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52. Breast Cancer Reconstruction: Design Criteria for a Humanized Microphysiological System

Author

Frazier, Trivia, primary, Williams, Christopher, additional, Henderson, Michael, additional, Duplessis, Tamika, additional, Rogers, Emma, additional, Wu, Xiying, additional, Hamel, Katie, additional, Martin, Elizabeth C., additional, Mohiuddin, Omair, additional, Shaik, Shahensha, additional, Devireddy, Ram, additional, Rowan, Brian G., additional, Hayes, Daniel J., additional, and Gimble, Jeffrey M., additional

Published
2021
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54. Communication: Broad manifold of excitonic states in light-harvesting complex 1 promotes efficient unidirectional energy transfer in vivo.

Author

Sohail, Sara H., Dahlberg, Peter D., Allodi, Marco A., Massey, Sara C., Po-Chieh Ting, Martin, Elizabeth C., Hunter, C. Neil, and Engel, Gregory S.

Subjects
EXCITON theory, ENERGY transfer, PHOTONS, FEMTOSECOND pulses, PHOTOCHEMISTRY, PHYSICAL & theoretical chemistry
Abstract

In photosynthetic organisms, the pigment-protein complexes that comprise the light-harvesting antenna exhibit complex electronic structures and ultrafast dynamics due to the coupling among the chromophores. Here, we present absorptive two-dimensional (2D) electronic spectra from living cultures of the purple bacterium, Rhodobacter sphaeroides, acquired using gradient assisted photon echo spectroscopy. Diagonal slices through the 2D lineshape of the LH1 stimulated emission/ground state bleach feature reveal a resolvable higher energy population within the B875 manifold. The waiting time evolution of diagonal, horizontal, and vertical slices through the 2D lineshape shows a sub-100 fs intra-complex relaxation as this higher energy population red shifts. The absorption (855 nm) of this higher lying sub-population of B875 before it has red shifted optimizes spectral overlap between the LH1 B875 band and the B850 band of LH2. Access to an energetically broad distribution of excitonic states within B875 offers a mechanism for efficient energy transfer from LH2 to LH1 during photosynthesis while limiting back transfer. Two-dimensional lineshapes reveal a rapid decay in the ground-state bleach/stimulated emission of B875. This signal, identified as a decrease in the dipole strength of a strong transition in LH1 on the red side of the B875 band, is assigned to the rapid localization of an initially delocalized exciton state, a dephasing process that frustrates back transfer from LH1 to LH2. [ABSTRACT FROM AUTHOR]

Published
2017
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58. Structures of Rhodopseudomonas palustris RC-LH1 complexes with open or closed quinone channels

Author

Swainsbury, David J. K., primary, Qian, Pu, additional, Jackson, Philip J., additional, Faries, Kaitlyn M., additional, Niedzwiedzki, Dariusz M., additional, Martin, Elizabeth C., additional, Farmer, David A., additional, Malone, Lorna A., additional, Thompson, Rebecca F., additional, Ranson, Neil A., additional, Canniffe, Daniel P., additional, Dickman, Mark J., additional, Holten, Dewey, additional, Kirmaier, Christine, additional, Hitchcock, Andrew, additional, and Hunter, C. Neil, additional

Published
2021
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59. Xanthophyll carotenoids stabilise the association of cyanobacterial chlorophyll synthase with the LHC-like protein HliD

Author

Proctor, Matthew S., primary, Pazderník, Marek, additional, Jackson, Philip J., additional, Pilný, Jan, additional, Martin, Elizabeth C., additional, Dickman, Mark J., additional, Canniffe, Daniel P., additional, Johnson, Matthew P., additional, Hunter, C. Neil, additional, Sobotka, Roman, additional, and Hitchcock, Andrew, additional

Published
2020
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60. ERK5 Is Required for Tumor Growth and Maintenance Through Regulation of the Extracellular Matrix in Triple Negative Breast Cancer

Author

Hoang, Van T., primary, Matossian, Margarite D., additional, Ucar, Deniz A., additional, Elliott, Steven, additional, La, Jacqueline, additional, Wright, Maryl K., additional, Burks, Hope E., additional, Perles, Aaron, additional, Hossain, Fokhrul, additional, King, Connor T., additional, Browning, Valentino E., additional, Bursavich, Jacob, additional, Fang, Fang, additional, Del Valle, Luis, additional, Bhatt, Akshita B., additional, Cavanaugh, Jane E., additional, Flaherty, Patrick T., additional, Anbalagan, Muralidharan, additional, Rowan, Brian G., additional, Bratton, Melyssa R., additional, Nephew, Kenneth P., additional, Miele, Lucio, additional, Collins-Burow, Bridgette M., additional, Martin, Elizabeth C., additional, and Burow, Matthew E., additional

