3 research outputs found
Hematopoietic Stem and Progenitor Cells as Effectors in Innate Immunity
Recent research has shed light on novel functions of hematopoietic stem and progenitor cells (HSPC). While they are critical for maintenance and replenishment of blood cells in the bone marrow, these cells are not limited to the bone marrow compartment and function beyond their role in hematopoiesis. HSPC can leave bone marrow and circulate in peripheral blood and lymph, a process often manipulated therapeutically for the purpose of transplantation. Additionally, these cells preferentially home to extramedullary sites of inflammation where they can differentiate to more mature effector cells. HSPC are susceptible to various pathogens, though they may participate in the innate immune response without being directly infected. They express pattern recognition receptors for detection of endogenous and exogenous danger-associated molecular patterns and respond not only by the formation of daughter cells but can themselves secrete powerful cytokines. This paper summarizes the functional and phenotypic characterization of HSPC, their niche within and outside of the bone marrow, and what is known regarding their role in the innate immune response
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HVAC filters as a sampling mechanism for indoor contaminants
Indoor air quality investigations often focus on air and settled dust samples to assess chemical and biological contamination. Although the information provided by these techniques is useful, HVAC filters represent a new option for investigating contaminants in the indoor environment. This dissertation explores the potential use of HVAC filters as long-term, passive samplers by investigating the contaminants found in HVAC dust and other indoor locations and by evaluating the likelihood that HVAC filters will capture indoor particles. A field investigation of heavy metal and culturable microbial contaminants found in air, settled dust and HVAC filter dust corroborated the hypothesis that HVAC filters hold promise as a sampling mechanism in residences. However, several factors including filter efficiency, HVAC cycling and particle size seemed to influence the results. Also, it was unclear how the composition of the microbial communities varied with sampling location. Subsequently, the bacterial and fungal communities present in several sampling locations within residences and in an unoccupied test house were investigated. In residences, the microbial communities encountered in HVAC filter dust were not different from those in high surface dust. High efficiency HVAC filters also seem to be a viable alternative to long-term air sampling. Occupants influence the composition of the microbial communities in residences and are viii associated with Actinobacteria and Firmicutes, while Proteobacteria dominate the air samples and might have an outdoor air origin. A fate analysis to assess the magnitude of the different particle removal mechanisms revealed that small and large particles are likely to deposit on surfaces, while intermediate sized particles stay suspended in air longer. HVAC filters can collect particulate matter over a broad size range and may be effective overall samplers of particle-bound contaminants. Nevertheless, filter efficiency and air recirculation rate are important parameters that influence the likelihood that filters will capture particles, while air exchange rate has little effect. The results from this study indicate that HVAC filters can be used as an alternative to traditional indoor sampling mechanisms for contaminants associated with particles.Civil, Architectural, and Environmental Engineerin