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PubMed2004

Intestinal protozoa in wild boars (Sus scrofa) in western Iran.

A total of 12 gastrointestinal tracts of wild boars (Sus scrofa) from western Iran (Luristan) were examined for protozoan infection between September 2000 and November 2001. Of 12 boars examined, 67% harbored one or more species of the following protozoa: Balantidium coli (25%), Tritrichomonas suis (25%), Blastocystis sp. (25%), Entamoeba polecki (17%), Entamoeba suis (8%), Iodamoeba butschlii (17%), and Chilomastix mesnili (8%). Four of these protozoan species also are reported in humans, and persons living in rural areas where wild boars are abundant should take precaution to avoid infection.

Animals↗
PubMedDate not supplied

Emerging intestinal protozoa: a diagnostic dilemma.

Increasing isolation of Cryptosporidium, Cyclospora, and microsporidia from immunocompromised patients with severe diarrhea has prompted study of these organisms. Only recently recognized as human pathogens, they have also been associated with several waterborne outbreaks of diarrhea in immunocompetent individuals. Cryptosporidium and Cyclospora have been shown to be transmitted through fecally contaminated food and water. The mode of transmission for microsporidia is still unclear. While the life cycle and pathogenesis of Cryptosporidium are beginning to be understood, the microsporidia and Cyclospora are less well elucidated. The laboratory diagnosis of these protozoa is difficult. The routine ova and parasites screen does not include screening for them. Many microscopic methods, including wet mounts, modified acid-fast and trichrome stains, and immunofluorescence methods have been shown to be effective screening methods in the hands of experienced microscopists. Enzyme immunoassay and polymerase chain reaction methods also show promise. The proper identification of these pathogens rests with well-trained laboratory personnel. As appropriate treatment differs for each genus, communication between the laboratory and the physician is vital to the recovery of the patient.

Animals↗
PubMed1999

Miniaturization and application of the MTT assay to evaluate metabolic activity of protozoa in the presence of toxicants.

This paper describes a critical evaluation of a miniaturised colorimetric assay, using MTT (3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) reduction, applied to protozoan viability testing. The toxic substances used were copper, zinc, Triton X-100 (a membrane surfactant) and cycloheximide (an inhibitor of the protein synthesis). The viability assay of the ciliate protozoan Tetrahymena pyriformis was optimised in terms of MTT concentration and incubation time. Since protozoa are non adherent cells the MTT assay was modified in order to maintain the medium in the well. MTT proved to be effective in the measurement of Tetrahymena pyriformis viability. Four hours of MTT incubation followed by 30 minutes of incubation with DMSO were found to be the best incubation times for optical density reading. Furthermore, 10 mg/ml of MTT solution was the concentration that gave higher values of optical densities with minor medium interference.

Animals↗
PubMedDate not supplied

[Seasonal variation of intestinal protozoa infections in outpatients of the north section of Santiago, Chile. 1995-1996].

Formalin preserved fecal samples from 6,058 and 5,863 outpatients were examined for intestinal parasites during 1995 and 1996 respectively. Prevalence rates of infections by intestinal protozoa in both years were similar. By age group (0-9, 10-19 and > 20 years old) Blastocystis hominis was observed in 18.6-19.3, 37.0-31.1 and 25.3-25.4% in 1995-1996 respectively. Prevalence of Giardia intestinalis infections decreased from 16.6-17.4% in the 0-9 year-old children group to 4.1-4.5% in patients over 20 years. Overall percentages of infection by Entamoeba histolytica varied between 4.2 and 10.9. Rates of infections by G. intestinalis, E. histolytica, and Entamoeba coli observed during rainy-cold months (april-september) of the year versus drywarmy period (october-march) were the same. On the contrary, more cases of B. hominis infection 25.8% versus 18.2% (this difference being statistically significant, p > 0.001) were observed during rainy-cold months of the year.

Adolescent↗
PubMed1999

Clinical and pathological observations on natural infections of cryptosporidiosis and flagellate protozoa in leopard geckos (Eublepharis macularius).

