Evaluation of schistosomicides against experimentally establishedschistosoma mansoniinfections in mice and hamsters

Abstract

The procedures employed at the Sterling Winthrop Research Institute for the maintenance of Schistosoma mansoni, method of infection, and measurement of efficacy are discussed. Data are presented illustrating the activities of a number of known antischistosomal agents in mice and hamsters against a Puerto Rican strain of the parasite with a well-documented origin.

Carcinogenic potential of hycanthone in mice and hamsters

“…Groups of 5 male and 5 female 6-week-old mice and 6-to 7-week-old hamsters were injected by Yarinsky's (1975) method with Schistosoma mansoni cercariae (SWRL Puerto Rican strain). The number of cercariae required to induce a mild infection was established as 30 cercariae/mouse and 15 cercariae/hamster (Bulay et al, 1977).…”

“…The possibility that hycanthone modifies naturally occurring hepatoma induction should be considered. Peraino and his colleagues (1971;1975) explored a two-phase mechanism of liver tumor induction in rats by using N-2-fluorenylacetamide as the " initiating " agent and phenobarbital as the developing agent. It is possible that hycanthone in mice acts as a tumor-developing agent and the results obtained reflect its ability to enhance the effects of chronic exposure to carcinogens in commercial diet rather than to its ability to induce cancer per se.…”

Antitrypanosomal Activity of Trivalent Antimonials <i>in vitro </i>and Its Significance

“…However, the relations of in vitro and in vivo activity among com pounds are extremely different upon chang ing animal species, due to the variations in the drug utilization, which is specific for each host [1,2,4,6].…”

“…In the Schistosoma mansoni infection of mice, the CD50 of APT is 6.45 mg/kg Sb, in that of the hamster, 1.61 mg/kg, but to reach the CD50 with Stibophen and stibocaptate, different increases of these two drugs are required in the two animal species [6],…”

“…In vivo effectiveness may depend on bio availability of Sb in the host and the direct action on the parasite, reflected by its in vitro activity. The interplay of these two factors leads to a different in vitro/in vivo activity relationship of the antimonials even in the same host (mouse) and to its variation in other host species.Both the individual activity of the triva lent antimonials (conveniently expressed in mg/kg terms) and their comparative effec tiveness against schistosomes or trypano somes vary in different hosts [1][2][3][4][5][6]. The to tal lack of correlation between findings on small rodents and in clinical practice pre sents a problem for the chemotherapist toxic and effective antimonial (Na or K an timony tartrate: AST, APT) and the least toxic and least effective one (stibocaptate) differs by 1:25, and the activity by 1:7.5-1:10, while in man the total Sb dose for the treatment of schistosomiasis man soni is 3.5-10.5 mg/kg Sb of the first and 7.7-10 mg/kg Sb of the second antimonial, dosages which are in their upper limit of to lerance.…”