In this paper, the variation of surface electricity of two Entamoeba histolytica isolar es was investigated using the cell electrophoretic technique. By testing the electrophoretic iondition of amoeba in gradient pH and the effect of some enzymes, we provided infor-nations for the physiology and pathogenicity of this parasite.Cell electrophoresis for the two isolates of E. histolytica (isolate A and isolate B) n pH 2.05-8.00 Mcllvaine buffer revealed that EPM (electrophoretic mobility) was negative under the pH gradients of 3.00-8.00, which meant the amoeba cell surfacecar- ried negative charge in this condition. Surface charge densities of isolates A and B were found to be ( + ) 148.3-(-) 6035.9 esu/cm2 and (+ )222.4-(-) 6624.0 esu/cm2 respectively. In addition, except in pH 2.05, the EPMs in Mcllvaine buffer were different between the two amoeba isolates, with significant statistical difference.The enzyme test demonstrated there was no neuraminic acid on the surface of these two amoeba isolates. The surface negative groups of the protozoa were sensitive to trypsin and deoxyribonuclease I.

Schistosoma japonicum were obtained from infected rabbits 24 hours after treatment with praziquantel at a single dose of 30,35,40 mg/kg. The drug-induced alterations of histochemistry of the worms have been studied.The results indicated that the glycogen content and AKP (alkaline phosphatase) activities of the worms decreased markedly or disappeared as compared with those of untreated worms; however, the activities of ACP (acid phosphatase) in both treated and untreated worms revealed no apparent change.

The trichomonadicidal activity of tinidazole (Fasigyn) was evaluated by the ire vitro cultivation of Trichomonas vaginalis and Trichomonas hominis with different drug concentrations. The results showed that, after 48-hour incubation with tinidazole, the 100% lethal concentration was 20?g/ml. The trichomonadicidal effect of tinidazole was one titre lower than that of metronidazole. With regard to T. hominis, after 48-hour incubation with tinidazole, the 100% lethal concentration was 20?g/ml. In comparison with metronidazole, the trichomonadicidal effect of tinidazole was similar.

Schistosoma japonicum were obtained from infected rabbits 24 hours after treatment with lower dose praziquantel (30~40mg/kg). The drug-induced tegu-mental surface alteiations of the worms were studied by rcanning electron microscopy. In comparison with untreated worms, the ultrastructures of oral and ventral suckers in both male and female worms were not affected by praziquantel. Major surface alterations including pronounced swellings, erosions and ulcerations were observed,The results showed that the female worms of S. japonicum and those treated with praziquantel at a dosage of 40 mg/kg were more seriously damaged than the male worms and those treated with praziquantel at other dosages.

The 60-90 KD antigen of Schistosama japanicum isolated from SEA by SDS-PAGE was used to immunize female C57BL/6 mice viasubcutaneous injection route. Protective immunity against challenge infection with cercariae of S. japonicum was evaluated by the adult worm reduction rate, and the levels on humoral and cellular immunity in immunized mice.A high level of anti-SEA antibody litre in sera collected from immunized mice was detected by ELISA. The value of the adult worm reduction rate showed that there was no significant protective effect on challenge infection and no obvious difference beween immunized mice and non-immunized control groups. In addition, the data of T-cell proliferative response to ConA of spleen cells revealed that 60-90 KD antigen inhibited the response of T-cell to the mutagen. The possibility of induction of different results of immunity was discussed.

The antischistosomal effects of Levo-praziquantel (L-PZQ) compared with racemic prazi-quantel (dL-PZQ) in vitro on miracidium and cercaria of Schistosoma japonicum were reported in this paper. The results indicated that the schistosomicidal effect on the two larval stages of the parasite induced by L-PZQ (0. 2 ?g/ml) and double amount of dL-PZQ (0. 4?g/ml) had no significant difference. Miracidial stage was more sensitive to the drugs than the cer-carial stage. The schistosomicidal mechanism caused by L-PZQ was discussed briefly.

A sectional survey with histochemical technique was carried out on Culex tritae-niorhynchus larvae infected with Coelomomyces indica in comparison to the noninfected larvae. Studies were pursued by using micrograph and imaging analysis. The results showed that the glycogen, protein and nucleic acid (RNA and DNA)reaction in the infected group were less than those of the control group. The gray level assessment in tissue imaging showed marked difference between the two groups. It is suggested that C. indica has significant effect on the above biochemical elements of the mosquito larvae, which might be considered an important mechanism in the pathogenicity of the fungus.