RESUMEN
Microplastics (MPs) are ubiquitous in aquatic environments, which can act as carriers to affect the bioavailability of heavy metals. The aging process in the environment changes the physicochemical properties of MPs, thereby affecting their environmental behavior and co-toxicity with other pollutants. However, relevant research is limited. In this study, we compared the properties and Cu2+ adsorption capacity of pristine and aged polytetrafluoroethylene (PTFE) MPs and further explored the influence on copper bioavailability and bio-effects on Microcystis aeruginosa. Aging process induced surface oxidation and cracks of PTFE MPs, and decreased the stability of MPs in water by increasing zeta potential. PTFE MPs had a strong adsorption capacity for Cu2+ and increased the bioavailability of copper to microalgae, which was not affected by the aging process. Pristine and aged PTFE MPs adhered to cyanobacterium surfaces and caused shrinkage and deformation of cells. Inhibition of cyanobacterium growth, photosynthesis and reduction of total antioxidant capacity were observed in the treatment of PTFE MPs. Combined exposure of pristine MPs and Cu2+ had stronger toxic effects to cyanobacterium, and increased Microcystin-LR release, which could cause harm to aquatic environment. Aging reduced the toxic effects of PTFE MPs on microalgae. Furthermore, soluble exopolysaccharide (EPS) content was significantly higher in co-exposure of aged MPs and Cu2+, which could reduce the toxicity to cyanobacterium cells. These results indicate that aging process alleviates the toxicity to microalgae and environmental risks caused by PTFE MPs. This study improves understanding of the combined toxicity of aged MPs and metals in freshwater ecosystems.
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Disponibilidad Biológica , Cobre , Microcystis , Microplásticos , Politetrafluoroetileno , Contaminantes Químicos del Agua , Microcystis/efectos de los fármacos , Cobre/toxicidad , Contaminantes Químicos del Agua/toxicidad , Microplásticos/toxicidad , Politetrafluoroetileno/química , Politetrafluoroetileno/toxicidad , Rayos Ultravioleta , Adsorción , Microalgas/efectos de los fármacosRESUMEN
Polymeric heart valves seem to be an attractive alternative to mechanical and biological prostheses as they are more durable, due to the superior properties of novel polymers, and have the biocompatibility and hemodynamics comparable to tissue substitutes. This study reports a comprehensive assessment of a nanocomposite based on the functionalised graphene oxide and poly(carbonate-urea)urethane with the trade name "Hastalex" in comparison with GORE-TEX, a commercial polymer routinely used for cardiovascular medical devices. Experimental data have proved that GORE-TEX has a 2.5-fold (longitudinal direction) and 3.5-fold (transverse direction) lower ultimate tensile strength in comparison with Hastalex (p < 0.05). The contact angles of Hastalex surfaces (85.2 ± 1.1°) significantly (p < 0.05) are lower than those of GORE-TEX (127.1 ± 6.8°). The highest number of viable cells Ea.hy 926 is on the Hastalex surface exceeding 7.5-fold when compared with the GORE-TEX surface (p < 0.001). The platelet deformation index for GORE-TEX is 2-fold higher than that of Hastalex polymer (p < 0.05). Calcium content is greater for GORE-TEX (8.4 mg/g) in comparison with Hastalex (0.55 mg/g). The results of this study have proven that Hastalex meets the main standards required for manufacturing artificial heart valves and has superior mechanical, hemocompatibility and calcific resistance properties in comparison with GORE-TEX.
