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Toluene Diisocyanate (toluene + diisocyanate)
Selected AbstractsToluene diisocyanate enhances human bronchial epithelial cells' permeability partly through the vascular endothelial growth factor pathwayCLINICAL & EXPERIMENTAL ALLERGY, Issue 10 2009H. Zhao Summary Background Toluene diisocyanate (TDI) is a recognized chemical asthmogen; yet, the mechanisms of its toxicity have not been elucidated. Objective To investigate the influence of TDI on the permeability of human bronchial epithelial cell (HBE; HBE135-E6E7) monolayers in vitro, and the expression of vascular endothelial growth factor (VEGF) in these cells. Methods TDI,human serum albumin (HSA) conjugates were prepared by a modification of Son's method. Fluorescein isothiocyanate-labelled dextran and transmission electron microscopy were used to evaluate the effects of TDI,HSA on HBE135-E6E7 permeability. RT-PCR and ELISA were used to evaluate VEGF gene expression and protein release from HBE135-E6E7 cells stimulated by TDI,HSA. A VEGF-neutralizing antibody was used in monolayer permeability experiments to determine the role of the VEGF pathway in this process. Results TDI,HSA significantly increased the permeability coefficients of HBE135-E6E7 monolayers (P<0.01). TDI,HSA treatment significantly increased the expression of VEGF165 and VEGF189 genes (P<0.01). ELISA showed that TDI significantly induces VEGF release from HBE135-E6E7 cells. Cells treated with TDI,HSA and VEGF-neutralizing antibody had significantly lower permeability coefficients than cells treated with TDI,HSA only (P<0.01), but still significantly higher than control cells (P<0.01). Cells treated with TDI,HSA had fewer tight junctions (TJs) than control and HSA-treated cells, and addition of the anti-VEGF antibody did not restore the original number of TJs. Conclusion TDI increases the permeability of HBE cell monolayers, partly through a VEGF-mediated pathway. This suggests the importance of VEGF in TDI-induced pulmonary diseases, but shows that other pathways may be involved in the pathogenic process. [source] Alpha-T-catenin (CTNNA3) gene was identified as a risk variant for toluene diisocyanate-induced asthma by genome-wide association analysisCLINICAL & EXPERIMENTAL ALLERGY, Issue 2 2009S-H. Kim Summary Background Toluene diisocyanate (TDI) is the most important cause of occupational asthma, but the genetic mechanism of TDI-induced asthma is still unknown. Objective The objective of the study was to identify susceptibility alleles associated with the TDI-induced asthma phenotype. Methods We conducted a genome-wide association study in 84 patients with TDI-induced asthma and 263 unexposed healthy normal controls using Affymetrix 500K SNPchip. We also investigated the relationships between genetic polymorphisms and transcript levels in Epstein,Barr virus-transformed lymphoblastoid cell lines from patients with TDI-induced asthma enrolled in this study. Results Genetic polymorphisms of CTNNA3 (catenin alpha 3, alpha-T catenin) were significantly associated with the TDI-induced asthma phenotype (5.84 × 10,6 for rs10762058, 1.41 × 10,5 for rs7088181, 2.03 × 10,5 for rs4378283). Carriers with the minor haplotype, HT2 [GG], of two genetic polymorphisms (rs10762058 and rs7088181) showed significantly lower PC20 methacholine level (P=0.041) and lower mRNA expression of CTNNA3 than non-carriers (P=0.040). A genetic polymorphism in the 3, downstream region of CTNNA3 (rs1786929), as identified by DNA direct sequencing, was significantly associated with the TDI-induced asthma phenotype (P=0.015 in recessive analysis model) and the prevalence of serum-specific IgG to cytokeratin 19 (P=0.031). Conclusion These findings suggested that multiple genetic polymorphisms of CTNNA3 may be determinants of susceptibility to TDI-induced asthma. [source] Chemical modification of polypropylene with diisocyanates for improved gas barrier and mechanical propertiesADVANCES IN POLYMER TECHNOLOGY, Issue 4 2009R. S. Jagadish Abstract In this investigation, modification of polypropylene (PP) with an objective to obtain packaging film with improved gas barrier properties has been studied. The chemical reaction of PP resin with hexamethylene diisocyanate and toluene diisocyanate was monitored by Fourier transform infrared spectroscopy, wherein the appearance of new peaks at 3333 cm,1 for NH stretching, 1620,1641 cm,1 for (CO)NH stretching and 1552,1578 cm,1 corresponding to NH bending in an amide moiety was observed for both the modified PP films. Films of excellent clarity and uniform thickness were obtained by the extrusion of cross-linked polypropylene. The barrier, mechanical, optical, and thermal properties of the modified PP films were studied. The results clearly indicated significant changes in gas barrier and mechanical properties. Food compatibility of the films was evaluated by overall migration in to different food simulants. