Biomedical subjects

Tania C Araújo-Jorge

Publications and source records attributed to Tania C Araújo-Jorge.

7 recordsLinked to original sources

PubMed2005

Magnetic resonance imaging in experimental Chagas disease: a brief review of the utility of the method for monitoring right ventricular chamber dilatation.

Chagas' disease caused by infection with Trypanosoma cruzi leads to a myocardiopathy that evolves from the acute to the chronic phase. Magnetic resonance imaging (MRI) is an important tool for monitoring cardiac morphology and function both in humans and in animals. In the present work, we present a brief review of MRI applications for the study of ventricular hypertrophy and dilatation of the right ventricle in murine models of Chagas' disease. Studies using MRI demonstrate an increase in right ventricular chamber dimension during both phases of infection, indicating that increase of the right ventricle is a marker for experimental chagasic myocardiopathy. Based on previous studies using MRI in these models we propose that this technique is an excellent approach for monitoring heart functionality from the acute through the chronic phase of infection in different parasite-host pairs and for monitoring the efficacy of cardioprotective or immune-therapeutic agents.

Animals↗

PubMed2005

Uptake of host cell transforming growth factor-beta by Trypanosoma cruzi amastigotes in cardiomyocytes: potential role in parasite cycle completion.

The cytokine transforming growth factor-beta (TGF-beta) plays various functions in the control of Trypanosoma cruzi infectivity and in the progression of Chagas' disease. When we immunostained T. cruzi-infected cardiomyocytes (after either in vivo or in vitro infections) for TGF-beta, we observed stronger immunoreactivity in parasites than in host cells. TGF-beta immunoreactivity evolved during parasite cycle progression, with intense staining in amastigotes versus very faint staining in trypomastigotes. TGF-beta was present on the surface of amastigotes, in the flagellar pocket, and in intraparasitic vesicles as revealed by electron microscopy. However, no ortholog TGF-beta gene could be identified in the genome of T. cruzi by in silico analysis or by extensive polymerase chain reaction and reverse transcriptase-polymerase chain reaction studies. Immunoreactive TGF-beta was most probably taken up by the parasite from the host cell cytoplasm because such an internalization process of biotinylated TGF-beta could be observed in axenic amastigotes in vitro. These observations represent the first example of a novel mechanism by which a primitive unicellular protozoan can use host cell TGF-beta to control its own intracellular life cycle.

Actins↗

PubMed2004

Microscopy images as interactive tools in cell modeling and cell biology education.

The advent of genomics, proteomics, and microarray technology has brought much excitement to science, both in teaching and in learning. The public is eager to know about the processes of life. In the present context of the explosive growth of scientific information, a major challenge of modern cell biology is to popularize basic concepts of structures and functions of living cells, to introduce people to the scientific method, to stimulate inquiry, and to analyze and synthesize concepts and paradigms. In this essay we present our experience in mixing science and education in Brazil. For two decades we have developed activities for the science education of teachers and undergraduate students, using microscopy images generated by our work as cell biologists. We describe open-air outreach education activities, games, cell modeling, and other practical and innovative activities presented in public squares and favelas. Especially in developing countries, science education is important, since it may lead to an improvement in quality of life while advancing understanding of traditional scientific ideas. We show that teaching and research can be mutually beneficial rather than competing pursuits in advancing these goals.

Animals↗

PubMed2003

Selenium supplementation at low doses contributes to the decrease in heart damage in experimental Trypanosoma cruzi infection.

Chagasic patients with cardiomyopathy have low levels of selenium (Se), a fundamental trace element. We evaluated the effect of supplementing infected mice with Se (0.25-16 ppm). Supplementation with 0.25 or 1 ppm Se led to parasitaemia and survival curves similar to those of the control group. Mice treated with 4-16 ppm showed a dose-dependent decrease of parasitaemia, significant for the highest concentration. This was probably due to a direct effect on the parasites, which were lysed after in vitro incubation with Se. Survival rates did not change significantly; however, heart damage was reduced in infected mice supplemented with 4 ppm Se, as indicated by a lower cardiac isoform of creatine kinase levels. Our results imply that Se supplementation does not lead to a general protection during infection, but may help protect the heart from inflammatory damage. The effect of Se supplementation in the course of T. cruzi infection depends on the host-parasite pair employed.

Acute Disease↗

PubMed2002

Implication of transforming growth factor-beta1 in Chagas disease myocardiopathy.

Cardiac dysfunction with progressive fibrosis is a hallmark of Chagas disease. To evaluate the involvement of transforming growth factor (TGF)-beta1 in this disease, TGF-beta1 levels in patients were measured at 3 stages: asymptomatic indeterminate (IND), cardiac with no or slight heart dysfunction (Card 1), and cardiac with moderate or severe heart dysfunction (Card 2). All patients had significantly higher circulating levels of TGF-beta1 than did healthy persons, and 27% of patients in the Card 1 group had higher TGF-beta1 levels than did patients in the IND group. Immunohistochemical analysis of cardiac biopsy specimens showed strong fibronectin staining in the extracellular matrix and staining for phosphorylated Smad 2 (activation of the TGF-beta1 signaling pathway) in cell nuclei. The higher levels of latent TGF-beta1 observed in patients with myocardiopathy, together with intracellular activation of the TGF-beta1 pathway and tissue fibrosis, suggest that TGF-beta1 plays an important role in Chagas disease. TGF-beta1 may represent a new target for preventive and curative treatments of Chagas disease.

Adult↗

PubMed2002

Trypanosoma cruzi: host selenium deficiency leads to higher mortality but similar parasitemia in mice.

Selenium is an essential trace element and its deficiency was implicated in heart diseases. We recently showed low Se levels in chronic chagasic patients with cardiomyopathy. Herein, mice were depleted in Se by feeding the mothers with chow containing only 0.005 mg Se/kg and maintaining this diet for offspring, that were further infected with Trypanosoma cruzi. Survival rate was significantly lower in Se deficient than in control mice. Parasitemia was similar in all groups. Necrotic heart lesions were found after infection (high CK-MB levels). No outbreaks of parasite growth were detected in chronic survivors submitted or not to a second Se depletion. The present results confirm our hypothesis that a nutritional deficiency in Se is associated to a higher mortality during T. cruzi infection. The potential beneficial effect of Se supplementation is a perspective. Hypothesis to explain the higher susceptibility of Se-depleted mice to T. cruzi infection are discussed.

Animals↗

PubMed2002

Progressive Chagas' cardiomyopathy is associated with low selenium levels.

Selenium (Se) deficiency is linked with some cardiomyopathies. Its status was determined in 170 patients with chronic Chagas' disease from 2 Brazilian regions (Rio de Janeiro and Belo Horizonte), clinically stratified into groups as follows: indeterminate or asymptomatic (IND); cardiac asymptomatic (CARDa); cardiac symptomatic with moderate to severe heart dysfunction (CARDb); and healthy adults (HA), used for comparison. In most HA, Se levels were normal, excluding an overall Se deficiency. Se was significantly lower in CARDb than in HA, IND, or CARDa patients. This was not associated with a concomitant decrease in activity of glutathione peroxidase. Thyrotropin was normal, excluding iodine deficiency. Se correlated positive and significantly with ventricular ejection fraction (assessed via echocardiography). Asymptomatic children with acute Chagas' disease had normal Se as well as 5 noninfectious cases of cardiomyopathy. Low Se was found in 6 of 10 chagasic patients with digestive megasyndromes. Thus, the decrease in Se in chagasic patients seems to be a biological marker for Trypanosoma cruzi infection and related to the progression of pathology.

Animals↗