Universidade Estadual de Londrina

About: Universidade Estadual de Londrina is a(n) education organization based out in Londrina, Brazil. It is known for research contribution in the topic(s): Population & Toxoplasma gondii. The organization has 13052 authors who have published 19291 publication(s) receiving 212123 citation(s).

Stress, depression, the immune system, and cancer

Abstract: The links between the psychological and physiological features of cancer risk and progression have been studied through psychoneuroimmunology. The persistent activation of the hypothalamic-pituitary-adrenal (HPA) axis in the chronic stress response and in depression probably impairs the immune response and contributes to the development and progression of some types of cancer. Here, we overview the evidence that various cellular and molecular immunological factors are compromised in chronic stress and depression and discuss the clinical implications of these factors in the initiation and progression of cancer. The consecutive stages of the multistep immune reactions are either inhibited or enhanced as a result of previous or parallel stress experiences, depending on the type and intensity of the stressor and on the animal species, strain, sex, or age. In general, both stressors and depression are associated with the decreased cytotoxic T-cell and natural-killer-cell activities that affect processes such as immune surveillance of tumours, and with the events that modulate development and accumulation of somatic mutations and genomic instability. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to new clinical and treatment strategies.

Averting biodiversity collapse in tropical forest protected areas

Abstract: The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon(1-3). With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses(4-9). As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world's major tropical regions. Our analysis reveals great variation in reserve 'health': about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.

Silver nanoparticles: A new view on mechanistic aspects on antimicrobial activity

Abstract: Silver nanoparticles are well known potent antimicrobial agents. Although significant progresses have been achieved on the elucidation of antimicrobial mechanism of silver nanoparticles, the exact mechanism of action is still not completely known. This overview incorporates a retrospective of previous reviews published and recent original contributions on the progress of research on antimicrobial mechanisms of silver nanoparticles. The main topics discussed include release of silver nanoparticles and silver ions, cell membrane damage, DNA interaction, free radical generation, bacterial resistance and the relationship of resistance to silver ions versus resistance to silver nanoparticles. The focus of the overview is to summarize the current knowledge in the field of antibacterial activity of silver nanoparticles. The possibility that pathogenic microbes may develop resistance to silver nanoparticles is also discussed. From the Clinical Editor Antibacterial effect of nanoscopic silver generated a lot of interest both in research projects and in practical applications. However, the exact mechanism is still will have to be elucidated. This overview incorporates a retrospective of previous reviews published from 2007 to 2013 and recent original contributions on the progress of research on antimicrobial mechanisms to summarize our current knowledge in the field of antibacterial activity of silver nanoparticles.

FREIRE, Paulo. Pedagogia da autonomia: saberes necessários à prática educativa. 25. ed. São Paulo: Paz e Terra, 1996.

Abstract: Paulo Freire inicia seu livro declarando sua aversao ao neoliberalismo e sua influencia na sociedade, tornando-a desigual e excludente. Critica ainda a malvadez transvestida de etica que o mercado adota para o seu proprio beneficio.

Water sorption and mechanical properties of cassava starch films and their relation to plasticizing effect

Abstract: Effects of plasticizers (glycerol, sorbitol, and 1:1 mixture of glycerol and sorbitol) on moisture sorption characteristics of cassava starch films were investigated at three levels of plasticizer concentration (0, 20, and 40 g/100 g starch). The combined effects of relative humidity and plasticizer on mechanical properties of starch films were also examined. Water affinities of cassava starch films were affected by hydrophilicity of the plasticizer and its concentration. Films plasticized with glycerol, under all RH conditions, adsorbed more moisture with higher initial adsorption rate, and films with higher plasticizers contents exhibited higher equilibrium moisture contents. Mechanical properties were affected by plasticizing effect, including the water adsorbed, resulting in higher strain and Young's modulus values for starch films and, in all cases, glycerol exerted a more effective plasticization.