Characterisation of an ATP diphosphohydrolase (Apyrase, EC 3.6.1.5) activity in Trichomonas vaginalis.

In the present report the enzymatic properties of an ATP diphosphohydrolase (apyrase, EC 3.6.1.5) in Trichomonas vaginalis were determined. The enzyme hydrolyses purine and pyrimidine nucleoside 5'-di- and 5'-triphosphates in an optimum pH range of 6.0--8.0. It is Ca(2+)-dependent and is insensitive to classical ATPase inhibitors, such as ouabain (1 mM), N-ethylmaleimide (0.1 mM), orthovanadate (0.1 mM) and sodium azide (5 mM). A significant inhibition of ADP hydrolysis (37%) was observed in the presence of 20 mM sodium azide, an inhibitor of ATP diphosphohydrolase. Levamisole, a specific inhibitor of alkaline phosphatase, and P(1), P(5)-di (adenosine 5'-) pentaphosphate, a specific inhibitor of adenylate kinase, did not inhibit the enzyme activity. The enzyme has apparent K(m) (Michaelis Constant) values of 49.2+/-2.8 and 49.9+/-10.4 microM and V(max) (maximum velocity) values of 49.4+/-7.1 and 48.3+/-6.9 nmol of inorganic phosphate x min(-1) x mg of protein(-1) for ATP and ADP, respectively. The parallel behaviour of ATPase and ADPase activities and the competition plot suggest that ATP and ADP hydrolysis occur at the same active site. The presence of an ATP diphosphohydrolase activity in T. vaginalis may be important for the modulation of nucleotide concentration in the extracellular space, protecting the parasite from the cytolytic effects of the nucleotides, mainly ATP.

Lysis of erythrocytes by Trichomonas gallinae.

The hemolytic activity of five live isolates of Trichomonas gallinae was investigated. The isolates were subsequently tested against the erythrocytes of seven adult animal species. Each of the five isolates tested lysed all human blood groups, as well as rabbit, rat, chicken, horse, bovine, and sheep erythrocytes. No hemolysin released by the parasite could be detected. Our preliminary results suggest that the hemolytic activity is not due to the hemolysin release by T. gallinae or to a product of its metabolism. Pretreatment of live trichomonads with concanavalin A reduced levels of hemolysis by 40%.

Hemolytic activity of Monocercomonas spp.

The hemolytic activity of an isolate of Monocercomonas spp. from Tropidophis melanurus (snake: Boidae) was investigated. The isolate was tested against human erythrocytes of groups A, B, AB and O and against erythrocytes of six adult animals of different species (rabbit, rat, chicken, horse, bovine, and sheep). Results show that Monocercomonas spp. exerted an hemolytic activity against all erythrocytes tested.

Interações entre antiparasitários e alimentos / Interactions between antiparasitic drugs and food

O uso, por vezes indiscriminado, de antiparasitários pode levar a consequências importantes na saúde do indivíduo, principalmente relacionadas a alterações no sistema gastrointestinal. As interações entre fármacos e nutrientes podem ocorrer quando um alimento ou nutriente altera a resposta esperada de um medicamento ou quando este interfere sobre o estado nutricional do indivíduo. Essa alteração da eficácia pode resultar em falha no tratamento ou até mesmo na toxicidade do fármaco. A fim de conhecer, identificar e prevenir interações indesejáveis entre antiparasitários e alimentos, o presente artigo de revisão aborda os principais fármacos e alimentos ou nutrientes envolvidos, bem como as consequências que tais interações podem acarretar ao indivíduo. O estado nutricional é de suma importância nas infecções parasitárias, pois é o determinante entre uma maior carga de parasitos ou a resistência total contra a infecção. De forma geral, indivíduos parasitados são inapetentes e emagrecidos, o que em crianças pode comprometer o desenvolvimento físico e intelectual. Portanto, o conhecimento e uma correta orientação médica, farmacêutica e nutricional levam a um tratamento bem sucedido...

The often indiscriminate use of antiparasitic drugs can lead to serious consequences for the health of the individual, mainly related to alterations in the gastrointestinal system. Interactions between drugs and nutrients may occur when a food or nutrient changes the expected response of a drug or when a medicine interferes with the individual's nutritional status. These changes may result in treatment failure or even toxicity of the drug. As an aid to the detection, identification and prevention of undesirable interactions between foods and antiparasite drugs, in this review we discuss the major drugs and foods or nutrients involved and the consequences that these interactions can have for the individual. Nutritional status is important in parasitic infections, as it is a factor determining the parasite load level or the total resistance against infection. Generally, individuals infected by parasites have a poor appetiteand are emaciated, which in children can damage physical and intellectual development. Therefore, knowledge of the parasite and proper medical, pharmaceutical and nutritional guidance lead to a more successful treatment...

