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Search Results: 1 - 10 of 401469 matches for " Shawna M Hengel "
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FRET Imaging of Diatoms Expressing a Biosilica-Localized Ribose Sensor
Kathryn E. Marshall, Errol W. Robinson, Shawna M. Hengel, Ljiljana Pa?a-Toli?, Guritno Roesijadi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033771
Abstract: Future materials are envisioned to include bio-assembled, hybrid, three-dimensional nanosystems that incorporate functional proteins. Diatoms are amenable to genetic modification for localization of recombinant proteins in the biosilica cell wall. However, the full range of protein functionalities that can be accommodated by the modified porous biosilica has yet to be described. Our objective was to functionalize diatom biosilica with a reagent-less sensor dependent on ligand-binding and conformational change to drive FRET-based signaling capabilities. A fusion protein designed to confer such properties included a bacterial periplasmic ribose binding protein (R) flanked by CyPet (C) and YPet (Y), cyan and yellow fluorescent proteins that act as a FRET pair. The structure and function of the CRY recombinant chimeric protein was confirmed by expression in E. coli prior to transformation of the diatom Thalassiosira pseudonana. Mass spectrometry of the recombinant CRY showed 97% identity with the deduced amino acid sequence. CRY with and without an N-terminal Sil3 tag for biosilica localization exhibited characteristic ribose-dependent changes in FRET, with similar dissociation constants of 123.3 μM and 142.8 μM, respectively. The addition of the Sil3 tag did not alter the affinity of CRY for the ribose substrate. Subsequent transformation of T. pseudonana with a vector encoding Sil3-CRY resulted in fluorescence localization in the biosilica and changes in FRET in both living cells and isolated frustules in response to ribose. This work demonstrated that the nano-architecture of the genetically modified biosilica cell wall was able to support the functionality of the relatively complex Sil3-CyPet-RBP-YPet fusion protein with its requirement for ligand-binding and conformational change for FRET-signal generation.
Enhanced top-down characterization of histone post-translational modifications
Zhixin Tian, Nikola Toli?, Rui Zhao, Ronald J Moore, Shawna M Hengel, Errol W Robinson, David L Stenoien, Si Wu, Richard D Smith, Ljiljana Pa?a-Toli?
Genome Biology , 2012, DOI: 10.1186/gb-2012-13-10-r86
Abstract: Histones are important chromatin proteins that act as spools to package and order DNA into structural and manageable chromosomes. Core histones are modified by multiple post-translational modifications (PTMs) such as lysine acetylation, lysine or arginine methylation, and serine or threonine phosphorylation, among others. These PTMs generate a 'histone code' [1] that is implicated in chromatin-related cellular processes [2] including transcription [3], replication [4], repair [5], and alternative splicing [6].Although core histones comprise only four families (H4, H2B, H2A, and H3), each family has thousands of potential isoforms generated by different combinations of PTMs and protein sequence variation. Traditional antibody-based methods target specific isoforms, typically analyzing one PTM at a time, which makes it virtually impossible to measure combinatorial modifications occurring within the same histone molecule. Recently, high-throughput bottom-up [7] and middle-down [8] proteomic methods demonstrated potential for global characterization of PTMs on histone tails. However, these methods are ill-suited for characterizing multiple PTMs dispersed along the entire protein sequence that have been previously discovered to have significant participation in chromatin regulation [2,9-11].Top-down proteomic and high-throughput approaches are clearly required to identify and quantify the modulation of multiple intra-molecular histone modifications that synergistically regulate histone functions. Recently, a global top-down study demonstrated the feasibility of intact protein analysis for this purpose by identifying more than 300 histone isoforms using extensive fractionation and customized bioinformatics for global proteome characterization [12]. In histone-focused studies, top-down approaches using an offline two-dimensional liquid chromatography (2D LC) separation and Fourier transform mass spectrometry (FTMS) characterized 34 H4 isoforms from approximately 150 μg of
Nonassociative Learning Promotes Respiratory Entrainment to Mechanical Ventilation
Shawna M. MacDonald, Gang Song, Chi-Sang Poon
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000865
Abstract: Background Patient-ventilator synchrony is a major concern in critical care and is influenced by phasic lung-volume feedback control of the respiratory rhythm. Routine clinical application of positive end-expiratory pressure (PEEP) introduces a tonic input which, if unopposed, might disrupt respiratory-ventilator entrainment through sustained activation of the vagally-mediated Hering-Breuer reflex. We suggest that this potential adverse effect may be averted by two differentiator forms of nonassociative learning (habituation and desensitization) of the Hering-Breuer reflex via pontomedullary pathways. Methodology/Principal Findings We tested these hypotheses in 17 urethane-anesthetized adult Sprague-Dawley rats under controlled mechanical ventilation. Without PEEP, phrenic discharge was entrained 1:1 to the ventilator rhythm. Application of PEEP momentarily dampened the entrainment to higher ratios but this effect was gradually adapted by nonassociative learning. Bilateral electrolytic lesions of the pneumotaxic center weakened the adaptation to PEEP, whereas sustained stimulation of the pneumotaxic center weakened the entrainment independent of PEEP. In all cases, entrainment was abolished after vagotomy. Conclusions/Significance Our results demonstrate an important functional role for pneumotaxic desensitization and extra-pontine habituation of the Hering-Breuer reflex elicited by lung inflation: acting as buffers or high-pass filters against tonic vagal volume input, these differentiator forms of nonassociative learning help to restore respiratory-ventilator entrainment in the face of PEEP. Such central sites-specific habituation and desensitization of the Hering-Breuer reflex provide a useful experimental model of nonassociative learning in mammals that is of particular significance in understanding respiratory rhythmogenesis and coupled-oscillator entrainment mechanisms, and in the clinical management of mechanical ventilation in respiratory failure.
