Trema

Tests using helminth infections in a variety of laboratory animals soon revealed that the avermectins had activity against a variety of nematodes but lacked activity toward cestodes and trema-todes. During the course of testing in a number of other assays, they were found active against the flour beetle, Tribolium confusum (14). This activity against arthropods was confirmed in mice infected with larvae of the bot fly, Cuterebra fontinella. 

The absence of GABA-mediated neurotransmission in cestodes and trema-todes explains the lack of activity of the avermectins against these organisms. 

Praziquantel is the agent of choice against all trema-todes apart from Fasciola hepatica where bithionol is the drug of first choice. It is also an anticestodal agent and, as also niclosamide, is a first choice drug for intestinal tapeworm infestations by Taenia solum (pork tapeworm), Taenia saginata (beef tapeworm), Taenia latum (fish tapeworm) and Hymenolepis nana (dwarf tapeworm) and it is a second choice drug af-... 

If this succeeds, schistosomes may be close to becoming a model for parasitic trema-todes. This would allow researchers to further develop and optimize techniques for the genetic modification of other parasitic flat-worms of medical or economic relevance. The combination of modern molecular approaches such as genomics, proteomics and transgenics, with classical disciplines such as systematics,... 

Mechanisms of snail innate immunity to trema-tode infection are known to involve genetic factors associated with both the humoral... 

The function of haemolytic factors in trema-todes may not, however, be exclusive to red cell lysis. A heat-stable haemolytic activity was also... 

Three major groups of helminths (or worms), the nematodes, trema-todes and cestodes, infect humans. As in all antibiotic regimens, the anthelminthic drugs (Figure 36.1) are aimed at metabolic targets that are present in the parasite but are either absent from or have different characteristics than those of the host. Figure 36.2 illustrates the high incidence of helminthic infections. 

Schistosomiasis (bilharziasis) (see also p. 292). The causative organisms are trema-todes with a complex life cycle that need (aquatic) snails as intermediate hosts. Free-swimming larval cercariae penetrate the intact skin of humans. The adult worms (Schistosoma mansoni, D) live in the venous vasculature. Occurrence tropical countries rich in aquatic habitats. About 200 million humans are af icted. Therapy praziquantel, 10-40 mg/kg, single dose, is highly effective with minimal adverse effects. Substances released from decaying worms may cause problems. 

Fernenol palmitate (176) and 3/8-acetoxyfern-9(ll)-ene (177) have been isolated from the fern Polypodium subpetiolatum Trematol (178), from the stem bark of Trema orientalis, is the C-21 epimer of fernenol with which it... 

Terminalia edulis Blanco/— Trema orientalis (L.) Blume/ Anabiong... 

Temstroemia gymnenthera Sprague/Japanese temstroemia Trema orientalis Bl./India-charcoal trema Trochodendron aralioides S. et Z./Bird-hme tree Zelkova formosana Hay./Taiwan zelkova... 

The trunk bark of Trema orientalis afforded two rare 9,10-dihydrophenanthrenes, 399 and 400. They are both 9,10-substituted and have a propenal side chain at C-7 [179]. This is the first report of dihydrophenanthrene occurrence in the family of Ulmaceae. 

S )-3-[7-(3,10-dihydroxy-9-hydroxymethyl-2,5-dimethoxy)-9,10-dihydrophenanthrenyl]propenal Trema orientalis L. 179... 

R. Bargagli, S. Corsolini, M. C. Fossi, J. C. Sanchez-Hernandez, S. Focardi, Antarctic fish Trema-... 

A variety of helminths belonging to the class nematoda (roundworms), trema-toda (flatworms or flukes) and cestoda (tapeworms) are known to infect humans and domestic animals. The diseases caused by these worms are not only responsible for occasional deaths and wide range of health problems in man, but also exert detrimental effect on the nutritional and immune status of the host resulting in low resistance against other infections. The presence of helminth infections in livestock leads to decrease in output of animal products (milk, fat, butter, meat, eggs, wool and leather etc.) and has, therefore, strong socio-economic impact in countries with agro-and dairy-based industries [7]. 

Johnson, P.T.J., K.B. Lunde, E.G. Ritchie, and A.E. Launer. 1999. The effect of trema-tode infection on amphibian limb development and survivorship. Science 284 802-804. 

Celtis paniculata (Endl.) Planchon Trema aspera (Brongn.) Blume... 

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