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PubMedDate not supplied

Migration testing of plastics and microwave-active materials for high-temperature food-use applications.

Temperatures have been measured using a fluoro-optic probe at the food/container or food/packaging interfaces as appropriate, for a range of foods heated in either a microwave or a conventional oven. Reheating ready-prepared foods packaged in plastics pouches, trays or dishes in the microwave oven, according to the manufacturers' instructions, resulted in temperatures in the range 61-121 degrees C. Microwave-active materials (susceptors) in contact with ready-prepared foods frequently reached local spot temperatures above 200 degrees C. For foods cooked in a microwave oven according to published recipes, temperatures from 91 degrees C to 200 degrees C were recorded, whilst similar temperatures (92-194 degrees C) were attained in a conventional oven, but over longer periods of time. These measurements form the basis for examining compliance with specific and overall migration limits for plastics materials. The testing conditions proposed depend on the intended use of the plastic - for microwave oven use for aqueous foods, for all lidding materials, and for reheating of foods, testing would only be required with aqueous simulants for 1 h at 100 degrees C; for unspecified microwave oven use, testing with olive oil would be required for 30 min at 150 degrees C; and for unspecified use in a conventional oven testing with olive oil would be required for 2 h at 175 degrees C. For microwave-active materials, it is proposed that testing is carried out in the microwave oven using a novel semi-solid simulant comprising olive oil and water absorbed onto an inert support of diatomaceous earth. The testing in this instance is carried out with the simulant instead of food in a package and heating in the microwave oven at 600 W for 4 min for every 100 g of simulant employed. There is an option in every case to test for migration using real foods rather than simulants if it can be demonstrated that results using simulants are unrepresentative of those for foods. The proposed testing conditions were validated as being realistic by measurement of the specific migration of various components from different plastics into foods under actual conditions of use and comparing with migration into simulants. Migration of plasticizers from PVC and VC/VDC copolymer films was monitored for both microwave reheating and cooking of foods. Total oligomer concentrations were measured from poly(ethylene terephthalate) (PET) trays, and volatile aromatics from thermoset polyester trays, using both types of container in microwave and conventional ovens.(ABSTRACT TRUNCATED AT 400 WORDS)

Adipates↗

PubMedDate not supplied

Kinetics of bacterial survival on polymer coatings with particular reference to indoor air quality.

The goal of the present study was to assess the bactericidal properties of various polyester coatings (PES) with and without anti-bacterial additives such as silver or polymer compounds. Under the experimental conditions used, the release of anti-bacterial additives was not an appreciable factor. The survival rate of Enterococcus faecalis mainly depended on environmental factors such as the relative humidity and the presence of nutrients. Based on the experimental points and the mathematics of disinfection, it was possible to model the survival kinetics of airborne bacteria after settling on polymer coatings. On clean materials, the coatings displayed an anti-bacterial property. Nevertheless, this was not sufficient, first, to ensure hygiene and indoor air quality and, secondly, to be adapted in domestic appliances or in hospitals. Indeed, most of the bacterial population still survived after several days' exposure. This weak effect of the anti-bacterial additives could be explained by their accessibility at the coating/bacteria interface.

Air Pollution, Indoor↗

PubMed1987

Long-term cotton dust exposure in the textile industry.

A three-year survey was conducted in six cotton-yarn manufacturing mills and one mill processing synthetic polyester fibers as part of a longitudinal epidemiologic investigation of the health experience of workers employed in the textile industry. A total of 1324 elutriated and total dust samples were collected during the three years of the study. The results indicate that the average elutriated dust concentrations in the surveyed mills were generally at or below the current OSHA standard and they ranged from 0.069 to 0.396 mg/m3, 0.089 to 0.391 mg/m3, and 0.106 to 0.210 mg/m3 for the first, second and third year surveys, respectively. Introduction of modern automated yarn processing equipment and elimination of some of the classic processes were associated with a decreasing trend in airborne dust concentrations in these mills.

Dust↗

PubMed1993

Excision of a trabecular ROI from resin-embedded vertebrae: report on a computer-assisted method.

