Digital Commons Network^™

Circulating Mirna Biomarkers In Early Breast Cancer Detection Following Mammography, Alexa Lean, Jialu Lucy Yang, Xiaohui Tan, Christine B. Teal, Rachel F. Brem, Sidney W. Fu

GW Research Days 2016 - 2020

The currently accepted stepwise model of breast tumorigenesis assumes a gradual transition from normal breast epithelial cells to atypical ductal hyperplasia (ADH), to ductal carcinoma in situ (DCIS) and then to invasive ductal carcinoma (IDC). Percutaneous core needle biopsy (CNB) is the standard technique following an abnormal mammographic finding. However, CNB is less reliable in differentiating simple ADH (sADH) from ADH component coexisted with advanced lesions such as DCIS and/or IDC (cADH). Therefore, to identify and validate novel reliable molecular biomarkers is essential in order to improve the efficiency of therapeutic recommendations, as well as to minimize anxiety and unnecessary …

Medical Student Competency In Wound Care Guidelines, Sophia Akhiyat, Sean Mcnish, Kara S. Couch, Victoria K. Shanmugam

GW Research Days 2016 - 2020

Chronic wounds that have failed to heal after 3 months of appropriate wound care affect approximately 6.5 million people in the US with a prevalence of 1% and costs estimated at $25 billion per year. Medical students currently receive limited wound care training, yet to effectively manage chronic wounds, providers must both understand the biology of healing, and also remain up-to-date with wound care guidelines published by the Agency for Healthcare Research and Quality (AHRQ). The purpose of this student-led project was to investigate medical students' knowledge and comfort with wound care guidelines.

Molecular Analyses Of Circadian Gene Variants Reveal Sex-Dependent Links Between Depression And Clocks, S-Q Shi, M. J. White, H. M. Borsetti, Julie S. Pendergast, A. Hida, C. M. Ciarleglio, P. A. De Verteuil, A. G. Cadar, C. Cala, D. G. Mcmahon, R. C. Shelton, S. M. Williams, C. H. Johnson

Biology Faculty Publications

An extensive literature links circadian irregularities and/or sleep abnormalities to mood disorders. Despite the strong genetic component underlying many mood disorders, however, previous genetic associations between circadian clock gene variants and major depressive disorder (MDD) have been weak. We applied a combined molecular/functional and genetic association approach to circadian gene polymorphisms in sex-stratified populations of control subjects and case subjects suffering from MDD. This approach identified significant sex-dependent associations of common variants of the circadian clock genes hClock, hPer3 and hNpas2 with major depression and demonstrated functional effects of these polymorphisms on the expression or activity of the hCLOCK …

Oncolog, Volume 61, Number 03, March 2016, Bryan Tutt, Sarah Bronson, Jill Delsigne, K Werner

OncoLog MD Anderson's Report to Physicians (All issues) Archives

• Innovations Decrease Toxic Effects of Radiation Therapy for Mediastinal Tumors from Hematological Malignancies: Anterior mediastinal masses caused by lymphoma or leukemia can be difficult to treat because sensitive tissues in the area are vulnerable to damage from radiation therapy. To treat these tumors while sparing healthy tissue, radiation oncologists at The University of Texas MD Anderson Cancer Center use a combination of advanced technologies and new techniques.
• Transoral Robotic Surgery Enables Less Toxic Treatment of Early Throat Cancers: For decades, many patients with hard-to-reach throat cancers received high-dose radiation and chemotherapy, with their often severe toxic effects, because conventional surgery …

Fear Conditioning And Extinction In Youth With Obsessive-Compulsive Disorder, Joseph F. Mcguire, Scott P. Orr, Monica S. Wu, Adam B. Lewin, Brent J. Small, Vicky Phares, Tanya K. Murphy, Sabine Wilhelm, Daniel S. Pine, Daniel Geller, Eric A. Storch

Psychology Faculty Publications

BACKGROUND: Fear acquisition and extinction are central constructs in the cognitive-behavioral model of obsessive-compulsive disorder (OCD), which underlies exposure-based cognitive-behavioral therapy (CBT). Youth with OCD may have impairments in fear acquisition and extinction that carry treatment implications. We examined these processes using a differential conditioning procedure.

METHODS: Forty-one youth (19 OCD, 22 community comparisons) completed a battery of clinical interviews, rating scales, and a differential conditioning task that included habituation, acquisition, and extinction phases. Skin conductance response (SCR) served as the primary dependent measure.

