Protozoan, parasitic

Mjcoplasmas rickettsiae chlamjdia, and protozoan parasites are also, in general, susceptible to tetracyclines (88—90) (see also Antiparasitic agents). 

Amphotericin B, is a polyene antibiotic, used in the therapy of systemic fungal infections. Its mode of action exploits differences in membrane composition between the pathogen and the human host. Ergosterol, the predominant sterol of fungi, plants, and some protozoan parasites, interacts with Amphotericin B, resulting in an increased ion permeability of the membrane. Humans contain cholesterol, which has a low affinity for amphotericin B. 

Malaria remains a major public health problem in many parts of the world, including Southeast Asia, sub-Saharan Africa and Latin America where an estimated 300-500 million people are infected. 1-3 million die of malaria every year. The etiologic agents of malaria are protozoan parasites of the genus Plasmodium. Of the four pathogens that can cause malaria in humans (Plasmodium falciparum, P. vivax, P. ovale,... 

Cryptosporidium is an intracellular protozoan parasite that is capable of completing its entire life cycle within one host. Humans become infected on ingestion of the oocysts, and autoinfection and persistent infections are possible owing to repeated life cycles within the GI tract.3 As few as 10 to 100 oocysts can cause infection.3... 

Scheme 45 summarizes Mori s synthesis of the male-produced sex pheromone [(l ,3 ,7S)-3-methyl-a-himachalene (31)] of the sandfly (Lutzomyia longipalpis) in Jacobina, Brazil [70]. This sandfly is the vector of Leishmania chagasU the causative protozoan parasite of visceral leishmaniasis in South America. The key-steps of the synthesis of 31 were the asymmetric methylation of A to give C via B and the intramolecular Diels-Alder reaction of D to give E. 

Copper sulfate is used to control protozoan fish ectoparasites including Ichthyopthirius, Tri-chodina, and Costia. The effectiveness of the treatment diminishes with increasing total alkalinity and total hardness of the water (Straus and Tucker 1993). Copper compounds now used to control protozoan parasites of cultured red drum (Sciaenops ocellatus) include copper sulfate, copper sulfate plus citric acid, and chelated copper compounds (forms of copper bound by sequestering agents, such as ethanolamine) chelated copper compounds are considered less toxic to fish than copper sulfate and at least as effective in controlling parasites (Peppard etal. 1991). 

Malaria, a tropical disease caused by protozoan parasites of the genus Plasmodium, has been a major concern for centuries and has now extended to a great deal of the world s population, killing every year 1-2 million people. Different medicines are in use to cure or to prevent malaria. The classical natural medicine quinine was soon replenished with synthetic compounds such as primaquine, chloroquine and mefloquine. However, a major problem is still an increasing resistance towards these compounds. 

Leishmaniasis is rare in the United States, but it gained considerable publicity here after a small number of cases were diagnosed in American military personnel who served in the Persian Gulf during Operation Desert Storm. Each of these cases began with the bite of a tiny brownish sand fly infected with a protozoan parasite. There is no way of knowing how many other Americans sand flies... 

The protozoan parasite Plasmodium is responsible for the disease. It lives within stomach and salivary glands of the Anopheles mosquito and is transmitted to humans through mosquito bites. The parasites move through the bloodstream to the liver, where they proliferate during an incubation stage... 

Fumidil-B manufactured by Abbott Laboratories is the water soluble bicyclohexylammonium salt of the antibiotic fumagillin produced by the fermentation of Aspergillus fumigatus and is used world-wide for the prevention and control of Nosema apis, a disease in adult honey bees. The drug attacks the actively multiplying disease producing protozoan parasites in the gut of the adult bee. 

Toxoplasmosis is caused by infection with the protozoan parasite Toxoplasma gondii. In the immuno-... 

The flagellate leishmania is transmitted to humans by the bite of the female sandfly of the genus Phlebotomus. Three principal diseases result from infection with Leishmania spp. L. donovani causes visceral leishmaniasis (kala-azar) L. tropica and L. major produce cutaneous leishmaniasis, and L. braziliensis causes South American mucocutaneous leishmaniasis. In visceral leishmaniasis, the protozoan parasitizes the reticuloendothelial cells, and this results in an enlargement of the lymph nodes, liver, and spleen the spleen can become massive. Cutaneous leishmaniasis remains localized to the site of inoculation, where it forms a raised disfiguring ulcerative lesion. South American leishmaniasis is variable in its presentation. It is characterized by ulceration of the mucous membranes of the nose, mouth, and pharynx some disfiguring skin involvement also is possible. 

N-Ribohydrolases have been found to be involved in novel pathways of purine salvage in protozoan parasites as well as in nucleic acid repair, and exhibit other interesting biological activities [178]. In order to investigate the molecular electrostatic potential surface of the enzyme from the trypanosome Crithidia fasci-culata, several l,4-dideoxy-l,4-imino-D-ribitol derivatives were synthesized as nucleoside analogues and their inhibitory powers were tested [179,180]. In the course of this work, l,4-dideoxy-l,4-imino-l(S)-phenyl-D-ribitol (97) was found to inhibit this enzyme with K 30 nmol/1. 

Malaria in man is caused by several species of protozoan parasites known as plasmodia. The oldest effective drug for the treatment of this disease is indisputably quinine (13), a... 

Mai ZM, Ghosh S, Frisardi M, Rosenthal B, Rogers R, Samuelson J (1999) Hsp60 is targeted to a cryptic mitochondrion-derived organelle (crypton) in the microaerophilic protozoan parasite Entamoeba histolytica. Mol Cell Biol 19 2198-2205... 

Wassman C, Hellberg A, Tannich E, Bruchhaus I (1999) Metronidazole resistance in protozoan parasite Entamoeba histolytica is associated with increased expression of iron-containing superoxide dismutase and peroxiredoxin and decreased expression of ferredoxin 1 and flavin reductase. J Biol Chem 274 26051-26056... 

Marti M, Regos A, Li Y, Schraner EM, Wild P, Muller N, Knopf LG, Hehl AB (2003) An ancestral secretory apparatus in the protozoan parasite Giardia intestinalis. J Biol Chem 278 24837-24848... 

Pereira, C.A. Alonso, G.D. Paveto, M.C. Iribarren, A. Cabanas, M.L. Torres, H.N. Flawia, M.M. Trypanosoma cruzi arginine kinase characterization and cloning. A novel energetic pathway in protozoan parasites. J. Biol. Chem., 275, 1495-1501 (2000)... 

Fig. 2. Postembedding technique. Section through part of a tissue cyst of the protozoan parasite Toxoplasma gondii immunostained with a rat monoclonal antibody (CC2) which recognizes a molecule located in the cyst wall (CW) and in dense granules within the parasite (for details, see ref. 2). N, nucleus PG, polysaccharide granules. Three-step protocol rat monoclonal followed by rabbit antirat Ig and visualized with goat antirabbit Ig conjugated to 10-nm gold. Bar is 0.5 pm.

For transformation experiments in general, biochemical or physical methods such as microinjection, electroporation or lipofection are available. These methods have been successfully applied for a variety of organisms including protozoan parasites (Clayton, 1999 De Koning-Ward et al., 2000) and were consequently tested for their ability to generate transiently transformed schistosomes by different laboratories. 

Ersfeld, K. (2003) Genomes and genome projects of protozoan parasites. Current Issues in Molecular Biology 5, 61-74. 

Robinson, K.A. and Beverley, S.M. (2003) Improvements in transfection efficiency and tests of RNA interference (RNAi) approaches in the protozoan parasite Leishmania. Molecular and Biochemical Parasitology 128, 21 7-228. 

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