OBJECTIVE: To investigate the prevalence of airway hyperresponsiveness induced by isocyanate at one petrochemical industry complex in Yeochon, Korea. METHOD: Questionnaires, allergic skin prick test, toluene diisocyanate (TDI)-specific IgE, and non-specific airway hyperresponsiveness (AHR) were studied in 73 exposed workers and 27 control subjects. Methacholine challenge tests were done and bronc hial responsiveness (BR index) was defined as log (% fall of FEV1)/ log (last concentration of methacholine +10). RESULTS: Twenty-three workers (31.5% ) had respiratory symptoms, 21 had nasal symptoms, and eight had skin symptoms. Exposed workers with respiratory symptoms (n=22) had significantly higher BR index than those without them (0.82+/-0.06 vs 0.60+/-0.02, p<0.05). Exposed workers tended to have higher BR index than controls (0.67+/-0.03 vs 0.62+/-0.02). Three exposed workers had PC20 methacholine <2.0 mg/ml. There were no significant differences in atopy score between exposed workers and controls (p>0.05). Specific IgE antibodies were found in 19.7% of exposed workers. FEV, showed a significant negative correlation with BR index (r =-0.25, p<0.05). Poor correlation was noted between BR index and atopy, smoking status, or exposure duration. CONCLUSION: These findings suggest that workers exposed to isocyanates are at higher risk of airway hyperresponsiveness.
Antibodies ; Immunoglobulin E ; Isocyanates* ; Korea ; Methacholine Chloride ; Plants* ; Prevalence ; Skin ; Smoke ; Smoking ; Toluene 2,4-Diisocyanate ; Surveys and Questionnaires

Activation of N-methyl-d-aspartic acid (NMDA) receptor plays an important role in neuronal apoptosis induced by cerebral ischemia but the underlying mechanisms are still unclear. The present study examined the neuroprotection of three chloride blockers in an in vitro cell model of cerebral ischemia established by treatment of cultured rat hippocampal neurons with NMDA. Hoechst 33258 staining and MTT assay were used to detect neuronal apoptosis and cell viability, respectively. The neuroprotective effects of chloride channel blockers on the cell viability and neuronal apoptosis were only observed when the blockers were applied before NMDA exposure. In comparison with DIDS, SITS showed more potent protective effect in a dose-dependent manner, whereas NPPB showed no significant neuroprotective effect. The results demonstrate that pretreatment with both SITS and DIDS have protective effect against neuronal apoptosis, which is achieved by blocking both NMDA receptor and chloride channel.
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid ; pharmacology ; 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid ; pharmacology ; Animals ; Animals, Newborn ; Apoptosis ; drug effects ; Bisbenzimidazole ; chemistry ; Cell Survival ; drug effects ; Cells, Cultured ; Chloride Channels ; antagonists & inhibitors ; Hippocampus ; cytology ; Microscopy, Fluorescence ; N-Methylaspartate ; pharmacology ; Neurons ; chemistry ; cytology ; drug effects ; Neuroprotective Agents ; pharmacology ; Rats ; Rats, Sprague-Dawley

The development of a serological marker for early diagnosis of isocyanate-induced occupational asthma (isocyanate-OA) may improve clinical outcome. Our previous proteomic study found that expression of vitamin D-binding protein (VDBP) was upregulated in the patients with isocyanate-OA. In the present study, we evaluated the clinical relevance of VDBP as a serological marker in screening for isocyanate-OA among exposed workers and its role in the pathogenesis of isocyanate-OA. Three study groups including 61 patients with isocyanate-OA (group I), 180 asymptomatic exposed controls (AECs, group II), 58 unexposed healthy controls (NCs, group III) were enrolled in this study. The baseline serum VDBP level was significantly higher in group I compared with groups II and III. The sensitivity and specificity for predicting the phenotype of isocyanate-OA with VDBP were 69% and 81%, respectively. The group I subjects with high VDBP (> or = 311 microg/ml) had significantly lower PC20 methacholine levels than did subjects with low VDBP. The in vitro studies showed that TDI suppressed the uptake of VDBP into RLE-6TN cells, which was mediated by the downregulation of megalin, an endocytic receptor of the 25-hydroxycholecalciferol-VDBP complex. Furthermore, toluene diisocyanate (TDI) increased VEGF production and secretion from this epithelial cells by suppression of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] production. The findings of this study suggest that the serum VDBP level may be used as a serological marker for the detection of isocyanate-OA among workers exposed to isocyanate. The TDI-induced VEGF production/secretion was reversed by 1,25(OH)2D3 treatment, which may provide a potential therapeutic strategy for patients with isocyanate-OA.
Adult ; Animals ; *Asthma/blood/chemically induced/pathology ; Cell Line ; Epithelial Cells ; Female ; Gene Expression/drug effects ; Humans ; Isocyanates/toxicity ; Male ; Middle Aged ; *Occupational Diseases/blood/chemically induced/pathology ; Rats ; Toluene 2,4-Diisocyanate/toxicity ; Vitamin D-Binding Protein/*blood

