[Pathologic studies on preventive and therapeutic effects of the formic mixture on experimental silicosis]

In order to investigate the preventive and therapeutic effects of formic mixture on experimental silicosis, 96 Wistar rats were divided randomly into three groups, 1st group was taken as preventive administration (Two days before exposure to dust), 2nd group-therapeutic administration (one month after exposure to dust) and 3rd control group-model of silicosis. All above-mentioned animals were instilled intratracheally with standard quartz dust. At 1st, 3rd, 6th and 12th month after instillation of dust, rats from each group were sacrificed and pathohistologic studies were performed on their lung tissue. The results showed that the progressive degree of silicotic fibrosis in various groups were greatly different, i. e. 3rd group was severest, 2nd group medium, and 1st group was mildest. Either the differences of grade or quantity of fibrosis in lung tissue was significant between 1st and 3rd group, P < 0.01. The difference of the grade of fibrosis between 2nd and 3rd group was also significant, P < 0.05, but that between 1st and 2nd group was insignificant. The results demonstrated that administration of formic mixture, in particular, preventive administration, could inhibit greatly the process of silicotic fibrosis, and provided a basis for clinical application of this drug.