A major problem when evaluating the accuracy of quantitative computed tomography (QCT) against chemical analysis of bone mineral is to ensure that the same region of interest (ROI) is measured with two techniques. The method described here attempts to reach this objective. Forty-nine lumbar vertebrae were scanned. The mid-vertebral portion was sawed and embedded in a polyester resin. The ROI defined with an automated contour detection was transmitted, using a Hewlett-Packard scanjet, to a computer-assisted milling machine which excised a trabecular ROI sample. The volume of each trabecular sample was determined using an Archimedian method. ROI volumes assessed on QCT were highly correlated with those obtained with the Archimedian method (r = 0.98). The standard error of the estimate was 170 mm3 (4.5%). These results suggest that trabecular samples obtained with this method optimally agree with the ROIs selected on QCT examination.

Bone and Bones↗

PubMed1996

Preparation of solid phantoms with defined scattering and absorption properties for optical tomography.

We have developed diffusely scattering solid phantoms with optical (scattering) properties amenable to theoretical calculations. Monodisperse quartz glass spheres were used as scatterers embedded in polyester resin. An infrared dye was added to simulate absorption by biological tissue. Solid phantoms were tested for their macroscopic homogeneity. Several phantoms were built with well-defined spatial variations in their transport scattering and absorption coefficients to be used for optical tomography. Scattering, transport scattering, and absorption coefficients of solid, homogeneous phantoms and of aqueous suspensions of monodisperse quartz glass spheres were derived from measurements of time-integrated collimated transmittance and time-resolved diffuse transmittance. For aqueous suspensions of monodisperse quartz glass spheres at known number density scattering and transport scattering coefficients calculated by Mie theory are in quantitative agreement with experimentally derived values. In addition, diffuse reflectance and diffuse transmittance of aqueous suspensions at various number densities were measured and found to be in excellent agreement with results of Monte Carlo calculations using theoretical values for the scattering coefficients and anisotropy parameters.

Humans↗

PubMed1994

Planned laparoscopic repair of a spigelian hernia using a composite prosthesis.

A planned elective repair, via the laparoscope, of a spigelian hernia is described. The repair was performed using a composite mesh prosthesis consisting of a sandwich of polyester fiber mesh and polyglactin 910 mesh, sutured together with polyglactin 910 suture at the operating table before introduction. The technique is applicable to other hernias of the anterior abdominal wall.

Adult↗

PubMed2005

Capillary activity of surgical sutures and suture-dependent bacterial transport: a qualitative study.

OBJECTIVE: To evaluate the multitude of new synthetic absorbable sutures (both monofilament and multifilament) in comparison with older materials with regard to capillarity and bacterial transport. METHODS: Sutures of United States Pharmacopoeia (USP) 4-0 thickness were arranged in a three-chamber system under sterile conditions. Either a colorant (liquid transport evaluation) or bacteria (bacterial transport evaluation) were added to the contamination chamber, and movement of colorant or bacteria was evaluated for as long as 30 days. RESULTS: None of the monofilament sutures transported colorant or bacteria. Colorant transport was found on the pseudomonofilament and multifilament sutures between the first and the fifth day. Escherichia coli were transported on the majority of the multifilament sutures, although no transport was found on silk or polyester sutures. Bacterial transport was most often evident in tests using the motile Proteus mirabilis. CONCLUSIONS: All multifilament and pseudomonofilament suture designs allowed transport of colorants and bacteria to some degree. The movement of fluids and bacteria did not depend on the absorptive capacity of the sutures, coating, or the presence of an open suture end.

Capillary Action↗

PubMedDate not supplied

Novel biphasic elastomeric scaffold for small-diameter blood vessel tissue engineering.

Compliance mismatch, thrombosis, and long culture times in vitro remain important challenges to the clinical implementation of a tissue-engineered small-diameter blood vessel (SDBV). To address these issues, we are developing an implantable elastomeric and biodegradable biphasic tubular scaffold. The scaffold design uses connected nonporous and porous phases as a basis to mimic, respectively, the intimal and medial layers of a blood vessel. Biphasic scaffolds were fabricated from poly(diol citrate), a novel class of biodegradable polyester elastomer. Scaffolds were characterized for tensile and compressive properties, burst pressure, compliance, foreign body reaction (via subcutaneous implantation in rats), and cell distribution and differentiation (via histology, scanning electron microscopy, and immunohistochemistry). Tensile tests, burst pressure, and compliance measurements confirm that the incorporation of a nonporous phase to create a "skin" connected to the porous phase of a scaffold can provide bulk mechanical properties that are similar to those of a native vessel. Compression tests confirm that the scaffolds are soft and recover from deformation. Subcutaneously implanted poly(diol citrate) porous scaffolds produce a thin fibrous capsule and allow for tissue ingrowth. In vitro culture of tubular biphasic scaffolds seeded with human aortic smooth muscle cells (HASMCs) and endothelial cells (HAECs) demonstrates the ability of this design to support cell compartmentalization, coculture, and cell differentiation. The newly formed HAEC monolayer stained positive for von Willebrand factor whereas collagen- and calponin-positive HASMCs were present in the porous phase.

