Extraction of Trypanosoma cruzi DNA from food: a contribution to the elucidation of acute Chagas disease outbreaks

Abstract: INTRODUCTION: Before 2004, the occurrence of acute Chagas disease (ACD) by oral transmission associated with food was scarcely known or investigated. Originally sporadic and circumstantial, ACD occurrences have now become frequent in the Amazon region, with recently related outbreaks spreading to several Brazilian states. These cases are associated with the consumption of açai juice by waste reservoir animals or insect vectors infected with Trypanosoma cruzi in endemic areas. Although guidelines for processing the fruit to minimize contamination through microorganisms and parasites exist, açai-based products must be assessed for quality, for which the demand for appropriate methodologies must be met. METHODS: Dilutions ranging from 5 to 1,000 T. cruzi CL Brener cells were mixed with 2mL of acai juice. Four Extraction of T. cruzi DNA methods were used on the fruit, and the cetyltrimethyl ammonium bromide (CTAB) method was selected according to JRC, 2005. RESULTS: DNA extraction by the CTAB method yielded satisfactory results with regard to purity and concentration for use in PCR. Overall, the methods employed proved that not only extraction efficiency but also high sensitivity in amplification was important. CONCLUSIONS: The method for T. cruzi detection in food is a powerful tool in the epidemiological investigation of outbreaks as it turns epidemiological evidence into supporting data that serve to confirm T. cruzi infection in the foods. It also facilitates food quality control and assessment of good manufacturing practices involving acai-based products

Content Sponsoring with Inter-ISP Transit Cost

As sponsored data gains popularity in industry, it is essential to understand its impact on the Internet service market. We investigate the interplay among Internet Service Providers (ISPs), Content Provider (CP) and End User (EU), where each player is selfish and wants to maximize its own profit. In particular, we consider multi-ISP scenarios, in which the network connectivity between the CP and the EU is jointly provided by multiple ISPs. We model the non-cooperative interaction between the players as a four-stage Stackelberg game, and derive the optimal behaviors of each player in equilibrium. Taking into account the transit price at intermediate ISP, we provide in-depth understanding on the sponsoring strategies of CP, and verify our results through numerical simulations

Trust-based exchange of services to motivate cooperation in P2P networks

In this paper we propose a trust-based exchange framework to motivate cooperation among peers of different consumption, contribution and service evaluation profiles. Our framework consists of distributed resource allocation and server selection policies based on local reputation vectors. We present how proposed policies outperform previous work and lead to the autonomic formation of coalitions between peers who mutually profit by exchanging their services. In this way the utilities of all peers progressively improve without pre-existing knowledge of one another's service evaluation and capability profiles. Peers' coalitions are dynamically reformatted, adapting to network changes, e.g., when new peers enter the system or peers vary their profiles. Only misbehaving (non contributive) peers cannot benefit by our framework, which efficiently blocks misbehavior