Published
2020
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61. Acellular Biologic Nipple–Areolar Complex Graft: In Vivo Murine and Nonhuman Primate Host Response Evaluation

Author

Pashos, Nicholas C., primary, Graham, David M., additional, Burkett, Brian J., additional, O'Donnell, Ben, additional, Sabol, Rachel A., additional, Helm, Joshua, additional, Martin, Elizabeth C., additional, Bowles, Annie C., additional, Heim, William M., additional, Caronna, Vince C., additional, Miller, Kristin S., additional, Grasperge, Brooke, additional, Sullivan, Scott, additional, Chaffin, Abigail E., additional, and Bunnell, Bruce A., additional

Published
2020
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62. Abstract C110: Applications of patient-derived triple-negative breast cancer xenografts that represent understudied patients in Louisiana in targeted therapeutic research

Author

Matossian, Margarite D., primary, Elliott, Steven, additional, Burks, Hope E., additional, Wright, Maryl, additional, Sabol, Rachel A., additional, Hoang, Van T., additional, Ucar, Deniz A., additional, Alfortish, Alex, additional, Zabaleta, Jovanny, additional, Hossain, Fokhrul, additional, Chang, Tiffany, additional, Wathieu, Henri, additional, Pashos, Nicholas, additional, Bunnell, Bruce, additional, Moroz, Krzysztof, additional, Zea, Arnold, additional, Riker, Adam, additional, Jones, Steven D., additional, Martin, Elizabeth C., additional, Miele, Lucio, additional, Collins-Burow, Bridgette M., additional, and Burow, Matthew E., additional

Published
2020
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64. Patient-Derived Xenografts as an Innovative Surrogate Tumor Model for the Investigation of Health Disparities in Triple Negative Breast Cancer

Author

Matossian, Margarite D., primary, Giardina, Alexandra A., additional, Wright, Maryl K., additional, Elliott, Steven, additional, Loch, Michelle M., additional, Nguyen, Khoa, additional, Zea, Arnold H., additional, Lau, Frank H., additional, Moroz, Krzysztof, additional, Riker, Adam I., additional, Jones, Steven D., additional, Martin, Elizabeth C., additional, Bunnell, Bruce A., additional, Miele, Lucio, additional, Collins-Burow, Bridgette M., additional, and Burow, Matthew E., additional

Published
2020
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65. Evaluation of intercellular communication between breast cancer cells and adipose-derived stem cells via passive diffusion in a two-layer microfluidic device

Author

Rahman, Sharif M., Campbell, Joshua M., Coates, Rachael N., Render, Katie M., Byrne, C. Ethan, Martin, Elizabeth C., Melvin, Adam T., Rahman, Sharif M., Campbell, Joshua M., Coates, Rachael N., Render, Katie M., Byrne, C. Ethan, Martin, Elizabeth C., and Melvin, Adam T.

Abstract

Breast cancer tumorigenesis and response to therapy is regulated by cancer cell interactions with the tumor microenvironment (TME). Breast cancer signaling to the surrounding TME results in a heterogeneous and diverse tumor microenvironment, which includes the production of cancer-associated fibroblasts, macrophages, adipocytes, and stem cells. The secretory profile of these cancer-associated cell types results in elevated chemokines and growth factors that promote cell survival and proliferation within the tumor. Current co-culture approaches mostly rely on transwell chambers to study intercellular signaling between adipose-derived stem cells (ASCs) and cancer cells; however, these methods are limited to endpoint measurements and lack dynamic control. In this study, a 4-channel, “flow-free” microfluidic device was developed to co-culture triple-negative MDA-MB-231 breast cancer cells and ASCs to study intercellular communication between two distinct cell types found in the TME. The device consists of two layers: a top PDMS layer with four imprinted channels coupled with a bottom agarose slab enclosed in a Plexiglas chamber. For dynamic co-culture, the device geometry contained two centered, flow-free channels, which were supplied with media from two outer flow channels via orthogonal diffusion through the agarose. Continuous fresh media was provided to the cell culture channel via passive diffusion without creating any shearing effect on the cells. The device geometry also allowed for the passive diffusion of cytokines and growth factors between the two cell types cultured in parallel channels to initiate cell-to-cell crosstalk. The device was used to show that MDA-MB-231 cells co-cultured with ASCs exhibited enhanced growth, a more aggressive morphology, and polarization toward the ASCs. The MDA-MB-231 cells were found to exhibit a greater degree of resistance to the drug paclitaxel when co-cultured with ASCs when compared to single culture studies. This microflui

Published
2020
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66. Is Good Credit Good? State Credit Ratings and Economic Insecurity, 1996–20121.

Author

Norris, Davon and Martin, Elizabeth C.

