Amoebic liver abscess production by Entamoeba dispar.

Although Entamoeba dispar displays a similar morphology to Entamoeba histolytica, cellular and molecular studies have revealed significant differences between these two amoebae, including the former being characterized as non-pathogenic and the later as pathogenic. However, recent in vivo and in vitro experiments have shown that E. dispar strains of different origin are capable of causing liver damage and destroying cell culture lines in the presence of common intestinal bacteria. These results suggested that E. dispar may present pathogenic behavior according to the specific E. dispar strain, culture and environmental conditions. To investigate this possibility, we carried out in vivo and in vitro studies using a xenic strain E. dispar (ICB-ADO) isolated from a symptomatic non-dysenteric Brazilian patient. This strain was able to induce liver necrosis in a hamster model that was more severe than that produced by E. histolytica. The ICB-ADO isolate also caused significantly more destruction of cultured MDCK cells and increased loss of transepithelial resistance than did the E. histolytica. Xenic E. dispar exhibited high proteolytic activity, which was partially inhibited by the addition of cysteine-protease inhibitors. Based on our biochemical and molecular characterization of E. dispar (ICB-ADO) xenic culture and its ability to produce liver abscesses, we conclude that this specific strain can indeed produce tissue damage, distinct from the frequently used non- pathogenic E. dispar SAW 760 strain.

Entamoeba histolytica: cysteine proteinase activity and virulence. Focus on cysteine proteinase 5 expression levels.

Cysteine proteinase (CP) activity and CP5 mRNA levels were analyzed in eleven samples of Entamoeba histolytica isolated from patients presenting different clinical profiles. The virulence degree of the isolates, determined in hamster liver, correlated well with the clinical form of the patient and culture conditions. CP5 mRNA levels were also determined in sample freshly picked up directly from liver amoebic abscess. Differences were not observed in the levels of CP5 mRNA and CP specific activity among the cultured samples. However, different levels of CP5 mRNA were observed in trophozoite freshly isolated from hepatic amoebic lesions. These results reinforce the importance of CP5 for the virulence of amoebae and the need for studies with the parasite present in lesions to validate mechanisms involved in pathogenesis of amoebiasis.

Prevalence of intestinal parasites in children from public daycare centers in the city of Belo Horizonte, Minas Gerais, Brazil.

The objective of this study was to verify the occurrence of intestinal parasites in 3 to 6-year-old children from daycare centers maintained by the municipal government of Belo Horizonte, Minas Gerais, Brazil. Coproparasitological tests performed in 472 children have shown that 24.6% of them had some type of parasites, 6.6% of the children having more than one type. Among protozoa, Entamoeba coli (14.0%) and G. duodenalis (9.5%) were the most prevalent, whereas Ascaris lumbricoides (3.0%) and Trichuris trichiura (1.1%) were the most frequent among the helminths. Thus, we can observe that intestinal parasites still represent a serious public health problem in Belo Horizonte, especially among children and in areas where the socioeconomic conditions are less favorable.

Prevalence of intestinal parasites in children from public daycare centers in the city of Belo Horizonte, Minas Gerais, Brazil / Prevalência de enteroparasitoses em crianças de creches públicas da cidade de Belo Horizonte, Minas Gerais, Brasil

The objective of this study was to verify the occurrence of intestinal parasites in 3 to 6-year-old children from daycare centers maintained by the municipal government of Belo Horizonte, Minas Gerais, Brazil. Coproparasitological tests performed in 472 children have shown that 24.6 percent of them had some type of parasites, 6.6 percent of the children having more than one type. Among protozoa, Entamoeba coli (14.0 percent) and G. duodenalis (9.5 percent) were the most prevalent, whereas Ascaris lumbricoides (3.0 percent) and Trichuris trichiura (1.1 percent) were the most frequent among the helminths. Thus, we can observe that intestinal parasites still represent a serious public health problem in Belo Horizonte, especially among children and in areas where the socioeconomic conditions are less favorable.

O objetivo deste trabalho foi verificar a ocorrência de parasitos intestinais em crianças de 3 a 6 anos de idade, oriundas de creches mantidas pela Prefeitura Municipal de Belo Horizonte, Minas Gerais, Brasil. Exames coproparasitológicos realizados em 472 crianças demonstraram que 24,6 por cento apresentavam algum tipo de parasitose, sendo que 6,6 por cento apresentavam mais de um parasito. Entre os protozoários, Entamoeba coli (14,0 por cento) e G. duodenalis (9,5 por cento) foram os mais prevalentes, enquanto Ascaris lumbricoides (3,0 por cento) e Trichuris trichiura (1,1 por cento) foram os mais encontrados entre os helmintos. Desta forma, observa-se que as parasitoses intestinais ainda são um problema de saúde pública em Belo Horizonte, principalmente entre a população infantil e em áreas onde as condições sócio-econômicas são menos favoráveis.

