Effect of single-dose oral artemether and tribendimidine on the tegument of adult Clonorchis sinensis in rats.

The tegument of trematodes plays a key role in nutrient absorption, exerts secretory functions, protects the parasite against the immune system of the host, and is a target for anti-trematocidal drugs. We performed a temporal examination of tegumental changes following artemether and tribendimidine administration on adult Clonorchis sinensis in rats using scanning electron microscopy. Rats infected with C. sinensis for 6 weeks were treated orally with a single dose of artemether (150 mg/kg) or tribendimidine (300 mg/kg). Worms were collected between 8 h and 7 days (artemether) and between 4 h and 2 days post-treatment (tribendimidine). Worms recovered from untreated rats served as controls. Eight hours after artemether administration, the tegument of C. sinensis was extensively disrupted, including severe swelling, fusion and vacuolization, and the suckers were damaged. Four hours after administration of tribendimidine, C. sinensis worms showed extensive tegumental alterations, characterized by massive sloughing, and the suckers were damaged. Interestingly, the severity of tegumental changes did not progress further with time. Our results show that both artemether and tribendimidine rapidly disrupt the tegument and damage the suckers of adult C. sinensis. The subtle differences in tegumental changes induced by artemether and tribendimidine might indicate different mechanisms of action of these drugs against C. sinensis.

Fasciola hepatica: Surface tegumental responses to in vitro and in vivo treatment with the experimental fasciolicide OZ78.

The tegumental alterations in adult Fasciola hepatica induced by the experimental fasciolide OZ78 were investigated utilizing scanning electron microscopy (SEM). Twelve weeks post-infection with F. hepatica, rats were treated with a single 100mg/kg oral dose of OZ78 and flukes were recovered from the bile ducts after 24-72 h. In vitro F. hepatica were incubated with OZ78 for 48 h at a concentration of 10 microg/ml in the absence or presence of haemin. Twenty-four and 48 h post-treatment of rats disruption of the tegument of F. hepatica as blebbing, swelling and furrowing was evident. The recovery of flukes 72 h post-treatment was low. Flukes examined at this time point showed an increasing severity of tegumental damage as sloughing and absence of spines, in particular in the tail region. SEM analysis of F. hepatica incubated in the presence of OZ78 without haemin showed only minor and localized damage of the tegument. In the presence of haemin extensive tegumental damage, including sloughing or blebbing, in particular in the anterior part, was observed. In conclusion, our experiments confirm the interesting fasciocidal properties of OZ78. The tegument of adult F. hepatica might play a role in the action of this drug.

Fasciola hepatica: tegumental alterations in adult flukes following in vitro and in vivo administration of artesunate and artemether.

The tegumental changes in adult Fasciola hepatica induced by artemether and artesunate were assessed utilizing scanning electron microscopy (SEM). F. hepatica were incubated with artemether and artesunate for 48h at a concentration of 10microg/ml in the absence or presence of haemin. For the latter experiment both, a triclabendazole-resistant and sensitive F. hepatica isolate were used. For the in vivo studies rats were treated with single 200mg/kg oral doses of artemether and artesunate and flukes recovered from the bile ducts after 24-96h. SEM analysis of the flukes incubated in the presence of the drugs without haemin showed only minor and localized damage of the tegument. In the presence of haemin extensive tegumental damage, including sloughing, blebbing and eruptions, particularly in the ventral and dorsal mid-body and tail region, was evident. No difference in the extent of damage could be observed between artemether and artesunate and between the triclabendazole-resistant and non-resistant flukes. After 24h in vivo disruption of the tegument was evident in the artemether-treated flukes, and the damage increased in severity 48-72h post-treatment. Sloughing, swelling and extensive furrowing of the tegument was observed in several flukes, in particular in the tail region and the ventral apical cone region. In the artesunate treatment, tegumental damage was evident after 72h, but seemed slightly less pronounced when compared to the artemether-treated specimens examined at the same time point. Concluding our experiments confirm that artemether and artesunate are potent fasciocidal drugs and the tegument of adult F. hepatica appears to be a target for the action of these drugs.

Changes in the oviducal epithelium during the estrous cycle in the marsupial Monodelphis domestica.

The Monodelphis oviduct can be divided into four anatomical segments: preampulla (comprising fimbriae and infundibulum), ampulla, isthmus with crypts and uterotubal junction. Ovaries are enclosed in a periovarial sac, the bursa, and in some specimens tubules of an epoophoron could be identified. In both structures non-ciliated cells develop small translucent vesicles, which accumulate in the cell apices and presumably produce fluid as often seen in the bursa and in the tubules of the epooophoron. These vesicles do not stain with Alcian blue or PAS. The same applies also to the non-ciliated cells of the fimbriae. The oviducal epithelium of ampulla and the surface epithelium of the isthmus consisting of ciliated and non-ciliated, secretory cells undergo considerable changes during the estrous cycle. Proestrus shows low numbers of ciliated cells, some are in the process of neo-ciliogenesis, non-ciliated cells carry solitary cilia and few remnant secretory granules from the previous cycle may be found. At estrus the amount of ciliated cells in ampulla and isthmus has increased, most non-cililated cells lost the solitary cilia, developed longer microvilli and formed numerous secretory granules in their cell apices. At postestrus secretory products, often surrounded by membranes, are extruded into the oviducal lumen and contribute towards egg coat formation. First signs of deciliation processes are apparent. Solitary cilia reappear. At metestrus only few secretory cells are left with some secretory material. The lumen is often filled with shed cilia and cell apices. Proliferation of basal bodies within non-secretory cells indicate the formation of new ciliated cells. The non-ciliated epithelial cells of the isthmic crypts form no secretory granules but accumulate a great number of translucent vesicles, which in contrast to the secretory granules do not stain with Alcian blue or PAS.

Changes in the epithelium of the vaginal complex during the estrous cycle of the marsupial Monodelphis domestica. 2. Scanning electron microscopy study.

The four stages of the estrous cycle in Monodelphis domestica, namely proestrus, estrus, postestrus and the transitional metestrus, were analyzed with the scanning electron microscope and compared with the results of the previously published transmission electron-microscopic paper [Cells Tissues Organs 2002;172:276-296]. During the estrous cycle the vaginal epithelium undergoes dramatic changes from a nonkeratinized to a highly keratinized epithelium. The predominant feature of proestrus with the beginning of keratinization is the presence of polygonal flat cells with pavement-like appearance, bordered by raised ridges and covered with microvilli. The epithelium is fully keratinized in estrus, and the superficial layers overlap like shingles. Many cells are still densely covered by microvilli, whereas others develop a complex pattern of microridges. In postestrus different epithelial structures are revealed depending on the actual stage of desquamation. In early postestrus surface cells resemble those present during estrus. In late postestrus, when only few keratinized cells are left, the nonkeratinized cells become exposed to the lumen through desquamation. These cells border the lumen during metestrus, a cycle stage during which numerous leukocytes migrate into the vaginal canal. A number of these uppermost cells is probably not yet prepared to function as metestrus cells and are therefore sloughed off as well. During metestrus compact cell masses stick in the vaginal furrows. Epithelial surface cells are highly irregular and bulging with their microvilli covered surfaces in the vaginal lumen. This study represents the first comprehensive description of alterations on the surface ultrastructure of a marsupial vagina during the estrous cycle, demonstrating considerable differences in comparison to many eutherians.