RESULTS: During habituation, no difference between groups was observed. During acquisition, differential fear conditioning was observed …

Adiponectin At Physiologically Relevant Concentrations Enhances The Vasorelaxative Effect Of Acetylcholine Via Cav-1/Adipor-1 Signaling., Yunhui Du, Rui Li, Wayne Bond Lau, Jianli Zhao, Bernard Lopez, Theodore A Christopher, Xin-Liang Ma, Yajing Wang

Department of Emergency Medicine Faculty Papers

Clinical studies have identified hypoadiponectinemia as an independent hypertension risk factor. It is known that adiponectin (APN) can directly cause vasodilation, but the doses required exceed physiologic levels several fold. In the current study, we determine the effect of physiologically relevant APN concentrations upon vascular tone, and investigate the mechanism(s) responsible. Physiologic APN concentrations alone induced no significant vasorelaxation. Interestingly, pretreatment of wild type mouse aortae with physiologic APN levels significantly enhanced acetylcholine (ACh)-induced vasorelaxation (P

Long Non-Coding Rnas As Prognostic Markers In Human Breast Cancer, Hairong Liu, Juan Li, Pratirodh Koirala, Xianfeng Ding, Binghai Chen, Yiheng Wang, Zheng Wang, Chuanxin Wang, Xu Zhang, Yin-Yuan Mo

Faculty Publications

Long non-coding RNAs (lncRNAs) have been recently shown to play an important role in gene regulation and normal cellular functions, and disease processes. However, despite the overwhelming number of lncRNAs identified to date, little is known about their role in cancer for vast majority of them. The present study aims to determine whether lncRNAs can serve as prognostic markers in human breast cancer. We interrogated the breast invasive carcinoma dataset of the Cancer Genome Atlas (TCGA) at the cBioPortal consisting of ~ 1,000 cases. Among 2,730 lncRNAs analyzed, 577 lncRNAs had alterations ranging from 1% to 32% frequency, which include …

Techniques And Approaches To Genetic Analyses In Nephrological Disorders., Laurel K. Willig

Manuscripts, Articles, Book Chapters and Other Papers

Inherited renal disease is a leading cause of morbidity and mortality in pediatric nephrology. High throughput advancements in genomics have led to greater understanding of the biologic underpinnings of these diseases. However, the underlying genetic changes explain only part of the molecular biology that contributes to disease manifestation and progression. Other omics technologies will provide a more complete picture of these cellular processes. This review discusses these omics technologies in the context of pediatric renal disease.

Occupational Health Of Self-Employed Skilled Labourers And Daily-Wage Workers In Pakistan., Noor Ul-Ain Baloch, Abdul Rehman Alvi, Muhammad Awais

Department of Surgery Docs

No abstract provided.

Cd33 Expression And Its Association With Gemtuzumab Ozogamicin Response: Results From The Randomized Phase Iii Children's Oncology Group Trial Aaml0531., Jessica A. Pollard, Michael Loken, Robert B. Gerbing, Susana C. Raimondi, Betsy A. Hirsch, Richard Aplenc, Irwin D. Bernstein, Alan S. Gamis, Todd A. Alonzo, Soheil Meshinchi

Manuscripts, Articles, Book Chapters and Other Papers

PURPOSE: CD33 is variably expressed on acute myeloid leukemia (AML) blasts and is targeted by gemtuzumab ozogamicin (GO). GO has shown benefit in both adult and pediatric AML trials, yet limited data exist about whether GO response correlates with CD33 expression level.

PATIENTS AND METHODS: CD33 expression levels were prospectively quantified by multidimensional flow cytometry in 825 patients enrolled in Children's Oncology Group AAML0531 and correlated with response to GO.

