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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gas chromatographic methods using solvent extraction for the analysis of cyclopropane and and trichloroethene (trichloroethylene) are described and evaluated; cyclopropane was extracted into carbon tetrachloride and trichloroethene into carbon disulphide, using chloroform and toluene respectively as the internal standards. Ostwald solubility coefficients were measured for cyclopropane, halothane and trichloroethene in Krebs solution: at 310 K the respective values +/- SEM of the Ostwald coefficients are 0.181 +/- 0.009, 0.78 +/- 0.02 and 1.54 +/- 0.02; over the temperature range 295-310 K the respective temperature coefficients of solubility are -2.27, -4.18 and -3.81 in units of per cent/K at 310 K.
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PMID:Gas chromatographic determination of Ostwald solubility coefficients for cyclopropane, halothane and trichloroethene (trichloroethylene). 86 Nov 7

To evaluate the role of airway neutral endopeptidase 24.11 (NEP) and epithelium removal in the contraction of airway smooth muscle in response to toluene diisocyanate (TDI), we studied the effects of the NEP inhibitor, phosphoramidon, on TDI-induced contractions of guinea-pig bronchial rings with intact epithelium and without epithelium. In preparations with intact epithelium, phosphoramidon (10 microM) potentiated the contractile response to TDI (0.3 mM) (mean +/- SEM, 23.7 +/- 2.5% versus 67.9 +/- 10.3%, p less than 0.01). Phosphoramidon also increased TDI-induced contractions in tissues without epithelium (36.9 +/- 4.9% versus 52.5 +/- 7.1%, p less than 0.05). Removal of the epithelium increased the contractile response to TDI (23.7 +/- 2.5% versus 36.9 +/- 4.9%, p less than 0.05). These results demonstrate the response to TDI is increased in epithelium-free compared to intact bronchi and that NEP 24.11 modulates the effects of endogenously released tachykinins by TDI at all of the sites where NEP is found in the airways.
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PMID:The effect of phosphoramidon and epithelium removal on toluene diisocyanate-induced contractions in guinea-pig bronchi. 131 95

We report the clinical findings and the results of inhalation challenge with toluene diisocyanate (TDI) and methacholine in 113 subjects with a history of exposure to TDI and work-related respiratory symptoms. Only some of the subjects (40.7%) had isocyanate asthma, diagnosed by a positive TDI inhalation challenge. Most reactors had a dual (30.4%) or a late (41.3%) response. The interval between the last occupational exposure and the specific challenge was significantly shorter in reactors, and among this group the number of immediate reactions to TDI decreased progressively with an increasing interval. The reactors had a significantly higher proportion of positive responses to methacholine and a significantly lower mean PD15 FEV-1 (provocative dose of methacholine which provoke a 15% decrease in forced expiratory volume in 1 second) (reactors: 557 micrograms, SEM 92.3; nonreactors: 1346 micrograms, SEM 128, P less than .01). Methacholine challenge could not identify subjects with isocyanate asthma.
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PMID:Toluene diisocyanate-induced asthma: clinical findings and bronchial responsiveness studies in 113 exposed subjects with work-related respiratory symptoms. 165 Aug 20

Occupational asthma induced by toluene diisocyanate (TDI) shares several features with allergic asthma, but the mechanism of action of TDI is poorly understood. Ten sensitised subjects, previously shown to develop a dual or late asthmatic reaction after inhaling TDI were examined. In each subject, forced expiratory volume in one second (FEV1) was measured and venous blood was taken before, and 30 minutes and eight, 24, 48, and 72 hours after exposure to TDI (0.005-0.015 ppm for 10-30 minutes). Filtered air was used as a control. Differential leucocyte counts were determined and phenotypic analysis was performed by immunofluorescence on mononuclear cells using monoclonal antibodies (anti-CD3, anti-CD4, anti-CD8, and anti-HLA-DR). Five subjects developed a dual asthmatic reaction and five had a late reaction. Percentage of CD8 positive lymphocytes increased significantly eight hours after exposure to TDI (from 27 +/- 3 (SEM) % to 42.1 +/- 5%) in the subjects with an isolated late reaction. A delayed significant further increase in suppressor/cytotoxic T lymphocytes was seen in seven of the 10 subjects 48 hours after active exposure (from 27 +/- 2% to 42 +/- 4.8%), irrespective of the type of asthmatic reaction developed after exposure to TDI. Eosinophil percentage increased from 2.5% +/- 1.0 to 6.4% +/- 1.2 24 hours after exposure to TDI and the increase was sustained for up to 48 hours (4.7 +/- 1.1%). No significant variations of FEV1 or cell percentages were seen in the controls. In conclusion, the events triggered by exposure to TDI in sensitised subjects included changes in lung function and systemic effects which lasted longer than bonchoconstriction and concerned suppressor/cytotoxic lymphocytes and eosinophils. These results suggest that TDI induced late asthmatic reactions may be associated with an immunological response to TDI or to its products.
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PMID:Increase in numbers of CD8 positive lymphocytes and eosinophils in peripheral blood of subjects with late asthmatic reactions induced by toluene diisocyanate. 184 21

