A systematic study of the distribution of intracellular parasites in the organs and tissues of mice acutely infected (15 days) with the CL strain of Trypanosoma cruzi was performed. Almost all tissues and organs were parasitized with different intensities, including several epithelial cell types. In addition to striated, cardiac, and smooth muscles a very high parasitism of fat cells, pancreas, and genital adnexa was observed. A smaller number of parasites was found in all other structures studied except in highly vascularized structures such as in the penile corpora cavernosa, pulmonary and renal parenchyma, islets of Langerhans, hepatic sinusoids, and in atrial endothelium. This paper also shows, for the first time in the literature, the parasitism of milky spots, cornea epithelium, cornea stroma, retroorbital fibroblasts, seminal vesicles, and coagulative, Cowper's, urethral, preputial, sebaceous anal, and clitoris glands. The results indicated that CL strain is highly invasive, being able to infect cells derived from the three embryonic layers (ectoderm, mesoderm, and endoderm), suggesting that the paninfectivity may influence the outcome of immunological and pathological events.

This study is the first to apply a comparative analysis of environmental chemistry, microbiological parameters and bacterioplankton 16S rRNA clone libraries from different areas of a 50 km transect along a trophic gradient in the tropical Guanabara Bay ecosystem. Higher bacterial diversity was found in the coastal area, whereas lower richness was observed in the more polluted inner bay water. The significance of differences between clone libraries was examined with LIBSHUFF statistics. Paired reciprocal comparisons indicated that each of the libraries differs significantly from the others, and this is in agreement with direct interpretation of the phylogenetic tree. Furthermore, correspondence analyses showed that some taxa are related to specific abiotic, trophic and microbiological parameters in Guanabara Bay estuarine system.

Plasmodium berghei ANKA infection in CBA/J mice leads to the development of cerebral malaria (CM) that kills 80-90% of the animals in 6-9 days. This model has been used to study the pathogenesis of CM, which is a major cause of morbidity and mortality in Plasmodium falciparum-infected individuals. The role of cytokines in the induction of CM in the murine model has been well documented, but most studies have been restricted to the peak of neurological manifestations. Here we used a sequential approach to compare mice that developed CM with those that developed no cerebral pathology. Animals were examined for systemic histopathological changes and plasma Tumor Necrosis Factor-alpha (TNF) levels. The objectives were (a) to further determine the importance of factors commonly associated with murine CM-such as elevated levels of TNF and the presence of hemorrhage and vascular plugging-by comparing mice at different stages of infection and/or with different outcomes following infection and (b) to examine the importance of systemic changes-course of parasitemia and histopathological alterations in brain, liver, and lungs-in the development of CM. The data suggest that (a) the clinical manifestation of CM appears to be associated with a wave of merozoite release on days 6-7, (b) murine CM does not present reliable histopathological indicators, (c) there is no topographic association between the occurrence of intravascular plugging and the hemorrhagic foci, (d) monocyte-monocyte and monocyte-endothelial cell adherence were the most expressive histopathological events and were not restricted to brain vessels, (e) blood levels of TNF are not indicative of the local tissue reaction, (f) adhesiveness of monocyte/endothelial cells fluctuate during infection and is dissociated from the lymphocyte homing to the liver, and (g) pulmonary megakaryocytosis (megakaryopoiesis?) is a late event in the lungs.

Guanabara Bay is an eutrophic estuarine system located in a humid tropical region surrounded by the second largest metropolitan area of Brazil. This study explores the contrasting environmental chemistry and microbiological parameters that influence the archaeaplankton diversity in a pollution gradient in Guanabara Bay ecosystem. The environments sampled ranged from completely anoxic waters in a polluted inner channel to the adjacent, relatively pristine, coastal Atlantic Ocean. Partial archaeal 16S rDNA sequences in water samples were retrieved by polymerase chain reaction (PCR) and analyzed using denaturing gradient gel electrophoresis (DGGE), cloning, and sequencing. Sequences were subjected to phylogenetic and diversity analyses. Community structure of the free-living archaeal assemblages was different from that of the particle-attached archaea according to DGGE. Gene libraries revealed that phylotype identification was consistent with environmental setting. Archaeal phylotypes found in polluted anoxic waters and in more pristine waters were closely related to organisms that have previously been found in these environments. However, inner bay archaea were related to organisms found in oil, industrial wastes, and sewage, implying that water pollution controls archaea communities in this system. The detection of a substantial number of uncultured phylotypes suggests that Guanabara Bay harbors a pool of novel archaeaplankton taxa.

Metallo-beta-lactamase production is emerging worldwide as an important mechanism of carbapenem resistance among nonfermentative Gram-negative isolates, and this mechanism is becoming frequently observed in Brazil. This study documents the occurrence and characteristics of an epidemic SPM-1-producing Pseudomonas aeruginosa strain in a teaching hospital located in Rio de Janeiro City, Brazil. The bla (SPM-1) gene and a class 1 integron were detected in 13 isolates, representing 20% of the 65 imipenem-resistant P. aeruginosa isolates obtained from January, 2000, to August, 2001. DNA sequencing revealed that this integron carries three gene cassettes that confer resistance to antimicrobials, aacA4, bla (OXA-56), and aadA7, and an orf1 encoding a putative transposase. All 13 SPM-producing P. aeruginosa isolates had closely related pulsed-field gel electrophoresis (PFGE) profiles, designated as clonal group A, suggesting nosocomial spread of the strain. This clonal group was the same as that observed in other SPM-1-producing P. aeruginosa isolates from distinct Brazilian states. The dissemination of this clone throughout Brazil could not be explained by transfer of infected patients and/or sharing of common health-care staff. It is likely that the spread of these strains occurred indirectly via the community.