Development of truncated microtriches in Echinococcus granulosus protoscolices

Ivermectin used in percutaneous drug injection method for the treatment of liver hydatid disease in sheep

BACKGROUND & AIMS

Ivermectin is a macrocyclic lactone (avermectins) produced by the actinomycete Streptomyces avermitilis. In this experimental study, the effectiveness of intracystic injection of ivermectin was studied as a new approach of percutaneous treatment of cystic echinococcosis.

METHODS

Twelve naturally infected sheep were selected and divided into 2 subgroups: treatment group (n = 9) and control group (n = 3). In the treatment group, approximate volume of ivermectin solution needed to achieve an intracystic concentration of 10 microg/mL was injected into cysts, but in the control group, sterile distillated water was applied. No reaspiration was performed at all.

RESULTS

In the following period of 6 months, repeated sonography revealed a significant decrease in cyst sizes and progressive solidification of the cysts in the treatment group. In the control group, volumes of the cysts were increased. No major complications occurred during or after the procedure. After 6 months, all sheep were killed and examined for macroscopic and microscopic changes. Pathologic examination in the treatment group showed pericyst hyalinization, inflammatory cells in the cyst wall, degeneration of laminated and germinal membrane, and necrotic material in the cyst cavity. No viable protoscolices or daughter cysts were observed.

CONCLUSIONS

Percutaneous treatment of cystic echinococcosis with ivermectin as a scolicidal agent seems to be effective in this animal model.

Echinococcus granulosus: in vitro effects of ivermectin and praziquantel on hsp60 and hsp70 levels

Martinez, J., Perez-Serrano, J., Bernadina, W. E., Rodriguez-Caabeiro, F. 1999 Echinococcus granulosus: In vitro effects of ivermectin and praziquantel on hsp60 and hsp70 levels. Experimental Parasitology93, 171-180. Organisms or cells exposed to injurious stresses such as heat shock or chemicals respond by increased (or altered) expression of heat-shock proteins (HSPs). Conversely, an earlier exposure to stress can prepare cells to cope with a subsequent more severe stress. In the present study, protoscolices of Echinococcus granulosus were subjected to several anthelmintic treatments, involving storage of the protoscolices for 18, 30, and 50 h with 0.1 mg/ml of ivermectin (IV), praziquantel (PZ), and a combination of each with albendazole (ALB). The organisms were analyzed for the effects of drug treatment on cell integrity and on levels of hsp60 and hsp70 production. Drug efficacy was evaluated by microscopy and by protein content measurement. Hsp60 and hsp70 were detected by Western blotting and incubation with anti-hsp60 and anti-hsp70 antibody, respectively, and quantitation of these proteins was obtained using image analysis. Incubation with IV alone produced the most damage to the protoscolices as indicated by viability loss, decreased protein content, and altered hsp60 and hsp70 levels; incubation with IV + ALB produced less damage as manifested by fewer changes in the aforementioned damage parameters but PZ and PZ + ALB, in this context, were poor anthelmintics. Exposure of protoscolices to thermal stress prior to anthelmintic treatment, in most cases, increased drug efficacy. It is concluded that in the E. granulosus model system drug efficacy is associated with decreased levels of hsp70 expression and increased levels of hsp60 expression.

In vitro stress response to elevated temperature, hydrogen peroxide and mebendazole in Trichinella spiralis muscle larvae

Three stimuli, elevated temperature, hydrogen peroxide and mebendazole, were compared for their ability to induce heat-shock responses in Trichinella spiralis muscle larvae (L1). In vitro effectiveness of each 'stressor' was evaluated by viability score, protein content and levels of hsp90, hsp70 and hsp60. Detection of the respective heat-shock proteins was done by Western blotting and the heat-shock proteins and quantitation of the immunoblots by image analysis. Exposure of L1 to elevated temperature (e.g. 45 degrees C, 2 h) had no measurable effect. However, exposure to hydrogen peroxide resulted in the induction of constitutive and higher mol. wt heat-shock proteins. In these experiments, heat-shock protein induction correlated strongly with other damage parameters, including loss of viability and increased mortality. Larvae stored in the presence of mebendazole showed no signs of damage. These data indicate that when L1 suffer damage through the action of stimuli, enhancement of heat-shock protein production and damage suffered are causally related.

Efficacies of albendazole sulfoxide and albendazole sulfone against In vitro-cultivated Echinococcus multilocularis metacestodes

The metacestode stage of Echinococcus multilocularis is the causative agent of alveolar echinococcosis (AE), a parasitic disease affecting the liver, with occasional metastasis into other organs. Benzimidazole carbamate derivatives such as mebendazole and albendazole are currently used for chemotherapeutic treatment of AE. Albendazole is poorly resorbed and is metabolically converted to its main metabolite albendazole sulfoxide, which is believed to be the active component, and further to albendazole sulfone. Chemotherapy with albendazole has been shown to have a parasitostatic rather than a parasitocidal effect; it is not effective in all cases, and the recurrence rate is rather high once chemotherapy is stopped. Thus, development of new means of chemotherapy of AE is needed. This could include modifications of benzimidazoles and elucidiation of the respective biological pathways. In this study we performed in vitro drug treatment of E. multilocularis metacestodes with albendazole sulfoxide and albendazole sulfone. High-performance liquid chromatography analysis of vesicle fluids showed that the drugs were taken up rapidly by the parasite. Transmission electron microscopic investigation of parasite tissues and nuclear magnetic resonance spectroscopy of vesicle fluids demonstrated that albendazole sulfoxide and albendazole sulfone had similar effects with respect to parasite ultrastructure and changes in metabolites in vesicle fluids. This study shows that the in vitro cultivation model presented here provides an ideal first-round test system for screening of antiparasite drugs.