Trypanosoma cruzi high infectivity in vitro is related to cardiac lesions during long-term infection in Beagledogs

Trypanosoma cruzi is a hemoflagelate parasite associated with heart dysfunctions causing serious problems in Central and South America. Beagle dogs develop the symptoms of Chagas disease in humans, and could be an important experimental model for better understanding the immunopathogenic mechanisms involved in the chagasic infection. In the present study we investigated the relation among biological factors inherent to the parasite (trypomastigote polymorphism and in vitro infectivity) and immunoglobulin production, inflammation, and fibrosis in the heart of Beagle dogs infected with either T. cruzi Y or Berenice-78 strains. In vitro infectivity of Vero cells as well as the extension of cardiac lesions in infected Beagle was higher for Y strain when compared to Berenice-78 strain. These data suggested that in vitro infectivity assays may correlate with pathogenicity in vivo. In fact, animals infected with Y strain, which shows prevalence of slender forms and high infectivity in vitro, presented cardiomegaly, inflammation, and fibrosis in heart area. Concerning the immunoglobulin production, no statistically significant difference was observed for IgA, IgM or IgG levels among T. cruzi infected animals. However, IgA together IgM levels have shown to be a good marker for the acute phase of Chagas disease

Histone deacetylase inhibition results in a common metabolic profile associated with HT29 differentiation

Cell differentiation is an orderly process that begins with modifications in gene expression. This process is regulated by the acetylation state of histones. Removal of the acetyl groups of histones by specific enzymes (histone deacetylases, HDAC) usually downregulates expression of genes that can cause cells to differentiate, and pharmacological inhibitors of these enzymes have been shown to induce differentiation in several colon cancer cell lines. Butyrate at high (mM) concentration is both a precursor for acetyl-CoA and a known HDAC inhibitor that induces cell differentiation in colon cells. The dual role of butyrate raises the question whether its effects on HT29 cell differentiation are due to butyrate metabolism or to its HDAC inhibitor activity. To distinguish between these two possibilities, we used a tracer-based metabolomics approach to compare the metabolic changes induced by two different types of HDAC inhibitors (butyrate and the non-metabolic agent trichostatin A) and those induced by other acetyl-CoA precursors that do not inhibit HDAC (caprylic and capric acids). [1,2-13C2]-d-glucose was used as a tracer and its redistribution among metabolic intermediates was measured to estimate the contribution of glycolysis, the pentose phosphate pathway and the Krebs cycle to the metabolic profile of HT29 cells under the different treatments. The results demonstrate that both HDAC inhibitors (trichostatin A and butyrate) induce a common metabolic profile that is associated with histone deacetylase inhibition and differentiation of HT29 cells whereas the metabolic effects of acetyl-CoA precursors are different from those of butyrate. The experimental findings support the concept of crosstalk between metabolic and cell signalling events, and provide an experimental approach for the rational design of new combined therapies that exploit the potential synergism between metabolic adaptation and cell differentiation processes through modification of HDAC activity

Immunological imbalance between IFN-³ and IL-10 levels in the sera of patients with the cardiac form of Chagas disease

The immune response is crucial for protection against disease; however, immunological imbalances can lead to heart and digestive tract lesions in chagasic patients. Several studies have evaluated the cellular and humoral immune responses in chagasic patients in an attempt to correlate immunological findings with clinical forms of Chagas disease. Moreover, immunoglobulins and cytokines are important for parasitic control and are involved in lesion genesis. Here, cytokine and IgG isotype production were studied, using total epimastigote antigen on sera of chagasic patients with indeterminate (IND, n = 27) and cardiac (CARD, n = 16) forms of the disease. Samples from normal, uninfected individuals (NI, n = 30) were use as controls. The results showed that sera from both IND and CARD patients contained higher levels of Trypanosoma cruzi-specific IgG1 (IgG1) antibodies than sera from NI. No difference in IgG2 production levels was observed between NI, IND and CARD patients, nor was a difference in IL-10 and IFN-³ production detected in the sera of IND, CARD and NI patients. However, IND patients displayed a positive correlation between IL-10 and IFN-³ levels in serum, while CARD patients showed no such correlation, indicating an uncontrolled inflammatory response in CARD patients. These findings support the hypothesis that a lack of efficient regulation between IFN-³ and IL-10 productions in CARD patients may lead to cardiac immunopathology.CNP

On the Peripheries of Planetary Urbanization: Globalizing Manaus and its Expanding Impact