Analysis of microtubule cytoskeleton distribution using a fluorescent taxoid in two trichomonadid protozoa: Trichomonas gallinae and Tritrichomonas foetus.

Trichomonas gallinae and Tritrichomonas foetus are flagellated parasitic protozoa of the upper digestive tract of birds and the urogenital tract of cattle, respectively. Both of these species are important in the veterinary field, due to the fact that they cause significant economic losses. Therefore, we investigated the morphology of these parasites by studying microtubule cytoskeleton organization. FLUTAX-2, an active fluorescent derivative of Taxol, was used in this study. This fluorescent taxoid binds to polymerized alphabeta-tubulin dimers. Our results showed that FLUTAX-2 was able to bind to and stabilize microtubules of intact T. gallinae and T. foetus trophozoites, allowing the microtubular cytoskeleton to be easily observed by fluorescence microscopy. T. foetus and T. gallinae had no differences in their FLUTAX-2 binding profiles. Further studies may allow this technique to be improved, and it may possibly be used as a routine laboratory method for the diagnosis of avian and bovine trichomonosis.

Heterogeneity in extracellular nucleotide hydrolysis among clinical isolates of Trichomonas vaginalis.

Trichomonas vaginalis is a parasitic protozoan that causes trichomonosis, a sexually-transmitted disease, with serious sequelae to women and men. As the host-parasite relationship is complex, it is important to investigate biochemical aspects of the parasite that contribute to our understanding of trichomonal biology and pathogenesis. Nucleoside triphosphate diphosphohydrolase 1 (NTPDase 1), which hydrolyses extracellular ATP and ADP, and ecto-5'-nucleotidase, which hyrolyses AMP, have been characterized in laboratory isolates of T. vaginalis. Here we show that the extracellular ATP: ADP hydrolysis ratio varies among fresh clinical isolates, which presented higher ATPase and ADPase activities than long-term-grown isolates. Growth of parasites in iron-replete and iron-depleted medium resulted in different, albeit minor, patterns in extracellular ATP and ADP hydrolysis among isolates. Importantly, some isolates had low or absent ecto-5'-nucleotidase activity, regardless of environmental conditions tested. For isolates with ecto-5'-nucleotidase activity, high- and low-iron trichomonads had increased and decreased levels of activity, respectively, compared to organisms grown in normal TYM-serum medium. This suggests a regulation in expression of either the enzyme amounts and/or activity under the control of iron. Finally, we found no correlation between the presence or absence of dsRNA virus infection among trichomonad isolates and NTPDase and ecto-5'-nucleotidase activities.

Hemolytic activity of Trichomonas vaginalis and Tritrichomonas foetus.

The hemolytic activity of live isolates and clones of Trichomonas vaginalis and Tritrichomonas foetus was investigated. The isolates were tested against human erythrocytes. No hemolytic activity was detected by the isolates of T. foetus. Whereas the isolates of T. vaginalis lysed erythrocytes from all human blood groups. No hemolysin released by the parasites could be detected. Our preliminary results suggest that hemolysis depend on the susceptibility of red cell membranes to destabilization and the intervention of cell surface receptors as a mechanism of the hemolytic activity. The mechanism could be subject to strain-species-genera specific variation of trichomonads. The hemolytic activity of T. vaginalis is not due to a hemolysin or to a product of its metabolism. Pretreatment of trichomonads with concanavalin A reduced levels of hemolysis by 40%.

Morphologic aspects of Tetratrichomonas didelphidis isolated from opossums Didelphis marsupialis and Lutreolina crassicaudata.

Tetratrichomonas didelphidis (Hegner & Ratcliffe, 1927) Andersen & Reilly, 1965 is a flagellate protozoan found in the intestine, cecum, and colon of Didelphis marsupialis. The parasitic protozoa used in this study was found and isolated in the intestine of opossums in Pavlova starch-containing medium in Florianópolis, State of Santa Catarina, Brazil, from D. marsupialis and Lutreolina crassicaudata. The strains were cultivated in Diamond medium without maltose and with starch solution, pH 7.5 at 28 degrees C. The specimens were stained by the Giemsa method and Heidenhain's iron hematoxylin. The light microscopy study of the trophozoites revealed the same morphologic characteristics as specimens previously described.