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PubMed1981

[Protozoa of the human oral cavity (epidemiological correlations and pathogenic possibilities].

The oral protozoa frequency has been studied in 300 patients consulting for oral problems. Entamoeba gingivalis has been isolated more frequently in culture than Trichomonas tenax (50.7% against 28%). The age range which showed the highest frequency in protozoa was the 30-34 year old group for the amoeba and the 45-54 year old group for the flagellae. The endemia increased progressively in relation to the OHIS index. Trichomonas tenax is three times more frequent in case of deep periodontal diseases whereas, Entamoeba gingivalis reached its highest frequency in the case of gingivitis. The pathogenic potentials of these protozoa have been discussed in the light of these correlations and some therapeutical arguments.

Adolescent↗
PubMed1978

Comparison of different methods for the detection of intestinal protozoa and helminths in stool.

A total of 1428 stool specimens were examined to evaluate the usefulness of different methods of detecting intestinal protozoa and helminths. The following methods were compared: a combination of routine laboratory methods (Normal saline, Lugol's solution and Iron-haematoxylin), the MIF technique (Mertheolate-iodine-formaldehyde) and the MF-Heidenhain method for protozoa. The Telemann method and MF-Telemann method for worm eggs. The MIFC technique for both protozoa and worm eggs. According to the criteria: diagnostic yield, accuracy, simplicity, time consumption and cost, it is concluded that the MIFC method is superior to the other methods used in this study.

Adolescent↗
PubMed1996

[Histopathology of protozoa].

Protozoa are single-celled animals hosted by animals and humans. Numerous parasites can be considered to be non-pathogenic for humans but, in tropical countries, pathology caused by protozoa is a major public health problem. The study of parasitic protozoa in tissues has provided fertile ground for investigation. In practical diagnosis, this test is useful when the parasite is not eliminated in stools or absent in the blood. This review considers all the morphological criteria allowing an accurate identification of species. The new infectious agents, recently emerged with HIV infection are analysed by simple technical procedures for their identification.

AIDS-Related Opportunistic Infections↗
PubMed1956

Mitochondria of protozoa.

A study of thin sections of Paramecium multimicronucleatum, Tetrahymena pyriformis, Tokophrya infusionum, and Amoeba proteus shows that the mitochondria in all these protozoa are similar in certain aspects of their fine structure to that described in metazoan cells. As in higher organisms the mitochondrion is surrounded by a double limiting membrane and contains protrusions directed inward from the innermost of the double membranes. There are, however, some differences. In a majority of higher organisms the internal structure of mitochondria consists of ridges or cristae mitochondriales and in a few instances only of finger-like projections, or microvilli. In all protozoa described here and elsewhere microvilli represent the dominant structure. They are characteristic therefore of protozoan mitochondria.

Amoeba↗
PubMed1995

Multidrug resistance and P-glycoproteins in parasitic protozoa.

Drug resistance has emerged as a devasting impediment to the treatment and control of diseases of parasitic origin. The underlying mechanisms that contribute to this drug resistance in field isolates, however, are poorly understood. Members of the P-glycoprotein gene (pgp) family have been identified, cloned, and sequenced in Plasmodia, Leishmania, and Entamoeba, and variations in pgp copy number and/or expression have been implicated as a basis for drug resistance in each of these genera. The spectrum of drugs to which parasitic protozoa containing amplified pgp genes and/or transcripts are refractory range from a phenotype similar to that observed with multidrug-resistant mammalian cells to those that are completely distinct. The availability of molecular probes to pgp genes provides valuable reagents to dissect the role of pgp gene amplification and overexpression in mediating drug resistance in parasitic protozoa and to determine the physiological function of P-glycoproteins in this clinically consequential group of human pathogens.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Influence of intoxication with organophosphates on rumen bacteria and rumen protozoa and protective effect of clinoptilolite-rich zeolite on bacterial and protozoan concentration in rumen.

