The Development of Attitudes Toward Scientific Models During a Participatory Modeling Process – The Impact of Participation and Social Network Structure

Scientific models are increasingly being used to support participatory natural resources management decision making processes. These models allow stakeholders and scientists to explore potential policy and management options and can help facilitate discussion surrounding concerning uncertainty and different sources of knowledge. The unique benefits of participatory modeling processes, however, are contingent upon stakeholders understanding of, engagement with, and willingness to use the scientific models as sources of knowledge and information. Little is known, however, about how stakeholders view scientific models within these processes. We examined changes in stakeholders’ attitudes toward scientific models over the course of OysterFutures, a 2-year, facilitated participatory modeling process that aimed to create consensus recommendations for oyster management in the Choptank River Complex, MD, United States. Five ordered logistic regression models were used to test hypotheses concerning the impact of social network measures, factors related to the participatory modeling process itself, and stakeholder characteristics on salience, credibility and legitimacy (SCL) attitudes toward models. Results suggested that stakeholders’ ways of knowing was a significant driver of salience, credibility and legitimacy elements of attitudes toward models. Additionally, acting as a gatekeeper within the social network resulted in significantly lower attitudes toward model credibility. These results indicate that the scientific model acted as a boundary object that facilitated discussion during the participatory modeling process. By better understanding the factors that influence model attitude formation, these processes can adjust their design and function to better take advantage of these models. Additionally, practitioners can have more realistic expectations concerning the role of models within participatory, collaborative natural resources decision-making processes

Intermittent or Continuous Therapy of Experimental Meningitis Due to Streptococcus pneumoniae in Rabbits: Preliminary Observations on the Postantibiotic Effect in Vivo

The relative effectiveness of bolus vs. constant intravenous administration of equivalent doses of penicillin G in killing bacteria in vivo was studied in a rabbit model of meningitis due to Streptococcus pneumoniae. Samples of cerebrospinal fluid (CSF) and serum were obtained from 30 rabbits at intervals of ⩽8 hr after treatment for determination of antibiotic concentrations and titers of viable bacteria in the CSF. When penicillin G was given by continuous infusion (105 units/hr after an initial l05-unit loading dose), concentrations of drug in serum and CSF reached a steady state in 1 hr. With intermittent bolus administration of 4 × 105 units every 4 hr, higher peak and lower trough concentrations were achieved, and these concentrations paralleled those in the CSF. Although an initial acceleration in bactericidal rate was observed with the bolus infusion between the first and second hour of therapy, after the second hour the rate of bacterial killing was identical for the two methods of administration. The duration of therapy required for sterilization of the CSF was dependent only on the bacterial count before treatment and not on the mode of drug administration. The effect of single bolus intravenous administration of ampicillin was examined in experimental pneumococcal meningitis. Ampicillin was given at various dosages (3.25-62.5 mg/kg), and frequent samples of CSF were obtained for determination of concentrations of pneumococci and ampicillin. A long postantibiotic effect was observed in the CSF of all animals, and this effect consistently was longer than that observed in vitr

Evaluation of azlocillin in-vitro and in discriminative animal models of infection