RESULTS: Patients with low CD33 expression (lowest quartile of expression [Q1]) had no benefit with the addition of GO to conventional chemotherapy (relapse risk [RR]: GO 36% v No-GO 34%, …

Alternative Regulation Of Myc In Lung Cancer, Patrick N. Backman

Open Access Theses

Lung cancer is the leading cause of cancer deaths in the United States, accounting for 27% of all cancer induced deaths1. In an attempt to create a effective targeted therapy for the treatment of lung cancer, a strategy used to treat an activated KrasG12D/+;p53 R172H/+ transgenic lung cancer mouse model was to deliver a known tumor suppressive microRNA (miRNA) to stop tumor growth. The tumor suppressive miRNA let-7 was lentivirally delivered in the form of its primary transcript, pri-let-7a-1, and resulted in increased lung size and inflammation compared to lungs exposed to a control lentivirus. It was identified …

Analysis Of Tumor Template From Multiple Compartments In A Blood Sample Provides Complementary Access To Peripheral Tumor Biomarkers., William M Strauss, Chris Carter, Jill Simmons, Erich Klem, Nathan Goodman, Behrad Vahidi, Juan Romero, Michael Masterman-Smith, Ruth O'Regan, Keerthi Gogineni, Lee Schwartzberg, Laura Austin, Paul W Dempsey, Massimo Cristofanilli

Kimmel Cancer Center Faculty Papers

Targeted cancer therapeutics are promised to have a major impact on cancer treatment and survival. Successful application of these novel treatments requires a molecular definition of a patient's disease typically achieved through the use of tissue biopsies. Alternatively, allowing longitudinal monitoring, biomarkers derived from blood, isolated either from circulating tumor cell derived DNA (ctcDNA) or circulating cell-free tumor DNA (ccfDNA) may be evaluated. In order to use blood derived templates for mutational profiling in clinical decisions, it is essential to understand the different template qualities and how they compare to biopsy derived template DNA as both blood-based templates are rare …

Caregiver Opinion Of In-Hospital Screening For Unmet Social Needs By Pediatric Residents., Jeffrey D. Colvin, Jessica L. Bettenhausen, Kaston D. Anderson-Carpenter, Vicki Collie-Akers, Paul J. Chung

Manuscripts, Articles, Book Chapters and Other Papers

OBJECTIVE: Child health is strongly influenced by social determinants. Little is known about the opinions of primary caregivers regarding the physicians' role in addressing social needs. Our objective was to examine caregivers' opinions about that role and any associations between those opinions, previous exposure to screening for needs by pediatric residents, and socioeconomic status (SES).

METHODS: Cross-sectional survey study of caregivers of hospitalized children. The survey collected information on caregiver opinion regarding their ability to ask physicians for help with social needs, whether physicians know how to help with those needs, and whether physicians should ask about social needs. The …

Role Of Heme Oxygenase-1 In The Pathogenesis And Tumorigenicity Of Kaposi's Sarcoma-Associated Herpesvirus, Lu Dai, Jing Qiao, David Nguyen, Amanda P. Struckhoff, Lisa Doyle, Karlie Bonstaff, Luis Del Valle, Chris Parsons, Bryan P. Toole, Rolf Renne, Zhiqiang Qin

School of Medicine Faculty Publications

Kaposi's Sarcoma-associated Herpesvirus (KSHV) is the etiologic agent of several malignancies, including Kaposi's Sarcoma (KS), which preferentially arise in immunocompromised patients such as HIV+ subpopulation and lack effective therapeutic options. Heme oxygenase-1 (HO-1) has been reported as an important regulator of endothelial cell cycle control, proliferation and angiogenesis. HO-1 has also been found to be highly expressed in KSHV-infected endothelial cells and oral AIDS-KS lesions. We previously demonstrate that the multifunctional glycoprotein CD147 is required for KSHV/LANA-induced endothelial cell invasiveness. During the identification of CD147 controlled downstream genes by microarray analysis, we found that the expression of HO-1 is significantly …

Significance Of Tumor Marker Ca15-3 In Metastatic Breast Cancer, Hoor Fatima, Amir Maqbool, Marium Siddiqui, Ghulam H, Habiba Sohail, Omema Saleem, Afarina Ahmed

Department of Medicine

Secondary spread of cancer to bones is commonest and frequent phenomenon and enhances the need of special care for sufferers. Bone metastases mostly are the first complication of different variety of cancers which increase the need of care and expensive facilities. Blood dissemination is another common route, might be due to the venous drainage from visceral organs directly into the axial bones. CA 15-3 is a mucinous tumor markers derived from MUC1 gene, provides better guide line about the treatment, recurrence and prognosis.