The effect of O-ethyl-S-(2-diisopropylaminoethyl) methylthiophosphonate on rumen bacteria and rumen protozoa was investigated in sheep (after premedication with clinoptilolite-rich zeolite and without that premedication). In control animals a decrease in the total concentration of rumen protozoa was observed 3-7 d after intoxication (particularly in small and large ones). In clinoptilolite-rich-zeolite-treated animals only a slight decrease in protozoan numbers occurred during the first hours after the intoxication. Similarly, in every category of rumen bacteria marked differences between the groups were recorded, particularly in concentration of lipolytic bacteria. The results suggest some protective effect of clinoptilolite-rich zeolite for rumen microbiota against the organophosphate poison.

Animals↗
PubMed1998

Intracellular bacteria in protozoa.

Intracellular bacteria in humans are typically detrimental, and such infections are regarded by the patients as accidental and abnormal. In protozoa it seems obvious that many bacteria have coevolved with their hosts and are well adapted to the intracellular way of life. Manifold interactions between hosts and intracellular bacteria are found, and examples of antibacterial resistance of unknown mechanisms are observed. The wide diversity of intracellular bacteria in protozoa has become particularly obvious since they have begun to be classified by molecular techniques. Some of the bacteria are closely related to pathogens; others are responsible for the production of toxins.

Animals↗
PubMed2006

Real-time PCR detection of the effects of protozoa on rumen bacteria in cattle.

A real-time PCR approach was used in this study to clarify the populations of major bacterial species in the rumens of faunated and unfaunated cattle. The sensitivity of this novel real-time PCR assay was evaluated by using 10(1) to 10(8) plasmid copies of target bacteria. The numbers of plasmid copies of Ruminococcus albus, Ruminococcus flavefaciens, Prevotella ruminicola, and the CUR-E cluster were higher in the unfaunated than in the faunated rumens. The CUR-E cluster belongs to the Clostridium group. In contrast, Fibrobacter succinogenes was higher in the faunated than in the unfaunated rumens. Although it is well known that an absence of protozoa brings about an increase in the bacterial population, it was clarified here that an absence of protozoa exerted differential effects on the populations of cellulolytic bacteria in cattle rumens (i.e., F. succinogenes, R. albus, and R. flavefaciens). In addition, real-time PCR analysis suggested that the CUR-E cluster was more prevalent in the unfaunated rumens.

Animals↗
PubMed1996

Electrophoretic forms of chitinolytic and lysozyme activities in ruminal protozoa.

Homogenates from a mixed ruminal protozoal population and a ruminal protozoon Entodinium caudatum were analyzed for chitinolytic and lysozyme activities by sodium dodecyl sulfate polyacrylamide gel electrophoresis. For chitinase activity, up to eight bands in mixed protozoa and seven bands in E. caudatum were detected. Estimated molecular mass ranged from 70 to 110 kDa. These enzymes did not display lysozyme activity. N-Acetyl-beta-glucosaminidase activity was also detected in both samples with an estimated molecular mass of 37 kDa. Lysozyme activity in mixed protozoa was present in two major and three minor bands, where one major band displayed the same motility as chicken egg white (CEW) lysozyme, and the other had an approximate molecular mass of 17.5 kDa. The latter remained active even when denatured in the presence of dithiothreitol and renatured under anaerobic conditions. Entodinium caudatum presented one major band coincident with that of CEW lysozyme and a minor band at the 17.5-kDa point. This study showed that protozoal chitinase and lysozyme activities are originated from several enzymes and that none of these enzymes exhibited both activities.

Acetylglucosaminidase↗
PubMed2003

Degradation of tryptophan and related indolic compounds by ruminal bacteria, protozoa and their mixture in vitro.

