title: In vitro excystation of Paragonimus heterotremus metacercariae.
abstract: In vitro excystation studies were carried out on the metacercariae cysts of Paragonimus heterotremus obtained from naturally infected crabs Potamon spp. The effects of elastase, trypsin, trypsin-dog bile, trypsin-bile salt, and dithiothreitol (DTT) were examined. The trypsin-dog bile medium stimulated maximum excystation. Of the media that contained 1 mM DTT, the optimum conditions for the excystation were shown to be pH 9, temperature of 39-40 C, and osmolarity of 250-350 mOsm. The DTT acceleration was antagonized by all of the following 6 protease inhibitors: leupeptin (0.5-4 microg/ml), L-trans-epoxysuccinyl leucylamido (4-guanidine) butane (1-8 microM), N-tosyl-L-phenylalanine chloromethyl ketone (0.1-0.4 mM), N alpha-p-tosyl-L-lysine chloromethyl ketone (25-200 microg/ml), iodoacetic acid (0.5-4 mM), and phenylmethylsulfonyl fluoride (1-4 mM). These results suggest that a number of extrinsic and intrinsic factors may modulate excystation.
authors.affiliation: Department of Parasitology, Faculty of Medicine, Khon Kaen University, Thailand.
authors.forename: P M
authors.initials: PM
authors.lastname: Intapan
authors.forename: W
authors.initials: W
authors.lastname: Maleewong
mesh_terms: D000818:Animals; D001646:Bile; D003386:Brachyura / Q000469:parasitology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004229:Dithiothreitol / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D010196:Pancreatic Elastase / Q000494:pharmacology; D010238:Paragonimus / Q000187:drug effects* / Q000254:growth & development*; D020358:Sodium Cholate / Q000494:pharmacology; D013696:Temperature; D013785:Thailand; D014357:Trypsin / Q000494:pharmacology
chemical_list: D015853:Cysteine Proteinase Inhibitors; D010196:Pancreatic Elastase; D014357:Trypsin; D020358:Sodium Cholate; D004229:Dithiothreitol