A group of adult leopard geckos (Eublepharis macularius) which had been losing weight for several months were found to be infected with Cryptosporidium species. Histological and electron microscopical investigations on the intestines of five of the lizards revealed the presence of large numbers of the developmental stages of Cryptosporidium species attached to the mucosal surface of the lower intestine, and large numbers of flagellate protozoa, suspected to be predominantly Trichomonas species, in the gut lumen. The clinical signs were attributed to the presence of one or both types of parasites.

Animals↗
PubMed2000

Horizontal Distribution Patterns of Testate Amoebae (Protozoa) in a Sphagnum magellanicum Carpet.

The distribution of soil microorganisms is generally believed to be patchy and to reflect habitat heterogeneity. Despite this general rule, the amount of existing data on species distribution patterns is scarce. Testate amoebae (Protozoa; Rhizopoda) are an important component of soil microbial communities and are increasingly used in ecological and paleoecological studies of Sphagnum-dominated peatlands, but data on the spatial structure of communities are completely lacking. This is an important aspect since quantitative models used for paleoecological reconstruction and monitoring are based on species assemblages. We explored the distribution patterns of testate amoebae distribution in a macroscopically homogeneous Sphagnum carpet, down to a scale of several centimeters. Distributions maps of the species and spatially constrained sample groups were produced. Multivariate and individual spatial autocorrelations were calculated. The importance of spatial structure was quantified by canonical correspondence analysis. Our ultimate goal is to find the finest resolution of environmental monitoring using testate amoebae. The distribution patterns differed among species, resulting in a complex spatial structure of the species assemblage in a whole. Spatial structure accounted for 36% of the total variation of species abundance in a canonical correspondence analysis constrained by spatial variables. This structure was partly correlated to altitude (microtopography) at a very fine scale. These results confirmed the existence of significant broad- and fine-scale spatial structures within testate amoebae communities that could in part be interpreted as effects of ecological gradients. This shows that, on a surface area of 0.25 m(2), ecological conditions which look uniform from a macroscopic point of view are not perceived as such by Sphagnum-inhabiting organisms. Therefore, testate amoebae could prove very useful to monitor fine-scale ecological processes or disturbances. Studies of the species' spatial distribution patterns in combination with autoecological studies are needed and should be included in the toolbox of biomonitoring itself.

Journal Article↗
PubMed2001

Multidrug resistance and ABC transporters in parasitic protozoa.

Drug resistance is an important problem in parasitic protozoa. We review here the role of ABC transporters in drug resistance in parasites. We have concentrated on gene and gene products for which there is a strong evidence for their role in resistance.

ATP-Binding Cassette Transporters↗
PubMedDate not supplied

[Lysozyme-antilysozyme interactions in protozoa-bacteria communities (a model Tetrahymena-Escherichia community)].

Lysozyme and antilysozyme activities present in a wide range of microorganisms determine the so-called lysozyme-antilysozyme system of hydrobionts, which greatly contribute to the formation of aquatic biocenoses. However, the mechanism of the functioning of this system in natural freshwater communities remains obscure. The experimental investigation of lysozyme-antilysozyme interactions in a model Tetrahymena--Escherichia community showed that the antilysozyme activity of Escherichia coli leads to incomplete phagocytosis, thus enhancing bacterial survival in a mixed culture with infusoria. The selection and reproduction of bacterial cells resistant to grazing by infusoria determine the character of host-parasite interactions and allow bacteria to survive. It was demonstrated that the antilysozyme activity of microorganisms, which is responsible for bacterial persistency in natural biocenoses, is involved in the maintenance of protozoa-bacteria communities in bodies of water.

Animals↗
PubMedDate not supplied

[On the notion of microrange of soil testaceans (Protozoa: Testacea)].

We studied species composition and population structure of testaceans (Protozoa: Testacea) in a series of soil microblock samples (weighing between 5 and 0.05 g) from podzol horizons L, F, A1A2, and A2 of cowberry-heath-lichen and gramineous-cowberry pine forests. Similarity between the testacean communities in the soil microblock samples from horizon A1A2 was at least 0.94 (by Morisita-Horn index of similarity, quantitative data), while in the enzymatic layer of litter it decreased to 0.34. The notion of microrange of soil-forming testaceans is proposed and discussed on the basis of the obtained and published data.