Asunto(s)
Materiales Biocompatibles , Grafito , Prótesis Valvulares Cardíacas , Nanocompuestos , Poliuretanos , Células A549 , Animales , Materiales Biocompatibles/toxicidad , Calcinosis/inducido químicamente , Bovinos , Módulo de Elasticidad , Grafito/toxicidad , Hemólisis/efectos de los fármacos , Células Endoteliales de la Vena Umbilical Humana , Humanos , Hibridomas/efectos de los fármacos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Nanocompuestos/toxicidad , Nanocompuestos/ultraestructura , Pericardio , Adhesividad Plaquetaria/efectos de los fármacos , Polímeros/toxicidad , Politetrafluoroetileno/toxicidad , Poliuretanos/toxicidad , Diseño de Prótesis , Ratas , Ratas Wistar , Propiedades de Superficie , Resistencia a la TracciónRESUMEN
BACKGROUND: Comparing the structural changes, and local host reactions to CorMatrix (CorMatrix Cardiovascular Inc., Roswell, Georgia, United States) and different biomaterials implanted subcutaneously in growing pig model. METHODS: Four pigs harboring implanted patches of CorMatrix, Vascutek porcine pericardium (Vascutek; Scotland, United Kingdom), SJM bovine pericardium (St. Jude Medical, Inc., Minnesota, United States), and Gore-Tex (W. L. Gore & Associates GmbH, Flagstaff, Arizona, United States) were studied for 1, 3, 6, and 12 months. The explants were examined histologically. RESULTS: CorMatrix showed gradual and consistent patch resorption and subsiding inflammatory and fibrosis process. Full scaffold degradation and replacement by mild fibrosis and subcutaneous tissue were seen by 1 year. Xenopericardial patches remained intact, and the initially severe inflammatory and fibrotic reactions reduced gradually to moderate fibrosis and chronic inflammation. Gore-Tex showed foreign body reaction. CONCLUSIONS: Patches were biotolerated by pigs. Xenopericardial patches elicited encapsulating fibrosis and no remodeling. CorMatrix resorbs completely and degrades consistently without leaving residues. Lack of encapsulating fibrosis toward CorMatrix allows tissue ingrowth and matrix remodeling.
Asunto(s)
Materiales Biocompatibles/toxicidad , Procedimientos Quirúrgicos Cardíacos/instrumentación , Matriz Extracelular/trasplante , Reacción a Cuerpo Extraño/etiología , Membranas Artificiales , Pericardio/trasplante , Politetrafluoroetileno/toxicidad , Tejido Subcutáneo/cirugía , Factores de Edad , Aloinjertos , Animales , Procedimientos Quirúrgicos Cardíacos/efectos adversos , Bovinos , Reacción a Cuerpo Extraño/metabolismo , Reacción a Cuerpo Extraño/patología , Xenoinjertos , Tejido Subcutáneo/metabolismo , Tejido Subcutáneo/patología , Porcinos , Porcinos Enanos , Factores de TiempoRESUMEN
Fluoride is ubiquitous in environment and profound in bones, teeth and calcified tissues of human body. Fluoride has been the topic of regular discussion and investigations. Besides its toxicity, fluoride has also been examined for its beneficial effects like prevention and treatment of tooth decay, microbial infection, inflammation, cancer, occurrence of renal stone and many more. Since last many decades, several efforts have been made at pre-clinical and clinical level to understand role of fluoride in biological system. The present review gives a brief account of prevalence, sources of fluoride toxicity and pre-clinical and clinical studies carried out on effects of fluoride in last six decades.
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Caries Dental/prevención & control , Intoxicación por Flúor/epidemiología , Fluoruros/administración & dosificación , Agua Potable/efectos adversos , Fluoruros/efectos adversos , Fluoruros/farmacología , Humanos , Politetrafluoroetileno/toxicidad , PrevalenciaRESUMEN
PTFE is used as an inner coating material in non-stick cookware. This unique polymer coating prevents food from sticking in the pans during the cooking process. Such cookware is also easy to wash. At normal cooking temperatures, PTFE-coated cookware releases various gases and chemicals that present mild to severe toxicity. Only few studies describe the toxicity of PTFE but without solid conclusions. The toxicity and fate of ingested PTFE coatings are also not understood. Moreover, the emerging, persistent, and well-known toxic environmental pollutant PFOA is also used in the synthesis of PTFA. There are some reports where PFOA was detected in the gas phase released from the cooking utensils under normal cooking temperatures. Due to toxicity concerns, PFOA has been replaced with other chemicals such as GenX, but these new alternatives are also suspected to have similar toxicity. Therefore, more extensive and systematic research efforts are required to respond the prevailing dogma about human exposure and toxic effects to PTFE, PFOA, and GenX and other alternatives.
