Browsing by Author "Maasa, Robinah K."

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    ASSESSMENT OF PROCEDURAL ASPECTS AND QUALITY CONTROL IN HUMAN PLACENTAL RNA ISOLATION PROTOCOLS
    (Office of the Vice Chancellor for Research, 2012-04-13) Maasa, Robinah K.; Sanders, Kerry L.; Creekmore, Amy L.; Lee, Men-Jean; Reiter, Jill L.
    High quality RNA is of paramount importance in accurately interpreting gene expression changes in the placenta throughout pregnancy, as well as in common placental pathologies. The purpose of this study was to develop a standard operating procedure for the collection of human placental tissue and isolation of high quality RNA for pregnancy-related molecular studies. To accomplish this task, we compared several different parameters to minimize RNA degradation, including preservation (liquid nitrogen vs. RNAlater), dis-ruption (mortar/pestle vs. homogenization), and isolation (Trizol vs. RNeasy). We performed 150 RNA isolations from 30 term placentas. The overall yield was 365 ± 197 ng RNA per mg of tissue. The A260/280 ratio for all samples was 2.11 ± 0.1 (mean ± s.d.) and the RQI was 7.1 ± 1.4. No significant differences in RNA purity, yield, or quality were observed between different placental collections or RNA isolation techniques. However, poor RQI values of 2.7 to 3.3 were obtained after brief thawing of frozen placental samples. We also compared storage of RNAlater stabilized tissue at 4 de-grees or room temperature for 1 day, 7 days, and 30 days. The integrity of RNA stored at room temperature for 1 day was significantly better (P‹0.05 RQI 7.3 ± 0.58, mean ± s.d) than RNA stored at room temperature for 30 days (RQI 5.0 ±1.2, mean ± s.d). The results of these studies will be useful for establishing standard procedures for placenta collection for pregnancy biobanks.
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    Interaction of Model Lipid Vesicles with Alveolar Macrophages
    (Office of the Vice Chancellor for Research, 2014-04-11) Maasa, Robinah K.; Justice, Matthew J.; Petrusca, Daniela N.; Petrache, Horia I.
    Macrophages are a type of white blood cells that play key roles in host defense by recognizing and engulfing foreign and apoptotic bodies. To accomplish this task, they rely on complex molecular interactions involving both lipids and proteins. Previous studies have shown that surface exposure of phosphatidylserine by apoptotic cells is required for their successful clearance, suggesting specific lipid-protein interactions at least for the initiation of phagocytosis of apoptotic cells. However, macrophages can engulf foreign and apoptotic bodies that substantially vary in size suggesting that non-specific interactions over a range of length scales may be relevant. The purpose of our study is to investigate the correlation between physical properties of lipid bilayers and their engulfment by macrophages. We modify bilayer properties systematically as a function of phospholipid headgroup composition and by addition of ceramide and cholesterol. We use a combination of scattering and spectroscopic methods to quantify lipid interactions and flow cytometry to measure engulfment rates. This study can help distinguish between the role of lipids and proteins in clearance of apoptotic and foreign particles.