Communication Challenges During the Development and Introduction of a New Meningococcal Vaccine in Africa.

BACKGROUND: A new group A meningococcal conjugate vaccine was developed to eliminate deadly meningitis epidemics in sub-Saharan Africa. METHODS: From the outset of the project, advocacy and communication strategies were developed and adjusted as the project evolved in Europe, Africa, India, and the United States. Communications efforts were evidence-based, and involved partnerships with the media and various stakeholders including African ministries of health, the World Health Organization, UNICEF, Gavi, the Centers for Disease Control and Prevention, and Médecins Sans Frontières. RESULTS: The implementation of an integrated communication strategy ensured the active cooperation of stakeholders while providing an organized and defined format for the dissemination of project-related developmental activities and the successful introduction of the vaccine. CONCLUSIONS: Early in the project, a communications strategy that engaged stakeholders and potential supporters was developed. The strategy was implemented and adapted as the project matured. Linked communication proved to be key to the successful wide-scale introduction of the PsA-TT (MenAfriVac) vaccine in Africa.

Reaction diffusion modeling of calcium dynamics with realistic ER geometry.

We describe a finite-element model of mast cell calcium dynamics that incorporates the endoplasmic reticulum's complex geometry. The model is built upon a three-dimensional reconstruction of the endoplasmic reticulum (ER) from an electron tomographic tilt series. Tetrahedral meshes provide volumetric representations of the ER lumen, ER membrane, cytoplasm, and plasma membrane. The reaction-diffusion model simultaneously tracks changes in cytoplasmic and ER intraluminal calcium concentrations and includes luminal and cytoplasmic protein buffers. Transport fluxes via PMCA, SERCA, ER leakage, and Type II IP3 receptors are also represented. Unique features of the model include stochastic behavior of IP3 receptor calcium channels and comparisons of channel open times when diffusely distributed or aggregated in clusters on the ER surface. Simulations show that IP3R channels in close proximity modulate activity of their neighbors through local Ca2+ feedback effects. Cytoplasmic calcium levels rise higher, and ER luminal calcium concentrations drop lower, after IP3-mediated release from receptors in the diffuse configuration. Simulation results also suggest that the buffering capacity of the ER, and not restricted diffusion, is the predominant factor influencing average luminal calcium concentrations.

Interplay of ryanodine receptor distribution and calcium dynamics.

Spontaneously generated calcium (Ca2+) waves can trigger arrhythmias in ventricular and atrial myocytes. Yet, Ca2+ waves also serve the physiological function of mediating global Ca2+ increase and muscle contraction in atrial myocytes. We examine the factors that influence Ca2+ wave initiation by mathematical modeling and large-scale computational (supercomputer) simulations. An important finding is the existence of a strong coupling between the ryanodine receptor distribution and Ca2+ dynamics. Even modest changes in the ryanodine receptor spacing profoundly affect the probability of Ca2+ wave initiation. As a consequence of this finding, we suggest that there is information flow from the contractile system to the Ca2+ control system and this dynamical interplay could contribute to the increased incidence of arrhythmias during heart failure.