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Plastics are not only the proverbial everyday commodity, but they also permeate almost every aspect of medical devices, from technology to clinical application. This article addresses some of the confusing features of plasticity as they relate to the materials called plastics, to the phenomena of material plasticity, and to the clinical and biological usage of the word.
The high level of plasticizer in plasticized poly(vinyl chloride) (PVC) ensures that plasticizer selection has an important influence on the suitability of PVC to function in blood-contacting applications. In this study, three types of plasticized PVC in sheet form, with di-(2-ethylhexyl)phthalate (DEHP), tri-(2-ethylhexyl)trimellitate (TEHTM) and n-butyryltri-n-hexyl citrate (BTHC) as plasticizer, were selected for assessment and single solute fibrinogen adsorption was utilized as an initial index of interactions with blood components. Fibrinogen adsorption behavior shows a strong dependence on the plasticizer selection, plasticizer level at the surface and the adsorption conditions, such as adsorption time and fibrinogen solution concentration. Results indicate that BTHC plasticized PVC possesses the lowest adsorption capacity in the three types of plasticized PVC, while TEHTM plasticized PVC seems to have the strongest reactivity in certain fibrinogen solution concentrations. The alteration of surface plasticizer level was achieved by a methanol-cleaning treatment with a variety of cleaning times and the fibrinogen adsorption on plasticized PVC decreases with the reduction of surface plasticizer level. The migration behavior of two phthalate esters (DEHP and TEHTM) was evaluated using UV-Spectrophotometer to determine the plasticizer level at the surfaces. In addition, the fibrinogen adsorption mechanism was examined with Freundlich adsorption modeling.
Pregnancy during plastic surgery residency poses unique challenges to the resident herself, to her resident colleagues, and to her residency director. Studies of the effects of pregnancy have been conducted that have combined all medical specialties or have included all surgeons as a statistically uniform group. The Women Plastic Surgeons' Caucus Committee of the American Society of Plastic and Reconstructive Surgeons has conducted a survey in order to obtain objective data on maternal fetal complications, time off work, maternal leave policies, call coverage, and other important issues. Response rates were 40 percent for the women residents and 45 percent for the program directors surveyed. The results show a 57 percent overall complication rate (excluding miscarriages), a 26 percent elective abortion rate, and a 33 percent infertility rate in women plastic surgeons, numbers that are higher than those currently in the literature. Data obtained regarding issues such as time off work, planning of pregnancy, call coverage, productivity and income, perceived peer support, program directors' opinions and policies, and possible solutions that might provide a mutually rewarding outcome are presented for discussion.
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The materials used in film coating technology are very important tools for pharmaceutical applications. The effects of four organic esters used as plasticizers (triacetin, diethyl phthalate (DEP), dibutyl phthalate (DBP) and tributyl citrate (TBC)) on the water absorption behavior and adhesive property of Eudragit films and on the glass transition temperature (T(g)) and plasticizer permanence of Eudragit E film were investigated. The results indicate that the water absorption of these Eudragit films was dependent on the type of Eudragit polymers and plasticizers used. Eudragit E film plasticized with triacetin showed a slight water absorption, but when plasticized with DEP, DBP or TBC did not. All Eudragit RL films showed significant uptake of water, but Eudragit RS films exhibited a lesser degree of water absorption. The adhesion (tack value) of all Eudragit films was markedly increased when the concentration of plasticizer was greater than 25%. Eudragit E film exhibited a greater adhesiveness than the Eudragit RL or RS film, particularly with higher plasticizer concentration. Weight loss of the Eudragit E film plasticized with triacetin or DEP was more pronounced with aging, but when plasticized with DBP or TBC weight loss was not seen. The results indicate that TBC may be the best choice of plasticizer for Eudragit film, particularly for the Eudragit E film.
(The) 3rd December 1952, 11 surgeons and other specialists found the French Society of Plastic and Reconstructive Surgery (SFCPR) which was officially published on (the) 28 September 1953. The first congress was during October 1953 and the first president as Maurice Aubry. The first secretary was Daniel Morel Fatio. The symposiums were after about three of four times each year and the thematic subjects were initially according the reconstructive surgery. The review "Annales de chirurgie plastique" was free in 1956. The members of the Society were about 30 initially, but their plastic surgery in the big hospitals at Paris and other big towns in France. The "specialty" of plastic surgery was created in 1971. On "syndicate", one French board of plastic reconstructive and aesthetic surgery, the increasing of departments of plastic surgery were the front of increasing of the plastic surgery in French and of the number of the French Society of Plastic Reconstructive surgery (580 in 2003). The French Society organized the International Congress of Plastic Surgery in 1975. The society SFCPR became the French Society of plastic reconstruction and Aesthetic Surgery (SFCPRE) in 1983 and the "logo" (front view) was in the 1994 SOF.CPRE.