Azlocillin was more active in vitro than ticarcillin or carbenicillin against 561 aminoglycoside-resistant strains of Pseudomonas aeruginosa collected from 74 hospitals distributed over a wide geographic area in the eastern United States. Azlocillin was compared with various other antimicrobial agents in discriminative animal models of Ps. aeruginosa pyelonephritis, osteomyelitis, endocarditis, and meningitis in a variety of mammalian species. Cefsulodin was more effective than azlocillin in reducing Ps. aeruginosa kidney concentrations in rat pyelonephritis induced by intrarenal inoculation. The mean±s.d. logl0 cfu/g kidney after three days of therapy were as follows: controls = 5.4±1.5, azlocillin = 4.4±1.8, cefsulodin = 2.6±0.9 (P < 0.01) but the MBC for the test strain was eight-fold higher for azlocillin (8 vs. 1 mg/l) and effective concentrations were maintained longer in rat serum for cefsulodin as against azlocillin. In addition, ticarcillin reduced kidney bacterial concentrations faster than azlocillin in a mouse pyelonephritis model induced by intravenous Ps. aeruginosa inoculation with subsequent iron loading. Azlocillin was less effective than tobramycin in experimental chronic Ps. aeruginosa osteomyelitis induced in rabbits by direct injection into the tibia. An azlocillin-tobramycin regimen was not more effective than tobramycin alone. After 28 days of therapy, the percentages of positive bone cultures after death were as follows: no antibiotic (controls) = 92%, azlocillin = 95%, tobramycin = 76%, azlocillin plus tobramycin = 60%. Both ticarcillin and azlocillin were less active than tobramycin in experimental Ps. aeruginosa endocarditis induced in rabbits by intravenous inoculation of 108 cfu following 1 h of catheter induced aortic valve trauma. The best results were noted with an azlocillin-tobramycin regimen. The mean±s.d. log10 cfu Ps. aeruginosa/g vegetation after five days of therapy were as follows: no antibiotic controls = 8.1 ± 1.1, tobramycin = 4.5 ±0.8, ticarcillin = 6.9 ± 0.8, azlocillin = 5.7 ± 1.5, ticarcillin phis tobramycin = 4.9 ± 1.0, azlocillin plus tobramycin = 3.3 ± 1.6. Sterile vegetations were rarely attained with any regimen. The mean percentage penetration into purulent cerebrospinal fluid (CSF) in experimental Ps. aeruginosa meningitis for azlocillin was 13.3%, comparable to many other β-lactam antibiotics. Azlocillin was the single most active (P < 0.01) agent evaluated after 8 h intravenous infusions in this model. An azlocillin-amikacin regimen was more rapidly bactericidal (P < 0.01) than either agent alone in vivo. None of the agents evaluated alone or in combination, however, produced a sterile CSF after 8 h of therapy in any anima

An A2A adenosine receptor agonist, ATL313, reduces inflammation and improves survival in murine sepsis models

<p>Abstract</p> <p>Background</p> <p>The pathophysiology of sepsis is due in part to early systemic inflammation. Here we describe molecular and cellular responses, as well as survival, in A_2Aadenosine receptor (AR) agonist treated and untreated animals during experimental sepsis.</p> <p>Methods</p> <p>Sepsis was induced in mice by intraperitoneal inoculation of live bacteria (<it>Escherichia coli </it>or <it>Staphylococcus aureus</it>) or lipopolysaccharide (LPS). Mice inoculated with live bacteria were treated with an A_2AAR agonist (ATL313) or phosphate buffered saline (PBS), with or without the addition of a dose of ceftriaxone. LPS inoculated mice were treated with ATL313 or PBS. Serum cytokines and chemokines were measured sequentially at 1, 2, 4, 8, and 24 hours after LPS was administered. In survival studies, mice were followed until death or for 7 days.</p> <p>Results</p> <p>There was a significant survival benefit in mice infected with live <it>E. coli </it>(100% vs. 20%, <it>p </it>= 0.013) or <it>S. aureus </it>(60% vs. 20%, <it>p </it>= 0.02) when treated with ATL313 in conjunction with an antibiotic versus antibiotic alone. ATL313 also improved survival from endotoxic shock when compared to PBS treatment (90% vs. 40%, <it>p </it>= 0.005). The serum concentrations of TNF-α, MIP-1α, MCP-1, IFN-γ, and IL-17 were decreased by ATL313 after LPS injection (<it>p </it>< 0.05). Additionally, ATL313 increased the concentration of IL-10 under the same conditions (<it>p </it>< 0.05). Circulating white blood cell concentrations were higher in ATL313 treated animals (<it>p </it>< 0.01).</p> <p>Conclusion</p> <p>Further studies are warranted to determine the clinical utility of ATL313 as a novel treatment for sepsis.</p

The thrombotic potential of oral pathogens

In recent times the concept of infectious agents playing a role in cardiovascular disease has attracted much attention. Chronic oral disease such as periodontitis, provides a plausible route for entry of bacteria to the circulation. Upon entry to the circulation, the oral bacteria interact with platelets. It has been proposed that their ability to induce platelet aggregation and support platelet adhesion is a critical step in the pathogenesis of the infection process. Many published studies have demonstrated multiple mechanisms through which oral bacteria are able to bind to and activate platelets. This paper will review the various mechanisms oral bacteria use to interact with platelets