Animals↗

PubMedDate not supplied

Ecology of toxic shock syndrome: amplification of toxic shock syndrome toxin 1 by materials of medical interest.

Historically, the literature suggests that staphylococcal exoproteins, including enterotoxins, are stimulated by various physicochemical ecologic factors, many of which have been shown to stimulate production of toxic shock syndrome toxin 1 (TSST-1). The propensity of different fibers and other substances to amplify TSST-1 production in toxic shock syndrome-associated strains of Staphylococcus aureus, as well as a comparative analysis of the underlying mechanisms of TSST-1 production, are reported. Two hundred twenty intravaginal devices or other products and materials and 60 experimental controls were examined for their propensity to induce TSST-1 production. Certain materials are superior to unaltered cotton in providing a more absorbent fiber--nutrients are efficiently drawn in, concentrating protein between fibers, and thereby creating an ideal physicochemical environment for the amplification of TSST-1 and other toxins. The greatest stimulation of TSST-1 was observed with (in decreasing order): polyester and carboxymethyl cellulose, polyacrylates, viscose rayon, gelatin foam, polyurethane, and cotton. No toxin was found with nasal tampons (polymer of polyvinyl acetal) or with vaginal cups (an elastomeric polymer). Results are discussed in terms of specific ecologic parameters from historical as well as recent perspectives.

Bacterial Toxins↗

PubMed1995

Efficient in situ electroporation of mammalian cells grown on microporous membranes.

Electroporation is a common technique for the introduction of DNA molecules into living cells. The method is currently limited by the necessity of applying the electrical discharge to cells in suspension. Adherent cells must therefore be removed from their substratum, which can induce unwanted physiological effects. We report here a new procedure for in situ electroporation of cells grown on microporous membranes of polyethylene terephthalate (PET) or polyester (PE). We demonstrate that this method of in situ electroporation employs only readily available materials and standard electroporation devices without any modifications, is as efficient as conventional electroporation of cells in suspension, and is applicable to a wide range of cell types. Efficient electroporation can be achieved under conditions of minimal cell killing, and can be performed with quiescent cells as well as with confluent epithelial sheets. The method is a useful extension of electroporation technology, and will allow the application of electroporation to a wider spectrum of biological systems.

Animals↗

PubMed2005

Inducible trans-activation of plastid transgenes: expression of the R. eutropha phb operon in transplastomic tobacco.

Deleterious effects of constitutive transgene expression can occur if gene products are harmful to the transformed plant. Constraints such as growth inhibition and male sterility have been observed in plastid transformants containing the phb operon encoding the genes required for the production of the polyester polyhydroxybutyric acid (PHB). In order to induce PHB synthesis in tobacco in a well-timed manner, we have constructed a trans-activation system to regulate transcription of the phb operon in plastids. This system consists of a nuclear-located, ethanol-inducible T7RNA polymerase (T7RNAP) which is targeted to plastids harboring the phb operon under control of T7 regulatory elements. Following treatment with 5% ethanol, moderate induction of PHB synthesis was found. PHB amounts reached 1,383 ppm in dry weight, and an overall background activity of 171 ppm was measured in uninduced tissues. On the transcriptional level, T7RNAP induction was proven and we found that the phb operon is transcribed into at least two mRNAs. Without ethanol induction, development of flowers and fertile seeds was possible. Thus, the main problem of inhibitory transgene expression was solved. Our results show that this inducible trans-activation system could serve as an alternative to constitutive expression of transgenes in the plastome.

Base Sequence↗

PubMed2004

Putting copper into action: copper-impregnated products with potent biocidal activities.

