Cercarial Penetration Studies: Steps Toward Chemoprophylaxis in Schistosomiasis.
Annual rept. 15 Aug 86-14 Aug 87,
ILLINOIS UNIV COLL OF MEDICINE AT ROCKFORD
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The scope of this research centers on elucidating the biochemical mechanisms involved in cercarial Schistosoma mansoni skin penetration and the evaluation of eicosanoid inhibitors as possible prophylactic agents. The most significant findings this year are 1 We have identified three potential prophylactic agents by virtual of their ability to inhibit cercarial stimulation by linoleate, They are praziquantel, ketoconazole, and sulfasalazine. 2 In vivo drug studies with praziquantel in male ICR mice indicate that this drug may hold promise as a prophylactic agent however, its effectiveness is vehicle dependent. 3 Cremophor El, a vehicle for praziquantel, was also effective in preventing cercarial penetration in ICR mice. This finding suggests that a combination of dietary and chemoprophylactic methods may be worth exploring. 4 Adult schistosomes, as well as the cercarial and schistosomular stages, secrete immunosuppressive eicosanoid species. Thus we supply evidence of an additional mechanism that may hide larval and adult stages from the host immunological defenses. 5 There are notable biochemical differences between various cercarial transformation methods, even though ultrastructural differences are minor. Mechanically transformed cercariae, at least out of 6 hrs., appear to be biochemically damaged when compared to other transformation methods. 6 We have correlated mouse tail skin HETE production with the ability of cercariae to penetrate tail skin.
- Medicine and Medical Research