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:233,245, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20168 [source] Thermomechanical characteristics of benzoxazine,urethane copolymers and their carbon fiber-reinforced compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009Sarawut Rimdusit Abstract Copolymers of polybenzoxazine (BA-a) and urethane elastomer (PU) with three different structures of isocyanates [i.e., toluene diisocyanate (TDI), diphenylmethane diisocyanate, and isophorone diisocyanate], were examined. The experimental results reveal that the enhancement in glass transition temperature (Tg) of BA-a/PU copolymers was clearly observed [i.e., Tg of the BA-a/PU copolymers in 60 : 40 BA-a : PU system for all isocyanate types (Tg beyond 230°C) was higher than those of the parent resins (165°C for BA-a and ,70°C for PU)]. It was reported that the degradation temperature increased from 321°C to about 330°C with increasing urethane content. Furthermore, the flexural strength synergism was found at the BA-a : PU ratio of 90 : 10 for all types of isocyanates. The effect of urethane prepolymer based on TDI rendered the highest Tg, flexural modulus, and flexural strength of the copolymers among the three isocyanates used. The preferable isocyanate of the binary systems for making high processable carbon fiber composites was based on TDI. The flexural strength of the carbon fiber-reinforced BA-a : PU based on TDI at 80 wt % of the fiber in cross-ply orientation provided relatively high values of about 490 MPa. The flexural modulus slightly decreased from 51 GPa for polybenzoxazine to 48 GPa in the 60 : 40 BA-a : PU system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Methods for the identi,cation of chemical respiratory allergens in rodents: comparisons of cytokine pro,ling with induced changes in serum IgEJOURNAL OF APPLIED TOXICOLOGY, Issue 4 2003R. J. Dearman Abstract No validated or widely recognized test methods are currently available for the prospective identi,cation of chemicals with the potential to cause respiratory allergy. The cellular and molecular mechanisms that result in the induction of chemical sensitization of the respiratory tract are unclear, although there is evidence for the selective development of T helper 2 (Th2)-type responses and, in some cases, the production of IgE antibody. We have therefore examined the utility of cytokine pro,ling using BALB/c mice, together with the measurement of induced increases in the total serum concentration of IgE in the Brown Norway (BN) rat, as markers for the prospective identi,cation of chemical respiratory allergens. Responses provoked by the reference respiratory allergen trimellitic anhydride (TMA) have been compared with those stimulated by the respiratory sensitizing diisocyanates toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) and by the acid anhydride hexahydrophthalic anhydride (HHPA). Topical exposure of BN rats to TMA, TDI and HHPA each provoked marked immune activation (increases in lymph node cellularity and proliferation). However, only treatment with TMA stimulated vigorous increases in the total serum concentration of IgE. In contrast, exposure to HHPA, TDI or HDI failed to provoke signi,cant changes in serum IgE concentration or induced only transient and relatively weak increases in serum IgE levels. In parallel experiments using BALB/c strain mice, however, topical application of all four chemical respiratory allergens provoked a marked Th2-type cytokine secretion pro,le in draining lymph node cells. These data suggest that the measurement of induced changes in serum IgE is not suf,ciently sensitive for the robust identi,cation of chemical respiratory allergens. Furthermore, irrespective of the reasons for variations in TMA-induced IgE production among BN rats, doubts remain regarding the utility of these animals for the characterization of immune responses to chemical allergens. Cytokine pro,ling using the BALB/c strain mouse apparently provides a more robust method for the hazard assessment of chemical respiratory allergens. Copyright © 2003 John Wiley & Sons, Ltd. [source] Fourier transform Raman and Fourier transform infrared spectra of cross-linked polyurethaneurea films synthesized from solutionsJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2002Valentina Romanova Cross-linked polyurethaneurea films based on polyoxytetramethylene glycol and polyoxypropylene glycol with toluene diisocyanate and 3,3,-dichloro-4,4,-diaminodiphenylmethane were synthesized in a solution where the solvent evaporates during the polymerization. FT-Raman and FTIR spectra were analysed and intermolecular force constants of hydrogen bonds were calculated. On the basis of the intensity of the Raman and IR spectral lines, which reflects hydrogen bond formation, the optimum structure of hydrogen bonds and the conformations of macromolecules of polyurethaneurea were observed for the solvent ethyl acetate. Copyright © 2002 John Wiley & Sons, Ltd. [source] Polyurethanes Based on Castor Oil: Kinetics, Chemical, Mechanical and Thermal PropertiesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2008Elodie Hablot Abstract Polyurethanes