Medicine and Health Sciences Commons^™

Proteolytic Regulation Of Toxin-Antitoxin Systems By Clppc In Staphylococcus Aureus, Niles P. Donegan, Earl T. Thompson, Zhibiao Fu, Ambrose L. Cheung

Dartmouth Scholarship

Bacterial toxin-antitoxin (TA) systems typically consist of a small, labile antitoxin that inactivates a specific longer-lived toxin. In Escherichia coli, such antitoxins are proteolytically regulated by the ATP-dependent proteases Lon and ClpP. Under normal conditions, antitoxin synthesis is sufficient to replace this loss from proteolysis, and the bacterium remains protected from the toxin. However, if TA production is interrupted, antitoxin levels decrease, and the cognate toxin is free to inhibit the specific cellular component, such as mRNA, DnaB, or gyrase. To date, antitoxin degradation has been studied only in E. coli, so it remains unclear whether similar mechanisms of regulation …

Gbdr Regulates Pseudomonas Aeruginosa Plch And Pchp Transcription In Response To Choline Catabolites, Matthew J. Wargo, Tiffany C. Ho, Maegan J. Gross, Laurie A. Whittaker, Deborah A. Hogan

Dartmouth Scholarship

Pseudomonas aeruginosa hemolytic phospholipase C, PlcH, can degrade phosphatidylcholine (PC) and sphingomyelin in eukaryotic cell membranes and extracellular PC in lung surfactant. Numerous studies implicate PlcH in P. aeruginosa virulence. The phosphorylcholine released by PlcH activity on phospholipids is hydrolyzed by a periplasmic phosphorylcholine phosphatase, PchP. Both plcH gene expression and PchP enzyme activity are positively regulated by phosphorylcholine degradation products, including glycine betaine. Here we report that the induction of plcH and pchP transcription by glycine betaine is mediated by GbdR, an AraC family transcription factor. Mutants that lack gbdR are unable to induce plcH and pchP in media …

Automatic Exposure Control And Estimation Of Effective System Noise In Diffuse Fluorescence Tomography, Dax L. Kepshire, Hamid Dehghani, Frederic Leblond, Brian W. Pogue

Dartmouth Scholarship

A diffuse fluorescence tomography system, based upon time-correlated single photon counting, is presented with an automated algorithm to allow dynamic range variation through exposure control. This automated exposure control allows the upper and lower detection levels of fluorophore to be extended by an order of magnitude beyond the previously published performance and benefits in a slight decrease in system effective noise. The effective noise level is used as a metric to characterize the system performance, integrating both model-mismatch and calibration bias errors into a single parameter. This effective error is near 7% of the reconstructed fluorescent yield value, when imaging …

A Privacy Framework For Mobile Health And Home-Care Systems, David Kotz, Sasikanth Avancha, Amit Baxi

Dartmouth Scholarship

In this paper, we consider the challenge of preserving patient privacy in the context of mobile healthcare and home-care systems, that is, the use of mobile computing and communications technologies in the delivery of healthcare or the provision of at-home medical care and assisted living. This paper makes three primary contributions. First, we compare existing privacy frameworks, identifying key differences and shortcomings. Second, we identify a privacy framework for mobile healthcare and home-care systems. Third, we extract a set of privacy properties intended for use by those who design systems and applications for mobile healthcare and home-care systems, linking them …

Mpcs: Mobile-Based Patient Compliance System For Chronic Illness Care, Guanling Chen, Bo Yan, Minho Shin, David Kotz, Ethan Burke

Dartmouth Scholarship

More than 100 million Americans are currently living with at least one chronic health condition and expenditures on chronic diseases account for more than 75 percent of the $2.3 trillion cost of our healthcare system. To improve chronic illness care, patients must be empowered and engaged in health self-management. However, only half of all patients with chronic illness comply with treatment regimen. The self-regulation model, while seemingly valuable, needs practical tools to help patients adopt this self-centered approach for long-term care. \par In this position paper, we propose Mobile-phone based Patient Compliance System (MPCS) that can reduce the time-consuming and …

A Comparison Of Frequentist And Bayesian Approaches To The Estimation Of Long-Stay Per-Diems, Jeff Hatcher, Jason M. Sutherland

Dartmouth Scholarship

Within many diagnosis related group (DRG) systems, there is recognition that a single cost weight per DRG is not suitable, and that cost weights should take into account extremely lengthy hospital stays. Long lengths of stay are considered to be due to factors largely beyond the control of the hospital, and a single weight per DRG would potentially place hospitals under financial risk.