Three diisocyanates can cause occupational asthma (OA): toluene diisocyanate (TDI), 4,4 diphenylmethane diisocyanate (MDI), and 1,6-hexamethylene diisocyanate (HDI). We analyzed potential biomarkers of isocyanate-induced OA, based on investigated immunologic, genetic, neurogenic, and protein markers, because there is no serological testing method. The prevalence of serum IgG to cytokeratin (CK)18 and CK19 in TDI-OA was significantly higher than in controls, although the prevalence of these antibodies was too low for them to be used as biomarkers. Another candidate biomarker was serum IgG to tissue transglutaminase (tTG), because the prevalence of serum specific IgG to tTG was significantly higher in patients with TDI-OA than in controls. The human leukocyte antigen (HLA) DRB1*1501-DQB1*0602-DPB1*0501 haplotype may be used as a genetic marker for TDI-OA in Koreans via enhanced specific IgE sensitization in exposed subjects. The genetic polymorphisms of catenin alpha 3, alpha-T catenin (CTNNA3) were significantly associated with TDI-OA. Additionally, examining the neurokinin 2 receptor (NK2R) 7853G>A and 11424 G>A polymorphisms, the NK2R 7853GG genotype had higher serum vascular endothelial growth factor (VEGF) levels than the GA or AA genotypes among Korean workers exposed to TDI. To identify new serologic markers using a proteomic approach, differentially expressed proteins between subjects with MDI-OA and asymptomatic exposed controls in a Korean population showed that the optimal serum cutoff levels were 69.8 ng/mL for ferritin and 2.5 microg/mL for transferrin. When these two parameters were combined, the sensitivity was 71.4% and the specificity was 85.7%. The serum cytokine matrix metalloproteinase-9 (MMP-9) level is a useful biomarker for identifying cases of TDI-OA among exposed workers. Despite these possible biomarkers, more effort should be focused on developing early diagnostic biomarkers using a comprehensive approach based on the pathogenic mechanisms of isocyanate-induced OA.
Antibodies ; Asthma ; Asthma, Occupational ; Biomarkers ; Cyanates ; Ferritins ; Genetic Markers ; Genotype ; GTP-Binding Proteins ; Haplotypes ; Humans ; Immunoglobulin E ; Immunoglobulin G ; Isocyanates ; Keratins ; Leukocytes ; Matrix Metalloproteinase 9 ; Polymorphism, Genetic ; Prevalence ; Proteins ; Receptors, Neurokinin-2 ; Serologic Tests ; Toluene 2,4-Diisocyanate ; Transferrin ; Transglutaminases ; Vascular Endothelial Growth Factor A

Regulating the cell volume is an important factorin secretory function of epithelial cells and regulatory volume decrease (RVD) phenomenon is involved in response to the changes of cell volume and osmolarity. RVD of epithelial cells reflects cellular release of K+ and C1- through channels and K+ and C1- channels were verified in the basal membrane of the non pigmented ciliary epithelial cells. Therefore, we attempted to observe the involvement of C1- channel in aqueous humor production by performing the fluorophotometry after administration of the DIDS(4.4-diisothiocyanatostilbene-2-2-disulfonic acid), the C1 channel blocker. Ten white New Zealand rabbits, 5 for tonometry and 5 for fluorophotometry, were used. One eye was injected 2x10-4M DIDS intravitreally using microsyringe and the other eye was injected normalsaline as a control in each rabbits. Tonometry was performed before the injection and every hour after dosing for 5 hours. Fluorophotometry was performed every 30 minutes for 3 hours starting 2 hours after injection. Wilcoxon`s signed rank test was used for statistical analysis. DIDS decreased intraocular pressure by 12.5%(P<0.05) and reduced aqueous humor flow rate by 28.5%(P0.05). In conclusion, it was observed.
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid ; Aqueous Humor* ; Cell Size ; Epithelial Cells ; Fluorophotometry ; Intraocular Pressure ; Manometry ; Membranes ; Osmolar Concentration ; Rabbits