Subjects
*CREDIT ratings, *INTEREST rates, *INFRASTRUCTURE (Economics), *STATE governments, *BONDHOLDERS
Abstract

Obtaining a good credit rating is an important financial goal for governments since good credit yields lower interest rates and signals fiscal responsibility. But what does a government's quest for better credit mean for the wellbeing of its residents? Although good credit gives governments access to cheaper borrowing to invest in socially beneficial services and infrastructure, working to obtain good credit may lead governments to act in ways that appease bondholders but are unfavorable to its residents. Using the case of state government credit ratings from 1996 to 2012, we demonstrate that increases in state credit ratings are associated with higher economic insecurity for a state's population, net of political and economic controls, as well as state and year fixed effects. We argue these findings illustrate that despite the economic rewards, good credit becomes detrimental once we consider the potential tradeoffs relative to other socially and economically meaningful relationships. [ABSTRACT FROM AUTHOR]

Published
2022
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67. Is Good Credit Good? State Credit Ratings and Economic Insecurity, 1996–20121.

Author

Norris, Davon and Martin, Elizabeth C.

Subjects
CREDIT ratings, INTEREST rates, INFRASTRUCTURE (Economics), STATE governments, BONDHOLDERS
Abstract

Obtaining a good credit rating is an important financial goal for governments since good credit yields lower interest rates and signals fiscal responsibility. But what does a government's quest for better credit mean for the wellbeing of its residents? Although good credit gives governments access to cheaper borrowing to invest in socially beneficial services and infrastructure, working to obtain good credit may lead governments to act in ways that appease bondholders but are unfavorable to its residents. Using the case of state government credit ratings from 1996 to 2012, we demonstrate that increases in state credit ratings are associated with higher economic insecurity for a state's population, net of political and economic controls, as well as state and year fixed effects. We argue these findings illustrate that despite the economic rewards, good credit becomes detrimental once we consider the potential tradeoffs relative to other socially and economically meaningful relationships. [ABSTRACT FROM AUTHOR]

Published
2022
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68. Generation of 3D Spheroids Using a Thiol–Acrylate Hydrogel Scaffold to Study Endocrine Response in ER+Breast Cancer

Author

Khan, Anowar H., Zhou, Sophia P., Moe, Margaret, Ortega Quesada, Braulio A., Bajgiran, Khashayar R., Lassiter, Haley R., Dorman, James A., Martin, Elizabeth C., Pojman, John A., and Melvin, Adam T.

Abstract

Culturing cancer cells in a three-dimensional (3D) environment better recapitulates in vivoconditions by mimicking cell-to-cell interactions and mass transfer limitations of metabolites, oxygen, and drugs. Recent drug studies have suggested that a high rate of preclinical and clinical failures results from mass transfer limitations associated with drug entry into solid tumors that 2D model systems cannot predict. Droplet microfluidic devices offer a promising alternative to grow 3D spheroids from a small number of cells to reduce intratumor heterogeneity, which is lacking in other approaches. Spheroids were generated by encapsulating cells in novel thiol–acrylate (TA) hydrogel scaffold droplets followed by on-chip isolation of single droplets in a 990- or 450-member trapping array. The TA hydrogel rapidly (∼35 min) polymerized on-chip to provide an initial scaffold to support spheroid development followed by a time-dependent degradation. Two trapping arrays were fabricated with 150 or 300 μm diameter traps to investigate the effect of droplet size and cell seeding density on spheroid formation and growth. Both trapping arrays were capable of ∼99% droplet trapping efficiency with ∼90% and 55% cellular encapsulation in trapping arrays containing 300 and 150 μm traps, respectively. The oil phase was replaced with media ∼1 h after droplet trapping to initiate long-term spheroid culturing. The growth and viability of MCF-7 3D spheroids were confirmed for 7 days under continuous media flow using a customized gravity-driven system to eliminate the need for syringe pumps. It was found that a minimum of 10 or more encapsulated cells are needed to generate a growing spheroid while fewer than 10 parent cells produced stagnant 3D spheroids. As a proof of concept, a drug susceptibility study was performed treating the spheroids with fulvestrant followed by interrogating the spheroids for proliferation in the presence of estrogen. Following fulvestrant exposure, the spheroids showed significantly less proliferation in the presence of estrogen, confirming drug efficacy.

