Impact of Extracellular DNA on Architectural Parameters of Leptospira biflexa Biofilm

Extracellular DNA (eDNA) is a major component of bacterial biofilms. In this study, we performed a three-dimensional analysis of Leptospira biofilm using advanced imaging by confocal laser scanning microscopy (CLSM) and multi-parameter analysis by COMSTAT 2 software, with quantification of Leptospira and eDNA fluorescence. To investigate the role of eDNA in Leptospira biofilm, we treated Leptospira biflexa biofilms with DNase I enzyme (DNase), which digested eDNA, and compared DNase treated biofilms and controls. There was a significant reduction of the biomass of biofilms treated with DNase, by spectrophotometry and COMSTAT analysis. The multiparameter analysis evidenced for DNase-treated biofilms a significant decrease in the surface area and the average thickness; opposing to a significant augmentation of the surface/biovolume ratio and the roughness coefficient (Ra*), when compared to controls. We analyzed the parameters of DNase-treated biofilms by Pearson's correlation coefficient and found significant positive correlations between biomass and average thickness; biomass and surface area; surface area and average thickness. On the other hand, there were significant negative correlations between Ra* and biomass; Ra* and average thickness; Ra* and surface area. These findings suggest that eDNA digestion results in biofilm instability and alteration of the three-dimensional architecture, justifying the negative correlation between Ra* and the above-mentioned parameters. In conclusion, our study showed that eDNA digestion produced a massive structural loss, instability, and dramatic changes in the three-dimensional architecture of Leptospira biflexa biofilm. These findings contribute to a better understanding of the role of eDNA and highlight the importance of eDNA as a key component in Leptospira biofilms.

How likely is Brazil to achieve its NDC commitments in the energy sector? A review on Brazilian low-carbon energy perspectives

This paper offers perspectives on the development of low-carbon energy technology in Brazil, pinpointing changes that have occurred since our former publication in 2011. It takes a fresh approach in terms of how likely Brazil will achieve its Nationally Determined Contributions Commitments in the energy sector. Many countries have implemented national climate policies to accomplish their pledged NDC and contribute to the temperature objectives of the Paris Agreement on climate change. Based on official reports and databases of energy development projections in Brazil and the socioeconomic context, we discuss what can be expected for the future of the Brazilian energy sector, the probability of implementing selected technologies, and the prospects of reaching the NDC targets for 2025 and 2030. In addition, this paper provides an overview of the current stage of development of these technologies, main directions, and bottlenecks in Brazil. Analyses have shown that the Brazilian renewable matrix tends to remain significant, driven by the development of solar and mostly small hydroelectric power sources, as well as different types of biomass. In addition, the system will include the replacement of thermoelectric plants powered by diesel and fuel oil by natural gas plants. The prospects for Brazil's official energy plan for 2027 are aligned with the reference technology scenario, which represents the business as usual scenario. Despite this, low-carbon technologies could be implemented far beyond the NDC's goals, given the abundance of renewable natural resources in the country.

Activation of anaplastic lymphoma kinase receptor tyrosine kinase induces neuronal differentiation through the mitogen-activated protein kinase pathway

Anaplastic lymphoma kinase (ALK) is a novel neuronal orphan receptor tyrosine kinase that is essentially and transiently expressed in specific regions of the central and peripheral nervous systems, suggesting a role in its normal development and function. To determine whether ALK could play a role in neuronal differentiation, we established a model system that allowed us to mimic the normal activation of this receptor. We expressed, in PC12 cells, a chimeric protein in which the extracellular domain of the receptor was replaced by the mouse IgG 2b Fc domain. The Fc domain induced the dimerization and oligomerization of the chimeric protein leading to receptor phosphorylation and activation, thus mimicking the effect of ligand binding, whereas the wild type ALK remained as a monomeric nonphosphorylated protein. Expression of the chimera, but not that of the wild type ALK or of a kinase inactive form of the chimera, induced the differentiation of PC12 cells. Analysis of the signaling pathways involved in this process pointed to an essential role of the mitogen-activated protein kinase cascade. These results are consistent with a role for ALK in neuronal differentiation.