Magnesium in Women’s Health and Gynecology  [PDF]
Shawna Tonick, Ozgul Muneyyirci-Delale
Open Journal of Obstetrics and Gynecology (OJOG) , 2016, DOI: 10.4236/ojog.2016.65041
Abstract: Magnesium is well known in the world of obstetrics for many important uses. It has been utilized in treating pre-eclampsia, eclampsia, and preventing preterm labor, though it has been found recently that prolonged magnesium administration in pregnant women may result in adverse outcomes to fetal bone metabolism, resulting in a new FDA warning [1]. Outside of obstetrics, magnesium is recommended for treating the arrhythmias torsades de pointes and rapid atrial fibrillation, treating severe acute asthma, improving migraine symptoms, and for treating dyspepsia and constipation [2]. Many women in our modern society are magnesium deficient due to low dietary intake, and low dietary magnesium intake resulting in hypomagnesaemia has recently been shown to have many deleterious effects. Magnesium’s uses are wide-reaching, touching many areas of women’s health and gynecology from pre-menstrual syndrome to menopause, PCOS to endometriosis, and beyond.
Metabolite Profiling of a Diverse Collection of Wheat Lines Using Ultraperformance Liquid Chromatography Coupled with Time-of-Flight Mass Spectrometry
Shawna B. Matthews, Meenakshi Santra, Meghan M. Mensack, Pamela Wolfe, Patrick F. Byrne, Henry J. Thompson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044179
Abstract: Genetic differences among major types of wheat are well characterized; however, little is known about how these distinctions affect the small molecule profile of the wheat seed. Ethanol/water (65% v/v) extracts of seed from 45 wheat lines representing 3 genetically distinct classes, tetraploid durum (Triticum turgidum subspecies durum) (DW) and hexaploid hard and soft bread wheat (T. aestivum subspecies aestivum) (BW) were subjected to ultraperformance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOF-MS). Discriminant analyses distinguished DW from BW with 100% accuracy due to differences in expression of nonpolar and polar ions, with differences attributed to sterol lipids/fatty acids and phospholipids/glycerolipids, respectively. Hard versus soft BW was distinguished with 100% accuracy by polar ions, with differences attributed to heterocyclic amines and polyketides versus phospholipid ions, respectively. This work provides a foundation for identification of metabolite profiles associated with desirable agronomic and human health traits and for assessing how environmental factors impact these characteristics.
A worksite prevention program for construction workers: design of a randomized controlled trial
Karen M Oude Hengel, Catelijne I Joling, Karin I Proper, Birgitte M Blatter, Paulien M Bongers
BMC Public Health , 2010, DOI: 10.1186/1471-2458-10-336
Abstract: The study is designed as a randomized controlled trial with a follow-up of one year. Employees eligible for this study are construction workers performing actual construction work. The worksite intervention will be compared with usual care. This intervention was developed by using the Intervention Mapping approach and consists of the following components: (1) two individual training sessions of a physical therapist to lower the physical workload, (2) a Rest-Break tool to improve the balance between work and recovery, and (3) two empowerment training sessions to increase the influence of the construction workers at the worksite. Outcome measures are assessed at baseline, 3, 6, and 12 months. The primary outcome measures of this study are work ability and health-related quality of life. Secondary outcome measures include need for recovery, musculoskeletal complaints, work engagement and self efficacy. Cost-effectiveness will be evaluated from the company perspective. Moreover, a process evaluation will be conducted.The feasibility of the intervention and the study has been enhanced by creating an intervention program that explicitly appeals to construction workers and will not interfere too much with the ongoing construction. The feasibility and effectiveness of this worksite prevention program will be investigated by means of an effect- and a process evaluation. If proven effective, this worksite prevention program can be implemented on a larger scale within the construction industry.NTR1278In order to face the challenges of the aging working population and to extend the healthy working lives of the workers, the construction industry in the Netherlands has reason to pay attention to maintaining and promoting work ability [1,2]. Work ability is defined as how well workers can perform their jobs at present and in the near future, and is the result of the interaction between the individuals' capacity and the work demands [3,4]. Work ability is determined by personal fac
Are Business Management Games a Suitable Tool for Analyzing the Boundedly Rational Behavior of Economic Agents?  [PDF]
Oliver Musshoff, Norbert Hirschauer, Philipp Hengel
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.24052
Abstract: Regulatory policies often aim to steer the behavior of economic agents by changing their economic environment. Assessing the potential impacts of regulatory policies requires forecasts regarding how humans adapt to such changes. One important prerequisite for meaningful policy impact analysis is in-depth knowledge of why and to what extent economic agents behave in a boundedly rational way. We propose that business management games can be used to contribute towards better understanding of agent behaviors, since they provide an inexpensive opportunity to reach beyond existing anecdotal evidence concerning “behavioral anomalies”. Modifying an existing business management game in which investment, financing and produc tion decisions have to be made, we demonstrate how bounded rationality can be quantified and separated into its two components: incomplete information and limited cognitive abilities. The resulting data show that decisions made by participants in this game are strongly influenced by bounded rationality. They also show that both incomplete information and limited cognitive abilities are relevant components of the bounded rationality displayed by players.