Published
2022
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69. Absence of the cbb3 Terminal Oxidase Reveals an Active Oxygen-Dependent Cyclase Involved in Bacteriochlorophyll Biosynthesis in Rhodobacter sphaeroides

Author

Chen, Guangyu E, Canniffe, Daniel P, Martin, Elizabeth C, and Hunter, C Neil

Subjects
Electron Transport Complex IV, Molecular Structure, Mutation, Articles, Amino Acid Sequence, Gene Expression Regulation, Bacterial, Rhodobacter sphaeroides, Bacteriochlorophylls, Gene Deletion, Gene Expression Regulation, Enzymologic
Abstract

The characteristic green color associated with chlorophyll pigments results from the formation of an isocyclic fifth ring on the tetrapyrrole macrocycle during the biosynthesis of these important molecules. This reaction is catalyzed by two unrelated cyclase enzymes employing different chemistries. Oxygenic phototrophs such as plants and cyanobacteria utilize an oxygen-dependent enzyme, the major component of which is a diiron protein named AcsF, while BchE, an oxygen-sensitive [4Fe-4S] cluster protein, dominates in phototrophs inhabiting anoxic environments, such as the purple phototrophic bacterium Rhodobacter sphaeroides. We identify a potential acsF in this organism and assay for activity of the encoded protein in a strain lacking bchE under various aeration regimes. Initially, cells lacking bchE did not demonstrate AcsF activity under any condition tested. However, on removal of a gene encoding a subunit of the cbb3-type respiratory terminal oxidase, cells cultured under regimes ranging from oxic to micro-oxic exhibited cyclase activity, confirming the activity of the oxygen-dependent enzyme in this model organism. Potential reasons for the utilization of an oxygen-dependent enzyme in anoxygenic phototrophs are discussed. IMPORTANCE The formation of the E ring of bacteriochlorophyll pigments is the least well characterized step in their biosynthesis, remaining enigmatic for over 60 years. Two unrelated enzymes catalyze this cyclization step; O2-dependent and O2-independent forms dominate in oxygenic and anoxygenic phototrophs, respectively. We uncover the activity of an O2-dependent enzyme in the anoxygenic purple phototrophic bacterium Rhodobacter sphaeroides, initially by inactivation of the high-affinity terminal respiratory oxidase, cytochrome cbb3. We propose that the O2-dependent form allows for the biosynthesis of a low level of bacteriochlorophyll under oxic conditions, so that a rapid initiation of photosynthetic processes is possible for this bacterium upon a reduction of oxygen tension.

Published
2016

70. Cryo-EM structure of the monomeric Rhodobacter sphaeroides RC-LH1 core complex at 2.5 Å.

Author

Pu Qian, Swainsbury, David J. K., Croll, Tristan I., Salisbury, Jack H., Martin, Elizabeth C., Jackson, Philip J., Hitchcock, Andrew, Castro-Hartmann, Pablo, Sader, Kasim, and Hunter, C. Neil

Subjects
RHODOBACTER sphaeroides, MEMBRANE proteins, ENERGY conservation, HYDROQUINONE, CAROTENOIDS, CYTOCHROME c, QUINONE
Abstract

Reaction centre light-harvesting 1 (RC-LH1) complexes are the essential components of bacterial photosynthesis. The membrane-intrinsic LH1 complex absorbs light and the energy migrates to an enclosed RC where a succession of electron and proton transfers conserves the energy as a quinol, which is exported to the cytochrome bc1 complex. In some RC-LH1 variants quinols can diffuse through small pores in a fully circular, 16-subunit LH1 ring, while in others missing LH1 subunits create a gap for quinol export. We used cryogenic electron microscopy to obtain a 2.5 Å resolution structure of one such RC-LH1, a monomeric complex from Rhodobacter sphaeroides. The structure shows that the RC is partly enclosed by a 14-subunit LH1 ring in which each aß heterodimer binds two bacteriochlorophylls and, unusually for currently reported complexes, two carotenoids rather than one. Although the extra carotenoids confer an advantage in terms of photoprotection and light harvesting, they could impede passage of quinones through small, transient pores in the LH1 ring, necessitating a mechanism to create a dedicated quinone channel. The structure shows that two transmembrane proteins play a part in stabilising an open ring structure; one of these components, the PufX polypeptide, is augmented by a hitherto undescribed protein subunit we designate as protein-Y, which lies against the transmembrane regions of the thirteenth and fourteenth LH1a polypeptides. Protein-Y prevents LH1 subunits 11-14 adjacent to the RC QB site from bending inwards towards the RC and, with PufX preventing complete encirclement of the RC, this pair of polypeptides ensures unhindered quinone diffusion. [ABSTRACT FROM AUTHOR]

Published
2021
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72. Self-injurious behaviors in rhesus macaques: potential glial mechanisms

Author

Ramsey, Joseph, Martin, Elizabeth C., Purcell, Olivia M., Lee, Kim M., and MacLean, Andrew G.