Copper ions, either alone or in copper complexes, have been used for centuries to disinfect liquids, solids, and human tissue. Today copper is used as a water purifier, algaecide, fungicide, nematocide, molluscicide, and antibacterial and antifouling agent. Copper also displays potent antiviral activity. We hypothesized that introducing copper into clothing, bedding, and other articles would provide them with biocidal properties. A durable platform technology has been developed that introduces copper into cotton fibers, latex, and other polymeric materials. This study demonstrates the broad-spectrum antimicrobial (antibacterial, antiviral, antifungal) and antimite activities of copper-impregnated fibers and polyester products. This technology enabled the production of antiviral gloves and filters (which deactivate HIV-1 and other viruses), antibacterial self-sterilizing fabrics (which kill antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci), antifungal socks (which alleviate symptoms of athlete's foot), and anti-dust mite mattress covers (which reduce mite-related allergies). These products did not have skin-sensitizing properties, as determined by guine pig maximization and rabbit skin irritation tests. Our study demonstrates the potential use of copper in new applications. These applications address medical issues of the greatest importance, such as viral transmissions; nosocomial, or healthcare-associated, infections; and the spread of antibiotic-resistant bacteria.

Acaridae↗

PubMed1989

Changes seen in lymph nodes draining the sites of large joint prostheses.

We report the histological findings seen in the lymph nodes draining the sites of large joint prostheses. Two patients underwent multiple prosthetic joint replacements. In one patient, the regional lymph nodes were enlarged during the revision of a total hip prosthesis, and a representative lymph node was resected. The other patient had undergone a pelvic lymph node dissection as part of a staging procedure for prostatic carcinoma. By light microscopy, the lymph nodes from both patients showed markedly dilated nodal sinuses filled with macrophages containing abundant eosinophilic, PAS-positive, granular material. Polarization microscopy revealed needle-like particles within the cytoplasm of the macrophages. We believe that the histological appearance of the lymph nodes represents a florid foreign body reaction to fragments of polyester or polyethylene derived from the articulating surfaces of the joint prostheses and transported to the regional lymph nodes via the lymphatic circulation. Sinus histiocytosis seen in the lymph nodes draining the sites of joint prostheses may resemble, and must be distinguished from, other conditions invoking a sinus pattern of lymphadenopathy, as well from benign and malignant diseases that involve the lymph nodes in a pattern mimicking sinus histiocytosis.

Adult↗

PubMedDate not supplied

Long-term results of a new antithrombogenic cardiac wall substitute.

We evaluated the long-term results of a new antithrombogenic cardiac wall substitute which is composed of collagen-coated ultrafine polyester mesh cross-linked by a hydrophilic polyepoxy compound (CUFP), and compared it with glutaraldehyde-treated equine pericardium (GA graft). In an animal study, 20 CUFPs and 18 GA control grafts were implanted as patches in the right ventricular outflow tract in 38 dogs. In the CUFP at 28 days after implantation, a thin neointima, which was almost endothelialized, had been formed. Fibroblasts and vasa vasorum were seen inside both the neointima and the graft wall. At 168 days, transmission electron microscopy revealed smooth muscle-like cells in the neointima, with endothelialization. The CUFP at 486 days had maintained a white, shiny, smooth, thin, and uniform neointima with endothelialization. Neither ulcer nor thrombus formation was seen on the surface, while in the GA graft at 353 days, no endothelialization was noticed in the center and almost no fibroblasts had infiltrated into the graft wall. From these results, the CUFP should be an ideal candidate for cardiac wall substitution.

Animals↗

PubMedDate not supplied

Graft compliance and anastomotic flow patterns.

The oscillatory flow patterns at the venous anastomosis of a hemodialysis angioaccess loop graft system were studied using two new compliant vascular prostheses: a longitudinally compliant polytetrafluoroethylene-composite (Baxter Ultraflex PTFE-Plus) graft (BA) and a radially compliant ultrafine polyester fiber (TORAY-UFPF) graft (TR). A non-compliant Gore-Tex polytetrafluoroethylene graft was used as the control. The experimental grafts were 8 mm inside diameter x 25 cm long. Flow experiments were done in a transparent, elastic bench-top flow model; fabrication was based on silicone rubber casts obtained from femoral-to-femoral arteriovenous loop grafts surgically implanted in dogs. The loop graft constructed in the dog model was made to mimic the branchial-to-cephalic angioaccess loop graft commonly used in hemodialysis patients. The flow model was connected to a pulse generator, an adjustable arterial afterload, and a venous afterload. Under identical input conditions, the pressure and flow waveforms were monitored simultaneously at the proximal and distal ends of both the arterial and venous anastomoses. For each graft studied, the anastomotic flow field was visualized using laser illuminated hydrogen bubbles as tracers. At pulse rates of 60 and 90 beats/min, graft flow rates were 2.2 and 2.5 L/min, respectively. Among the grafts studied, measurable differences in pressure and flow wave attenuation and their respective phase lags resulted in characteristically dissimilar flow patterns at the venous anastomosis. Growth of the separation zone at the toe of the anastomosis, and the pattern of retrograde flow in the distal vein are visibly different in all three grafts.

