Comparison of the effects of local and uncontrolled levamisole preparations on mice naturally infected with Aspiculuris tetraptera.

This study was performed to compare effectiveness of two levamisole preparations prepared in two different countries (Iran and Turkey) in mice naturally infected with Aspiculuris tetraptera. For this purpose, natural infection was diagnosed using the cellophane tape method on the perianal region and centrifugal flotation technique on the feces of mice obtained from the experimental Animal Unit of the Faculty of Medicine, University of Yüzüncü Yil, Van. Mice naturally infected with A. tetraptera were then divided in three groups. Animals in Group 1 (8 animals) received levamisole prepared in Iran, animals in Group 2 (8 animals) received levamisole prepared in Turkey and animals in Group 3 (6 animals) were used as untreated controls. Both levamisole preparations were used in a 10 mg/kg dose. After drug administrations, stool samples of the animals in all groups were examined for seven days. On the eighth day, the animals were humanely destroyed using inhalation anesthesia. After euthanasia, parasites in the intestine were also counted. As a result; levamisole coming through uncontrolled border trade from Iran was 69.3% effective against A. tetraptera and the levamisole prepared in Turkey was 91.7% effective in naturally infected mice. Results obtained from this study compared statistically and the differences were found to be significant (p < 0.001).

The efficacy of levamisole, and a mixture of oxfendazole and levamisole, against the arrested stages of benzimidazole-resistant Haemonchus contortus and Ostertagia circumcincta in sheep.

Sheep were allowed to graze pasture that had been seeded with benzimidazole-resistant Haemonchus contortus and Ostertagia circumcincta in order to acquire a burden of arrested larvae. Following housing, sheep were dosed orally with either oxfendazole at a dose rate of 4.7 mg/kg (to confirm the benzimidazole-resistant status of the species of nematode), levamisole at a dose rate of 7.5 mg/kg, or an oxfendazole/levamisole mixture at a dose rate of 4.6 mg/kg oxfendazole and 8.1 mg/kg levamisole. The efficacies of the treatments were assessed by estimation of the arrested larval burden in the abomasum of each sheep, either at 10 or 11 days (oxfendazole and oxfendazole/levamisole mixture), or 12 or 13 days (levamisole), after treatment. Compared to the untreated controls, the protection afforded by a single dose of either levamisole or the oxfendazole/levamisole mixture was >99% against the arrested stages of both Haemonchus contortus and Ostertagia circumcincta. Treatment with oxfendazole confirmed the benzimidazole-resistance status of the two species.

Immunomodulatory action of levamisole--II. Enhancement of concanavalin A response by levamisole is associated with an oxidation degradation product of levamisole formed during lymphocyte culture.

Previously we determined that levamisole (LMS), when stored for a period of time, breaks down to three degradation products at neutral and alkaline pH. At low concentrations (10(-6) M), Product 1 inhibits the lymphocyte response to concanavalin A (Con A). Product 2 enhances the response and Product 3 has no effect. At higher concentrations (10(-5) M) all three products inhibit the response. To determine if these products are formed in culture media under culture conditions (e.g. in RPMI-1640 bicarbonate buffered medium, 37 degrees C, pH 7.0-7.5, during a 72 h culture period), we added freshly prepared LMS solutions to culture media with and without lymphocytes present and maintained the pH at 7.0, 7.25 or 7.5 by varying the amount of CO2 present. Periodically over a 72 h period, aliquots of the media were removed and analyzed for the presence of LMS and the three degradation products. Within 4 h, two of the degradation product began to form in culture media with or without lymphocytes present. Product No. 1, 3-(2-mercaptoethyl)-5-phenylimidazolidine-2-one or dl-2-oxy-3-(2-mercaptoethyl)-5-phenylimidazolidine (OMPI), which inhibits the lymphocyte response to concanavalin A (Con A) at concentrations above 0.4 micrograms/ml, was formed at pH 7.0, 7.25 and 7.5, but the compound did not reach inhibitory concentrations in the lymphocyte cultures during the 72 h culture period. Product No. 2, 6-phenyl-2,3-dihydroimidazo (2,1-b) thiazole, which enhances the Con A response between concentrations of 0.5 and 10 micrograms/ml, was detected at concentrations between 2.5 and 3.5 micrograms/ml at pH 7.25 and 7.5. Product 2 was not detected in cultures at pH 7.0 and subsequently when we cultured lymphocytes with freshly prepared LMS and maintained the pH at 7.0, no significant enhancement of the Con A response was observed.(ABSTRACT TRUNCATED AT 250 WORDS)