Subjects
Disease Models, Animal, Behavior, Animal, Animals, Brain, Immunohistochemistry, Macaca mulatta, Neuroglia, Self-Injurious Behavior, Article
Abstract

BACKGROUND: Self-injurious behaviour (SIB) can be classified as intentional, direct injuring of body tissue usually without suicidal intent. In its non-suicidal form it is commonly seen as a clinical sign of borderline personality disorder, autism, PTSD, depression, and anxiety affecting a wide range of ages and conditions. In rhesus macaques SIB is most commonly manifested through hair plucking, self-biting, self-hitting, and head banging. SIB in the form of self-biting is observed in approximately 5–15% of individually housed monkeys. Recently, glial cells are becoming recognised as key players in regulating behaviors. METHOD: The goal of this study was to determine the role of glial activation, including astrocytes, in macaques that had displayed SIB. To this end, we performed immunohistochemistry and next generation sequence of brain tissues from rhesus macaques with self-injurious behaviours. RESULTS: Our studies showed increased vimentin, but not nestin, expression on astrocytes of macaques displaying SIB. Initial RNA Seq analyses indicate activation of pathways involved in tissue remodeling, neuroinflammation and cAMP signaling. CONCLUSIONS: Glia are most probably activated in primates with self-injury, and are therefore potential novel targets for therapeutics.

Published
2018

73. Comparative proteomic analyses of human adipose extracellular matrices decellularized using alternative procedures

Author

Porch-Thomas, Caasy, Li, Jie, Zanata, Fabiana, Martin, Elizabeth C, Pashos, Nicholas, Genemaras, Kaylynn, Poche, Nicholas J, Totaro, Nicholas P, Bratton, Melyssa R, Gaupp, Dina, Frazier, Trivia, Wu, Xiying, Ferreira, Lydia Masako, Tian, Weidong, Wang, Guangdi, Bunnell, Bruce A, Flynn, Lauren, Hayes, Daniel, and Gimble, Jeffrey M

Subjects
Cell and Developmental Biology, adipose tissue, bioscaffold, decellularization, extracellular matrix, mass spectrometry proteomics, regenerative medicine, Anatomy
Abstract

Decellularized human adipose tissue has potential clinical utility as a processed biological scaffold for soft tissue cosmesis, grafting, and reconstruction. Adipose tissue decellularization has been accomplished using enzymatic-, detergent-, and/or solvent-based methods. To examine the hypothesis that distinct decellularization processes may yield scaffolds with differing compositions, the current study employed mass spectrometry to compare the proteomes of human adipose-derived matrices generated through three independent methods combining enzymatic-, detergent-, and/or solvent-based steps. In addition to protein content, bioscaffolds were evaluated for deoxyribose nucleic acid depletion, extracellular matrix composition, and physical structure using optical density, histochemical staining, and scanning electron microscopy. Mass spectrometry based proteomic analyses identified 25 proteins (having at least two peptide sequences detected) in the scaffolds generated with an enzymatic approach, 143 with the detergent approach, and 102 with the solvent approach, as compared to 155 detected in unprocessed native human fat. Immunohistochemical detection confirmed the presence of the structural proteins actin, collagen type VI, fibrillin, laminin, and vimentin. Subsequent in vivo analysis of the predominantly enzymatic- and detergent-based decellularized scaffolds following subcutaneous implantation in GFP(+) transgenic mice demonstrated that the matrices generated with both approaches supported the ingrowth of host-derived adipocyte progenitors and vasculature in a time dependent manner. Together, these results determine that decellularization methods influence the protein composition of adipose tissue-derived bioscaffolds. (c) 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2481-2493, 2018.

Published
2018

78. Comparative proteomic analyses of human adipose extracellular matrices decellularized using alternative procedures

Author

Thomas-Porch, Caasy, primary, Li, Jie, additional, Zanata, Fabiana, additional, Martin, Elizabeth C., additional, Pashos, Nicholas, additional, Genemaras, Kaylynn, additional, Poche, J. Nicholas, additional, Totaro, Nicholas P., additional, Bratton, Melyssa R., additional, Gaupp, Dina, additional, Frazier, Trivia, additional, Wu, Xiying, additional, Ferreira, Lydia Masako, additional, Tian, Weidong, additional, Wang, Guangdi, additional, Bunnell, Bruce A., additional, Flynn, Lauren, additional, Hayes, Daniel, additional, and Gimble, Jeffrey M., additional

Published
2018
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81. Trauma induced heterotopic ossification patient serum alters mitogen activated protein kinase signaling in adipose stem cells

Author

Martin, Elizabeth C., primary, Qureshi, Ammar T., additional, Llamas, Claire B., additional, Boos, Elaine C., additional, King, Andrew G., additional, Krause, Peter C., additional, Lee, Olivia C., additional, Dasa, Vinod, additional, Freitas, Michael A., additional, Forsberg, Jonathan A., additional, Elster, Eric A., additional, Davis, Thomas A., additional, and Gimble, J. M., additional

Published
2018
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82. Probing the local lipid environment of the cytochrome bc1 and Synechocystis sp. PCC 6803 cytochrome b6f complexes with styrene maleic acid

Author

Swainsbury, David J.K., primary, Proctor, Matthew S., additional, Hitchcock, Andrew, additional, Cartron, Michaël L., additional, Qian, Pu, additional, Martin, Elizabeth C., additional, Jackson, Philip J., additional, Madsen, Jeppe, additional, Armes, Steven P., additional, and Hunter, C. Neil, additional

Published
2018
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85. Student Loans and Financial Hardship during the Great Recession.