Asunto(s)
Contaminantes Atmosféricos/toxicidad , Utensilios de Comida y Culinaria/normas , Gases/toxicidad , Politetrafluoroetileno/toxicidad , Animales , Culinaria , Calor , Humanos , Politetrafluoroetileno/químicaRESUMEN
Since satiety is largely due to stretch of the stomach and people tend to eat a consistent weight of food, increasing food volume and mass increases satiety. This can be achieved without increasing the calories of food by mixing food with a material that cannot be metabolized. Such a material should be inert, safe, resistant to stomach acid, lack taste, available in powder form, smooth, resistant to heat, and cost effective. Polytetrafluoroethylene (PTFE) is an ideal substance for this purpose. It is a soft plastic that is widely considered to be the most inert material known and is extremely stable. Animal feeding trials showed that rats fed a diet of 25% PTFE for 90 days had no signs of toxicity and that the rats lost weight. This article publishes the data from these subchronic animal feeding trials, reviews the relevant available literature, and hypothesizes that increasing the volume of food by mixing the food with PTFE powder at a ratio of 3 parts food to 1 part PTFE by volume will substantially improve satiety and reduce caloric consumption in people.
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Politetrafluoroetileno , Respuesta de Saciedad/efectos de los fármacos , Animales , Peso Corporal , Ingestión de Alimentos , Humanos , Politetrafluoroetileno/administración & dosificación , Politetrafluoroetileno/toxicidad , RatasRESUMEN
INTRODUCTION: CPoint is a polymeric endodontic point that takes advantage of water-induced, non-isotropic radial expansion to adapt to canal irregularities. This study evaluated the effects of CPoint on the viability and mineralization potential of odontoblast-like cells. METHODS: The biocompatibility of CPoint and commercially available gutta-percha points was evaluated by using a rat odontoblast-like cell line (MDPC-23). Cell viability was evaluated with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, and confocal laser scanning microscopy. The mineralization potential of MDPC-23 cells, in the presence of the root-filling materials, was evaluated by examining the changes in osteogenic gene marker expression (quantitative real-time polymerase chain reaction), alkaline phosphatase activity, alizarin red S assay, and transmission electron microscopy. RESULTS: CPoint showed higher initial cytotoxicity compared with gutta-percha and Teflon (P < .05), which became nonsignificant after 4 immersion cycles. Significant differences were also found between eluents from CPoint and gutta-percha at 1:1 concentration (P < .05) but not at 1:10 or 1:100 concentration. Both materials induced minimal apoptosis-induced alteration in plasma membrane permeability, as evidenced by flow cytometry and confocal laser scanning microscopy. Compared with the Teflon negative control, CPoint and gutta-percha groups showed up-regulation of most osteogenic gene markers except for dentin sialophosphoprotein, which was down-regulated. Alkaline phosphatase activity and alizarin red assay for CPoint and gutta-percha were both significantly higher than for Teflon but not significantly different from each other (P > .05). Transmission electron microscopy showed discrete nodular electron-dense mineralization foci in all 3 groups. CONCLUSIONS: The in vitro biocompatibility of CPoint is comparable to gutta-percha with minimal adverse effects on osteogenesis after elution of potentially toxic components.