In this paper I argue that global urbanism produces peripherality in ways that cannot be adequately problematized without taking into account its actual extent and geographically uneven development. Therefore, planetary urbanization needs to engage scholarly traditions attuned to regional urbanization if the discourse is to move past limitations in the urban globalization canon and its narrow focus on cities. To that end, I examine research on extensive urbanization in the Amazon region. Illustrative case studies show how attempts to globalize Manaus precipitated territorial restructuring and sociospatial change far beyond the city's boundaries. Manaus is now a more unequal city. Selective metropolitan expansion to the Rio Negro's south bank has led to the simultaneous upgrading and peripheralization of Iranduba. Yet, the building of a city-centric regional network of roadways also shaped Roraima State's transformation from isolated borderland to bypassed periphery. Moreover, financial and symbolic appropriations of standing rainforests by metropolitan conservationism marginalize remote communities even in the absence of exploitative deforestation and resource extraction. Final remarks emphasize the need for further research on the hybrid (urban—rural) conditions and functional articulations of distant-yet-impacted peripheries. Such efforts may broaden the political horizons of planetary urbanization by informing extensive contestations of entrepreneurial urbanism

Point Mutations in c-Myc Uncouple Neoplastic Transformation from Multiple Other Phenotypes in Rat Fibroblasts

Deregulation of c-Myc (Myc) occurs in many cancers. In addition to transforming various cell types, Myc also influences additional transformation-associated cellular phenotypes including proliferation, survival, genomic instability, reactive oxygen species production, and metabolism. Although Myc is wild type in most cancers (wtMyc), it occasionally acquires point mutations in certain lymphomas. Some of these mutations confer a survival advantage despite partially attenuating proliferation and transformation. Here, we have evaluated four naturally-occurring or synthetic point mutations of Myc for their ability to affect these phenotypes, as well as to promote genomic instability, to generate reactive oxygen species and to up-regulate aerobic glycolysis and oxidative phosphorylation. Our findings indicate that many of these phenotypes are genetically and functionally independent of one another and are not necessary for transformation. Specifically, the higher rate of glucose metabolism known to be associated with wtMyc deregulation was found to be independent of transformation. One mutation (Q131R) was greatly impaired for nearly all of the studied Myc phenotypes, yet was able to retain some ability to transform. These findings indicate that, while the Myc phenotypes examined here make additive contributions to transformation, none, with the possible exception of increased reliance on extracellular glutamine for survival, are necessary for achieving this state

Membrane Cholesterol Regulates Lysosome-Plasma Membrane Fusion Events and Modulates Trypanosoma cruzi Invasion of Host Cells

Trypanosoma cruzi, is the etiological agent of a neglected tropical malady known as Chagas' disease, which affects about 8 million people in Latin America. 30–40% of affected individuals develop a symptomatic chronic infection, with cardiomyopathy being the most prevalent condition. T. cruzi utilizes an interesting strategy for entering cells: T. cruzi enhances intracellular calcium levels, which in turn trigger the exocytosis of lysosomal contents. Lysosomes then donate their membrane for the formation of the parasitophorous vacuole. Membrane rafts, cholesterol-enriched microdomains in the host cell plasma membrane, have also been implicated in T. cruzi invasion process. Since both plasma membrane and lysosomes collaborate in parasite invasion, we decided to study the importance of these membrane domains for lysosomal recruitment and fusion during T. cruzi invasion into host cells. Our results show that drug dependent depletion of plasma membrane cholesterol changes raft organization and induces excessive lysosome exocytosis in the earlier stages of treatment, leading to a depletion of lysosomes near the cell cortex, which in turn compromises T. cruzi invasion. Based on these results, we propose that cholesterol depletion leads to unregulated exocytic events of pre-docked lysosomes, reducing lysosome availability at the cell cortex and consequently compromising T. cruzi infection

Notch signaling in glioblastoma: a developmental drug target?

Malignant gliomas are among the most devastating tumors for which conventional therapies have not significantly improved patient outcome. Despite advances in imaging, surgery, chemotherapy and radiotherapy, survival is still less than 2 years from diagnosis and more targeted therapies are urgently needed. Notch signaling is central to the normal and neoplastic development of the central nervous system, playing important roles in proliferation, differentiation, apoptosis and cancer stem cell regulation. Notch is also involved in the regulation response to hypoxia and angiogenesis, which are typical tumor and more specifically glioblastoma multiforme (GBM) features. Targeting Notch signaling is therefore a promising strategy for developing future therapies for the treatment of GBM. In this review we give an overview of the mechanisms of Notch signaling, its networking pathways in gliomas, and discuss its potential for designing novel therapeutic approaches

PI3Kinase signaling in glioblastoma

Glioblastoma (GBM) is the most common primary tumor of the CNS in the adult. It is characterized by exponential growth and diffuse invasiveness. Among many different genetic alterations in GBM, e.g., mutations of PTEN, EGFR, p16/p19 and p53 and their impact on aberrant signaling have been thoroughly characterized. A major barrier to develop a common therapeutic strategy is founded on the fact that each tumor has its individual genetic fingerprint. Nonetheless, the PI3K pathway may represent a common therapeutic target to most GBM due to its central position in the signaling cascade affecting proliferation, apoptosis and migration. The read-out of blocking PI3K alone or in combination with other cancer pathways should mainly focus, besides the cytostatic effect, on cell death induction since sublethal damage may induce selection of more malignant clones. Targeting more than one pathway instead of a single agent approach may be more promising to kill GBM cells