To explore whether Cl- channel blockers interact with the ATP-sensitive K+ (KATP) channel, I have examined the effect of two common Cl- channel blockers on the KATP channel activity in isolated rat ventricular myocytes using patch clamp techniques. In inside-out patches, 4,4'-diisothio-cyanatostilbene-2,2'-disulfonic acid (DIDS) and niflumic acid applied to bath solution inhibited the KATP channel activity in a concentration-dependent manner with IC50 of 0.24 and 927 muM, respectively. The inhibitory action of DIDS was irreversible whereas that of niflumic acid was reversible. Furthermore, DIDS-induced block was not recovered despite exposure to ATP (1 mM). In cell-attached and inside-out patches, DIDS blocked the pinacidil- or 2,4-dinitrophenol (DNP)-induced KATP channel openings. In contrast, niflumic acid did not block the pinacidil-induced KATP channel openings in inside-out patches, but inhibited it in cell-attached patches. DIDS and niflumic acid produced additional block in the presence of ATP and did not affect current-voltage relationship and channel kinetics. All these results indicate that DIDS among Cl- channel blockers specifically blocks the cardiac KATP channel.
2,4-Dinitrophenol ; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid ; Adenosine Triphosphate ; Animals ; Baths ; Inhibitory Concentration 50 ; Kinetics ; Muscle Cells ; Niflumic Acid ; Patch-Clamp Techniques ; Rats

During depolarization, extrusion of Ca2+ from sarcoplasmic reticulum through forward-mode Na+ - Ca2+ exchange was studied in the rat ventricular myocytes patch-clamped in whole-cell configuration. In order to confine the Ca2+ responses in a micro-domain by limiting the Ca2+ diffusion time, rat ventricular myocytes were dialyzed with high (14 mM) EGTA. K+ current was suppressed by substituting KCl with 105 mM CsCl and 20 mM TEA in the pipette filling solution and by omitting KCl in the external Tyrode solution. Cl- current was suppressed by adding 0.1 mM DIDS in the external Tyrode solution. During stimulation roughly mimicking action potential, the initial outward current was converted into inward current, 47+/-1% of which was suppressed by 0.1 mM CdCl2. 10 mM caffeine increased the remaining inward current after CdCl2 in a cAMP-dependent manner. This caffeine-induced inward current was blocked by 1 muM ryanodine, 10 muM thapsigargin, 5 mM NiCl2, or by Na+ and Ca2+ omission, but not by 0.1 muM isoproterenol. The IapprxV relationship of the caffeine-induced current elicited inward current from -45 mV to +3 mV with the peak at -25 mV. Taken together, it is concluded that, during activation of the rat ventricular myocyte, forward-mode Na+ - Ca2+ exchange extrudes a fraction of Ca2+ released from sarcoplasmic reticulum mainly by voltage-sensitive release mechanism in a micro-domain in the t-tubule, which is functionally separable from global Cai2+ by EGTA.
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid ; Action Potentials ; Animals ; Cadmium Chloride ; Caffeine ; Diffusion ; Egtazic Acid* ; Isoproterenol ; Muscle Cells* ; Rats* ; Ryanodine ; Sarcoplasmic Reticulum ; Tea ; Thapsigargin

