3 resultados para defense mechanisms

em Digital Commons at Florida International University


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In a study of the effects on animals of seed protein extracts of 15 Malesian members of the Leguminosae (including 11 rain forest tree species), most of the taxa agglutinated red blood cells, induced mitosis, and inhibited amylases. These results are consistent with the hypothesis that these proteins interact with other organisms, most probably in defense mechanisms against predation by animals. The functions of these proteins are most profitably studied in rain forest environments where their activity is so marked, and where biological interactions are particularly important.

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Majority of the microbial activity in humans is in the form of biofilms i.e. an Exopolysaccharide-enclosed bacterial mass. Unlike planktonic cells and the cells on the surface of the biofilm, the biofilm-embedded cells are more resistant to the effects of the antibiotics and the host cellular defense mechanisms. A combination of biofilm growth and inherent resistance prevents effective antibiotics treatment of Pseudomonas aeruginosa infections including those in patients with cystic fibrosis. This has lead to an increasing interest in alternative modalities of treatment. Thus, phages that multiply in situ, only in the presence of susceptible hosts can be used as natural, self-limiting, and deeply penetrating antibacterial agents. The objective of this study is to identify effective phages against a collection of P. aeruginosa isolates (PCOR strains) including the prototype PAOl and the isogenic constitutively alginate-producing PD0300 strains.These PCOR strains were tested against six phages (P105, P134, P140, P168, P175B and P182). Analysis shows 69 % of the PCOR isolates are sensitive and the rest are resistant to all six phages. These phages were then tested for their ability to inhibit biofilm formation using a modified biofilm assay. The analysis demonstrated that the sensitive strains showed increased resistance but none of the sensitive strains from the initial screening were resistant. Using the minimum biofilm eradication concentration (MBEC) assay for biofilm formation, the biofilm eradication ability of the phages was tested. The data showed that a higher volume of phage was required to eradicate preformed biofilms than the volume required to prevent colonization of planktonic cells. This data supports the idea of phage therapy more as a prophylactic treatment.

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For the first time in more than fifty years, the domestic and external conflicts in Latin America and the Caribbean (LAC) are not primarily ideological in nature. Democracy continues to thrive and its promise still inspires hope. In contrast, the illegal production, consumption, and trading of drugs – and its links to criminal gangs and organizations – represent major challenges to the region, undermining several States’ already weak capacity to govern. While LAC macroeconomic stability has remained resilient, illegal economies fill the region, often offering what some States have not historically been able to provide – elements of human security, opportunities for social mobility, and basic survival. Areas controlled by drug trafficking organizations (DTOs) are now found in Central America, Mexico, and the favelas of Rio de Janeiro and São Paulo, reflecting their competition for land routes and production areas. Cartels such as La Familia, Los Zetas, and Primeiro Comando da Capital (PCC-Brazil), among others, operate like trade and financial enterprises that manage millions of dollars and resources, demonstrating significant business skills in adapting to changing circumstances. They are also merciless in their application of violence to preserve their lucrative enterprises. The El Salvador-Guatemala-Honduras triangle in Central America is now the most violent region in the world, surpassing regions in Africa that have been torn by civil strife for years. In Brazil’s favelas and Guatemala’s Petén region, the military is leaving the barracks again; not to rule, however, but to supplement and even replace the law enforcement capacity of weak and discredited police forces. This will challenge the military to apply lessons learned during the course of their experience in government, or from the civil wars that plagued the region for nearly 50 years during the Cold War. Will they be able to conduct themselves according to the professional ethics that have been inculcated over the past 20 years without incurring violations of human rights? Belief in their potential to do good is high according to many polls as the Armed Forces still enjoy a favorable perception in most societies, despite frequent involvement in corruption. Calling them to fight DTOs, however, may bring them too close to the illegal activities they are being asked to resist, or even rekindle the view that only a “strong hand” can resolve national troubles. The challenge of governance is occurring as contrasts within the region are becoming sharper. There is an increasing gap between nations positioned to surpass their “developing nation” status and those that are practically imploding as the judicial, political and enforcement institutions fall further into the quagmire of illicit activities. Several South American nations are advancing their political and economic development. Brazil in particular has realized macro-economic stability, made impressive gains in poverty reduction, and is on track to potentially become a significant oil producer. It is also an increasingly influential power, much closer to the heralded “emerging power” category that it aspired to for most of the 20th century. In contrast, several Central American States have become so structurally deficient, and have garnered such limited legitimacy, that their countries have devolved into patches of State controlled and non-State-controlled territory, becoming increasingly vulnerable to DTO entrenchment. In the Caribbean, the drug and human trafficking business also thrives. Small and larger countries are experiencing the growing impact of illicit economies and accompanying crime and violence. Among these, Guyana and Suriname face greater uncertainty, as they juggle both their internal affairs and their relations with Brazil and Venezuela. Cuba also faces new challenges as it continues focusing on internal rather than external affairs and attempts to ensure a stable leadership succession while simultaneously trying to reform its economy. Loosening the regime’s tight grip on the economy while continuing to curtail citizen’s civil rights will test the leadership’s ability to manage change and prevent a potential socio-economic crisis from turning into an existential threat. Cuba’s past ideological zest is now in the hands of Venezuela’s President Hugo Chavez, who continues his attempts to bring the region together under Venezuelan leadership ideologically based on a “Bolivarian” anti-U.S. banner, without much success. The environment and natural disasters will merit more attention in the coming years. Natural events will produce increasing scales of destruction as the States in the region fail to maintain and expand existing infrastructure to withstand such calamities and respond to their effects. Prospects for earthquakes, tsunamis, and hurricanes are high, particularly in the Caribbean. In addition, there are growing rates of deforestation in nearly every country, along with a potential increase in cross-sector competition for resources. The losers might be small farmers, due to their inability to produce quantities commensurate to larger conglomerates. Regulations that could mitigate these types of situations are lacking or openly violated with near impunity. Indigenous and other vulnerable populations, including African descendants, in several Andean countries, are particularly affected by the increasing extraction of natural resources taking place amongst their terrain. This has led to protests against extraction activities that negatively affect their livelihoods, and in the process, these historically underprivileged groups have transitioned from agenda-based organization to one that is bringing its claims and grievances to the national political agenda, becoming more politically engaged. Symptomatic of these social issues is the region’s chronically poor quality of education that has consistently failed to reduce inequality and prepare new generations for jobs in the competitive global economy, particularly the more vulnerable populations. Simultaneously, the educational deficit is also exacerbated by the erosion of access to information and freedom of the press. The international panorama is also in flux. New security entities are challenging the old establishment. The Union of South American Nations, The South American Defense Council, the socialist Bolivarian Alliance, and other entities seem to be defying the Organization of American States and its own defense mechanisms, and excluding the U.S. And the U.S.’s attention to areas in conflict, namely Iraq, Afghanistan, and Pakistan – rather than to the more stable Latin America and Caribbean – has left ample room for other actors to elbow in. China is now the top trading partner for Brazil. Russian and Iran are also finding new partnerships in the region, yet their links appear more politically inclined than those of China. Finally, the aforementioned increasing commercial ties by LAC States with China have accelerated a return to the preponderance of commodities as sources of income for their economies. The increased extraction of raw material for export will produce greater concern over the environmental impact that is created by the exploitation of natural resources. These expanded trade opportunities may prove counterproductive economically for countries in the region, particularly for Brazil and Chile, two countries whose economic policies have long sought diversification from dependence on commodities to the development of service and technology based industries.