PURPOSE: In polymeric coatings, plasticizers are used to improve the film-forming characteristic of the polymers. In this study, a computerized method (VolSurf with GRID) was used as a novel tool for the prediction plasticization efficiency (beta) of test compounds, and for determining the critical molecular properties needed for polymer plasticization. METHODS: The film-former, starch acetate DS 2.8 (SA), was plasticized with each of 24 tested compounds. A decrease in glass transition temperature of the plasticized free films (determined by differential scanning calorimeter (DSC)) was used as an indicator for beta. Partial least squares discriminant analysis was used to correlate the experimental data with the theoretical molecular properties of the plasticizers. RESULTS: A good correlation (r2 = 0.77, q2 = 0.58) between the molecular modeling results and the experimental data demonstrated that beta can be predicted from the three-dimensional molecular structure of a compound. Favorable structural properties identified for the potent SA plasticizer were strong hydrogen bonding capacity and a definitive hydrophobic region on the molecule. CONCLUSIONS: The VolSurf method is a valuable tool for predicting the plasticization efficiency of a compound. The correlation between experimental and calculated glass transition temperature values verifies that physicochemical properties are primary factors influencing plasticization efficiency of a compound.
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An investigation has been made of the significance of the level of the plasticizer di-(2-ethylhexyl)phthalate at the surface of plasticized polyvinyl chloride for interactions with blood components. Plasticized polyvinyl chloride before and after treatment with methanol to reduce the plasticizer surface level was assessed in terms of fibrinogen and albumin adsorption with unplasticized polyvinyl chloride acting as a control. As the plasticizer surface level decreased, fibrinogen adsorption decreased almost linearly while albumin adsorption increased initially before decreasing slightly. The investigation indicates that reduction in the amount of plasticizer at the surface improves the blood compatibility of plasticized polyvinyl chloride, and the influence on blood is due primarily to the plasticizer rather than the polyvinyl chloride itself.
To assess the significance of migration of polymeric plasticizers into foods, chemical characterization and quantification of individual oligomeric species is required. This paper reports the identification of seven individual oligomers isolated from a poly(butylene adipate) plasticizer. Based on mass spectrometry, NMR and chemical degradation, the oligomers were identified as a series of diol-terminated units ranging from a trimer up to an 11-monomer unit, along with a cyclic tetramer, all in the molecular weight range of 300-1100. A study of the migration of polymeric plasticizer from PVC film into olive oil indicated preferential migration of low molecular weight species. These oligomers which comprised 24% of the parent plasticizer contributed more than 90% of the plasticizer migration with the smallest oligomers migrating 90-fold more readily than the bulk of the plasticizer. From a knowledge of total polymeric plasticizer migration from PVC films under actual conditions of food-use, the abundance of individual oligomers in the foods has been estimated.
Plasticity is one of the most extensively studied aspects in neuroscience. Interest in it has primarily been related to its proposed role in learning and memory and its relevance to adaptive changes following injury. Plasticity can be evoked by changes in molecular, cellular, and synaptic properties, either as a result of activity-dependent effects, or by relatively slow-acting neuromodulatory transmitters. In addition, it is increasingly recognized that the plasticity evoked by these individual effects can be altered by previous inputs and is thus itself plastic. Here, I will review studies in the lamprey spinal cord that have examined individual and interactive activity-dependent and neuromodulator-mediated plasticity. The results show that activity-dependent and neuromodulator-mediated plasticity evoke neuron-and synapse-specific effects at different levels in the spinal cord, and that interactions within and between these effects can evoke dynamic changes in cellular, synaptic, and network plasticity.
We investigated the labeling and content of plasticizers of soft plastic toys. First, we investigated material labeling in 96 products purchased in fiscal years 2000 and 2001. Among these products, 43% of those purchased in fiscal 2000 and 68% of those purchased in fiscal 2001 were labeled. We then investigated the kinds and amounts of plasticizers in 73 soft polyvinyl chloride (PVC) toys. Three kinds of phthalates and six other kinds of plasticizers were detected in the soft PVC toys. Diisononyl phthalate, di(2-ethylhexyl) phthalate, diisononyl adipate, and O-acetyl tributyl citrate were detected at high frequency, and in large amounts. The average total content of all plasticizers was 280 mg/g for the products purchased in fiscal 2000 and 227 mg/g for those in fiscal 2001. In fiscal 2001, antioxidants, 4-nonylphenol, and bisphenol A were investigated in addition to plasticizers.