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Resinas Acrílicas/química , Materiales Biocompatibles/química , Nylons/química , Materiales de Obturación del Conducto Radicular/química , Agua/química , Absorción , Resinas Acrílicas/toxicidad , Acrilonitrilo/química , Acrilonitrilo/toxicidad , Adsorción , Fosfatasa Alcalina/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Materiales Biocompatibles/toxicidad , Calcificación Fisiológica/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Línea Celular , Permeabilidad de la Membrana Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Proteínas de la Matriz Extracelular/efectos de los fármacos , Gutapercha/química , Gutapercha/toxicidad , Ensayo de Materiales , Microscopía Electrónica de Transmisión , Nylons/toxicidad , Odontoblastos/efectos de los fármacos , Osteogénesis/efectos de los fármacos , Fosfoproteínas/efectos de los fármacos , Politetrafluoroetileno/química , Politetrafluoroetileno/toxicidad , Polivinilos/química , Polivinilos/toxicidad , Pirrolidinonas/química , Pirrolidinonas/toxicidad , Ratas , Materiales de Obturación del Conducto Radicular/toxicidad , Sialoglicoproteínas/efectos de los fármacos , Propiedades de Superficie , Regulación hacia ArribaRESUMEN
We investigated the performance of small-caliber polyurethane (PU) small-diameter vascular prosthesis generated using the electrospinning technique. PU was electrospun into small-diameter, small-caliber tubular scaffolds for potential application as vascular grafts. We investigated the effects of electrospinning conditions (solution concentration, mandrel rotation speed) on the microstructure and porosity of the scaffolds for the purpose of preparing scaffolds with optimum microstructures and properties. We evaluated the mechanical properties of the scaffolds by tensile tests and the cytotoxicity of the PU small-diameter, small-caliber PU synthetic vascular graft by the MTT assay. The adhesion of endothelial cells to the PU scaffold was characterized by Hoechst staining and fluorescence microscopy, and we measured endothelial cell proliferation on the PU scaffold by the CCK-8 assay. We analyzed the prosthesis microstructure and endothelial cell morphology using scanning electron microscopy. With increasing PU concentration in the electrospinning solution, the fiber diameter of the vascular graft increased and the porosity decreased. In addition, with increasing electrospinning time, the wall thickness increased and the porosity decreased. We found that regular fiber orientation can be obtained by adjusting the rotation speed of the mandrel. Cell proliferation was not inhibited as the small-caliber PU synthetic vascular grafts showed little cytotoxicity. The endothelial cells had faster adherence to the PU scaffolds than to the PTFE surface during the initial contact. After prolonged cell culture, significantly higher endothelial cell proliferation rate was observed in the PU scaffold groups than the PTFE group. We obtained small-caliber PU vascular grafts with optimal fiber arrangement, excellent mechanical properties, and optimal biocompatibility by optimizing the electrospinning conditions. This study provides in vitro biocompatibility data that is helpful for the clinical application of the PU small-diameter, small-caliber PU vascular grafts.
Asunto(s)
Prótesis Vascular , Poliuretanos/farmacología , Diseño de Prótesis/métodos , Animales , Adhesión Celular/efectos de los fármacos , Línea Celular , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Endoteliales de la Vena Umbilical Humana/citología , Células Endoteliales de la Vena Umbilical Humana/efectos de los fármacos , Humanos , Ensayo de Materiales , Ratones , Politetrafluoroetileno/química , Politetrafluoroetileno/farmacología , Politetrafluoroetileno/toxicidad , Poliuretanos/química , Poliuretanos/toxicidad , Porosidad , Rotación , Resistencia a la TracciónRESUMEN
A 29-year-old Japanese man presented with fever, dyspnoea and non-productive cough after massive inhalation of evaporant from a polytetrafluoroethylene-coated cooking pan. Chest CT scan showed diffuse interstitial infiltration in both lungs. Based on the patient history, images and the pan he brought to the hospital, polymer fume fever was strongly suspected. His symptoms dramatically improved over the following 2 days after admission.
Asunto(s)
Fiebre/inducido químicamente , Politetrafluoroetileno/toxicidad , Adulto , Utensilios de Comida y Culinaria , Humanos , Masculino , HumoRESUMEN
Two groups of chickens (Gallus domesticus; White Leghorn; age, 4 d and 2 wk) housed in a university research vivarium were found dead or moribund without prior signs of illness. The overall mortality rates were 92.3% (60 of 65 birds) for the 4-d-old birds and 80% (8 of 10) for the 2-wk-old birds. All chicks were housed in brooders with heat lamps in a temperature- and humidity-controlled room. Primary gross findings were mild to moderate dehydration and hepatic lipidosis. The most consistent histologic findings were pulmonary hemorrhage and edema in all 7 of the 4-d-old birds evaluated and in all 4 of the 2-wk-old birds assessed. In addition, 1 of the 4-d-old birds had multifocal centrilobular hepatic necrosis. These findings suggested an inhaled toxicant and hypoxia, respectively. Inspection of the animal room revealed that approximately 50% of the heat lamp bulbs in the brooder cage were coated with polytetrafluoroethylene (PTFE). Two published case reports detail similar experiences in birds exposed to PTFE-coated heat-lamp bulbs. Birds are highly sensitive to inhaled toxicants owing to the high efficiency of their respiratory systems, and PTFE toxicosis is known to cause pulmonary edema and hemorrhage in pet birds after exposure to overheated nonstick cookware. In the present case, the bulbs were replaced, and no similar problems subsequently have been noted. This case illustrates the sensitivity of avian species to respiratory toxicants and serves as a reminder that toxicosis can be encountered even in the controlled environment of a laboratory vivarium.
