented from the physical, mechanical, and biological characterization of Hexsyn. Procedures are described for the synthesis, compounding, and post-molding extraction for Hexsyn. The physical testing of Hexsyn reported includes determinations of its density at 23 and 37 degrees C, initial hardness and hardness after aging in oxygen, blood, pseudoextracellular fluid and polyethylene glycol 600, typical molecular weights determined by gel permeation chromatography/low angle laser light scattering and intrinsic viscosity, thermal analyses by differential scanning calorimetry of Hexsyn gum, and vulcanized Hexsyn after exposure to blood and blood/fatigue conditions. Also reported are results of differential thermal analyses, thermomechanical analyses of virgin and annealed samples, and thermogravimetric analyses conducted in helium and in air. Dynamic mechanical analyses of Hexsyn include Clash-Berg and Rheovibron tests. Swelling was conducted to determine lot-to-lot and sheet-to-sheet variation for quality control and also a number of solvents were used so that the polymer-solvent interaction parameters could be determined. The permeability of Hexsyn to water, water vapor, and a variety of gases is reported. The permeability by contact angle measurements, refractive index, residual solvent analyses, migration of blood components into Hexsyn, melt rheology by Monsanto Rheometer, resistance to acids, and typical mold shrinkage for Hexsyn are reported. Mechanical testing of Hexsyn includes tensile strength, elongation, and tensile stress (modulus) at 23 and 37 degrees C and after conditions including exposure to blood, pseudoextracellular fluid, polyethylene glycol, oxygen, 100% relative humidity, and fatigue testing. Stress/strain calibration curves, flexural rigidity after aging in blood, tension set, compression set, stress relaxation, and the effect of repeated cycling on the elastic modulus are presented along with the results of Pico abrasion, skid resistance tests on wet concrete.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

Fast and robust method for the determination of microstructure and composition in butadiene, styrene-butadiene, and isoprene rubber by near-infrared spectroscopy.

In the tire industry, synthetic styrene-butadiene rubber (SBR), butadiene rubber (BR), and isoprene rubber (IR) elastomers are essential for conferring to the product its properties of grip and rolling resistance. Their physical properties depend on their chemical composition, i. e., their microstructure and styrene content, which must be accurately controlled. This paper describes a fast, robust, and highly reproducible near-infrared analytical method for the quantitative determination of the microstructure and styrene content. The quantitative models are calculated with the help of pure spectral profiles estimated from a partial least squares (PLS) regression, using (13)C nuclear magnetic resonance (NMR) as the reference method. This versatile approach allows the models to be applied over a large range of compositions, from a single BR to an SBR-IR blend. The resulting quantitative predictions are independent of the sample path length. As a consequence, the sample preparation is solvent free and simplified with a very fast (five minutes) hot filming step of a bulk polymer piece. No precise thickness control is required. Thus, the operator effect becomes negligible and the method is easily transferable. The root mean square error of prediction, depending on the rubber composition, is between 0.7% and 1.3%. The reproducibility standard error is less than 0.2% in every case.

Journal Article↗
PubMed1989

Patency and durability of small diameter silicone rubber vascular prostheses.

This study evaluated the long-term patency and durability of 6 mm internal diameter (ID), 18-30 micron pore size replamineform silicone rubber vascular prostheses as canine aortic interposition and arteriovenous (A-V) grafts. Six prostheses (6 mm ID x 8 cm length) were evaluated as aortic grafts for 24 to 30 months, and 10 prostheses (6 mm ID x 8-10 cm length) were studied as A-V grafts from 2 weeks to 10 months. Three of the A-V prostheses were punctured for sham dialysis once or twice/week with two 16 gauge needles (total of approximately 50 needle punctures). The porous wall of the silicone rubber prostheses was incorporated with capillaries and fibrohistiocytic cellular elements from 2 weeks of implantation. This cellular incorporation remained constant up to 2 1/2 years. Needle puncture of the arteriovenous grafts over a 3 to 5 month period produced no complications such as thrombosis, perigraft hematoma formation or bleeding through the puncture site. The silicone rubber sealed the holes with no evidence of tearing. Explanted prostheses had no evidence of enlargement or false aneurysm formation. This study supports our hypothesis that Replamineform silicone rubber prostheses are hemocompatable and demonstrate long-term durability for dialysis access. Clinical evaluation of this graft is planned in the near future.