Within Canada's acute-care, inpatient grouping methodology - Case Mix Groups (CMG+) - long-stay episodes represent approximately 4.5% of all discharges. Within a CMG (analogous to DRG), the cost weight assigned to long-stay cases consists of the typical …

Activity-Aware Ecg-Based Patient Authentication For Remote Health Monitoring, Janani Sriram, Minho Shin, Tanzeem Choudhury, David Kotz

Dartmouth Scholarship

Mobile medical sensors promise to provide an efficient, accurate, and economic way to monitor patients' health outside the hospital. Patient authentication is a necessary security requirement in remote health monitoring scenarios. The monitoring system needs to make sure that the data is coming from the right person before any medical or financial decisions are made based on the data. Credential-based authentication methods (e.g., passwords, certificates) are not well-suited for remote healthcare as patients could hand over credentials to someone else. Furthermore, one-time authentication using credentials or trait-based biometrics (e.g., face, fingerprints, iris) do not cover the entire monitoring period and …

Activity-Aware Ecg-Based Patient Authentication For Remote Health Monitoring, Janani Sriram, Minho Shin, Tanzeem Choudhury, David Kotz

Dartmouth Scholarship

Mobile medical sensors promise to provide an efficient, accurate, and economic way to monitor patients' health outside the hospital. Patient authentication is a necessary security requirement in remote health monitoring scenarios. The monitoring system needs to make sure that the data is coming from the right person before any medical or financial decisions are made based on the data. Credential-based authentication methods (e.g., passwords, certificates) are not well-suited for remote healthcare as patients could hand over credentials to someone else. Furthermore, one-time authentication using credentials or trait-based biometrics (e.g., face, fingerprints, iris) do not cover the entire monitoring period and …

Levels Of The Secreted Vibrio Cholerae Attachment Factor Gbpa Are Modulated By Quorum-Sensing-Induced Proteolysis, Brooke A. Jude, Raquel M. Martinez, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Vibrio cholerae is the etiologic agent of cholera in humans. Intestinal colonization occurs in a stepwise fashion, initiating with attachment to the small intestinal epithelium. This attachment is followed by expression of the toxin-coregulated pilus, microcolony formation, and cholera toxin (CT) production. We have recently characterized a secreted attachment factor, GlcNAc binding protein A (GbpA), which functions in attachment to environmental chitin sources as well as to intestinal substrates. Studies have been initiated to define the regulatory network involved in GbpA induction. At low cell density, GbpA was detected in the culture supernatant of all wild-type (WT) strains examined. In …

Human Uterine Natural Killer Cells But Not Blood Natural Killer Cells Inhibit Human Immunodeficiency Virus Type 1 Infection By Secretion Of Cxcl12, Teddy F. Mselle, Aexandra L. Howell, Mimi Ghosh, Charles R. Wira, Charles L. Sentman

Dartmouth Scholarship

Natural killer (NK) cells derived from the human female reproductive tract (FRT) are phenotypically and functionally distinct from those obtained from peripheral blood. Because the FRT is a primary site of human immunodeficiency virus type 1 (HIV-1) infection in women, we determined whether soluble factors secreted by uterine-derived NK (uNK) cells inhibit HIV-1 infection. Clonal populations of uNK cells were activated with interleukin-12 (IL-12) and IL-15, and conditioned media (CM) from these cultures evaluated for their ability to inhibit infection of cells by HIV-1_IIIB, HIV-1_NL4.3, and HIV-1_HC4 (X4-tropic) or HIV-1_BaL (R5-tropic) viruses. We found …

Wnt Pathway Reprogramming During Human Embryonal Carcinoma Differentiation And Potential For Therapeutic Targeting, Grace E. Snow, Allison C. Kasper, Alexander M. Busch, Elisabeth Schwarz, Katherine E. Ewings, Thomas Bee, Michael J. Spinella, Ethan Dmitrovsky, Sarah J. Freemantle

Dartmouth Scholarship

Testicular germ cell tumors (TGCTs) are classified as seminonas or non-seminomas of which a major subset is embryonal carcinoma (EC) that can differentiate into diverse tissues. The pluripotent nature of human ECs resembles that of embryonic stem (ES) cells. Many Wnt signalling species are regulated during differentiation of TGCT-derived EC cells. This study comprehensively investigated expression profiles of Wnt signalling components regulated during induced differentiation of EC cells and explored the role of key components in maintaining pluripotency.