Animals↗

PubMedDate not supplied

Activation of plasma components by leukocyte removal filters.

The technique of leukocyte filtration has been introduced into cardiac surgery to reduce leukocyte mediated reperfusion injury. When autologous whole blood (WB) is used as filtrate, it is more likely to be activated by the filter material than are banked red blood cell concentrates (RCC), because of its richness in plasma components. This study was designed to compare the activation of plasma components during leukocyte filtration from WB (n = 10) taken from the heart-lung machine, with RCC (n = 10) obtained from the blood bank. Leukocyte filters made from either cellulose acetate or polyester were used. Blood samples were taken simultaneously from the inlet and outlet of the filter after filtration of either 700 ml of WB or 350 ml of RCC. Results indicated that the complement cascade was activated, as reflected by the increase of C3a and C5a during filtration of WB by filters made from cellulose acetate. In contrast, there was no significant increase of C3a and C5a during filtration of RCC. The clotting system, indicated by fibrinopeptide A, and the fibrinolytic system, indicated by fibrinogen degradation products, were not activated during leukocyte filtration. These data suggest that it is the WB taken from the heart-lung machine rather than the RCC from the blood bank that is being activated during leukocyte filtration. Thus, careful selection of filter material is important for leukocyte filtration of autologous whole blood during cardiac surgery.

Cellulose↗

PubMedDate not supplied

Measurement of CD11/CD18 integrin expression on the polymorphonuclear cell surface after incubation with synthetic vascular prostheses.

Polymorphonuclear (PMN) cell activation in the presence of synthetic vascular grafts was studied by using flow cytometry to measure CD11/CD18 leukocyte adhesion molecule expression at the cell surface. Polymorphonuclear cells isolated from the blood of 10 healthy human donors were incubated with six knitted polyester vascular prostheses (Vasculour II, Albumin-Coated Graft, Triaxial, Gelatin-Impregnated Gelseal, Dialine I, and Bovine Collagen-Impregnated Dialine II) for 60 min at 37 degrees C. The authors' study demonstrated that CD11/CD18 integrin expression varies among donors for a given vascular prosthesis, and that each donor has his or her own pattern of responsiveness toward synthetic vascular grafts. The current study indicates that PMN activation measured by CD11/CD18 integrin expression is a sensitive method of measuring the blood compatibility of a given foreign surface for a given patient.

Animals↗

PubMed1995

Repair of patellar tendon disruptions without hardware.

Acute repair of disruptions of the knee extensor mechanism is indicated to reestablish extensor continuity and allow for early motion. This study reviews the results of acute primary repair of patellar tendon ruptures augmented by a nonabsorbable polyester tape (Mersilene; Ethicon, Inc.) followed by immediate mobilization. Twenty-four patients with disruptions of their patellar tendons were treated using the described technique. The ruptured tendon was initially approximated using an end-to-end suture repair with no. 5 Ticron suture in a whipstitch manner. An O Vicryl suture was used to approximate the free tendon edges. A 5-mm Mersilene tape was then used in a cerclage manner to augment and protect the repair. Postsurgery, passive range of motion (ROM) was begun immediately in the knees with isolated injury or in those patients whose concomitant injuries would allow for early motion. Using clinical and radiographic criteria, follow-up evaluations of 19 patients were performed at an average of 22.4 months. In patients with isolated injuries, active ROM was from 0 degrees extension to 132 degrees flexion (contralateral knee 0-135 degrees). Two patients had prominent knots: in one, the knots were painful and were removed surgically. Six patients developed patellofemoral chondrosis. Five patients had the Mersilene tape tied with the knee in full extension, and all developed patellofemoral pain. The other repairs were done with the knee flexed to 90 degrees before tying; one patient in this group developed patellofemoral symptoms. All patients with isolated injuries have returned to employment. There were no reruptures or infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