In vitro experiments were conducted to examine the degradation of d- and l-isomers of tryptophan (Trp) and 10 related indolic compounds by mixed rumen bacteria (B), protozoa (P) and a combination of the two (BP). The analyses were carried out by HPLC. d-Trp (1.0 mM) was not degraded by rumen microorganisms during the 24-h incubation period. The net degradation of 1 mM l-Trp was 46.5%, 8.7% and 80.0% by B, P and BP suspensions, respectively. Trp was degraded into indoleacetic acid, indolelactic acid and indole by rumen bacteria and protozoa, and into skatole, p-cresol and indolepropionic acid by rumen bacteria only. Of them, indoleacetic acid was the major product of Trp found in B (15.4%) and P (3.1%), and skatole in BP (43.2%). This is the first report of the production of indolelactic acid and p-cresol from Trp by rumen microbes. Starch, d-glucose, salinomycin and monensin inhibited the production of skatole and indole from Trp, and skatole from indoleacetic acid by rumen bacteria.

Animals↗
PubMed1994

Multiple drug resistance in the pathogenic protozoa.

Evidence for the phenomenon of multiple drug resistance (MDR) in the well studied pathogenic protozoa has been examined. This has been placed in the more familiar context of the MDR efflux transporters and the cloned mdr genes of mammalian cells. Homologues of the mdr gene family in protozoa and their possible role in drug efflux have been compared with their mammalian counterparts. Possible mechanisms and models for drug efflux have been considered. The unusual and extensive range of substrates transported by the ATP-binding cassette (ABC) family of transporters which includes the MDRs has been raised. The impact of kinetics, structure and bioenergetics of the MDR family members on mechanisms of transport has been accentuated to argue that MDR efflux considered in isolation appears bizarre but may be better understood in a broader context.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1988

Ciliated protozoa in the colonic wall of horses.

Ciliated protozoa of several morphological types were found in the colonic tissue of 8 horses, mostly immature Standardbreds. Most of the protozoa observed appeared similar to those normally found as commensals in the equine large intestinal lumen. In all cases, organisms were located in the lamina propria; organisms were also found in the submucosa of 2 horses. The association of colonic disease with the presence of intramural ciliates was unclear.

Animals↗
PubMed1982

The purine metabolism of protozoa.

Protozoa possess a wealth of purine-salvage enzymes, many with unique, or unusual, substrate specificities. As a result, many opportunities for the chemotherapist exist. An exemplification is found in the conversion in schistosomes of allopurinol ribonucleoside to the corresponding ribonucleotide followed by further anabolism to the very toxic 4-aminopyrazolo(3,4-d)pyrimidine 1-ribonucleotide. The same organisms convert another inosine analog, formycin B, to the ribonucleotide, but its inhibitory effects appear to be exercised primarily by inhibition of the organism's adenylosuccinate synthase. A substantial segment of the Phylum Protozoa shows no vestigial traces of ability to synthesize purines de novo although thymidylate synthase appears to be present in many. The absence of other tetrahydrofolate catalyzed reactions suggests that these functions were never acquired.

Allopurinol↗
PubMed1984

A bifunctional thymidylate synthetase-dihydrofolate reductase in protozoa.

Thymidylate synthetase and dihydrofolate reductase exist as a bifunctional protein in a number of species of protozoa which span diverse groups of the subkingdom. The enzymes copurify upon gel filtration and on affinity chromatography columns specific for dihydrofolate reductase. The bifunctional protein has been found in species of Crithidia, Leishmania, Trypanosoma, Plasmodium, Eimeria, Tetrahymena and Euglena. For reasons unknown, neither enzyme could be detected in Entamoeba histolytica or E. invadens. Since neither enzyme has yet been found as a separate protein in protozoa, it is likely that the bifunctional protein is widespread among these primitive eukaryotes. In most cases, the apparent size of the native protein is approximately twice that of the subunit possessing thymidylate synthetase. Further, with one exception, the subunit sizes are close to the sum of the subunit sizes of the separate enzymes found in other sources.

Animals↗
PubMed1993

Rapid isolation of DNA from trypanosomatid protozoa using a simple 'mini-prep' procedure.

