Biomedical subjects

A Murciano

Publications and source records attributed to A Murciano.

5 recordsLinked to original sources

PubMed1998

Learning and stabilization of altruistic behaviors in multi-agent systems by reciprocity.

Optimization of performance in collective systems often requires altruism. The emergence and stabilization of altruistic behaviors are difficult to achieve because the agents incur a cost when behaving altruistically. In this paper, we propose a biologically inspired strategy to learn stable altruistic behaviors in artificial multi-agent systems, namely reciprocal altruism. This strategy in conjunction with learning capabilities make altruistic agents cooperate only between themselves, thus preventing their exploitation by selfish agents, if future benefits are greater than the current cost of altruistic acts. Our multi-agent system is made up of agents with a behavior-based architecture. Agents learn the most suitable cooperative strategy for different environments by means of a reinforcement learning algorithm. Each agent receives a reinforcement signal that only measures its individual performance. Simulation results show how the multi-agent system learns stable altruistic behaviors, so achieving optimal (or near-to-optimal) performances in unknown and changing environments.

Altruism↗

PubMed1997

Specialization in multi-agent systems through learning.

Specialization is a common feature in animal societies that leads to an improvement in the fitness of the team members and to an increase in the resources obtained by the team. In this paper we propose a simple reinforcement learning approach to specialization in an artificial multi-agent system. The system is composed of homogeneous and non-communicating agents. Because there is no communication, the number of agents in the team can easily scale up. Agents have the same initial functionalities, but they learn to specialize and so cooperate to achieve a complex gathering task efficiently. Simulation experiments show how the multi-agent system specializes appropriately so as to reach optimal (or near-to-optimal) performance in unknown and changing environments.

Animal Communication↗

PubMed1990

A novel enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to HIV-1 envelope glycoproteins based on immobilization of viral glycoproteins in microtiter wells coated with concanavalin A.

We have developed a novel method that greatly simplifies the preparation of solid-phase HIV-1 envelope glycoproteins for use in an ELISA that detects serum antibodies to HIV envelope antigens. This method utilizes concanavalin A absorbed to wells of microtiter plates to affinity immobilize detergent-solubilized viral glycoproteins released in culture fluids of HIV-1 infected cell lines grown in serum free medium. Antibodies binding to ConA-immobilized viral antigens are detected by peroxidase-conjugated antibodies and appropriate enzyme substrates. Unlike most commercial HIV ELISAs, which utilize gp120 depleted-purified virus as the source of antigens and thus favor detection of antibodies to core antigens, the ConA envELISA is highly sensitive for detecting antibodies to native gp120, as evidenced by the strong reactivity of gp120-specific human monoclonal antibodies. Our results also suggest that representation of gp41 in the assay varies and depends on which virus infected cell lines are used for antigen production. Since this assay accurately identified 14 HIV-1 antibody positive patient sera and no false positives were detected among 16 HIV-1 negative sera, the ConA envELISA shows promise as an inexpensive assay for the serologic diagnosis of HIV infections.

Animals↗

PubMed1990

Successful treatment of disseminated Fusarium infection in an immunocompromised child.

We report the first know case of disseminated fungal infection due to Fusarium proliferatum in a bone marrow transplant recipient to our knowledge. Fusarium was cultured from the blood, a paranasal sinus, and necrotic skin lesions. The isolate was sensitive to amphotericin B and on further sensitivity testing, synergy was demonstrated using rifampin in combination with amphotericin B. The patient had this infection while she was receiving alternate-day amphotericin, rifampin, and 5-flucytosine (5-FC) therapy. The infection was documented within 48 h of discontinuing daily granulocyte transfusions, which she had received for 3 weeks. The 5-FC was discontinued when sensitivities showed the organism resistant. After 6 weeks of treatment she showed complete remission of the infection, although neutrophil counts remained below 0.25 X 10(9)/L. From this case and from a review of the literature, it appears that synergic antifungal agents combined with leukocyte transfusions may be beneficial in the successful treatment of fusariosis in the compromised host.

Amphotericin B↗

PubMed1990

Paecilomyces lilacinus infection in an immunocompromised patient.

Systemic infections caused by saprophytic fungi are being diagnosed more frequently. We describe the second reported instance of Paecilomyces lilacinus causing infection in an immunocompromised host. The diagnosis and treatment of this unusual pathogen are discussed.

Child↗