Amoeba↗
PubMedDate not supplied

[Testaceans (Protozoa: Testacea) in quaternary permafrost sediments of Bykovsky Peninsula, arctic Yakutia].

The results of the first protozoological study in terms of paleoecology of long-term sediments and buried soils formed in the cryolite zone of northeastern Siberia are discussed. The data on testaceans (Protozoa: Testacea) inhabiting various sites of Bykovsky Peninsula, Laptev Sea coast near estuary of Lena, within the last 53,000 years (late Pleistocene and Holocene).

Amoeba↗
PubMed1964

EFFECT OF ABSENCE OF CILIATE PROTOZOA FROM THE RUMEN ON MICROBIAL ACTIVITY AND GROWTH OF LAMBS.

A survey of the components of the rumen ciliate population in a series of adult sheep, raised in the Faculty of Agriculture, University of Alexandria, has shown that a mixture of Entodinium, Isotricha, Ophryoscolex, Diplodinium, and Polyplastron species was found in the rumen contents of Egyptian sheep; no Epidinium and a negligible number of Dasytricha ruminantium were also observed. The microbial population, reducing sugars, ammonia, volatile fatty acids (VFA) production, and growth rate of 14 lambs inoculated with whole rumen contents from a mature sheep were compared over a 6-month period with those of 13 lambs maintained under the same conditions, except that they were strictly isolated from other ruminants. Certain large oval organisms and large numbers of flagellates and Oscillospira were frequently observed in the rumen contents of the isolated lambs. The reducing sugars, ammonia, and VFA levels, measured before and at intervals after feeding, in the inoculated lambs showed a pronounced rise above the values found in the ciliate-free animals. The propionic acid-acetic acid ratio in the rumen contents of the faunated lambs was considerably higher than in the nonfaunated controls. The inoculated lambs grew faster than the isolated lambs. Differences in weight gain which ranged from 15 to 17% were statistically significant. The inoculated animals impressed the observers by their good appearance which was superior to that of the ciliate-free lambs. It was, therefore, concluded that the rumen ciliate protozoa are essential for the metabolism and growth of young lambs.

Acetic Acid↗
PubMed2003

The cell cycle of parasitic protozoa: potential for chemotherapeutic exploitation.

There is an urgent need to develop new drugs against eukaryotic parasitic protozoa such as Plasmodium, Trypanosoma and Leishmania, which cause the diseases malaria, trypanosomiasis and the leishmaniases respectively. The biology of these organisms has many unusual facets that might be exploited for drug design, and the recent availability of parasite genome sequence data has facilitated the search for novel drug targets. Here we review current understanding of the cell cycle in these parasites and show that important structural and functional differences exist between parasite and mammalian cell cycle control machineries and signal transduction pathways, which might be utilised for rational drug design. Potential targets include protein kinases from the cyclin-dependent kinase, cAMP-dependent kinase and mitogen activated protein kinase families.

Animals↗
PubMed1992

[Nuclear differentiation and nuclear heteromorphism in the protozoa].

This is a review based upon a lecture given at the Developmental Biology School near Moscow in November 1991. Cases of successive and simultaneous nuclear differentiation are defined, and examples from various groups of protozoa are considered. Three cases of simultaneous nuclear differentiation, leading to the nuclear dualism phenomenon (heteromorphism) are analysed in detail. In heterokaryotic agamonts of some Foraminifera, nuclear differentiation occurs at the diploid level, proved to be irreversible and caused by either deletion or stable repression of some genes. In the Karyorelictid ciliates, the somatic nuclei (macronuclei) are paradiploid, metabolically active but unable to divide. They are irreversibly differentiated due to deletion of part of the initial (micronuclear) genome. Differentiation occurs in every cell cycle from the generative nuclei (micronuclei), which retain omnipotency and reproduce by mitosis. In most (higher) ciliates the differentiation of macronuclei occurs at an early stage of replication and involves a more or less drastic reorganization of the micronuclear genome, including both deletions and transpositions. Thereafter, the reorganized (and generally reduced) genome is strongly amplified to provide a high dose of active genes. The chromosomes of the majority of ciliates are fragmented in their macronuclei into either subchromosome-sized or gene-sized molecules, both being acentric. Systems regulating the differential replication of these molecules are likely to exist in macronuclei to keep the respective gene doses within certain limits.

