Katelaris P, Seow F, Ngu M
Gastroenterology Unit, Concord Hospital, Sydney, Australia.
Parasitology. 1991 Aug;103 Pt 1:35-9. doi: 10.1017/s0031182000059266.
Infection with Giardia lamblia often causes only minor mucosal changes to the small intestine yet frank fat malabsorption may still occur. Some evidence suggests abnormal pancreatic exocrine function in subjects with giardiasis although the mechanism and significance of this is unclear. Studies were conducted in vitro to determine the effect of G. lamblia trophozoites or culture filtrates from the organism on lipolysis of triglyceride by porcine pancreatic lipase. Live trophozoites significantly inhibited lipolysis. The degree of inhibition increased with longer duration of lipase exposure to trophozoites. Total amounts of enzyme inhibited were proportional to enzyme concentration, while the percentage inhibition was greatest at lowest concentration. At a lipase concentration of 1.7 i.u./ml, enzyme activity was reduced by 89.7% compared to controls after incubation for 4 h with trophozoites. The effect was abolished using killed, intact trophozoites. Culture filtrates of G. lamblia did not inhibit lipolysis. Specificity of the effect was suggested by the failure of another flagellate protozoan, Trichomonas vaginalis, to inhibit lipase. In this assay system the inhibition of lipolysis was not dependent on the bile salt concentration present. The impact of this effect in vivo remains to be determined but it may contribute to fat malabsorption in giardiasis.
感染蓝氏贾第鞭毛虫通常仅引起小肠轻微的黏膜变化，但仍可能出现明显的脂肪吸收不良。一些证据表明，贾第虫病患者存在胰腺外分泌功能异常，但其机制和意义尚不清楚。进行了体外研究，以确定蓝氏贾第鞭毛虫滋养体或该生物体的培养滤液对猪胰脂肪酶甘油三酯脂解作用的影响。活滋养体显著抑制脂解作用。随着脂肪酶与滋养体接触时间延长，抑制程度增加。被抑制的酶总量与酶浓度成正比，而在最低浓度时抑制百分比最大。在脂肪酶浓度为1.7国际单位/毫升时，与滋养体孵育4小时后，与对照组相比酶活性降低了89.7%。使用灭活的完整滋养体可消除这种作用。蓝氏贾第鞭毛虫的培养滤液不抑制脂解作用。另一种鞭毛虫原生动物阴道毛滴虫不能抑制脂肪酶，提示了这种作用的特异性。在该测定系统中，脂解作用的抑制不依赖于存在的胆盐浓度。这种作用在体内的影响尚待确定，但它可能导致贾第虫病中的脂肪吸收不良。