Animals↗
PubMed1999

Seroepidemiologic survey of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group rickettsiae in rubber estate workers in Malaysia.

The seroprevalence of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group (SFG) rickettsiae in 300 rubber estate workers in Slim River, Malaysia was determined in December 1996 and March 1997. In December, which was the wet season, 23.3%, 3.0%, and 57.3% of the population had antibodies detected against the three rickettsiae, respectively. The highest seropositive rate of 40% was detected for single infection with SFG rickettsiae, followed by a rate of 15.3% for both O. tsutsugamushi and SFG rickettsiae among the rubber estate workers. Subjects less than 21 years old had a lower seroprevalence of SFG rickettsiae compared with the other age groups. Indians had a higher seroprevalence of O. tsutsugamushi compared with other ethnic groups. Rubber tappers had a higher seroprevalence of SFG rickettsiae compared with other occupational groups. During the dry season in March 1997, there was a significant increase in the seroprevalence of R. typhi. The seroconversion rates for IgM against O. tsutsugamushi, R. typhi, and SFG rickettsiae were 5.7%, 12.3%, and 15.1%, respectively, during the four-month period. Significant variations of antibody titers towards the three rickettsiae was noted among subjects who were bled twice. This suggests a significant and continual exposure of rubber estate workers to the three rickettsiae.

Adolescent↗
PubMed2002

Effects of wearing knitted or rubber gloves on the transfer of Escherichia cohi between hands and meat.

On eight occasions, five volunteers each handled five pieces of meat with bare hands or while wearing dry or wet knitted gloves or rubber gloves after hands had been inoculated with Escherichia coli or after handling a piece of meat inoculated with E. coli. On each occasion, after all meat was handled, each piece of meat, glove, and hand were sampled to recover E. coli. When hands were inoculated, E. coli was recovered from all meat handled with bare hands, in lesser numbers from some pieces handled with knitted gloves, and from only one piece handled with rubber gloves. When pieces of inoculated meat were handled, the numbers of E. coli transferred to uninoculated meat from bare hands or rubber gloves decreased substantially with each successive piece of uninoculated meat, but decreases were small with knitted gloves. The findings indicate that, compared with bare hands, the use of knitted gloves could reduce the transfer of bacteria from hands to meat but could increase the transfer of bacteria between meat pieces, whereas the use of rubber gloves could largely prevent the first and greatly reduce the second type of bacteria transfer.

Bacterial Adhesion↗
PubMed1995

A room temperature vulcanizing silicone rubber sport splint.

Athletic hand and wrist injuries may be treated by immobilizing the affected extremity in a rigid splint to protect the injury site for an extended time period. For athletes, this means a reduction in playing time, perhaps being out for an entire playing season. The use of a room temperature vulcanizing silicone rubber compound allows for a playing splint that complies with athletic regulations. Proper application of the room temperature vulcanizing silicone rubber provides an excellent, reliable protective playing splint allowing for safe, functional athletic performance for the injured player during the game. This article describes the fabrication process of a silicone rubber protective playing splint for athletic hand and wrist injuries. The effectiveness of the silicone rubber protective playing splint is illustrated via case studies.

Adolescent↗
PubMed1995

Allergy to latex rubber.

OBJECTIVE: To summarize the clinical symptoms of latex rubber allergy and provide guidelines for the management of this allergy. DATA SOURCES: The English-language literature was searched from 1979 through 1994 manually and using MEDLINE. Conference proceedings and reference lists of relevant articles were reviewed. DATA EXTRACTION: Studies clinically relevant to latex allergy were selected. RESULTS: The most common clinical presentation of latex allergy is a nonimmunologic, irritant dermatitis of the hand. Contact dermatitis (type IV delayed hypersensitivity reactions to rubber additives) is the most common immunologic manifestation of latex rubber allergy. Type I allergic responses are less common and include contact urticaria, rhinoconjunctivitis, asthma, and anaphylaxis. Seven percent to 10% of health care workers regularly exposed to latex and 28% to 67% of children with spina bifida have a positive skin test result to latex proteins indicating increased blood levels of IgE antibody. About one third of patients with positive skin test results, however, do not yet have symptoms of latex allergy. Systemic (life-threatening) anaphylactic shock can occur intraoperatively in highly sensitive patients because of mucosal absorption of latex protein allergens from the surgeon's gloves. The present treatment for latex allergy is careful avoidance of latex materials. In addition, the use of powder-free latex gloves can eliminate airborne latex exposure and can allow health care workers with inhalant allergic reactions to return to work. CONCLUSION: Latex allergy currently affects thousands of people. These persons have IgE-mediated cutaneous, respiratory, and systemic allergic reactions. A reduction of the total protein level on latex rubber devices may prevent further sensitization and eliminate latex allergic reactions.