Sarz Promotes The Expression Of Virulence Factors And Represses Biofilm Formation By Modulating Sara And Agr In Staphylococcus Aureus, Sandeep Tamber, Ambrose L. Cheung

Dartmouth Scholarship

Staphylococcus aureus is a remarkably adaptable organism capable of multiple modes of growth in the human host, as a part of the normal flora, as a pathogen, or as a biofilm. Many of the regulatory pathways governing these modes of growth are centered on the activities of two regulatory molecules, the DNA binding protein SarA and the regulatory RNAIII effector molecule of the agr system. Here, we describe the modulation of these regulators and their downstream target genes by SarZ, a member of the SarA/MarR family of transcriptional regulators. Transcriptional and phenotypic analyses of a sarZ mutant demonstrated that the …

Minimal Membrane Docking Requirements Revealed By Reconstitution Of Rab Gtpase-Dependent Membrane Fusion From Purified Components, Christopher Stroupe, Christopher M. Hickey, Joji Mima, Amy S. Burfeind, William Wickner

Dartmouth Scholarship

Rab GTPases and their effectors mediate docking, the initial contact of intracellular membranes preceding bilayer fusion. However, it has been unclear whether Rab proteins and effectors are sufficient for intermembrane interactions. We have recently reported reconstituted membrane fusion that requires yeast vacuolar SNAREs, lipids, and the homotypic fusion and vacuole protein sorting (HOPS)/class C Vps complex, an effector and guanine nucleotide exchange factor for the yeast vacuolar Rab GTPase Ypt7p. We now report reconstitution of lysis-free membrane fusion that requires purified GTP-bound Ypt7p, HOPS complex, vacuolar SNAREs, ATP hydrolysis, and the SNARE disassembly catalysts Sec17p and Sec18p. We use this …

Polysorbate 80 Inhibition Of Pseudomonas Aeruginosa Biofilm Formation And Its Cleavage By The Secreted Lipase Lipa, C M. Toutain-Kidd, S C. Kadivar, C T. Bramante, S A. Bobin, Michael E. Zegans

Dartmouth Scholarship

Surface-associated bacterial communities known as biofilms are an important source of nosocomial infections. Microorganisms such as Pseudomonas aeruginosa can colonize the abiotic surfaces of medical implants, leading to chronic infections that are difficult to eradicate. Our study demonstrates that polysorbate 80 (PS80), a surfactant commonly added to food and medicines, is able to inhibit biofilm formation by P. aeruginosa on a variety of surfaces, including contact lenses.

Mast Cell–Derived Particles Deliver Peripheral Signals To Remote Lymph Nodes, Christian A. Kunder, Ashley L. St. John, Guojie Li, Kam W. Leong, Brent Berwin, Herman F. Staats, Soman N. Abraham

Dartmouth Scholarship

During infection, signals from the periphery are known to reach draining lymph nodes (DLNs), but how these molecules, such as inflammatory cytokines, traverse the significant distances involved without dilution or degradation remains unclear. We show that peripheral mast cells, upon activation, release stable submicrometer heparin-based particles containing tumor necrosis factor and other proteins. These complexes enter lymphatic vessels and rapidly traffic to the DLNs. This physiological drug delivery system facilitates communication between peripheral sites of inflammation and remote secondary lymphoid tissues.

