A cross-sectional investigation for allergology was performed of 15 painters exposed to high concentrations of toluene diisocyanate (TDI) (0.07-0.17 ppm) during the process of handling polyurethane varnish in a furniture manufacturing factory. Asthmatic reactions such as dyspnea, wheezing related to workshifts and contact dermatitis were observed in four and three cases respectively by questionnaire survey. Lung function tests on the painters showed significant decline in FEV1, %FEV1 and MMF compared to the referents. An increment in mast cell degranulation percentage could be seen in the painters. And also, patch testing with TDI were positive in five cases. From the results, it was suggested that both allergic pulmonary effects and contact sensitization had occured in TDI-exposed painters in this factory.
Metallothioneins (MTs) are heavy metal-binding proteins which play key roles in protection against heavy metal toxicity, and therefore it is toxicologically important to understand the regulatory mechanism of MT production. In the present work, I isolated mouse cell clones which express the bacterial neo gene (G418-resistance gene) under the control of an MT gene regulatory sequence; such cells will serve as parents for the isolation of mutants defective in MT gene regulation. C-127 and L-929 cells were transformed with a plasmid construct containing the regulatory region of the human MTIIA gene linked to the neo structural gene, and stable G418-resistant transformants were selected. When Zn was given during the selection, the number of the resulting colonies increased significantly, suggesting a Zn-induced expression of the introduced neo gene. The C-127 transformants selected in the presence of Zn have several copies of the neo sequence in the chromosome, and express a neo message in a Zn-inducible manner. When Zn was removed from the medium, G418 damaged the cells. These cell clones are expected to be useful for isolating mutants that will help further understanding of the control mechanism of MT gene expression.
In order to compare the longitudinally and cross-sectionally determined annual decline of spirometric measurements, we measured spirograms from 326 male adults four times over five years. Acceptable results were obtained three times or more in 269 subjects aged 30 to 55 at the initial survey. Longitudinal annual changes in the height-squared proportional values of forced vital capacity (CFVC), forced expiratory volume in one second (CFEV1), and maximal expiratory flow at 50% and 25% of FVC (CVmax 50 and CVmax 25), was estimated by the model in which the effect of each individual's level was included as an explanatory variable. The cross-sectional annual change in those indices was determined by including the effect of each survey's level in the model. The longitudinal estimate of annual decline was significantly smaller than the cross-sectional estimate for all indices except CVmax 25. No evidence suggested that systemic error of measurement or a learning effect caused singificant bias in the data. The discrepancy in the estimated annual changes seemed to be caused by the cohort effect in our subjects, since the cross-sectional analysis is primarily sensitive to harmful factors operating in the past. We concluded that the longitudinal data for individuals or groups should not be compared with any reference value based on a cross-sectional analysis.
Subjective symptoms, hematology, serum biochemistry and other clinical signs were investigated in 56 dry-cleaning workers exposed to tetrachloroethylene at 20 ppm (as a geometric mean of 8-hr time-weighted average), and the results were compared with the findings in 69 non-exposed controls from the same factories. There were exposure-related increases in the prevalence of subjective symptoms during the work as well as in the past 3 month period, whereas there was no significant changes in hematology. Effects of the exposure on liver and kidney functions were also negative as judged by emission enzyme activities, BUN and creatinine in the serum.