Algorithms↗
PubMedDate not supplied

Dispersion-casting thin and ultrathin fabric-reinforced silicone rubber membrane for use in the membrane lung.

Pinholes in thin silicone rubber membrane have previously been traced to undispersed silica filer aggregates within the silicone rubber. This was overcome by centrifuging the dispersion to remove the aggregates prior to membrane fabrication. Thin (less than 75 mu) and ultra-thin (less than 25 mum) membrane could then be dispersion-cast. To facilitate handling and to increase mixing of blood in the membrane lung, it is often desirable to reinforce the silicone rubber membrane with fabric. Unfortunately, this process frequently introduces pinholes of its own. We have found than pinhole-free fabric-reinforced silicone rubber membrane can consistently be produced by the double-layer casting technique. First, the dispersion is cast onto aluminum foil, solvent evaporated, and partially cured. A second layer is next cast on top of it, followed by fabric. After solvent evaporation, final cure is under nitrogen using organic peroxide catalysts. This technique has permitted us to consistently cast strong pinhole-free membranes as thin as 9 mu.

Humans↗
PubMed2001

Blue rubber bleb nevus syndrome: a case report with long-term follow-up.

Blue rubber bleb nevus syndrome is an uncommon condition manifested by gastrointestinal and skin hemangiomas that lead to gastrointestinal bleeding and anemia. The purpose of this report is to present a case with long-term follow-up. The patient is a 37-year-old female with a life-long history of blue rubber bleb nevus syndrome. She underwent multiple resectional operations that combined to give her a partial gastrectomy, partial small bowel resection, total abdominal colectomy, and end ileostomy. She continues to need endoscopy with sclerotherapy. In addition, she has iron-deficiency anemia, nephrolithiasis, major depression, and malnutrition despite vitamin and caloric supplements. There are no other reports showing these complications of blue rubber bleb nevus syndrome or with this length of follow-up. Therapy for blue rubber bleb nevus syndrome should be conservative if possible, because operative therapy may lead to significant long-term complications.

Adult↗
PubMed1998

[Reconstruction with silicone rubber tube after resection of hypopharyngeal and cervical esophageal cancer].

OBJECTIVE: To treat the benign stenosis and defects caused by resection of cancers of hypopharyngeal and cervical esophagus. METHODS: Silicone rubber tubes made by ourselves were utilized to reconstruct the defect. It was found that in animal models, the granulation surface was covered with epithelial tissues and new lumen formed. RESULTS: Among 30 cases treated with silicone rubber tubes, 6 cases (20.0%) developed hypopharyngeal fistulae after operations. Twenty-five cases with cancer and 5 cases with benign stenoses and hypopharyngeal fistulae were followed-up from 5 months to 4 years. The silicone rubber tubes in 25 cases were decannulated, of them, 23 cases recovered normal swallowing function. Two cases developed severe stenosis again and 2 cases were under observation. In 25 cases with cancer, 2 had local relapse of cancer three to six months after the first operation. Four cases had cervical metastasis. All these 6 cases died within one year after operation. One case died of lung metastasis, two cases died of inflammation of lungs. Among 25 patients with cancers, the three-year survival rate was 50.0% (5/10). CONCLUSION: For defects in hypopharynx and cervical esophagus less than 10 cm, silicone rubber tube reconstruction is satisfactory.

Adult↗
PubMed2002

Rubber matting on an obstacle course causes anterior cruciate ligament ruptures and its removal eliminates them.

In June 1998, six unexpected anterior cruciate ligament (ACL) ruptures within 12 months were detected by routine injury surveillance in a cohort of Australian Army recruits. Local investigation, reported separately as a Case Report in this issue, suggested the cause to be an excessive coefficient of friction between rubber boot soles and newly laid rubber matting on one obstacle course, creating excessive knee torques. The matting was removed progressively, but not before two more ruptures occurred on one remaining section. In this retrospective study, chi 2 analyses were used to compare the incidence of ACL rupture in prehazard, hazard-exposed, and postintervention cohorts, and the average costs to the institution of each ACL rupture were determined. Zero, eight, and zero ACL ruptures occurred in the prehazard, hazard-exposed, and postintervention cohorts, respectively (chi 2 > 4.75 for 1 df, p < 0.03 for each change in incidence). The temporal relationships between hazard introduction or removal and changes in the incidence of ACL rupture were strong. The average institutional cost of each ACL rupture was AU$54,627 or US$34,322. Rubber matting on obstacle courses increases the risk of ACL rupture in the presence of speed and rubber-soled footwear. Routine injury surveillance and simple preventive processes save money and personnel.