Statistical Hypothesis Testing For Postreconstructed And Postregistered Medical Images, Eugene Demidenko

Dartmouth Scholarship

Postreconstructed and postregistered medical images are typically treated as the raw data, implicitly assuming that those operations are error free. We question this assumption and explore how the precision of reconstruction and affine registration can be assessed by the image covariance matrix and confidence interval, called the confidence eigenimage, using a statistical model-based approach. Various hypotheses may be tested after image reconstruction and registration using classical statistical hypothesis testing vehicles: Is there a statistically significant difference between images? Does the intensity at a specific location or area of interest belong to the “normal” range? Is there a tumor? Does the …

Phosphoinositides And Snare Chaperones Synergistically Assemble And Remodel Snare Complexes For Membrane Fusion, Joji Mima, William Wickner

Dartmouth Scholarship

Yeast vacuole fusion requires 4 SNAREs, 2 SNARE chaperone systems (Sec17p/Sec18p/ATP and the HOPS complex), and 2 phosphoinositides, phosphatidylinositol 3-phosphate [PI(3)P] and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P₂]. By reconstituting proteoliposomal fusion with purified components, we now show that phosphoinositides have 4 distinct roles: PI(3)P is recognized by the PX domain of the SNARE Vam7p; PI(3)P enhances the capacity of membrane-bound SNAREs to drive fusion in the absence of SNARE chaperones; either PI(3)P or PI(4,5)P₂ can activate SNARE chaperones for the recruitment of Vam7p into fusion-competent SNARE complexes; and either PI(3)P or PI(4,5)P₂ strikingly promotes synergistic SNARE complex remodeling …

Long-Term Immunity To Lethal Acute Or Chronic Type Ii Toxoplasma Gondii Infection Is Effectively Induced In Genetically Susceptible C57bl/6 Mice By Immunization With An Attenuated Type I Vaccine Strain, Jason P. Gigley, Barbara A. Fox, David J. Bzik

Dartmouth Scholarship

C57BL/6 (B6) mice are genetically highly susceptible to chronic type II Toxoplasma gondii infections that invariably cause lethal toxoplasmic encephalitis. We examined the ability of an attenuated type I vaccine strain to elicit long-term immunity to lethal acute or chronic type II infections in susceptible B6 mice. Mice immunized with the type I cps1-1 vaccine strain were not susceptible to a lethal (100-cyst) challenge with the type II strain ME49. Immunized mice challenged with 10 ME49 cysts exhibited significant reductions in brain cyst and parasite burdens compared to naive mice, regardless of the route of challenge infection. Remarkably, cps1-1 strain-immunized …

Ras Activity Levels Control The Development Of Pancreatic Diseases, Baoan Ji, Lilian Tsou, Huamin Wang, Sebastian Gaiser, David Chang, Jaroslaw Daniluk, Yan Bi, Tobias Grote, Daniel Longnecker, Craig Logsdon

Dartmouth Scholarship

Differentiated pancreatic acinar cells expressing endogenous levels of mutant K-Ras do not spontaneously develop pancreatic ductal adenocarcinoma (PDAC). However, we hypothesized that acinar cells would develop PDAC in the presence of Ras activity levels mimicking those of human tumor cells.We measured Ras activity in PDAC cells from mice and humans using a Raf pull-down assay. We compared the effects of acinar cell expression of mutant K-Ras at endogenous and elevated levels on Ras activity and on the development of PDAC.

Low-Dose Arsenic Compromises The Immune Response To Influenza A Infection In Vivo, Courtney D. Kozul, Kenneth H. Ely, Richard I. Enelow, Joshua W. Hamilton

Dartmouth Scholarship

Background:

Arsenic exposure is a significant worldwide environmental health concern. We recently reported that 5-week exposure to environmentally relevant levels (10 and 100 ppb) of As in drinking water significantly altered components of the innate immune response in mouse lung, which we hypothesize is an important contributor to the increased risk of lung disease in exposed human populations.

Objectives:

We investigated the effects of As exposure on respiratory influenza A (H1N1) virus infection, a common and potentially fatal disease.