Animals↗
PubMedDate not supplied

[Hygienic aspects of the Tiber river: presence of pathogenic protozoa and correlation with microbiological and physico-chemical parameters].

An investigation on the hygienic quality of the Tiber river was conducted with the aim both to enumerate Giardia cysts and Cryptosporidium oocysts in the water and to determine possible correlations between them and bacterial indicators, pathogens and physico-chemical parameters. A low hygienic water quality was evidenced, with high counts of microorganisms. Furthermore, variable concentrations of Giardia and Cryptosporidium were observed. No correlation was found between the protozoa concentrations and that of the other microorganisms, whilst a significant correlation with redox potential and Giardia cysts was calculated.

Animals↗
PubMed2004

Effects of intestinal protozoa infection on gastrointestinal transit and contractility in experimental animals.

Three groups of animals each was orally infected with Cryptosporidia parvum oocysts, Enterocytozoon bieneusi spores or Cyclospora cayetanensis oocysts. At the time peak of colonization of infected animals, each group and its corresponding control were infused orally with radioactive isotope. Gastric emptying of isotope was significantly greater in infected compared to controls in both fasted and fed states, to determine the effect of each parasite on the contractility of longitudinal and circular muscle, isometric tension of jejunal segments was recorded. The development of active tension with stretch and the dose-response curve to muscarinic against were significantly increased in the longitudinal muscle of infected animals compared to controls. The circular smooth muscle did not show an increase in contractility. The results suggest that an altered gastrointestinal transit and smooth muscle contractility may be involved in the intestinal protozoa infections' pathophysiology.

Animals↗
PubMed1978

[Effect of glycolysis inhibitors on the uptake of metronidazole by the protozoa Tritrichomonas foetus and Entamoeba invadens].

Uptake of metronidazole by the anaerobic protozoa, Tritichomonas foetus and Entamoeba invadens is dependent on the energy metabolism of these organisms. The inhibitors of glycolysis, iodoacetamide and sodium fluoride, inhibit the uptake. An atmosphere of hydrogen eliminates this inhibition in the hydrogenase-containing T. foetus but not in E. invadens which lacks the enzyme.

Energy Metabolism↗
PubMed1992

Cytokine activation of human macrophages infected with HIV-1 to inhibit intracellular protozoa.

Peripheral blood mononuclear cells (PBMCs) from HIV-seronegative donors were infected in vitro with HIV-1. Infection was monitored by cytopathology, supernatant p24 antigen, and by immunocytochemical staining. After 14 days in culture, approximately 70-90% of the cells became infected with HIV, as indicated by cell fusion and immunostaining for virus. At this time, recombinant HuIFN-gamma was added to the cultures, followed by infection 24 h later with the intracellular protozoan parasites Toxoplasma gondii, Trypanosoma cruzi, or Leishmania chagasi. Percentages of intracellular parasites were determined at various points thereafter. Using a system capable of detecting both virus and parasite infection, we determined that (a) cells infected with HIV were capable of ingesting and/or being infected by each of these parasitic protozoa, (b) HIV-infected macrophages could be activated to inhibit the replication of all three parasites following treatment with IFN-gamma, and (c) cultures of HIV-infected macrophages could respond to IFN-gamma with increased oxidative burst activity. The degree of parasite infection or inhibition observed in infected cells was not significantly different from that observed in non-HIV-infected cells. From these observations, we concluded that HIV-1 infection does not render macrophages unresponsive to IFN-gamma activation for microbicidal activity.

Animals↗
PubMed2005

Study on the frequency of protozoa and mycetes in the oral cavity.

The importance of a good knowledge in microbiology of the oral cavity is every day more and more indispensable in order to propose proper therapeutic treatments. In this study, the most frequent protozoa and mycetes present in the oral cavity are described, distinguishing the different species and their pathologies.

Animals↗