Although several methods for isolating genomic DNA from trypanosomatid protozoa exist, all are time-consuming and cumbersome. Faster, simpler and efficient protocols for preparation of DNA from these protozoa are needed to ease the screening of mutants and transfectants. We describe the use of a bacterial lysis method to isolate chromosomal DNA from a wide range of trypanosomatids. The method is based on the finding reported by He et al., who noticed that phenol/chloroform treatment of Escherichia coli cells in the presence of LiCl and Triton X-100 solubilizes plasmid DNA, while precipitating unwanted chromosomal DNA and denatured cellular proteins. In applying this lysis method to the isolation of episomal DNA from transfected trypanosomatids, we found that, unlike bacterial genomic DNA, chromosomal DNA of trypanosomatids was soluble in the phenol/chloroform/Triton/LiCl mixture. This observation prompted us to use the bacterial lysis method as a routine protocol for extraction of DNA from trypanosomatids.

Animals↗
PubMed1994

Detection of ubiquinone in parasitic and free-living protozoa, including species devoid of mitochondria.

Ubiquinone (coenzyme Q, CoQ) was analyzed and individual homologues quantified in 11 species of parasitic and free-living protozoa by a combination of thin-layer chromatography and high performance liquid chromatography. Fast atom bombardment ionization-mass spectrometry was used for the first time to confirm the identity of the fractionated CoQ homologues and proved to be a fast, gentle and convenient method for ubiquinone identification. Ubiquinone was detected in all organisms including those devoid of identifiable mitochondria. However, significantly lower levels of CoQ were present in those organisms lacking this respiratory organelle (5- to 50-fold lower in Entamoeba histolytica (CoQ9) and 15- to 350-fold for Giardia lamblia (CoQ9) and Tritrichomonas foetus (CoQ10)). Coenzyme Q9 was the predominant homologue in promastigotes of Leishmania donovani and Leishmania major. Lower amounts of CoQ8 and CoQ10 were also detected in L. donovani, and CoQ8 in L. major. Comparison of the in vitro cultivated promastigote and amastigote forms of Leishmania pifanoi and Leishmania amazonensis revealed CoQ9 to be the sole detectable ubiquinone homologue in the amastigote (macrophage) stage, whereas CoQ8 and CoQ10 were also present in the promastigotes (life cycle stage found in the insect gut) of L. pifanoi, and CoQ7 and CoQ8 in promastigotes of L. amazonensis. Interestingly, the total amounts of CoQ were similar in both forms of these organisms. The free-living ciliates, Tetrahymena thermophila and Paramecium tetraurelia contained CoQ8 as the predominant ubiquinone species and this homologue was also present in the isolated cilia from P. tetraurelia. The marine ciliate, Parauronema acutum contained CoQ7 as well as CoQ8. Comparison of xenosome-containing P. acutum with organisms lacking the symbiont revealed that twice the level of CoQ8 was present in cells grown with this cytoplasmic gram-negative bacterium. Results suggest that CoQ is ubiquitous amongst the protozoa, regardless of the presence of mitochondria, and may function in alternative roles to that of mitochondrial electron transport chain component.

Animals↗
PubMed1988

Viruses of parasitic protozoa.

Associations are increasingly recognized between parasitic protozoa and smaller organisms such as bacteria (see Parasitology Today 1, 143), and viruses. Their revelation, originally by ultrastructural studies, may now be indicated by observations of 'rogue bands' on gel electrophoresis of parasite nucleic acids. The origins and roles of parasite 'parasites' are still uncertain, but, as Michael Miles suggests here, they may prove of particular importance as agents to introduce genes for important immunogens into non-pathogenic protozoa for vaccine delivery.

Journal Article↗
PubMed1988

Cell motility of sporozoan protozoa.

Parasitic protozoa need to be capable of movement. This is particularly important for their ability to locate and invade target cells or the organs of their hosts, and could therefore represent a novel target for chemotherapy or immune-mediated attack. Unlike the crawling movement of amoebae and vertebrate fibroblasts, sporozoon protozoa are characterized by a 'gliding movement' in which no obvious changes occur in cell shape. Here Conrad King discusses cellular motility particularly in sporozoites of Eimeria and Plasmodium, discussing current ideas about the possible motor mechanisms involved.

Journal Article↗