Methods:

In this study, we exposed C57BL/6J mice to 100 ppb As in drinking water for 5 weeks, followed by intranasal …

Characterization Of Two Outer Membrane Proteins, Flgo And Flgp, That Influence Vibrio Cholerae Motility, Raquel M. Martinez, Madushini N. Dharmasena, Thomas J. Kirn, Ronald K. Taylor

Dartmouth Scholarship

Vibrio cholerae is highly motile by the action of a single polar flagellum. The loss of motility reduces the infectivity of V. cholerae, demonstrating that motility is an important virulence factor. FlrC is the sigma-54-dependent positive regulator of flagellar genes. Recently, the genes VC2206 (flgP) and VC2207 (flgO) were identified as being regulated by FlrC via a microarray analysis of an flrC mutant (D. C. Morris, F. Peng, J. R. Barker, and K. E. Klose, J. Bacteriol. 190:231-239, 2008). FlgP is reported to be an outer membrane lipoprotein required for motility that functions as a colonization factor. The study reported …

Microbial Nad Metabolism: Lessons From Comparative Genomics, Francesca Gazzaniga, Rebecca Stebbins, Sheila Z. Chang, Mark A. Mcpeek, Charles Brenner

Dartmouth Scholarship

NAD is a coenzyme for redox reactions and a substrate of NAD-consuming enzymes, including ADP-ribose transferases, Sir2-related protein lysine deacetylases, and bacterial DNA ligases. Microorganisms that synthesize NAD from as few as one to as many as five of the six identified biosynthetic precursors have been identified. De novo NAD synthesis from aspartate or tryptophan is neither universal nor strictly aerobic. Salvage NAD synthesis from nicotinamide, nicotinic acid, nicotinamide riboside, and nicotinic acid riboside occurs via modules of different genes. Nicotinamide salvage genes nadV and pncA, found in distinct bacteria, appear to have spread throughout the tree of life …

Distinction Of The Memory B Cell Response To Cognate Antigen Versus Bystander Inflammatory Signals, Micah J. Benson, Raul Elgueta, William Schpero, Michael Molloy, Weijun Zhang, Edward Usherwood, Randolph J. Noelle

Dartmouth Scholarship

The hypothesis that bystander inflammatory signals promote memory B cell (B_MEM) self- renewal and differentiation in an antigen-independent manner is critically evaluated herein. To comprehensively address this hypothesis, a detailed analysis is presented examining the response profiles of B-2 lineage B220 + IgG + B_MEM toward cognate protein antigen in comparison to bystander inflammatory signals. After in vivo antigen encounter, quiescent B_MEM clonally expand. Surprisingly, proliferating B_MEM do not acquire germinal center (GC) B cell markers before generating daughter B_MEM and differentiating into plasma cells or form structurally identifiable GCs. In striking contrast to …

Disruption Of Histone Modification And Carm1 Recruitment By Arsenic Represses Transcription At Glucocorticoid Receptor-Regulated Promoters, Fiona D. Barr, Lori J. Krohmer, Joshua W. Hamilton, Lynn A. Sheldon

Dartmouth Scholarship

Chronic exposure to inorganic arsenic (iAs) found in the environment is one of the most significant and widespread environmental health risks in the U.S. and throughout the world. It is associated with a broad range of health effects from cancer to diabetes as well as reproductive and developmental anomalies. This diversity of diseases can also result from disruption of metabolic and other cellular processes regulated by steroid hormone receptors via aberrant transcriptional regulation. Significantly, exposure to iAs inhibits steroid hormone-mediated gene activation. iAs exposure is associated with disease, but is also used therapeutically to treat specific cancers complicating an understanding …

Urogenital Abnormalities In Men Exposed To Diethylstilbestrol In Utero: A Cohort Study, Julie R. Palmer, Arthur L. Herbst, Kenneth L. Noller, Deborah A. Boggs, Rebecca Troisi, Linda Titus-Ernstoff, Elizabeth E. Hatch, Lauren A. Wise, William C. Strohsnitter, Robert N. Hoover

Dartmouth Scholarship

Background: Diethylstilbestrol (DES), a synthetic estrogen widely prescribed to pregnant women during the 1940s70s, has been shown to cause reproductive problems in the daughters. Studies of prenatally-exposed males have yielded conflicting results.