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Pollos , Hemorragia/veterinaria , Enfermedades Pulmonares/veterinaria , Politetrafluoroetileno/toxicidad , Enfermedades de las Aves de Corral/inducido químicamente , Enfermedades de las Aves de Corral/epidemiología , Enfermedades de las Aves de Corral/patología , Edema Pulmonar/veterinaria , Animales , Animales de Laboratorio , Brotes de Enfermedades/veterinaria , Resultado Fatal , Hemorragia/inducido químicamente , Hemorragia/epidemiología , Hemorragia/patología , Vivienda para Animales , Enfermedades Pulmonares/inducido químicamente , Enfermedades Pulmonares/epidemiología , Enfermedades Pulmonares/patología , Edema Pulmonar/inducido químicamente , Edema Pulmonar/epidemiología , Edema Pulmonar/patologíaRESUMEN
Polypropylene (PP), Polyethylene (PE) and polytetrafluoroethylene (FE) are high molecular materials in medical use. They are also used as the negative control materials for ISO 10993-6 international standard biological evaluation of medical devices. We examined tissue reactions to these materials embedded subcutaneously in the dorsal area of male ddY mice. One week and 12 weeks after embedding, the tissue surrounding the embedding site was removed and then histopathological examination was performed. Our results demonstrate that the basic histopathological reaction is the formation of fibrous capsule consisting of granulation tissue around the embedded materials. Based on our results, we believe that the high molecular materials such as, PP, PE and FE, can be considered for medical use as a biomaterials within the body.
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Materiales Biocompatibles/farmacología , Polímeros/farmacología , Tejido Subcutáneo/efectos de los fármacos , Animales , Materiales Biocompatibles/química , Materiales Biocompatibles/toxicidad , Reacción a Cuerpo Extraño/patología , Tejido de Granulación/patología , Masculino , Ensayo de Materiales , Ratones , Peso Molecular , Polietileno/farmacología , Polietileno/toxicidad , Polímeros/química , Polímeros/toxicidad , Polipropilenos/farmacología , Polipropilenos/toxicidad , Politetrafluoroetileno/farmacología , Politetrafluoroetileno/toxicidad , Prótesis e Implantes/efectos adversos , Tejido Subcutáneo/patologíaRESUMEN
INTRODUCTION: This study investigated the setting time and micohardness of a premixed calcium phosphate silicate-based sealer (EndoSequence BC Sealer; Brasseler USA, Savannah, GA) in the presence of different moisture contents (0-9 wt%). The moisture content that produced the most optimal setting properties was used to prepare set EndoSequence BC Sealer for cytotoxicity comparison with an epoxy resin-based sealer (AH Plus; Dentsply Caulk, Milford, DE). METHODS: Standardized disks were created with BC Sealer, AH Plus, Pulp Canal Sealer EWT (positive control) (SybronEndo, Orange CA), and Teflon (Small Parts Inc., Miami Lakes, FL; negative control). Disks were placed in Transwell Inserts, providing indirect contact with MC3T3-E1 cells. Succinate dehydrogenase activity of the cells was evaluated over a 6-week period using MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cytotoxicity profiles of BC Sealer and AH Plus were fitted with polynomial regression models. The time for 50% of the cells to survive (T(0.5)) was analyzed using the Wald statistic with a two-tailed significance level of 0.05. RESULTS: BC Sealer required at least 168 hours to reach the final setting using the Gilmore needle method, and its microhardeness significantly declined when water was included in the sealer (P = .004). All set sealers exhibited severe cytotoxicity at 24 hours. The cytotoxicity of AH Plus gradually decreased and became noncytotoxic, whereas BC Sealer remained moderately cytotoxic over the 6-week period. A significant difference (P < .001) was detected between T(0.5) of BC Sealer (5.10 weeks; 95% confidence interval [CI], 4.69-5.42, standard error [SE] = 0.09) and T(0.5) of AH Plus (0.86 weeks; 95% CI, 0.68-1.05; SE = 0.18). CONCLUSIONS: Further studies are required to evaluate the correlation between the length of setting time of BC Sealer and its degree of cytotoxicity.