We studied the association of nonspecific bronchial hyperresponsiveness with general characteristics, exposure concentration, respiratory symptoms, chest x-ray findings, past histories and pulmonary function. We determined bronchial hyperresponsiveness by methacholine challenge test. And we conducted a respiratory symptom questionnaire and performed spirometry on 111 workers occupationally exposed to isocyanates in various industries. About 21.6% of subjects had bronchial hyperresponsiveness. No significant differences were observed between the hyperresponsive and non-responsive group with respect to age, sex, employment period, height, and smoking histories cough and breathlessness were significantly associated with the bronchial hyperresponsiveness. The hyperresponsive group had more experience of bronchitis and asthma in the past than the non-responsive group. The lower FEV1 and FEV1 % were closely related with bronchial hyperresponsiveness. Bronchial hyperrespoosiveness seems to be associated with some of respiratory symptoms, past histories and pulmonary function parameters in workers exposed to isocyanates.
Asthma ; Bronchitis ; Cough ; Employment ; Isocyanates* ; Methacholine Chloride ; Occupations ; Surveys and Questionnaires ; Smoke ; Smoking ; Spirometry ; Thorax

OBJECTIVETo establish the method of detecting the concentrations of methyl isocyanate (MIC) in air of workplaces with high performance liquid chromatographic (HPLC).

METHODSSamples are collected by XAD-7 tubes coated with 1-(2-pyridyl) piperazine (1-2PP). Samples are desorbed with acetonitrile (ACN) and analyzed by high performance liquid chromatography (HPLC) using a fluorescence detector.

RESULTSThere was a linear relationship within the range of 0.01 ∼ 10 µg/ml, and the detection limit was 5.3×10(-4) µg/ml. The minimum detectable concentration was 0.01 µg/ml, and the lowest detected concentration was 3.3×10(-3) mg/m(3). The relative standard deviation was 2.2% ∼ 5.3%. The average desorption efficiency was 90% and the sampling efficiencies were 100%. The samples could be stored for 10 days in cold storage condition.

CONCLUSIONThe present method could meet with the requirements of Guide for establishing occupational health standards-Part4 Determination methods of air chemicals in workplace and be feasible for determination of MIC in workplace air.

Toluene diisocyanate (TDI) is widely used in the production of flexible polyurethane foams, as well as in the formulation of polyurethane paints and coatings. The commercial material is generally a mixture of 2,4- and 2,6-TDI, the predominant mix being 80% 2,4 and 20% 2,6-TDI. The 2,4-isomer is considerably more reactive than the 2,6-TDI at ambient temperatures due to steric factors involving the positions of the isocyanate groups relative to the ring methyl group. Because of this difference in the reactivities of the isomers, it seemed probable that there might be an increase in the amount of 2,6-TDI offgased relative to the 2,4-isomer. Therfore a relative enrichment of the 2,6-TDI has been found in industrial atmospheres. Toluene diamines, which are metabolites of TDI, in urine have a linear relation with exposure to TDI, so that urianry TDA could be used as a biological index of the exposure to TDI. This study was conducted to investigate the distribution of TDI isomer in industrial atmospheres and to propose proper biological monitoring methods by identifying the relationships between the environmental TDI exposure and concentration of TDA in urine. Concentrations of 2,4-TDI and 2,6-TDI in air were 4.38microgram/m3 and 25.43microgram/m3, respectively. The Threshold Limited Value of 40microgram/m3 was exceeded for the 2,6-TDI in about 46.8% (22samples) of the samples, while the 2,4-TDI was not at all exceeded. The ratio between 2,4-TDI and 2,6-TDI varied in air samples in the range, of 2.4%:97.6%-51.0%:49.0%. There was an enrichment of 2,6-TDI in air relative to the 2,4-TDL Concentrations of 2,4-TDA and 2,6-TDA in urine were 1.31microgram/g creatinine and 4.16microgram/g creatinine, respectively. The ratio between 2, 4-TDA and 2,6-TDA varied in urine samples in the range of 1.4%:98.6%-99.9%:0.1%. There was an enrichment of 2,6-TDA in urine relative to the 2,4-TDA. No relation between the concerations of TDA isomer in urine and concerations of TDI isomer in air was found. Above results of this study, workers were more exposed to the 2,6-TDI relative to the 2,4-TDI in industrial atmospheres. Therefore, the establishment of TLV for 2,6-TDI should be considered. Also, the further studies on biological monitorigs of workers exposed to TDI should be continued.
Atmosphere ; Creatinine ; Diamines ; Environmental Monitoring ; Paint ; Polyurethanes ; Toluene 2,4-Diisocyanate* ; Toluene*