Methods: In data from a collaborative follow-up of three U.S. cohorts of DES-exposed sons, we examined the relation of prenatal DES exposure to occurrence of male urogenital abnormalities. Exposure status was determined through review of prenatal records. Mailed questionnaires (1994, 1997, 2001) asked about specified abnormalities of the urogenital tract. Risk ratios (RR) were estimated by Cox regression with constant time at risk and control for year of …

Aging And Environmental Exposures Alter Tissue-Specific Dna Methylation Dependent Upon Cpg Island Context, Brock C. Christensen, E Andres Houseman, Carmen J. Marsit, Shichun Zheng, Margaret R. Wrensch, Joseph L. Wiemels, Heather H. Nelson, Margaret R. Karagas

Dartmouth Scholarship

Epigenetic control of gene transcription is critical for normal human development and cellular differentiation. While alterations of epigenetic marks such as DNA methylation have been linked to cancers and many other human diseases, interindividual epigenetic variations in normal tissues due to aging, environmental factors, or innate susceptibility are poorly characterized. The plasticity, tissue-specific nature, and variability of gene expression are related to epigenomic states that vary across individuals. Thus, population-based investigations are needed to further our understanding of the fundamental dynamics of normal individual epigenomes. We analyzed 217 non-pathologic human tissues from 10 anatomic sites at 1,413 autosomal CpG loci …

Uncoupling Scavenger Receptor A-Mediated Phagocytosis Of Bacteria From Endotoxic Shock Resistance, Eyal Amiel, Julie L. Acker, Ryan M. Collins, Brent Berwin

Dartmouth Scholarship

Unresolved infection by gram-negative bacteria can result in the potentially lethal condition known as endotoxic shock, whereby uncontrolled inflammation can lead to multiple organ failure and death of the infected host. Previous results have demonstrated that animals deficient in class A scavenger receptor (SRA), a trafficking receptor for bacteria and bacterium-derived molecules, are more susceptible to endotoxic shock. This has been proposed to be a result of impaired SRA-dependent phagocytic clearance of bacteria resulting in stronger proinflammatory stimuli. In this report, we test the hypothesis that there is an obligate reciprocal relationship between SRA-mediated phagocytosis of bacteria and susceptibility to …

Real Time Pcr Detection Of The Pi*Z And Pi*S Mutations Associated With Alpha-1 Antitrypsin Deficiency, Claudine L. Bartels, Angela L. Marchetti, W. Edward Highsmith, Gregory J. Tsongalis

Dartmouth Scholarship

Alpha-1 antitrypsin (A1AT or AAT) is a serine protease inhibitor (PI) which, when present at low levels, can cause chronic obstructive pulmonary disease (COPD) and liver disease in both children and adults. Several mutations within the SERPINA1 gene have been found to cause this deficiency. The most common variants are PI*Z and PI*S, each caused by a single nucleotide polymorphism (SNP). We describe a real time polymerase chain reaction (PCR) assay for the rapid genotyping of these polymorphisms. DNA was extracted from fourteen EDTA-anticoagulated whole blood samples using the Qiagen EZ1 blood extraction kit. SNP genotyping was performed using primer/probe …

Flagellum-Mediated Biofilm Defense Mechanisms Of Pseudomonas Aeruginosa Against Host-Derived Lactoferrin, Jeff G. Leid, Mathias Kerr, Candice Selgado, Chelsa Johnson, Gabriel Moreno, Alyssa Smith, Mark E. Shirtliff, Georg A. O'Toole, Emily K. Cope

Dartmouth Scholarship

Chronic infection with the gram-negative organism Pseudomonas aeruginosa is a leading cause of morbidity and mortality in human patients, despite high doses of antibiotics used to treat the various diseases this organism causes. These infections are chronic because P. aeruginosa readily forms biofilms, which are inherently resistant to antibiotics as well as the host's immune system. Our laboratory has been investigating specific mutations in P. aeruginosa that regulate biofilm bacterial susceptibility to the host. To continue our investigation of the role of genetics in bacterial biofilm host resistance, we examined P. aeruginosa biofilms that lack the flgK gene. This mutant …

A Functional Difficulty And Functional Pain Instrument For Hip And Knee Osteoarthritis, Alan M. Jette, Christine M. Mcdonough, Pengsheng Ni, Stephen M. Haley

Dartmouth Scholarship

The objectives of this study were to develop a functional outcome instrument for hip and knee osteoarthritis research (OA-FUNCTION-CAT) using item response theory (IRT) and computer adaptive test (CAT) methods and to assess its psychometric performance compared to the current standard in the field.