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Materiales Biocompatibles/química , Cerámica/química , Materiales de Obturación del Conducto Radicular/química , Células 3T3 , Animales , Materiales Biocompatibles/toxicidad , Fosfatos de Calcio/química , Fosfatos de Calcio/toxicidad , Supervivencia Celular/efectos de los fármacos , Cerámica/toxicidad , Colorantes , Combinación de Medicamentos , Resinas Epoxi/química , Resinas Epoxi/toxicidad , Dureza , Ensayo de Materiales , Ratones , Osteoblastos/efectos de los fármacos , Óxidos/química , Óxidos/toxicidad , Politetrafluoroetileno/química , Politetrafluoroetileno/toxicidad , Materiales de Obturación del Conducto Radicular/toxicidad , Silicatos/química , Silicatos/toxicidad , Succinato Deshidrogenasa/análisis , Sales de Tetrazolio , Tiazoles , Factores de Tiempo , Agua/químicaRESUMEN
Polyurethane (PU) and polytetrafluoroethylene (PTFE) are two commonly used blood-contacting biomaterials. In the present study, we used a noncontact coculture model to evaluate the thrombosis-causing potential of monocyte-mediated PU and PTFE. We used human endothelial cells from umbilical cord (HUVECs) and human monocytes (THP1 cells). The THP1 cells were directly exposed to PU/PTFE, and the resultant cell-free supernatants were harvested for stimulating HUVECs. The treated HUVECs constituted the test group. HUVECs treated with supernatants of LPS-stimulated THP1 cells were used as the positive controls. To investigate the effects of the supernatant treatment on HUVECs, we measured the expression of the leukocyte-endothelial-cell adhesion molecules (CAMs) CD54 (ICAM-1), CD106 (VCAM-1), and CD62E (E-selectin) and evaluated the release of tissue factor (TF). The results demonstrated that both PU and PTFE induced the expressions of CD62E and TF. These activation effects were accompanied by activation of the NF-kappaB transcription factor. To further investigate the monocyte-derived soluble factors that might contribute to these effects, we evaluated the effects of the PU/PTFE stimulation on the expression of reactive oxygen species (ROS), TNF-alpha, IL-1beta, and IL-6 in monocyte monocultures. In comparison with the results for the negative control, both PU and PTFE significantly induced ROS release after 0.5h, while the expressions of TNF-alpha, IL-1beta, and IL-6 were variably increased after 24h. Our results suggest that the biomaterial induces monocytic activation and subsequently causes the release of soluble factors, which contribute to the inflammatory activation in HUVECs.
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Células Endoteliales/efectos de los fármacos , Inflamación/inducido químicamente , Monocitos/efectos de los fármacos , Politetrafluoroetileno/toxicidad , Poliuretanos/toxicidad , Línea Celular , Técnicas de Cocultivo , Citocinas/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , FN-kappa B/metabolismo , Especies Reactivas de OxígenoRESUMEN
The estrogenic potentials of leachate samples collected at Laogang Sanitary Landfill in Shanghai, China were measured together with the associated dissolved organic matter (DOM) in leachate samples. Over 99% of the DOM in fresh leachate was removed upon 3-7 years of landfill, leaving only DOM with strong fluorescent activity. Anoxic or aerobic treatment of landfill leachate can further degrade DOM of MW<300 Da and transform those with fluorescent activity of MW>10(5) Da to those of 2000-10(5) Da. Neither landfilling nor storage in anoxic pond effectively removed estrogenic potential of leachate. Fractionation test revealed that residual organic matters of MW 3000-14000 Da and of <600 Da with high UV254 contributed most of the estrogenic activities in leachate. Aerobic SBR treatment considerably reduced the estrogenic potential of these organic matters in leachate.