Author

Martin, Elizabeth C. and Dwyer, Rachel E.

Subjects
STUDENT loans, STUDENT loan debt, ECONOMIC indicators, FINANCIAL risk, RECESSIONS, SOCIAL indicators
Abstract

There is growing concern over student loan indebtedness in American society, as the burden of paying for higher education has increasingly shifted from the state onto families and students. While scholars debate whether there is indeed a student debt crisis, we argue that these discussions often overlook a more intangible factor in taking on loans, which is the financial risk associated with carrying debt. One of the burdens of debt is it puts households in a worsened financial position if faced with hard times. In this paper, we use the case of the Great Recession, a financial shock that affected most American households, to understand the financial vulnerability of holding student loan debt when faced with difficult financial circumstances. Employing the 2007-2009 panel of the Survey of Consumer Finances, we examine the relationship between holding student loan debt at the beginning of the Recession, and the likelihood of increased financial problems by the end of the Recession. We find a robust relationship using four different measures of student loans, and holding constant a whole host of indicators of financial health, including financial problems experienced just before the Recession. This study allows us to draw broader conclusions about how risky student loans are, and the effects of holding student loan debt during the more every day, individual-level financial shocks common in an era of rising insecurity. [ABSTRACT FROM AUTHOR]

Published
2019

86. Is Good Credit Good? State Credit Ratings and Economic Insecurity, 1994-2012.

Author

Norris, Davon N. and Martin, Elizabeth C.

Subjects
CREDIT ratings, CREDIT, INTEREST rates, DEBTOR & creditor, CONFLICT of interests
Abstract

Obtaining good credit ratings is an important financial goal for many governments, as good credit ratings yield lower interest rates and signals fiscal responsibility. But what does a government's quest for better credit mean for the wellbeing of its citizens? On one hand, good credit means governments can borrow to invest in services to improve citizen livelihood without spending as much on interest payments. On the other hand, working to obtain good credit may lead the government to take actions to appease creditors and bondholders that are not in the best interest of its citizens. Using the case of state government credit ratings from 1994-2012, we demonstrate that increases in state credit ratings are associated with higher levels of economic insecurity for a state's citizens. This relationship is robust to political and economic controls, as well as state and year fixed effects. By emphasizing relationships outside of a government's relationship to its credit rating, we recast borrowers as not simply borrowers, but as actors suspended between a variety of overlapping and conflicting interests. This helps us to problematize previously accepted ideas about the nature of good credit. Good credit is beneficial because of the economic rewards attached to it but becomes detrimental when we consider the potential trade-offs relative to other socially and economically meaningful relationships. [ABSTRACT FROM AUTHOR]

Published
2019

87. Acellular Biologic Nipple–Areolar Complex Graft: In VivoMurine and Nonhuman Primate Host Response Evaluation

Author

Pashos, Nicholas C., Graham, David M., Burkett, Brian J., O'Donnell, Ben, Sabol, Rachel A., Helm, Joshua, Martin, Elizabeth C., Bowles, Annie C., Heim, William M., Caronna, Vince C., Miller, Kristin S., Grasperge, Brooke, Sullivan, Scott, Chaffin, Abigail E., and Bunnell, Bruce A.

Abstract

There are more than 3 million breast cancer survivors living in the United States of which a significant number have undergone mastectomy followed by breast and nipple–areolar complex (NAC) reconstruction. Current strategies for NAC reconstruction are dependent on nonliving or nonpermanent techniques, including tattooing, nipple prosthetics, or surgical nipple-like structures. Described herein is a tissue engineering approach demonstrating the feasibility of an allogeneic acellular graft for nipple reconstruction. Nonhuman primate (NHP)-derived NAC tissues were decellularized and their extracellular matrix components analyzed by both proteomic and histological analyses. Decellularized NHP nipple tissue showed the removal of intact cells and greatly diminished profiles for intracellular proteins, as compared with intact NHP nipple tissue. We further evaluated the biocompatibility of decellularized grafts and their potential to support host-mediated neovascularization against commercially available acellular dermal grafts by performing in vivostudies in a murine model. A follow-up NHP pilot study evaluated the host-mediated neovascularization and re-epithelialization of onlay engrafted decellularized NAC grafts. The murine model revealed greater neovascularization in the decellularized NAC than in the commercially available control grafts, with no observed biocompatibility issues. The in vivoNHP model confirmed that the decellularized NAC grafts encourage neovascularization as well as re-epithelialization. These results support the concept that a biologically derived acellular nipple graft is a feasible approach for nipple reconstruction, supporting neovascularization in the absence of adverse systemic responses.Impact statementCurrently, women in the United States most often undergo a mastectomy, followed by reconstruction, after being diagnosed with breast cancer. These breast cancer survivors are often left with nipple–areolar complex (NAC) reconstructions that are subsatisfactory, nonliving, and/or nonpermanent. Utilizing an acellular biologically derived whole NAC graft would allow these patients a living and permanent tissue engineering solution to nipple reconstruction.