We evaluated the ability of alpha-phenyl-tert-butyl nitrone (PBN) to trap free radicals and to protect the rat myocardium during ischemia and reperfusion. Isolated bicarbonate buffer-perfused hearts (n = 8) were subjected to 20 min global ischemia (37 degrees C) followed by reperfusion with 0.4 to 4.0 mM PBN. Coronary effluent containing the PBN adduct was extracted in toluene. Electron spin resonance analysis of the toluene extract revealed a PBN-hydroxyl adduct. To verify this assignment, a Fenton system was used to generate an authentic PBN-hydroxyl adduct (n = 8), which yielded the same ESR spectra as the reperfusion-derived adduct. The structure of the adduct formed in the Fenton system was confirmed by gas chromatography-mass spectrometry. The ESR parameters of the PBN-hydroxyl adduct were exquisitely sensitive to solvent polarity during extraction of the adduct. Extraction of an authentic PBN-hydroxyl adduct into chloroform, chloroform:methanol, and toluene closely matched the ESR parameters obtained during reperfusion of ischemic myocardium in other animal models. To determine whether PBN could confer any protective effect during ischemia or reperfusion, hearts (n = 8/group) were subjected to 35 min global ischemia at 37 degrees C with the St. Thomas' II cardioplegic solution followed by 30 min reperfusion. Percent recovery (mean +/- SEM) of developed pressure, rate pressure product, and leakage of lactate dehydrogenase during reperfusion in control hearts were 58 +/- 3%, 48 +/- 4% and 3.2 +/- 0.5 IU/15 min/g wet wt. PBN at a concentration of 0.4 mM or 4.0 mM when present either during ischemia alone or reperfusion alone did not exert any effect upon recovery of developed pressure, rate pressure product or post-ischemic enzyme leakage. We conclude that PBN fails to improve contractile recovery and reduce enzyme leakage during reperfusion of myocardium subjected to global ischemia.
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PMID:Lack of protection of PBN in isolated heart during ischemia and reperfusion: implications for radical scavenging mechanism. 801 39

Microbiological and kinetic aspects of a biofilter inoculated with a consortium of five bacteria and two yeast adapted to remove toluene vapors were investigated. Initially the toluene sorption isotherm on peat and the effect of different environmental conditions on the toluene consumption rates of this consortium were measured. The fast start-up of the biofilter and the decay in the elimination capacity (EC) were reproduced using microcosm assays with toluene successive additions. Nutrient limitation and a large degree of heterogeneity were also detected. EC values, extrapolated from microcosms, were higher than biofilter EC when it was operating close to 100% efficiency but tended to relate better as the biofilter EC diminished. In studies on the microbial evolution in the biofilter, an increase in the cell count and variation in the ecology of the consortium were noted. Bacterial counts up to 10 x 10(11) cfu/gdry peat were found in 88 days, which corresponds to about a 10(4) increase from inoculum. Observations with SEM showed a nonuniform biofilm development on the support and the presence of an extracellular material. The results obtained in this work demonstrated that activity measurement in microcosms concomitant to the biofilter operation could be an important tool for understanding, predicting and improving the biofiltration performance. Copyright 1999 John Wiley & Sons, Inc.
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PMID:Microbiological and kinetic aspects of a biofilter for the removal of toluene from waste gases 1009 94