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Disruptores Endocrinos/toxicidad , Estrógenos no Esteroides/toxicidad , Contaminantes Químicos del Agua/toxicidad , Unión Competitiva/efectos de los fármacos , Fenómenos Químicos , Química Física , Cromatografía en Gel , Receptor alfa de Estrógeno/efectos de los fármacos , Politetrafluoroetileno/química , Politetrafluoroetileno/toxicidad , Espectrometría de Fluorescencia , Espectrofotometría UltravioletaRESUMEN
STATEMENT OF PROBLEM: The biocompatibility of new dental ceramics has not been assessed with the same scrutiny as has been applied to alloys and composites. Yet, the biocompatibility of ceramics is critical to the long-term success of dental prostheses because ceramics are in close contact with oral tissues for extended periods. MATERIAL AND METHODS: Five dental ceramics (2 traditional feldspathic veneer porcelains [Vita Omega and Duceragold], 2 lithium disilicate pressable materials [Stylepress and Empress-2], and a pressable leucite-based material [Empress-1]) were tested for their ability to alter cellular mitochondrial dehydrogenase activity after fabrication using a tetrazolium assay, after aging for 2 weeks in a biologic solution and after post-aging polishing with either a fine diamond or diamond polishing paste. Cellular responses were compared with polytetrafluoroethylene controls (analysis of variance, Tukey pairwise post-hoc comparison, alpha=.05). RESULTS: The feldspathic porcelains caused only mild (<25% of controls) mitochondrial suppression regardless of aging or polishing. The pressable leucite-based material initially caused a 5% stimulation (not significant) of mitochondrial activity, which decreased significantly (P<.05) by 30% with aging to levels comparable to the feldspathic porcelains, and did not change with polishing. Both lithium disilicate materials caused an initial suppression of mitochondrial activity that decreased significantly with aging, but Empress-2 was severely cytotoxic initially (<20% of controls, P<.01), and became more cytotoxic again after polishing. Stylepress was less cytotoxic initially (85% of controls, not significant) and did not become cytotoxic again after polishing. CONCLUSIONS: Dental ceramics are not equivalent in their in vitro biologic effects, even within the same class of material, and biologic safety should not be assumed. Most ceramics caused only mild in vitro suppression of cell function to levels that would be acceptable on the basis of standards used to evaluate alloys and composites. However, 1 Li-disilicate material (Empress-2) exhibited cytotoxicity that would not be deemed biologically acceptable on the basis of prevailing empirical standards for dental alloys and composites.
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Materiales Biocompatibles/toxicidad , Cerámica/toxicidad , Materiales Dentales/toxicidad , Silicatos de Aluminio/toxicidad , Análisis de Varianza , Animales , Células 3T3 BALB/efectos de los fármacos , Colorantes , Pulido Dental , Porcelana Dental/toxicidad , Compuestos de Litio/toxicidad , Análisis por Apareamiento , Ensayo de Materiales , Ratones , Mitocondrias/efectos de los fármacos , Politetrafluoroetileno/toxicidad , Compuestos de Potasio/toxicidad , Succinato Deshidrogenasa/efectos de los fármacos , Propiedades de Superficie , Sales de Tetrazolio , Tiazoles , Factores de TiempoRESUMEN
Highly filled composites, Ormocers (organically modified ceramics) and 'smart' materials have been developed to overcome the polymerization shrinkage problems of conventional composite materials. The purpose of the current study was to investigate the effect of longer-term (up to 8 weeks) ageing of these resin-based dental restorative materials and determine the effect of post-curing on cytotoxicity. Twelve discs of each material (Colombus/IDR, Definite/Degussa, Ariston pHc/Vivadent) were either light-cured (Lc) or light-cured and post-cured (Pc). For cytotoxicity testing, the discs were placed in contact with cell culture medium (DMEM) and incubated at 37 degrees C. Extracts from composite materials were collected after 24 h and weekly over a time period of 8 weeks. Cytotoxicity of the eluates to cultured fibroblasts (Balb/c3T3) were measured by the succinic dehydrogenase (SDH) activity (MTT assay) and the results expressed in percentage of negative controls (Teflon discs). The results showed that ageing significantly influenced the cytotoxicity of the materials. Except for Ariston pHc, materials were less cytotoxic after 8 weeks of ageing than they were in early intervals and post-curing was not generally useful in reducing cytotoxicity. The Ariston pHc was initially moderately toxic, but then become highly cytotoxic for 5 weeks before returning to initial levels. The current study demonstrated the importance of assessing the cytotoxicity of resin composite materials at multiple times.