Absence of Cross-Presenting Cells in the Salivary Gland and Viral Immune Evasion Confine Cytomegalovirus Immune Control to Effector CD4 T Cells
Senta M. Walton,Sanja Mandaric,Nicole Torti,Albert Zimmermann,Hartmut Hengel,Annette Oxenius
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1002214
Abstract: Horizontal transmission of cytomegaloviruses (CMV) occurs via prolonged excretion from mucosal surfaces. We used murine CMV (MCMV) infection to investigate the mechanisms of immune control in secretory organs. CD4 T cells were crucial to cease MCMV replication in the salivary gland (SG) via direct secretion of IFNγ that initiated antiviral signaling on non-hematopoietic cells. In contrast, CD4 T cell helper functions for CD8 T cells or B cells were dispensable. Despite SG-resident MCMV-specific CD8 T cells being able to produce IFNγ, the absence of MHC class I molecules on infected acinar glandular epithelial cells due to viral immune evasion, and the paucity of cross-presenting antigen presenting cells (APCs) prevented their local activation. Thus, local activation of MCMV-specific T cells is confined to the CD4 subset due to exclusive presentation of MCMV-derived antigens by MHC class II molecules on bystander APCs, resulting in IFNγ secretion interfering with viral replication in cells of non-hematopoietic origin.
Factors influencing receptivity to future screening options for pancreatic cancer in those with and without pancreatic cancer family history
Carmen M Radecki Breitkopf, Pamela S Sinicrope, Kari G Rabe, Tabetha A Brockman, Christi A Patten, Robert R McWilliams, Shawna L Ehlers, Gloria M Petersen
Hereditary Cancer in Clinical Practice , 2012, DOI: 10.1186/1897-4287-10-8
Abstract: At-risk family members and primary care controls were surveyed regarding perceived PC risk, PC worry/concern, attitude toward cancer screening, screening test accuracy, and intentions regarding PC screening via blood testing or more invasive endoscopic ultrasound (EUS).PC family members reported greater perceived risk of PC than controls (54% vs. 6%, respectively, p?<?0.0001). PC family members also reported higher levels of PC worry/concern than controls (p?<?0.0001), although 19% of PC family members indicated they were “not at all concerned” about getting PC. PC family members indicated greater acceptance of a false-negative result on a PC screening test relative to controls (12% vs. 8%, p?=?0.02). Both groups reported high (>89%) receptivity to the potential PC screening options presented, though receptivity was greater among PC family members as compared to controls (p?<?0.0001) for EUS. In multivariable analyses, degree of PC concern (p?<?0.0001) was associated with intention to screen for PC by blood test and EUS, while perceived PC risk was associated with likelihood of undergoing EUS only (p?<?0.0001).Receptivity to screening options for PC appears high. Clinicians should address behavioral and genetic risk factors for PC and foster appropriate concern regarding PC risk among at-risk individuals.
FANCJ/BACH1 Acetylation at Lysine 1249 Regulates the DNA Damage Response
Jenny Xie,Min Peng,Shawna Guillemette,Steven Quan,Stephanie Maniatis,Yuliang Wu,Aditya Venkatesh,Scott A. Shaffer,Robert M. Brosh Jr.,Sharon B. Cantor
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1002786
Abstract: BRCA1 promotes DNA repair through interactions with multiple proteins, including CtIP and FANCJ (also known as BRIP1/BACH1). While CtIP facilitates DNA end resection when de-acetylated, the function of FANCJ in repair processing is less well defined. Here, we report that FANCJ is also acetylated. Preventing FANCJ acetylation at lysine 1249 does not interfere with the ability of cells to survive DNA interstrand crosslinks (ICLs). However, resistance is achieved with reduced reliance on recombination. Mechanistically, FANCJ acetylation facilitates DNA end processing required for repair and checkpoint signaling. This conclusion was based on the finding that FANCJ and its acetylation were required for robust RPA foci formation, RPA phosphorylation, and Rad51 foci formation in response to camptothecin (CPT). Furthermore, both preventing and mimicking FANCJ acetylation at lysine 1249 disrupts FANCJ function in checkpoint maintenance. Thus, we propose that the dynamic regulation of FANCJ acetylation is critical for robust DNA damage response, recombination-based processing, and ultimately checkpoint maintenance.
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