Published
2020
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88. Augmenting light coverage for photosynthesis through YFP-enhanced charge separation at the Rhodobacter sphaeroides reaction centre

Author

Grayson, Katie J., primary, Faries, Kaitlyn M., additional, Huang, Xia, additional, Qian, Pu, additional, Dilbeck, Preston, additional, Martin, Elizabeth C., additional, Hitchcock, Andrew, additional, Vasilev, Cvetelin, additional, Yuen, Jonathan M., additional, Niedzwiedzki, Dariusz M., additional, Leggett, Graham J., additional, Holten, Dewey, additional, Kirmaier, Christine, additional, and Neil Hunter, C., additional

Published
2017
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91. Abstract 1596: Induction of mesenchymal-to-epithelial transition through pan-MEK inhibition in triple-negative breast cancer

Author

Hoang, Van T., primary, Elliott, Steven, additional, Martin, Elizabeth C., additional, Rhodes, Lyndsay V., additional, Burks, Hope E., additional, Matossian, Margarite, additional, Chakrabarty, Suravi, additional, Monlish, Darlene, additional, Phamduy, Theresa B., additional, Curley, Lowry, additional, Anbalagan, Muralidharan, additional, Rowan, Brian G., additional, Chrisey, Doug, additional, Cavanaugh, Jane E., additional, Flaherty, Patrick T., additional, Collins-Burow, Bridgette M., additional, and Burow, Matthew E., additional

Published
2016
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92. Abstract 4410: ZEB2 drives cell motility and metastasis in ER+ breast cancer cells through a novel, E-cadherin independent pathway

Author

Burks, Hope E., primary, Rhodes, Lyndsay V., additional, Martin, Elizabeth C., additional, Hoang, Van T., additional, Elliott, Steven, additional, Badoo, Melody, additional, Phamduy, Theresa, additional, Buechlein, Aaron, additional, Rusch, Douglas, additional, Chrisey, Douglas, additional, Flemington, Erik, additional, Nephew, Kenneth, additional, Collins-Burow, Bridgette, additional, and Burow, Matthew E., additional

Published
2016
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95. Preferential Star Strand Biogenesis of Pre-miR-24-2 Targets PKC-alpha and Suppresses Cell Survival in MCF-7 Breast Cancer Cells

Author

Martin, Elizabeth C., Elliott, Steven, Rhodes, Lyndsay V., Antoon, James W., Fewell, Claire, Zhu, Yun, Driver, Jennifer L., Jodari-Karimi, Mona, Taylor, Christopher W., Flemington, Erik K., Beckman, Barbara S., Collins-Burow, Bridgette M., and Burow, Matthew E.

Subjects
Binding Sites, Protein Kinase C-alpha, Base Sequence, Cell Survival, Breast Neoplasms, Article, Gene Expression Regulation, Neoplastic, Isoenzymes, Mice, MicroRNAs, Cell Transformation, Neoplastic, Cell Line, Tumor, MCF-7 Cells, Animals, Humans, Female, RNA Interference, skin and connective tissue diseases, Base Pairing
Abstract

microRNAs (miRNA) are regulators of cellular pathways and alterations of normal miRNA expression levels have been shown to increase tumorigenesis. miR-24 has been demonstrated as having both tumor suppressive and oncogenic properties depending on cell context. Here, we demonstrate a possible role for pre-miR-24-2 as a tumor suppressor in the MCF-7 breast cancer cell line through the preferential processing of mature miR-24-2* over miR-24. Specifically, we show that the ectopic expression of miR-24-2* in MCF-7 breast cancer cells results in a suppression of cellular survival both in vivo and in vitro. Notably, the overexpression of miR-24-2* results in a dampening of cell survival through the targeted suppression of PKCα. In addition, a similar biological change is observed in vivo where MCF-7 cells overexpressing pre-miR-24-2 have decreased tumorigenicity and tumor incidence. Taken together our data demonstrate that when overexpressed biogenesis of the pre-miR-24-2 favors miR-24-2* in the MCF-7 breast cancer cell line and suggests a tumor suppressive role for miR-24-2* observed through the inhibition of PKCα-mediated cellular survival.