Evaluation of different methods for Plasmodia detection, in well defined population groups in an endemic area of Brazil (1)

In Brazil, more than 500,000 new cases of malaria were notified in 1992. Plasmodium falciparum and P. vivax are the responsible species for 99.3% of the cases. For adequate treatment, precoce diagnosis is necessary. In this work, we present the results of the traditional Plasmodia detection method, thick blood film (TBF), and the results of alternative methods: Immunofluorescence assay (IFA) with polyclonal antibody and Quantitative Buffy Coat method (QBC) in a well defined population groups. The analysis were done in relation to the presence or absence of malaria clinical symptoms. Also different classes of immunoglobulins anti-P.falciparum were quantified for the global analysis of the results, mainly in the discrepant results. We concluded that alternative methods are more sensitive than TBF and that the association of epidemiological, clinical and laboratory findings is necessary to define the presence of malaria.

[The heart-lung transplant. Initial clinical experience]

PURPOSE

To assess this initial clinical experience with heart-lung transplantation in Brazil.

METHODS

Four patients underwent heart-lung transplantation from December 1988 to March 1990, one patient with cardiomyopathy and high pulmonary resistance, two patients with primary pulmonary hypertension and another with pulmonary silicosis. The heart lung blocks were harvested from the donor using cardiopulmonary bypass and deep hypothermia. They were transplanted to the recipient by anastomosing the trachea, right atrium or venae cavae, and the ascending aorta.

RESULTS

The second patient died on the 5th postoperative day due to respiratory insufficiency with consequent brain lesions. The first and third patients had survived nine months and 42 days respectively. The 4th patients is asymptomatic eight months after the operation. The main complications were bleeding in two patients, acute pulmonary rejection in three of them and obliterans bronchiolitis in one patients.

CONCLUSION

The heart lung transplantation is a challenging procedure which results are progressively improving with the development of better surgical technique and clinical concepts.

Five cases of nosocomial and community-acquired Legionnaires' disease in São Paulo, Brazil

Legionella sp has been emerging over the last decade as an important cause of pneumonia both hospital and community-acquired. Following an outbreak in a Renal-Transplant Unit stocked serum was tested for antibodies against Legionella pneumophila serogroup 1, and 5 cases of Legionnaires' Disease were reviewed. Two of the cases were nosocomial and three cases were community-acquired. Clinical and laboratorial aspects were similar to those expected for other causes of pneumonia, however jaundice was encountered in two cases. This study suggests that the real incidence of pneumonia caused by Legionella sp is being underestimated and the authors emphasize the importance of considering Legionnaires' Disease when empirically treating community-acquired pneumonia.

[Heart-lung transplantation. Initial clinical experience]

PURPOSE

To assess this initial clinical experience with heart-lung transplantation in Brazil.

METHODS

Four patients underwent heart-lung transplantation from December 1988 to March 1990, one patient with cardiomyopathy and high pulmonary resistance, two patients with primary pulmonary hypertension and another with pulmonary silicosis. The heart lung blocks were harvested from the donor using cardiopulmonary bypass and deep hypothermia. They were transplanted to the recipient by anastomosing the tracheae, right atrium or venae cavae, and the ascending aorta.

RESULTS

The second patient died on the 5th postoperative day due to respiratory insufficiency with consequent brain lesions. The first and third patients had survived nine months and 42 days respectively. The 4th patients is asymptomatic eight months after the operation. The main complications were bleeding in two patients, acute pulmonary rejection in three of them and obliterans bronchiolitis in one patients.

CONCLUSION

The heart lung transplantation is a challenging procedure which results are progressively improving with the development of better surgical technique and clinical concepts.