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[en] The techniques for cryopreserving schistosome schistosomula and microfilariae of several species of filarial worms are described

[en] Most xenobiotic agents are metabolized by cytochrome P450 system. In the present study, Western blotting was used to investigate the effect of different levels of Schistosoma Mansoni infection on the expression of somr cytochrome P450 isozymes (CYP 2E1, 2B1/2, 2C6, 4A) and to enzyme assay their related metabolic functions in mouse liver microsomes. Male mice were infected with 60, 120, 180, 300 and 600 Schistosoma Mansoni cercariae per mouse for 33 days and 60, 120, 180 and 300 cercariae/mouse with no change at the last level of Schistosoma Mansoni infection. Also the expression of CYP 4A was potentially induced at all levels of Schistosoma Mansoni infection. A significant induction of CYP 2B1/2 expression was observed at all levels of Schistosoma Mansoni infection with loss of signal at 180 cercariaea/mouse. In contrast, CYP 2C6 expression was induced at the first two levels and such expression was decreased at the last three levels. In addition, the infection of the mouse with 60, 120 and 180 cercariae/mouse decreased; [1] 7-methoxycoumarin O-demethylase activity by 36, 54 and 58% respectively; [2] 7-ethoxycoumarin O-deethylase activity by 33, 40 and 57% respectively; [3] coumarin hydroxlase activity by 33, 45 and 55% respectively. However, 300 and 600 cercariae/mouse induced: [1] 7-methoxycoumarin O-demethylase activity by 45 and 97% respectively: [2] 7-ethoxycoumarin O-deethylase activity by 26 and 90% respectively; [3] coumarin hydroxylase activity by 100 and 200% respectively. In addition, all levels of Schistosoma Mansoni infection decreased the sleeping time caused by hexobarital. It is concluded that different levels of Schistosoma Mansoni infection change the expression of different CYPisozymes and that these alterations could enhance the carcinogenicity of N-nitrosamines which is mainly dependent on CYP 2E1. The alterations in the expression of CYP 2E1, 4A and 2B1/2 isozymes as a result of Schistosoma Mansoni infection may change the therapeutic actions of drugs that are primarily metabolized by the P 450 system, when administered to patients with schistosomiasis. (author)

[en] When evaluating metal accumulation patterns in parasite-host assemblages species specific metal requirements should be taken into account. The aim of the present study was therefore to determine the metal specific partitioning in a parasite-host assemblage of the cestode Ligula intestinalis and the cyprinid fish Rastrineobola argentea and to determine the effect of the parasites on the metal balance of the fish. To this purpose the host-parasite assemblage was analysed for several metals at sites in the coastal zone of Lake Victoria differing in metal contamination. Our results showed that some elements (Ca, Sr, and Mg) reflected the physiological differences of bone formation and ionic balance and pointed to physiological disturbances of infested R. argentea. Other essential metals including Cu and Co were subject of element competition between fish and parasite, while only a micro-element (Cr) and a non-essential metal (Cd) displayed a partitioning with high concentration in the parasite. The present study clearly demonstrated the impact of the large cestodes on their small fish hosts and it is concluded that the partitioning of metals in the assemblage of R. argentea and L. intestinalis is subject to metal specific mechanisms for essential and non-essential elements.

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[en] The field of parasitic immunochemistry has advanced considerably in recent years. One reason is that increasing attention has been placed in identifying target antigens of proven or potential importance in acquired resistance or in serodiagnosis. This review concerns some aspects of antigen purification in trematode infections, with emphasis on those studies which used gel filtration or antibody affinity chromatography. Purification of Schistosoma and Fasciola serodiagnostic antigens is discussed

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[en] Eight research and development projects completed during the period under review confirmed the potency of atomic energy in seeking solutions to local problems. Significant among the completed projects are those which unearthed unknown facts that disease-spawning shells could be controlled and underground leaks in a water system could easily be detected. The former studied the dispersion and movement of Lymnaea Aurecalasia Rublginosa, a snail specie, in its natural habitat, while the other brought about the detection of leaka in the underground firewater pipeline system of a big industrial firm in Manila. Knowledge obtained from the snail research will help in the successful fruition of a bigger job to control the spread of the fasciola infection of animals, while the leak detection work realized large savings for the company and has proven the efficacy of atomic radiations for industrial work as well. Now in progress are 40 research projects all of which are geared to the national development .program and which tend to be applicationoriented. Areas of interest ore agriculture, biology and medicine, chemistry, physics and engineering.

[en] The experiment was designed to find the minimal effective dose (MED) of irradiation that can inhibit the maturation of O. viverrini. The parasite life cycle was established and maintained in laboratory and the animal model for bioassay was investigated. Hamster was found to be the appropriate model and was used in all experiments. Pure metacercariae (metacercariae dissected from fish before irradiation) were exposed to 0.1, 0.2, 0.3, and 0.5 kGy. No physical change was observed in the exposed metacercariae. The MED was found to be 0.1 kGy. When whole infected fish was irradiated and metacercariae fed to hamsters, the MED was also 0.1 kGy. However, due to technical error either the irradiation technique or parasitological manipulation, one hamster from each group receiving 0.2 and 0.3 kGy irradiated metacercariae was found to have one adult fluke. This fluke has no significant difference in morphology from that of the control, except the eggs in the uterus and in the master's gall bladders were not well developed. In conclusion, the results suggested that 0.1 kGy appears to be the MED of liver fluke in fish. However, fish irradiation to control liver fluke infection in the rural communities may be difficult since the transmission of this infection is normally from the home-made dish prepared from fresh fish available all water beds