The prognostic importance of specific and general tests of immune function were examined among a cohort of 170 subjects infected with human immunodeficiency virus type-1 (HIV), living in an area endemic for the fungal infection coccidioidomycosis. Using the proportional hazards model and multivariate analysis, lack of expression of coccidioidal delayed-type hypersensitivity (DTH) was found to be dependent on anergy in response to the non-coccidioidal antigens mumps, Trichophyton and Candida (relative hazard 4.2, 95% CI 1.8-9.8, P=0.001). Among subjects with CD4 lymphocyte counts >/=250 microl-1 on entry into the study, the in vitro lymphocyte transformation (LT) response to the coccidioidal antigen toluene spherule lysate was 4967+/-1652 (mean counts per minute (c.p.m.)+/-SEM) in subjects with coccidioidal DTH compared with 136+/-222 in those with negative DTH (P<0.001). However, amongst those whose CD4 count was <250 microl-1, LT responses were low and there was no significant difference based on coccidioidal DTH (P=0.965). Using the proportional hazards model and multivariate analysis, only a CD4 count <250 microl-1 was prognostically associated with the development of either active coccidioidomycosis or AIDS. These data indicate that immunodeficiency, particularly a CD4 lymphocyte count <250 microl-1, is the most important factor in the lack of expression of specific immunity to coccidioidomycosis and in the development of active coccidioidomycosis among HIV-infected individuals living in the coccidioidal endemic area.
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PMID:Delayed-type hypersensitivity, in vitro T-cell responsiveness and risk of active coccidioidomycosis among HIV-infected patients living in the coccidioidal endemic area. 1042 59

The present study was designed to evaluate whether pre-incubation with serum, obtained from both control and toluene diisocyanate (TDI)-immunized guinea-pigs, modified the contractile response to TDI in isolated guinea-pig bronchial rings. Guinea-pigs were anaesthetized and the main bronchi dissected in two rings. Bronchial rings were incubated with normal or immune serum (100 microl ml(-1) for 2 h) and dose-response curves to TDI (0.03-1000 microM) were studied isometrically. Before serum incubation, in eight bronchial rings, epithelium was removed by rubbing the luminal surface gently with a gauze. In control rings, TDI produced a concentration-dependent contraction, whereas in rings pre-incubated with either normal or TDI-immune serum, it produced a concentration-dependent relaxation. Relaxation was 101.4 (SEM 17.4)% and 94.9 (SEM 21)% of the relaxation induced by isoproterenol (1 mM) respectively with normal and TDI-immune serum. Similarly to the pre-incubation with serum, pre-incubation with albumin produced a concentration-dependent relaxation to TDI. Serum-induced relaxant response to TDI was not affected by capsaicin desensitization, it was only partially inhibited by an NK1-tachykinin antagonist, whereas it was blocked by indomethacin. In bronchial rings without epithelium, pre-incubated with serum, TDI caused contraction at highest doses, while it still induced relaxation at the lowest doses. This study shows that one or more components of the serum modify the contractile response to TDI in isolated guinea-pig bronchi. In bronchial rings without epithelium serum was able to inhibit the contration induced by low doses of TDI.
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PMID:Serum-mediated relaxant response to toluene diisocyanate (TDI) in isolated guinea-pig bronchi. 1139 76

Solid-state properties of piroxicam benzoate, an ester prodrug of piroxicam, were investigated. Samples were prepared by recrystallization from various organic solvents (toluene, ethanol, methanol, ethyl acetate and acetone). Recrystallized samples were characterized by means of FTIR, DSC, TGA, SEM and XRPD. DSC, TGA and XRPD methods confirmed that piroxicam benzoate crystallized in two pseudopolymorphic forms, A and B. Pseudopolymorphic form A was obtained by recrystallization from ethanol and methanol by slow cooling at room temperature and by rapid cooling in an ice-cold bath, and also from toluene by rapid cooling in an ice-cold bath. Pseudopolymorphic form B was obtained by recrystallization from toluene by slow cooling at room temperature.
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PMID:Solid-state investigation of piroxicam benzoate. 1476 40

A new type of fiber adsorbent attached with silica microparticles was prepared. The silica microparticles were formed by the polymerization of silica oligomers on glass fibers, which were woven into a glass filter. The surface of the silica microparticles was chemically modified by bonding C18-ligands. SEM images indicated that the diameter of the uniform and spherical silica microparticles fixed on glass fibers was on the order of micrometers. It was confirmed that the glass filter adsorbent was effective for the adsorptive removal of toluene of low concentrations.
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PMID:Preparation of a new type of fiber adsorbent attached with silica microparticles. 1529 2


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