Aim: Aim of the study was to signify the role of tumor marker CA15-3 in metastatic breast …

Pressure To Publish For Residency Applicants In Dermatology, Jordan V. Wang, Matthew S. Keller

Department of Dermatology and Cutaneous Biology Faculty Papers

As it grows increasingly difficult to match into a dermatology residency program each year, there is a widening gap in research accomplishments between those who have and have not matched successfully. Applicants should be aware of the current trends in order to maximize their chances of matching. Such research inequality may subsequently lead to increases in the pressure to publish and the incidence of academic misrepresentation. Academic dermatology programs should be aware of these issues in order to help their students successfully match and exercise caution when reviewing the curricula vitae of applicants. We believe that student mentors in dermatology …

Is Whole-Exome Sequencing An Ethically Disruptive Technology? Perspectives Of Pediatric Oncologists And Parents Of Pediatric Patients With Solid Tumors, Laurence B Mccullough, Melody J Slashinski, Amy L Mcguire, Richard L Street, Christine M Eng, Richard A Gibbs, D William Parsons, Sharon E Plon

Faculty, Staff and Students Publications

BACKGROUND: It has been anticipated that physician and parents will be ill prepared or unprepared for the clinical introduction of genome sequencing, making it ethically disruptive.

PROCEDURE: As a part of the Baylor Advancing Sequencing in Childhood Cancer Care study, we conducted semistructured interviews with 16 pediatric oncologists and 40 parents of pediatric patients with cancer prior to the return of sequencing results. We elicited expectations and attitudes concerning the impact of sequencing on clinical decision making, clinical utility, and treatment expectations from both groups. Using accepted methods of qualitative research to analyze interview transcripts, we completed a thematic analysis …

C-Src/Cav1-Dependent Activation Of The Egfr By Dsg2., Andrew M. Overmiller, Kathleen P. Mcguinn, Brett J. Roberts, Felicia Cooper, Donna M. Brennan-Crispi, Takahiro Deguchi, Sirkku Peltonen, James K. Wahl, Mỹ G. Mahoney

Department of Dermatology and Cutaneous Biology Faculty Papers

The desmosomal cadherin, desmoglein 2 (Dsg2), is deregulated in a variety of human cancers including those of the skin. When ectopically expressed in the epidermis of transgenic mice, Dsg2 activates multiple mitogenic signaling pathways and increases susceptibility to tumorigenesis. However, the molecular mechanism responsible for Dsg2-mediated cellular signaling is poorly understood. Here we show overexpression as well as co-localization of Dsg2 and EGFR in cutaneous SCCs in vivo. Using HaCaT keratinocytes, knockdown of Dsg2 decreases EGFR expression and abrogates the activation of EGFR, c-Src and Stat3, but not Erk1/2 or Akt, in response to EGF ligand stimulation. To determine whether …

Two Separate Colorectal Granular Cell Tumors: A Case Report, Danica N. Giugliano, Md, Danielle Fortuna, Md, Scott D. Goldstein, Md, Benjamin Philllips, Md, Gerald A. Isenberg, Md

Department of Surgery Posters

Introduction, Case Report, Discussion, Conclusion and References.

Abnormal Tau Induces Cognitive Impairment Through Two Different Mechanisms: Synaptic Dysfunction And Neuronal Loss, J. Di, L. S. Cohen, C. P. Corbo, Greg R. Phillips, Abdeslem El Idrissi, Alejandra D. Alonso

Publications and Research

The hyperphosphorylated microtubule-associated protein tau is present in several neurodegenerative diseases, although the causal relationship remains elusive. Few mouse models used to study Alzheimerlike dementia target tau phosphorylation. We created an inducible pseudophosphorylated tau (Pathological Human Tau, PH-Tau) mouse model to study the effect of conformationally modified tau in vivo. Leaky expression resulted in two levels of PH-Tau: low basal level and higher upon induction (4% and 14% of the endogenous tau, respectively). Unexpectedly, low PH-Tau resulted in significant cognitive deficits, decrease in the number of synapses (seen by EM in the CA1 region), reduction of synaptic proteins, and localization …

Conjugate Haemophilus Influenzae Type B Vaccines For Sickle Cell Disease., Slimane Allali, Martin Chalumeau, Odile Launay, Samir K. Ballas, Mariane De Montalembert

Cardeza Foundation for Hematologic Research

BACKGROUND: People affected with sickle cell disease are at high risk of infection from Haemophilus influenzae type b. Before the implementation of Haemophilus influenzae type b conjugate vaccination in high-income countries, this was responsible for a high mortality rate in children under five years of age. In African countries, where coverage of this vaccination is still extremely low, Haemophilus influenzae type b remains one of the most common cause of bacteraemias in children with sickle cell disease. The increased uptake of this conjugate vaccination may substantially improve the survival of children with sickle cell disease.