Anterior Cruciate Ligament Injuries↗
PubMed2001

Results of rubber band ligation of esophageal varices.

BACKGROUND: The aim of the paper is to analyze the results of endoscopic rubber band ligation of esophageal varices performed between 1 January 1998 and 1 November 2000 at the Department of GI Surgery of 4th Military University Hospital. MATERIAL AND METHODS: Cases of 50 patients with massive upper GI variceal bleeding present on admission or with the history of such a bleeding were reviewed. A total of 85 endoscopic procedures of rubber band ligation were performed. In 9 (18%) cases ligation was performed due to massive variceal bleeding, in 1 case the complementary obliteration of stomach fundus varices with Aethoxysclerol was performed. In 10 (20%) cases in grade C of Child-Pough scale of liver failure, 3 endoscopic procedures were performed, in 15 (30%) in grade B--2 procedures, in the remaining 25 (50%) cases, also in grade B--1 procedure was performed. Procedures were conducted with Wilson-Cook Multi-Band Ligator SAEED SixShooter. RESULTS: In all cases with non-bleeding esophageal varices the overall good result of treatment was achieved, with collapsing of variceal columns. In 8 (88.8%) of 9 cases treated due to variceal bleeding, good hemostasis was achieved and no reintervention was necessary. In 1 case of massive variceal bleeding endoscopic treatment failed and patient eventually died. In 25 (50%) cases the complementary (1 or 2) rubber band ligations were performed. Follow-up period has ranged from 1 to 34 months. No cases of severe complications after the procedure were noted. In early period after the procedure 43 (86%) patients complained of transient, mild retrosternal pain and mild to moderate dysphagia. CONCLUSIONS: Endoscopic rubber band ligation is a safe and effective treatment for esophageal varices both in cases of variceal bleeding and as elective procedure.

Adult↗
PubMed2002

[Trabeculetomy combined with implantation of silicon rubber slice for intractable glaucoma].

PURPOSE: To investigate the lowering-pressure outcome and postoperative complications of trabeculectomy with implantation of silicon rubber slice for intractable glaucoma. METHODS: Sixty eyes with intractable glaucoma, including 12 eyes with neovascular glaucoma, 14 eyes with aphakic or pseudophakic glaucoma, 4 eyes with congenital glaucoma, 18 eyes with failed filtering surgery glaucoma and 12 eyes with glaucoma secondary to trauma, were performed trabeculectomy with implantation of silicon rubber slice. The postoperative lowering-pressure outcome and complications also were observed. RESULTS: All patients were follow-up for 5 to approximately 34 months ( mean, 18.3 months) . The postoperative intraocular pressure of patients was 17.30 to approximately 37.19 mmHg [mean, (23.36 +/- 4.06) mmHg] at the last visit. Of 60 eyes, the postoperative intraocular pressure was below 21 mmHg in 38 eyes (63.3%), between 21 to 30 mmHg in 18 eyes (30%) and higher than 30 mmHg only in 4 eyes (6.7%). No serious complications and rejection related to implantation of silicon rubber slice occurred in this group during the follow-up period. CONCLUSION: Trabeculectomy combined with implantation of silicon rubber slice seems to be an ideal procedure for treatment of intractable glaucoma in developing countries, especially in vast country hospital in China, this surgery also can replace the expensive import drainage device implant (Molteno tube implant) therapy for intractable glaucoma.

Adolescent↗
PubMedDate not supplied

Outcome of rubber band ligation of haemorrhoids using suction ligator.

