987 resultados para REACTIVE POLYMERS
Resumo:
Acetaminophen [N-acetyl-p-aminophenol (APAP)] is the most common antipyretic/analgesic medicine worldwide. If APAP is overdosed, its metabolite, N-acetyl-p-benzo-quinoneimine (NAPQI), causes liver damage. However, epidemiological evidence has associated previous use of therapeutic APAP doses with the risk of chronic obstructive pulmonary disease (COPD) and asthma. The transient receptor potential ankyrin-1 (TRPA1) channel is expressed by peptidergic primary sensory neurons. Because NAPQI, like other TRPA1 activators, is an electrophilic molecule, we hypothesized that APAP, via NAPQI, stimulates TRPA1, thus causing airway neurogenic inflammation. NAPQI selectively excites human recombinant and native (neuroblastoma cells) TRPA1. TRPA1 activation by NAPQI releases proinflammatory neuropeptides (substance P and calcitonin gene-related peptide) from sensory nerve terminals in rodent airways, thereby causing neurogenic edema and neutrophilia. Single or repeated administration of therapeutic (15-60 mg/kg) APAP doses to mice produces detectable levels of NAPQI in the lung, and increases neutrophil numbers, myeloperoxidase activity, and cytokine and chemokine levels in the airways or skin. Inflammatory responses evoked by NAPQI and APAP are abated by TRPA1 antagonism or are absent in TRPA1-deficient mice. This novel pathway, distinguished from the tissue-damaging effect of NAPQI, may contribute to the risk of COPD and asthma associated with therapeutic APAP use.-Nassini, R., Materazzi, S., Andre, E., Sartiani, L., Aldini, G., Trevisani, M., Carnini, C., Massi, D., Pedretti, P., Carini, M., Cerbai, E., Preti, D., Villetti, G., Civelli, M., Trevisan, G., Azzari, C., Stokesberry, S., Sadofsky, L., McGarvey, L., Patacchini, R., Geppetti, P. Acetaminophen, via its reactive metabolite N-acetyl-p-benzo-quinoneimine and transient receptor potential ankyrin-1 stimulation causes neurogenic inflammation in the airways and other tissues in rodents. FASEB J. 24, 4904-4916 (2010). www.fasebj.org
Resumo:
Reaction of trans-[Pt(NC5H4CHBu2n)(2)Cl-2] 1 with an excess of HC=CR (R = Ph, C6H4Me, C6H4NO2) affords the monomeric complex trans-[Pt(NC5H4CHBu2n)(2)(C=CR)(2)] (R = Ph 2a, C6H4Me 2b, C6H4NO2 2c), the trans arrangement of the alkynyl ligands being confirmed from spectroscopic data and by an X-ray analysis of 2c;when 1 is treated with 1 equiv, of HC=CC6H2(Me)(2)C=CH the polymer [Pt(NC5H4CHBu2n)(2)C=CC6H2Me2C=C](n) is formed, which is soluble in a range of organic solvents.
Resumo:
The new platinum complex [PtCl[C6H2(CH(2)NMe(2))(2) -2,6-(C=CH)-4)] exhibits a polymeric linear -C=CH ... ClPt-hydrogen-bonded structure in the solid state.
Resumo:
This paper examines the positive contributions made toward restructuring the regulatory framework of Turkey's banking and financial sectors prior to and post the 2000–2001 financial crisis. Drawing on a framework initially developed by Onis and Senses, 2007 and Onis and Senses, 2009 and further referred to by Onis, 2009 and Onis, 2010 it argues that financial reforms undertaken by the Turkish government would not have been successful without the strong support of domestic coalitions. While the external pressures put on the Turkish government from the International Monetary Fund, The World Bank and the European Union for financial reforms were necessary to kick start the reforms as a reactive process, these pressures on their own may have served only the interests of financial business elites at the expense of the broader stakeholders. Empirical data for the study was collected from documentary analysis of key financial institutions and interviews with twenty major Turkish regulatory agents and other stakeholders. The paper then discusses how the perceptions of these stakeholders are embodied into, and have influenced, regulatory regime change in Turkey from a reactive state to a more proactive one.
Resumo:
The phase behavior of a model system of colloidal platelets and nonadsorbing polymers is studied using computer simulations and perturbation theory. The equation of state for the pure platelet reference system is obtained by Monte Carlo simulations, and the free volume fraction accessible to polymers is measured by a trial insertion method. The free volume fraction is also calculated using scaled particle theory. Subsequently, the phase diagram for platelet-polymer mixtures is calculated. For a platelet aspect ratio L/D=0.1 and a polymer to platelet size ratio d/D>0.2, we observe coexistence between two isotropic phases with different densities. For smaller polymers d/D
Resumo:
Robust, active, anatase titania films, 250 nm thick, are deposited onto glass at low temperatures, i.e., 2.0 for the photocatalytic mineralization of stearic acid. These films are typically 6.9 times more active than a sample of commercial self-cleaning glass, comprising a 15 nm layer of fitania deposited by CVD, mainly because they are much thicker and, therefore, absorb more of the incident UV light. The most active of the films tested comprised particles of P25, but lacked any significant physical robustness. Similar results, but much more quickly obtained, were generated using a photocatalyst- sensitive ink, based on the redox dye, resazurin, Rz. All fitania films tested, including those produced by magnetrom sputtering exhibited photo-induced superhydrophilicity. The possible future application of PAR-DG-MS for producing very active photocatalytic films on substrates not renowned for their high temperature stabilities, such as plastics, is noted. (c) 2006 Elsevier B.V All rights reserved.
Resumo:
This study examined the mechanical/textural, viscoeiastic and mucoadhesive properties of a range of aqueous gels composed of either hydroxyethylcellulose (HEC) or sodium carboxymethylcellulose (Na CMC). The mechanical/textural properties of each formulation were determined using texture profile analysis. The viscoelastic properties of each formulation were examined over a defined frequency range (0.01-1.0 Hz) using oscillatory rheometry in conjunction with stainless steel parallel plate geometry. The mucoadhesive properties of the gels were evaluated by measuring the tensile force required to overcome the gel/mucin adhesive interaction. Both gel hardness and compressibility, properties that affect the ease of product removal from a container and spreadability, increased as a function of increasing polymer concentrations. This is attributed to the effects of HEC and Na CMC on gel viscosity. Gel adhesiveness, a property related to bioadhesion, also increased as a function of polymer concentration and is attributed to the reported adhesive nature of these polymers. Increasing frequency of oscillation increased the storage and loss moduli yet decreased bath the dynamic viscosity of each gel type and also the loss tangent of HEC (but not Na CMC) gels. Therefore, following exposure to the range of oscillatory stresses that may be expected in vivo, HEC gels will be more susceptible than Na CMC gels to alterations in these rheological properties. Consequently, it would be expected that the clinical performance of HEC gels will be modified to a greater extent than Na CMC gels. In general, HEC gels exhibited a greater elastic nature than Na CMC gels over the frequency range employed for oscillation The storage and loss moduli and dynamic viscosity of both gel types increased, yet the loss tangent of both gel types decreased as a function of increasing polymer concentration. Gel mucoadhesive strength was dependent on both the time of contact of the formulation with mucin and also on polymer concentration. In conclusion, this study has characterised a number of gels containing either HEC or Na CMC in terms of their mechanical/textural, viscoelastic and mucoadhesive properties. Due to its relevance to the clinical performance, it is suggested that the information derived from these methods may be usefully combined to provide a more rational basis for the selection of polymers and their formulation as topical drug delivery systems. (C) 1997 Elsevier Science B.V.