Phthalate ester plasticizers were found to be extracted by blood from plastic tubing and from plastic bags used for blood storage. One such plasticizer was metabolized by the isolated perfused rat liver while another was found to be accumulated in the liver unchanged. In addition, this latter plasticizer was identified in samples of human tissue taken from patients who had received transfusions of blood stored in plastic bags. The biological implications of these observations are considered.
Phenotypic plasticity itself evolves, as does any other quantitative trait. A very different question is whether phenotypic plasticity causes evolution or is a major evolutionary mechanism. Existing models of the evolution of phenotypic plasticity cover many of the proposals in the literature about the role of phenotypic plasticity in evolution. I will extend existing models to cover adaptation to a novel environment, the appearance of ecotypes and possible covariation between phenotypic plasticity and mean trait value of ecotypes. Genetic assimilation does not sufficiently explain details of observed patterns. Phenotypic plasticity as a major mechanism for evolution--such as, invading new niches, speciation or macroevolution--has, at present, neither empirical nor model support.
Earlier flowering is triggered by vernalization in some but not all Arabidopsis ecotypes, often reflecting allelic variation at the FRIGIDA (FRI) locus. Using a recombinant inbred (RI) population polymorphic at FRI, we examined fitness consequences of variation for plasticity. Flowering and fitness were scored for 68 RI genotypes following full and partial vernalization treatments. Within-environment and mixed-model anovas estimated variance components for a genotype effect and a G x E term, respectively. Selection analyses examined whether delayed bolting increases fitness; a plasticity costs analysis asked whether increased plasticity lowers fitness. We also explored whether trait QTL had environment-specific effects, colocated in the immediate vicinity of FRI, or overlapped with fitness QTL. Selection may favor fri alleles and constitutive early flowering, especially in conditions that only partially vernalize plants. Plasticity costs, detected only after partial vernalization and only marginally significant, were nonetheless consistent with FRI-FLC function. We discuss how information about QTL with environment-specific effects, fitness QTL, and knowledge about plasticity genes can improve interpretation of selection or plasticity cost analyses.
OBJECTIVE: To investigate the apparently poor access of one district's residents to plastic surgery services. DESIGN: Retrospective study of age-standardised operation rates for the year 1991-92. Operation rates were taken as a proxy measure for access. SETTING: Sunderland District Health Authority, and Durham District Health Authority. MAIN OUTCOME MEASURES: Operation rates for surgical specialties in the two districts. RESULT: There were considerable differences in the operation rates for plastic surgery between districts in the Region. Detailed analysis of two districts revealed a significant difference between the two (Sunderland 2.25/1,000; Durham 4.24/1,000, P < 0.001). Sixteen diagnoses were identified as contributing to this difference. However, when these diagnoses were examined across all surgical specialties, the difference in operation rates virtually disappeared (Sunderland 6/1,000; Durham 6.16/1,000). CONCLUSION: Sunderland residents were far more likely to have 'plastic' cases treated by other than plastic surgery specialists, which reflects the balance and expertise of specialties in the district. The need for plastic surgery services will be affected by the local interest and expertise. Operation rates should not be used on their own to indicate inequity in access.
A view that is emerging is that the brain has multiple forms of plasticity that must be governed, at least in part, by independent mechanisms. This view is illustrated by: (1) the apparent separate governance of some non-neural changes by activity, in contrast to synaptic changes driven by learning; (2) the apparent independence of different kinds of synaptic changes that occur in response to the learning aspects of training; (3) the occurrence of separate patterns of synaptic plasticity in the same system in response to different task demands; and (4) apparent dissociations between behaviorally induced synaptogenesis and LTP. The historical focus of research and theory in areas ranging from learning and memory to experiential modulation of brain development has been heavily upon synaptic plasticity since shortly after the discovery of the synapse. Based upon available data, it could be argued that: (1) synaptic, and even neuronal, plasticity is but a small fraction of the range of changes that occur in response to experience; and (2) we are just beginning to understand the importance of these other forms of brain plasticity. Appreciation of this aspect of the brain's adaptive process may allow us to better understand the capacity of the brain to tailor a particular set of changes to the demands of the specific experiences that generated them.