BACKGROUND: Haemorrhoids are a common surgical problem seen in the outpatient department. Rubber band ligation using suction is an effective treatment for symptomatic haemorrhoids but associated with significant morbidity. This prospective observational study was carried out to assess the efficacy, effectiveness and complications of rubber band ligation performed in outpatient for symptomatic haemorhoids using suction ligator. The results and outcome of procedure performed by the consultants and senior residents were also compared. METHODS: 56 consecutive patients with symptomatic haemorrhoids underwent rubber band ligation in the outpatient clinic of the department of general surgery, Pakistan Institute of Medical Sciences. Outcome measures were symptomatic cure i.e. stoppage of bleeding and reduced mucosal prolapse. Complications were categorized as immediate, early (within one week) and late (within 3 months). RESULTS: Symptomatic cure was achieved in 50(89.20%) patients (stoppage of bleeding and reduced mucosal prolapse). Six (10.72%) patients required further banding. Pain (mild to severe) was most common immediate and intermediate complication (14 and 20 patient's respectively). CONCLUSION: Rubber band ligation is an effective, outdoor procedure for symptomatic haemorrhoids, but associated with certain degree of morbidity.

Adult↗
PubMedDate not supplied

Performance evaluation of hydroxylated and acylated silicone rubber coatings.

Hydroxylated and C16 acylated silicone rubber films were prepared with enhanced albumin binding. Lee-White clotting times were significantly increased for both treatments. Hydroxylation significantly reduced C5a production. Hydroxylated silicone rubber femoral vein catheters in canines reduced 111In-labeled platelet activity, compared with bilateral silicone rubber catheter controls. The results suggest hydroxylated silicone rubber films have enhanced biocompatibility.

Animals↗
PubMed1991

Temporary closure of the abdominal wall by use of silicone rubber sheets after operative repair of ruptured abdominal aortic aneurysms.

Management of patients after operative repair of abdominal aortic aneurysms can be further complicated if primary closure of the abdominal wall cannot be technically accomplished or is associated with profound increases in intraabdominal and peak inspiratory pressures. We recently treated five patients with ruptured abdominal aortic aneurysms and one patient with a ruptured thoracoabdominal aneurysm whose abdominal incisions had to be closed with a Dacron reinforced, silicone sheet. All patients were hemodynamically unstable either at admission to the hospital or became so during operation. Four patients required the insertion of a silicone rubber sheet at the primary operation because of massive retroperitoneal hematoma or edema of the bowel wall or both. Incisions in two patients were closed primarily, but the patients required reexploration and secondary closure with silicone rubber sheets because of the development of marked increases in peak inspiratory pressures, intraabdominal pressures, and decreased urinary output. Four of the six patients subsequently underwent successful removal of the silicone rubber sheets with delayed primary closure of the abdominal wall, and two others died before removal. The patient with the ruptured thoracoabdominal aneurysm died on postoperative day 20 because of pulmonary sepsis but had a healed abdominal incision. The three surviving patients have been discharged. A silicone rubber sheet may be necessary for closure of the abdominal wall after repair of ruptured abdominal aortic aneurysm in patients where primary abdominal wall closure is impossible or where it results in compromise in respiratory or renal function.

Abdomen↗
PubMed1978

A rubber band powered, piston-valve aspirator.

A new valved surgical aspirator is described which overcomes the shortcomings of conventional, valve-less suction devices. The valve piston which controls the flow of fluid is retained in the valve body by an ordinary rubber band. When the valve is opened by depressing the piston, the rubber band is stretched. When the piston is released, the rubber band shortens, automatically returning the valve to the closed position. Occluding the flow of air through a surgical aspirator between actual usages reduces the risk of bacterial wound contamination and reduces noise levels in the operating room. The rubber band powered, piston-valve aspirator is simple and efficient, and therefore it is suitable for hospital use.

Humans↗
PubMed1980

[Changes in electrical capacitance of silicone rubber impression materials during setting process (author's transl)].

Since the silicone rubber impression materials have the high dielectrics, the changes in electrical capacitance during its setting process were measured. The time coordinate of the point of inflexion in the curve of percent changes in its electrical capacitance V.S. time at the setting process were compared with setting time in mechanical measurement. The results were summerized as follows. 1) The degree of advancement of the setting reaction in silicone rubber impression materials were able to be observed by measuring its electrical capacitance. 2) Since the change of the electrical capacitance measured here is corresponding to the setting process of the silicone rubber impression material in this system, the point of inflexion of the curve of the reduced electrical capacitance is the indication of the setting process. 3) The time which demands to reach to this point of inflexion highly corresponds to the setting time of the same material by the mechanical measurements. 4) It is possible to determine the setting time of the silicone rubber impression material by means of measuring the changes in its electrical capacitance.

Dental Impression Materials↗