based on vegetable oil were synthesized with castor oil and toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, using dibutyltin dilaurate as a catalyst. The effects of the nature of the diisocyanate on the evolution of the kinetics, as well as the physical and mechanical properties and the thermal stability, of the different synthesized polyurethanes were investigated, and these complement data from the literature on equivalent systems. The polymerization kinetics, degree of swelling and mechanical properties were greatly affected by the diisocyanate nature, whereas the rheological properties and thermal stability were found to be similar for all polyurethanes. [source] HLA DRB1*15-DPB1*05 haplotype: a susceptible gene marker for isocyanate-induced occupational asthma?ALLERGY, Issue 7 2006S.-H. Kim Background:, There has been no study for evaluating the associations of human leukocyte antigen (HLA) class I and II alleles with toluene diisocyanate (TDI)-induced asthma in an Asian population. Objective:, The aim of this study was to investigate a susceptible or protective marker of HLA class I and II alleles in TDI-induced asthma. Methods:, Fifty-five patients with TDI-induced asthma patients (group I) showing positive responses on TDI bronchoprovocation test, 47 asymptomatic exposed subjects (group II) and 95 unexposed healthy nonatopic controls (group III) were enrolled in our study. HLA class I and II genotyping was done by the direct DNA sequencing method. Results:, The allelic frequency of C*09 (15.5%) was significantly higher in group I than in group III (6.8%, P = 0.019), but this statistical significance disappeared after correction was made for multiple comparisons. On two-locus and three-locus haplotype analysis, the allelic frequency of HLA DRB1*15-DPB1*05 in group I (10.6%) was significantly higher than that of group II (0%, P = 0.001) and group III (2.5%, P = 0.003). The allelic frequencies of HLA A*02-DRB1*15, A*02-DQB1*06, B*62-C*09 and A*02-DRB1*15-DQB1*06 were significantly higher in group I (8.5%, 10.3%, 8.2% and 6.8%, respectively) than those allelic frequencies of group III (1.3%, P = 0.002; 1.6%, P = 0.001; 0.6%, P < 0.0001; 0%, P < 0.0001, respectively). The allelic frequencies of HLA DQB1*06-DPB1*05 and DRB1*15-DQB1*06-DPB1*05 were significantly higher in group I (16.0% and 10.5%) than those in group II (2.5%, P = 0.001; 0%, P = 0.001), while the frequencies of DRB1*09-DPB1*05 and DRB1*09-DQB1*0303-DPB1*05 were significantly lower in group I (0% and 0%) than those of group II (7.4%, P = 0.004; 7.5%, P = 0.004). These differences remained statistically significant even after the correction for multiple comparisons. Conclusions:, The HLA haplotype DRB1*15-DPB1*05 can be a susceptibility gene marker for the development of TDI-induced asthma among the exposed workers in the Korean population. [source] Mechanical and viscoelastic properties of semi-interpenetrating polymer networks of poly(vinyl chloride)/thermosetting resin blendsPOLYMER ENGINEERING & SCIENCE, Issue 6 2000Charles U. Pittman Jr. Semi-interpenetrating polymer networks (SIPNs) of PVC/thermoset were prepared by premixing porous, 150 ,m diameter particles of PVC and a small quantity (from 5 to 15% by weight) of a single thermosetting liquid preresin from one of five types (e.g. methylene bis-phenyl diisocyanate (MDI), oligomeric MDI isocyanates (PAPI), toluene diisocyanate (TDI) prepolymer, epoxy, and vinyl ester resins, respectively). Two roll milling of these mixtures was followed by hot-press curing. Mechanical testing indicated that most of these blends exhibited increased tensile, impact, and flexural strengths. The strength increments were greater when going from 0 to 5% thermoset content than when going from 5 to 10% or 10 to 15% thermoset. In many cases, increasing thermoset content from 10 to 15% gave slightly decreased or unchanged tensile, impact, and flexural strengths. This behavior is in accord with a "thermoset dilution effect" in PVC. Most of these SIPN blends exhibited a tan , peak temperature lower than that for pure PVC in the glass transition region. The tan , peak temperatures were progressively lowered as the amounts of thermoset increased. Also, a single distinct peak existed in the E, curves for most of the blends. Only the PVC/epoxy (90/10) blend showed two peak maxima in E, vs. temperature curves. All blends exhibited peak E, values at a lower temperature than those of PVC which had been exposed to the same processing temperatures. These observations seem to rule out the presence of large domains of PVC, which are phase-separated from PVC/thermoset SIPN, and pure thermoset domains. A substantial amount of the added thermoset appears to exist in SIPN type phases in these five blend types. [source] Specific immunoglobulin E and immunoglobulin G antibodies to toluene diisocyanate-human serum albumin conjugate: useful markers for predicting long-term prognosis in toluene diisocyanate-induced asthmaCLINICAL & EXPERIMENTAL ALLERGY, Issue 4 2002H.