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  1. Abstract

    Bloodstream infections, especially those that are antibiotic resistant, pose a significant challenge to health care leading to increased hospitalization time and patient mortality. There are different facets to this problem that make these diseases difficult to treat, such as the difficulty to detect bacteria in the blood and the poorly understood mechanism of bacterial invasion into and out of the circulatory system. However, little progress has been made in developing techniques to study bacteria dynamics in the bloodstream. Here, we present a new approach using anin vivoflow cytometry platform for real‐time, noninvasive, label‐free, and quantitative monitoring of the lifespan of green fluorescent protein‐expressingStaphylococcus aureusandPseudomonas aeruginosain a murine model. We report a relatively fast average rate of clearance forS. aureus(k= 0.37 ± 0.09 min−1, half‐life ~1.9 min) and a slower rate forP. aeruginosa(k= 0.07 ± 0.02 min−1, half‐life ~9.6 min). We also observed what appears to be two stages of clearance forS. aureus, whileP. aeruginosaappeared only to have a single stage of clearance. Our results demonstrate that an advanced research tool can be used for studying the dynamics of bacteria cells directly in the bloodstream, providing insight into the progression of infectious diseases in circulation. © 2019 International Society for Advancement of Cytometry

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  2. Abstract

    Most cancer patients die from metastatic disease as a result of a circulating tumor cell (CTC) spreading from a primary tumor through the blood circulation to distant organs. Many studies have demonstrated the tremendous potential of using CTC counts as prognostic markers of metastatic development and therapeutic efficacy. However, it is only the viable CTCs capable of surviving in the blood circulation that can create distant metastasis. To date, little progress has been made in understanding what proportion of CTCs is viable and what proportion is in an apoptotic state. Here, we introduce a novel approach toward in situ characterization of CTC apoptosis status using a multicolor in vivo flow cytometry platform with fluorescent detection for the real‐time identification and enumeration of such cells directly in blood flow. The proof of concept was demonstrated with two‐color fluorescence flow cytometry (FFC) using breast cancer cells MDA‐MB‐231 expressing green fluorescein protein (GFP), staurosporine as an activator of apoptosis, Annexin‐V apoptotic kit with orange dye color, and a mouse model. The future application of this new platform for real‐time monitoring of antitumor drug efficiency is discussed. © 2019 International Society for Advancement of Cytometry

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