Blastocystis hominis undergoing programmed cell death via cytotoxic gamma irradiation.

Blastocystis hominis is a worldwide common enteric parasite. Its pathogenic potential has not yet been established, although many reports suggest that it may cause the development of various gastrointestinal symptoms. The aim of the present study is to evaluate the destructive effect of different doses of cytotoxic gamma (γ) irradiation combined with and compared to metronidazole (MTZ) on Blastocystis spp. in vitro. The detection of the parasite in the stool specimen was conventionally done by light microscopic examination of direct smears, cultivation, followed by PCR-sequencing. Evaluation of γ-irradiation and MTZ effects on B. hominis was carried out by trypan blue exclusion assay, caspase activity detection, acridine orange staining, DNA fragmentation assay and transmission electron microscopic (TEM) examination. The current study demonstrated that exposure to γ-irradiation in a dose of 0.5 kGray (kGy) significantly (P < 0.05) reduced the viability of B. hominis subtype 2 by 95.2% compared to the untreated and MTZ-treated parasites (87.1%) after 48 h incubation. Combining the same dose of irradiation (0.5 kGy) with MTZ yielded a viability reduction of 94.2% and 94% after 24 and 48 h respectively, which were statistically significant (P < 0.05) compared to MTZ alone. Moreover, our results showed features of programmed cell death in the form of morphological, biochemical, and molecular changes (TEM abnormalities, caspase-like activity, and DNA fragmentation, respectively) with the high doses of γ-irradiation (0.3 and 0.5 kGy) either singly or combined with MTZ. In conclusion, cytotoxic γ-irradiation plays an important role in the inactivation of Blastocystis spp., so, it can be a promising prophylactic water-sterilizing tool against blastocystosis.

INVESTIGATION OF AMOEBICIDAL POTENTIAL OF ARACHIS HYPOGAEA L. PERICARP ON CYSTS OF ACANTHAMOEBA ASTRONYXIS T7 GENOTYPE.

Acanthamoeba is an opportunistic pathogen cauAing keratitis and fatal encephalitis. Early diagnosis, followed by intense treatment using a drugs mixture is a necessity for effective therapy. Many natural compounds have proved lethal effects, yet the search for original natural amebicidal agents is still of current concern. This study investigated the acanthamoebicidal effect of A. hypogaea L. pericarp; total ethanol extract and its successive fractions, n-hexane, dichloro-methane, ethyl acetate, and methanol as well as resveratrol. Acanthamoebae were isolated and cultivated on E. coli seeded non-nutrient agar, genotyped, and the in vitro acanthamoebicidal potentials of different concentrations of A. hypogaea L. pericarp; total extract ethanol and its successive fractions and resveratrol compound was investgated on cysts of A. astronyxis T7 genotype. The results showed variable degrees of lethal potentials were obtained by all examined A. hypogaea L. pericarp ethanol extract and its successive fractions, with the highest mean of non-viable cysts on the first and the second days. bf the study by total ethanol extract followed by the methanol fraction . On the third day of the study n-hexane and ethyl acetate gave the highest mean of non-viable cysts. Resveratrol showed the lowest mean of non-viable cysts count all through the study duration. Significantly higher difference was observed between all examined A. hypogaea L. pericarp extract and fractions and chlorohexidine, except for resveratrol compound the difference was found to be noinsignificant.