OBJECTIVES: The primary objective was …

Soothing Relaxation Journeys: Designing Evidence Based Music And Imagery Opportunities, Amy Clements-Cortés

Music Faculty Publications

This paper provides information on the creation of an original collection of music and imagery journeys based on the literature in oncology and palliative care. Background evidence is shared about music and relaxation, music relaxation in medical settings, and music and relaxation in oncology/hospice treatment. The development of the resource is illuminated with respect to principles that guided the design. The Journeys collection is a tool that can be used independently by persons experiencing a variety of issues including: anxiety, pain, stress, low self-esteem, and low mood, etcetera; as well as with groups when implemented by a healthcare professional. While …

Molecular Evolution And Intraclade Recombination Of Enterovirus D68 During The 2014 Outbreak In The United States., Yi Tan, Ferdaus Hassan, Jennifer E. Schuster, Ari Simenauer, Rangaraj Selvarangan, Rebecca A. Halpin, Xudong Lin, Nadia Fedorova, Timothy B. Stockwell, Tommy Tsan-Yuk Lam, James D. Chappell, Tina V. Hartert, Edward C. Holmes, Suman R. Das

Manuscripts, Articles, Book Chapters and Other Papers

In August 2014, an outbreak of enterovirus D68 (EV-D68) occurred in North America, causing severe respiratory disease in children. Due to a lack of complete genome sequence data, there is only a limited understanding of the molecular evolution and epidemiology of EV-D68 during this outbreak, and it is uncertain whether the differing clinical manifestations of EV-D68 infection are associated with specific viral lineages. We developed a high-throughput complete genome sequencing pipeline for EV-D68 that produced a total of 59 complete genomes from respiratory samples with a 95% success rate, including 57 genomes from Kansas City, MO, collected during the 2014 …

Hydroxycarbamide Versus Chronic Transfusion For Maintenance Of Transcranial Doppler Flow Velocities In Children With Sickle Cell Anaemia-Tcd With Transfusions Changing To Hydroxyurea (Twitch): A Multicentre, Open-Label, Phase 3, Non-Inferiority Trial., Russell E Ware, Barry R Davis, William H Schultz, R Clark Brown, Banu Aygun, Sharada Sarnaik, Lori Luchtman-Jones, +Several Additional Authors

Pediatrics Faculty Publications

BACKGROUND: For children with sickle cell anaemia and high transcranial doppler (TCD) flow velocities, regular blood transfusions can effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxycarbamide (hydroxyurea) in this setting is unknown; we performed the TWiTCH trial to compare hydroxyurea with standard transfusions.

METHODS: TWiTCH was a multicentre, phase 3, randomised, open-label, non-inferiority trial done at 26 paediatric hospitals and health centres in the USA and Canada. We enrolled children with sickle cell anaemia who were aged 4-16 years and had abnormal TCD flow velocities (≥ 200 cm/s) but no severe vasculopathy. After screening, eligible …

AΒ40 Reduces P-Glycoprotein At The Blood-Brain Barrier Through The Ubiquitin-Proteasome Pathway, Anika M. S. Hartz, Yu Zhong, Andrea Wolf, Harry Levine Iii, David S. Miller, Björn Bauer

Sanders-Brown Center on Aging Faculty Publications

Failure to clear amyloid-β (Aβ) from the brain is in part responsible for Aβ brain accumulation in Alzheimer's disease (AD). A critical protein for clearing Aβ across the blood–brain barrier is the efflux transporter P-glycoprotein (P-gp) in the luminal plasma membrane of the brain capillary endothelium. P-gp is reduced at the blood–brain barrier in AD, which has been shown to be associated with Aβ brain accumulation. However, the mechanism responsible for P-gp reduction in AD is not well understood. Here we focused on identifying critical mechanistic steps involved in reducing P-gp in AD. We …

Pi(4)P Promotes Phosphorylation And Conformational Change Of Smoothened Through Interaction With Its C-Terminal Tail, Kai Jiang, Yajuan Liu, Junkai Fan, Jie Zhang, Xiang-An Li, B. Mark Evers, Haining Zhu, Jianhang Jia