Published
2012

96. Origin of the S* Excited State Feature of Carotenoids in Light-Harvesting Complex 1 from Purple Photosynthetic Bacteria

Author

Niedzwiedzki, Dariusz M., Swainsbury, David J. K., Martin, Elizabeth C., Hunter, C. Neil, and Blankenship, Robert E.

Abstract

This spectroscopic study investigates the origin of the transient feature of the S* excited state of carotenoids bound in LH1 complexes from purple bacteria. The studies were performed on two RC-LH1 complexes from Rba. sphaeroidesstrains that bound carotenoids with different carbon–carbon double bond conjugation N, neurosporene (N= 9) and spirilloxanthin (N= 13). The S* transient spectral feature, originally associated with an elusive and optically silent excited state of spirilloxanthin in the LH1 complex, may be successfully explained and mimicked without involving any unknown electronic state. The spectral and temporal characteristics of the S* feature suggest that it is associated with triplet–triplet annihilation of carotenoid triplets formed after direct excitation of the molecule via a singlet fission mechanism. Depending on pigment homogeneity and carotenoid assembly in the LH1 complex, the spectro-temporal component associated with triplet–triplet annihilation may simply resolve a pure T-S spectrum of a carotenoid. In some cases (like spirilloxanthin), the T-S feature will also be accompanied by a carotenoid Stark spectrum and/or residual transient absorption of minor carotenoid species bound into LH1 antenna complex.

Published
2024
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98. Spatial variability in habitat structure and heterogenic coral reef fish assemblages inside a small-scale marine reserve after a coral mass mortality event

Author

Jörgensen, Tove Lund, Martin, Elizabeth C., Burt, April J., Jörgensen, Tove Lund, Martin, Elizabeth C., and Burt, April J.

Abstract

Coral reefs at the inner granitic islands in the Seychelles were heavily affected by the worldwide bleaching event in 1998, which led to subsequent coral mortality and widespread phase shifts to macroalgae dominated reefs. In this study, five sites within a small, but well enforced marine reserve at Cousin Island, were investigate using various methods to explore differences in coral habitat quality, coral recruitment, fish assemblages, key invertebrate grazers, and rugosity. The objective of the study was to collect a broad set of scientific data, which could be useful to describe linkage between coral reef and fish assemblages after a large-scale disturbance, as well as for future management decisions regarding marine resources, in terms of MPA protection and recovery abilities. The results showed high spatial variation in coral coverage between sites (from 1.5% to 43.2%), which were higher than previously reported, as well as high variation in dispersal of coral recruits. Furthermore, there were large heterogenic differences in fish densities and composition, which were directly linked to coral habitat quality, e.g. total fish abundance was 15 times higher on sites with high coral coverage in comparison to sites with low coral cover. In summary, this study demonstrates that coral reef habitat and fish assemblage may display high spatial variability and heterogenic differences after large-scale disturbances and suggests that potential recovery from coral mass mortality may occur in a non-linear and patchy procedure, which in turn may depend on underlying stocastical processes that affect coral recruitment and survivorship.

Published
2015
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99. Carotenoid to bacteriochlorophyll energy transfer in the RC-LH1-PufX complex from Rhodobacter sphaeroides containing the extended conjugation keto-carotenoid diketospirilloxanthin.

Author

Šlouf, Václav, Keşan, Gürkan, Litvín, Radek, Swainsbury, David J. K., Martin, Elizabeth C., Hunter, C. Neil, and Polívka, Tomáš

Abstract

RC-LH1-PufX complexes from a genetically modified strain of Rhodobacter sphaeroides that accumulates carotenoids with very long conjugation were studied by ultrafast transient absorption spectroscopy. The complexes predominantly bind the carotenoid diketospirilloxanthin, constituting about 75% of the total carotenoids, which has 13 conjugated C=C bonds, and the conjugation is further extended to two terminal keto groups. Excitation of diketospirilloxanthin in the RC-LH1-PufX complex demonstrates fully functional energy transfer from diketospirilloxanthin to BChl a in the LH1 antenna. As for other purple bacterial LH complexes having carotenoids with long conjugation, the main energy transfer route is via the S-Q pathway. However, in contrast to LH2 complexes binding diketospirilloxanthin, in RC-LH1-PufX we observe an additional, minor energy transfer pathway associated with the S state of diketospirilloxanthin. By comparing the spectral properties of the S state of diketospirilloxanthin in solution, in LH2, and in RC-LH1-PufX, we propose that the carotenoid-binding site in RC-LH1-PufX activates the ICT state of diketospirilloxanthin, resulting in the opening of a minor S/ICT-mediated energy transfer channel. [ABSTRACT FROM AUTHOR]

Published
2018
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