-S. Park Summary Background Our previous study reported that more than 50% of toluene diisocyanate (TDI)-induced asthma patients had persistent asthmatic symptoms even after complete avoidance. Although specific IgE (sIgE) has been detected in a portion of patients with TDI-asthma, a recent investigation suggests that the presence of serum specific IgG (sIgG), not sIgE, is more closely associated with positive bronchoprovocation test (BPT) results. Objective To evaluate the possible role of sIgE and sIgG in predicting long-term prognosis of TDI-asthma. Materials and methods Forty-one TDI-asthma patients whose diagnosis was confirmed by TDI-BPT, and 20 unexposed healthy controls were enrolled. Both sIgE and sIgG to TDI-human serum albumin (HSA) conjugate were detected by ELISA. All patients with persistent asthmatic symptoms took anti-asthmatic medications during the follow-up period (mean: 67.5 months) and were instructed to avoid exposure to TDI. Airway hyper-responsiveness to methacholine (AHM) was monitored every year during the study period. The patients were classified into three groups according to changing patterns of AHM and asthmatic symptoms as follows: group I, no improvement with persistent asthmatic symptoms (n = 12); group II, partial improvement with persistent asthmatic symptoms (n = 13); group III, in remission (n = 16). Results Favourable prognosis was associated with a mild degree of AHM at initial diagnosis (P < 0.05). Although there were no significant differences in the prevalence of sIgE antibody to TDI-HSA conjugate among the three groups (P > 0.05), prevalence of sIgG in group I tended to be higher than in group II (0.05 < P < 0.1). However, the levels of sIgG were significantly higher in group I than in group II (P = 0.05), whereas levels of sIgE were significantly higher in group II than in group I (P = 0.014). No significant differences were noted in exposure duration, sex, age, atopic status, and total IgE level among the three groups (P > 0.05). Conclusion This study confirmed that a favourable outcome is related to a mild degree of AHM and to low levels of sIgG to predict persistent asthmatic symptoms, it also suggested that the presence of high serum-specific IgE at initial diagnosis may represent a better prognosis. [source] Synthesis of poly(vinyl ether) polyols with pendant oxyethylene chains and properties of hydrophilic, thermo-responsive polyurethanes prepared therefromJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2010Tamotsu Hashimoto Abstract Hydroxy-terminated telechelic poly(vinyl ether)s with pendant oxyethylene chains were synthesized by the reaction of the CH3CH(OCOCH3)O[CH2]4OCH(OCOCH3)CH3/Et1.5AlCl1.5/THF-based bifunctional living cationic polymers of 2-methoxyethyl vinyl ether (MOVE), 2-ethoxyethyl vinyl ether (EOVE), and 2-(2-methoxyethoxy)ethyl vinyl ether (MOEOVE) with water and the subsequent reduction of the aldehyde polymer terminals with NaBH4. The obtained poly(vinyl ether) polyols were reacted with an equimolar amount of toluene diisocyanates [a mixture of 2,4- (80%) and 2,6- (20%) isomers] to give water-soluble polyurethanes. The aqueous solutions of these polyurethanes caused thermally induced precipitation at a particular temperature depending on the sort of the thermosensitive poly(vinyl ether) segments containing oxyethylene side chains. These polyurethanes also function as polymeric surfactants, lowered the surface tension of their aqueous solutions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1641,1648, 2010 [source] Synthesis and dissociation of amine-blocked diisocyanates and polyurethane prepolymersPOLYMER INTERNATIONAL, Issue 3 2002T Philip Gnanarajan Abstract Substituted N -methylanilines are shown to act as blocking agents for toluenediisocyanate. N -methylaniline-, N -methyl- p -anisidine- and N -methyl- p -nitroaniline-blocked toluene diisocyanates have been prepared and characterized by FTIR, 1H NMR and 13C NMR spectroscopies, and nitrogen content analysis. A new method for determining the minimum deblocking temperature of the blocked isocyanate is described. The method has advantages in that it can be used to find the minimum deblocking temperature of even non-volatile blocking agents. The minimum deblocking temperature of the adducts is found to be in the following order: N -methyl- p -anisidine,TDI adduct,<,N -methyaniline,TDI adduct,<,N -methyl- p -nitroaniline,TDI adduct. The anilines exhibit the same trend when they block a polyurethane prepolymer prepared using polypropylene glycol of molecular weight 2000,g,mol,1 and tolylene-2,6-diisocyanate. The deblocking temperatures are lower in the case of blocked prepolymers than in the blocked adducts. The blocked adducts and prepolymers are reacted with pyromellitic dianhydride (PMDA) in dimethylpropylene urea (DMPU) and the evolution of carbon dioxide is monitored to study the completion of imidization. The reaction time is in accordance with the deblocking ability of the adducts. The regeneration of the blocking agent is confirmed by gas chromatography. © 2002 Society of Chemical Industry [source] | ||||||||||||||||