Asunto(s)
Materiales Biocompatibles/toxicidad , Resinas Compuestas/toxicidad , Materiales Dentales/toxicidad , Células 3T3 , Análisis de Varianza , Animales , Materiales Biocompatibles/química , Cariostáticos/química , Cariostáticos/toxicidad , Colorimetría , Colorantes , Resinas Compuestas/química , Medios de Cultivo , Materiales Dentales/química , Restauración Dental Permanente , Ensayo de Materiales , Metacrilatos/química , Metacrilatos/toxicidad , Ratones , Ratones Endogámicos BALB C , Mitocondrias/enzimología , Polímeros/química , Politetrafluoroetileno/química , Politetrafluoroetileno/toxicidad , Siloxanos/química , Siloxanos/toxicidad , Estadística como Asunto , Succinato Deshidrogenasa/análisis , Temperatura , Terpenos/química , Terpenos/toxicidad , Sales de Tetrazolio , Tiazoles , Factores de TiempoRESUMEN
In the article the questions of fluoroplastes destruction, opportunity of migration in foodstuff non-polymerized monomers, additives and chemical substances formed as a result of thermal disintegration of polymer are considered.
Asunto(s)
Embalaje de Alimentos , Politetrafluoroetileno/química , Animales , Fenómenos Químicos , Química Física , Interacciones Farmacológicas , Higiene , Politetrafluoroetileno/toxicidadRESUMEN
PTFE (polytetrafluoroethylene) fumes consisting of large numbers of ultrafine (uf) particles and low concentrations of gas-phase compounds can cause severe acute lung injury. Our studies were designed to test three hypotheses: (i) uf PTFE fume particles are causally involved in the induction of acute lung injury, (ii) uf PTFE elicit greater pulmonary effects than larger sized PTFE accumulation mode particles, and (iii) preexposure to the uf PTFE fume particles will induce tolerance. We used uf Teflon (PTFE) fumes (count median particle size approximately 16 nm) generated by heating PTFE in a tube furnace to 486 degrees C to evaluate principles of ultrafine particle toxicity. Teflon fumes at ultrafine particle concentrations of 50 microg/m(3) were extremely toxic to rats when inhaled for only 15 min. We found that when generated in argon, the ultrafine Teflon particles alone are not toxic at these exposure conditions; neither were Teflon fume gas-phase constituents when generated in air. Only the combination of both phases when generated in air caused high toxicity, suggesting either the existence of radicals on the surface or a carrier mechanism of the ultrafine particles for adsorbed gas compounds. Aging of the fresh Teflon fumes for 3.5 min led to a predicted coagulation to >100 nm particles which no longer caused toxicity in exposed animals. This result is consistent with a greater toxicity of ultrafine particles compared to accumulation mode particles, although changes in particle surface chemistry during the aging process may have contributed to the diminished toxicity. Furthermore, the pulmonary toxicity of the ultrafine Teflon fumes could be prevented by adapting the animals with short 5-min exposures on 3 days prior to a 15-min exposure. Messages encoding antioxidants and chemokines were increased substantially in nonadapted animals, yet were unaltered in adapted animals. This study shows the importance of preexposure history for the susceptibility to acute ultrafine particle effects.