麦草中的土尘对家兔致病作用的实验研究

An Experimental Study on the Pathogenicity of the Soil Dust from Wheat Hay Residue in Rabbits

长期认为,甘肃西部地区马气喘病与麦草粉尘有关。通过过筛分离和焚化从专草中取得土尘,就其致病性在家兔进行了试验。使用家兔24只,每只气管内一次注射土尘200mg(90％<5μm),分别于实验的第1、2、3、4月末期扑杀,每期6只,并设立矽尘和生理盐水对照组。形态学检查证明,这种土尘可在家兔引起尘肺,其病变特征为:肺泡腔尘细胞积聚,尘细胞结节形成,局灶性肺泡间隔增厚,轻度纤维化和细支气管及血管周围淋巴组织增生。矿物学分析表明,土尘肺组织中的Si,Al、Fe和Ti元素含量显著高于生理盐水对照(P<0.05)。电子探针和电镜下EDAX能谱分析证明,沉积在肺组织和被巨噬细胞吞噬的矿粒的主要成分是Si和Al。结果表明,该尘肺是一种铝硅酸盐尘肺,与甘肃西部地区马气喘病的无机尘肺相同。从而推断,麦草中的土尘为该地区马类动物气喘病病因之一。

Wheat hay residue has long been blamed for causing heaves in equine animals in the western part of Gansu province. Soil dust was obtained from the wheat hay residue through sifting and incineration and was examined for its pathogenicity in 24 rabbits, each of which received a single intratracheal instillation of 200 mg of the soil dust(90％<0.5μm).Six rabbits were sacrificed each time at the end of the first, second, third and fourth month of the experiment. Silica dust group and saline water group were used as controls. Morphologic study demonstrated that the soil dust may cause pneumoconiosis in rabbits with lung lesions characterized by aggregate of dust-laden macrophages in alveoli, the formation of dust-laden macrophage nodules,focal alveolar interstitial thickening, mild fibrosis and hyperplasia- of lymphoid tissue around the small bronchioles and small blood vessels. The amount of Si, Al, Fe,and Ti in the lungs of the soil dust group was shown significantly higher than that of the saline water group(P<0.05) as revealed by the minerologic analysis, Mineral crystals deposited in the lung tissue and phagocytosed by the macrophages were shown mainly to be Si and Al by electron and X-ray diffraction and EDAX analysis under transmission electronic microscope. This pneumoconiosis was shown an Al-silicate one and much the same as that seen in the equine animals in the western part of Gansu province.it may thus be concluded that the soil dust from wheat hay residue is one of the causes of equine 'Brokenwind' in this region.