Markey Cancer Center Faculty Publications

In Hedgehog (Hh) signaling, binding of Hh to the Patched-Interference Hh (Ptc-Ihog) receptor complex relieves Ptc inhibition on Smoothened (Smo). A longstanding question is how Ptc inhibits Smo and how such inhibition is relieved by Hh stimulation. In this study, we found that Hh elevates production of phosphatidylinositol 4-phosphate (PI(4)P). Increased levels of PI(4)P promote, whereas decreased levels of PI(4)P inhibit, Hh signaling activity. We further found that PI(4)P directly binds Smo through an arginine motif, which then triggers Smo phosphorylation and activation. Moreover, we identified the pleckstrin homology (PH) domain of G protein-coupled receptor kinase 2 (Gprk2) as an …

Therapeutic Effect Of Melatonin On Pediatric Functional Dyspepsia: A Pilot Study., Katherine Zybach, Craig A. Friesen, Jennifer V. Schurman

Manuscripts, Articles, Book Chapters and Other Papers

AIM: To study the effectiveness of melatonin vs placebo in children with functional dyspepsia (FD).

METHODS: The study was conducted as a double blind, randomized, placebo controlled crossover trial. Subjects were aged 8-17 years and diagnosed with FD based on Rome III criteria. All subjects had failed to respond to 4 wk of acid suppression. Subjects receive a continuous two weeks of placebo and a continuous two weeks of melatonin in an order blinded to the participant and the study team. A Global Clinical Score was obtained to assess changes in abdominal pain. Pain was self-reported to be worse (grade …

The Significance Of A Common Idiotype (1f7) On Antibodies Against Human Immune Deficiency Virus Type 1 And Hepatitis C Virus, Sybille Muller, Matthew S. Parsons, Heinz Kohler, Michael Grant

Microbiology, Immunology, and Molecular Genetics Faculty Publications

In this review, we trace the concept and potential functional role of regulatory idiotypes in the immune response to human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency virus, and hepatitis C virus (HCV). A major idiotype involved in these viral infections is recognized and defined by a murine monoclonal antibody (1F7). Antibodies expressing the idiotype defined by 1F7 are dominant in HIV-1 infection and are also found on many broadly neutralizing antibodies against HIV-1. This regulatory idiotypic axis offers opportunities for exploitation in vaccine development for HIV-1, HCV, and other chronic viral infections.

Development And Pilot-Testing Of A Patient Decision Aid For Left Ventricular Assist Device Placement, Kristin Kostick, Estevan D. Delgado, Lidija A. Wilhelms, Courtenay R. Bruce, Jerry D. Estep, Matthias Loebe, Charles Minard, Jennifer S. Blumenthal-Barby

The VAD Journal

Objectives: This paper describes the development methodology and pilot-testing of a decision aid for Left Ventricular Assist Device (LVAD) placement, combining traditional needs-assessment with a novel user-centered approach.

Background: Studies indicate suboptimal patient understanding of the capabilities, lifestyle implications, and risks of LVAD therapy.

Methods and Results: We developed the decision aid in line with the Ottawa Decision Support Framework (ODSF) and the International Patient Decision Aids Standards (IPDAS) for ensuring quality, patient-centered content. Structured interviews were conducted with patients, caregivers, candidates for LVAD treatment, and expert clinicians (n=71) to generate content based on patient values and …

Structural And Evolutionary Analyses Show Unique Stabilization Strategies In The Type Iv Pili Of Clostridium Difficile, Kurt H. Piepenbrink, Grace A. Maldarelli, Claudia F. Martinez De La Pena, Tanis C. Dingle, George L. Mulvey, Amanda Lee, Erik Von Rosenvinge, Glen D. Armstrong, Michael S. Donnenberg, Eric J. Sundberg

Food for Health: Publications

Type IV pili are produced by many pathogenic Gram-negative bacteria and are important for processes as diverse as twitching motility, biofilm formation, cellular adhesion and horizontal gene transfer. However, many Gram-positive species, including C. difficile, also produce Type IV pili. Here, we identify the major subunit of the Type IV pili of C. difficile, PilA1, and describe multiple three-dimensional structures of PilA1, demonstrating the diversity found in three strains of C. difficile. We also model the incorporation of both PilA1 and a minor pilin, PilJ, into the pilus fiber. Although PilA1 contains no cysteine residues, and therefore cannot form the …