Glycogen as a carbohydrate energy reserve in trophozoites of Giardia lamblia.

Although there is indirect evidence to suggest that glycogen is present in G. lamblia, to date it has not been purified and identified from this organism. In this study, a high molecular weight carbohydrate was purified and characterized and its physiological role as an energetic reserve was established. The monosaccharide constituents of the carbohydrate reserve were identified as glucose by two independent methods: thin layer chromatography and an enzymatic assay. The degree of branching of the molecule was evaluated by comparing its absorbance spectrum in the presence of lugol with spectra of standard solutions of glycogen and starch under the same conditions. The results strongly suggest that glycogen is present in G. lamblia and acts as an energy reserve in trophozoites of this organism.

Molecular characterization of Brazilian human Giardia duodenalis isolates using isoenzyme and random amplified polymorphic DNA analysis.

Isoenzymes and RAPD (random amplified polymorphic DNA) analysis were used to characterize three Brazilian human isolates of Giardia duodenalis and its clones. The Portland-1 strain (ATCC 30888) was included in the study as a reference pattern. Both methods divided the isolates into two main groups, one represented by the Portland-1 strain, the other constituted by the Brazilian isolates, which, in turn, were divided into 2 subgroups. The dendogram constructed with the RAPD data, using seven primers, revealed a great heterogeneity between Brazilian isolates and the Portland-1 strain. There was no relationship to the clinical characteristics of the isolates. Although a lot of similarity has been observed among Brazilian isolates and its clones, individual polymorphism was detected, which could be related to the clonal reproduction of this protozoan.

Arbitrarily primed PCR fingerprinting of RNA and DNA in Entamoeba histolytica

Differences were detected in the gene expression of strains of E. histolytica using RNA (RAP-PCR) and DNA fingerprinting (RAPD). Analysis of the electrophoretic profiles of the gels revealed some polymorphic markers that could be used in the individual characterization of the strains. The 260 bands generated by using five different primers for RAP-PCR, as well as RAPD, were employed in the construction of dendograms. The dendogram obtained based on the RAPD products permitted the distinction of symptomatic and asymptomatic isolates, as well the correlation between the polymorphism exhibited and the virulence of the strains. The dendogram obtained for the RAP-PCR products did not show a correlation with the virulence of the strains but revealed a high degree of intraspecific transcriptional variability that could be related to other biological features, whether or not these are involved in the pathogenesis of amebiasis

Virulence parameters in the characterization of strains of Entamoeba histolytica

A caracterizacao quanto a virulencia das diferentes cepas de E. histolytica foi avaliada atraves de ensaios in vivo e in vitro. Discrepancias nesta caracterizacao tem surgido quando se compara os diferentes ensaios. Avaliamos alguns parametros de virulencia na caracterizacao de 5 cepas axenicas de E. histolystica. Estas cepas foram caracterizadas com relacao a sua capacidade para induzir abscesso em figado de hamster, eritrofagocitose e efeito citopatico sobre celulas VERO...

Comparaçäo de diferentes testes sorológicos no diagnóstico da amebíase no Brasil / Amoebiasis diagnostic and its comparision with different sera tests

Foram testados, frente às reaçöes de hemaglutinaçäo indireta (HAI), reaçäo de imunofluorescência indireta (RIFI), fixaçäo de complemento (RFC) e contraimunoeletroforese (CIE), soros de 154 pacientes com diagnóstico parasitológico positivo para E. histolytica, sendo 78 sintomáticos e 76 assintomáticos, na tentativa de melhorar e facilitar o diagnóstico da amebiase no Brasil. Todos os testes sorológicos se mostraram bons para discriminar amebiase invasiva de näo invasiva. Contudo näo se mostraram adequados para detectar os sintomáticos com colite näo disentérica e os assintomáticos, que representam a maioria dos casos de amebiase no Brasil. Os soros dos indivíduos infectados com outras amebas näo se mostraram reativos, demonstrando a especificidade das reaçöes utilizadas no diagnóstico da amebiase. Nossos resultados demonstraram que a RIFI doi o teste mais sensível e a CIE o mais específico, a HAI seria o teste de escolha para levantementos epidemiológicos e a RFC o teste com menor especificidade