Publications by authors named "Andrea Haller"

9 Publications

  • Page 1 of 1

Should neurologists diagnose and manage functional neurologic disorders? It is complicated.

Neurol Clin Pract 2019 Apr;9(2):165-167

Department of Neurology (DLP), Functional Neurology Research Group, Cognitive Behavioral Neurology Unit, Massachusetts General Hospital, Harvard Medical School; Department of Psychiatry (DLP), Neuropsychiatry Unit, Massachusetts General Hospital, Harvard Medical School, Boston; Athinoula A. Martinos Center for Biomedical Imaging (DLP), Massachusetts General Hospital, Harvard Medical School, Charlestown; Fort Wayne Neurological Center (ALH), Fort Wayne; Department of Neurology (ALH), Indiana University School of Medicine, Indianapolis; and Department of Neurology (AJE), University of Cincinnati Medical Center, OH.

Whereas only neurologists can "rule in" functional neurologic disorders (FNDs)-using physical signs and semiologic features-their role in follow-up care remains debated. We outlined the arguments for and against a neurologist's primary role in both assessing and managing FNDs. Favorable arguments include the following: (1) FND presents neurologically, and thus, only neurologists can ascertain the etiology of new neurologic deficits appearing on follow-up, and (2) neurologic encounters facilitate acceptance of diagnosis and enhance treatment engagement. Counter arguments include the following: (1) FND is a Diagnostic and Statistical Manual of Mental Disorders, 5th Edition codified psychiatric disorder with largely psychiatric treatments, and (2) neurologists can reassess patients if new neurologic symptoms develop without playing a primary follow-up role. Although more research is needed to clarify optimal approaches, neurologic expertise could be leveraged for diagnostic and coordinating roles if the pool of neurologists, psychiatrists, psychotherapists, physical and occupational therapists, and other allied clinicians trained in the interdisciplinary care of FNDs is substantially increased.
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http://dx.doi.org/10.1212/CPJ.0000000000000573DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6461419PMC
April 2019

Analysis of Varicella-Zoster Virus in Temporal Arteries Biopsy Positive and Negative for Giant Cell Arteritis.

JAMA Neurol 2015 Nov;72(11):1281-7

Department of Neurology, University of Colorado School of Medicine, Aurora20Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora.

Importance: Giant cell arteritis (GCA) is the most common systemic vasculitis in elderly individuals. Diagnosis is confirmed by temporal artery (TA) biopsy, although biopsy results are often negative. Despite the use of corticosteroids, disease may progress. Identification of causal agents will improve outcomes. Biopsy-positive GCA is associated with TA infection by varicella-zoster virus (VZV).

Objective: To analyze VZV infection in TAs of patients with clinically suspected GCA whose TAs were histopathologically negative and in normal TAs removed post mortem from age-matched individuals.

Design, Setting, And Participants: A cross-sectional study for VZV antigen was performed from January 2013 to March 2015 using archived, deidentified, formalin-fixed, paraffin-embedded GCA-negative, GCA-positive, and normal TAs (50 sections/TA) collected during the past 30 years. Regions adjacent to those containing VZV were examined by hematoxylin-eosin staining. Immunohistochemistry identified inflammatory cells and cell types around nerve bundles containing VZV. A combination of 17 tertiary referral centers and private practices worldwide contributed archived TAs from individuals older than 50 years.

Main Outcomes And Measures: Presence and distribution of VZV antigen in TAs and histopathological changes in sections adjacent to those containing VZV were confirmed by 2 independent readers.

Results: Varicella-zoster virus antigen was found in 45 of 70 GCA-negative TAs (64%), compared with 11 of 49 normal TAs (22%) (relative risk [RR] = 2.86; 95% CI, 1.75-5.31; P < .001). Extension of our earlier study revealed VZV antigen in 68 of 93 GCA-positive TAs (73%), compared with 11 of 49 normal TAs (22%) (RR = 3.26; 95% CI, 2.03-5.98; P < .001). Compared with normal TAs, VZV antigen was more likely to be present in the adventitia of both GCA-negative TAs (RR = 2.43; 95% CI, 1.82-3.41; P < .001) and GCA-positive TAs (RR = 2.03; 95% CI, 1.52-2.86; P < .001). Varicella-zoster virus antigen was frequently found in perineurial cells expressing claudin-1 around nerve bundles. Of 45 GCA-negative participants whose TAs contained VZV antigen, 1 had histopathological features characteristic of GCA, and 16 (36%) showed adventitial inflammation adjacent to viral antigen; no inflammation was seen in normal TAs.

Conclusions And Relevance: In patients with clinically suspected GCA, prevalence of VZV in their TAs is similar independent of whether biopsy results are negative or positive pathologically. Antiviral treatment may confer additional benefit to patients with biopsy-negative GCA treated with corticosteroids, although the optimal antiviral regimen remains to be determined.
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http://dx.doi.org/10.1001/jamaneurol.2015.2101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5110206PMC
November 2015

Escherichia coli ribosomal protein S1 unfolds structured mRNAs onto the ribosome for active translation initiation.

PLoS Biol 2013 Dec 10;11(12):e1001731. Epub 2013 Dec 10.

Architecture et Réactivité de l'ARN, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire-CNRS, Strasbourg, France.

Regulation of translation initiation is well appropriate to adapt cell growth in response to stress and environmental changes. Many bacterial mRNAs adopt structures in their 5' untranslated regions that modulate the accessibility of the 30S ribosomal subunit. Structured mRNAs interact with the 30S in a two-step process where the docking of a folded mRNA precedes an accommodation step. Here, we used a combination of experimental approaches in vitro (kinetic of mRNA unfolding and binding experiments to analyze mRNA-protein or mRNA-ribosome complexes, toeprinting assays to follow the formation of ribosomal initiation complexes) and in vivo (genetic) to monitor the action of ribosomal protein S1 on the initiation of structured and regulated mRNAs. We demonstrate that r-protein S1 endows the 30S with an RNA chaperone activity that is essential for the docking and the unfolding of structured mRNAs, and for the correct positioning of the initiation codon inside the decoding channel. The first three OB-fold domains of S1 retain all its activities (mRNA and 30S binding, RNA melting activity) on the 30S subunit. S1 is not required for all mRNAs and acts differently on mRNAs according to the signals present at their 5' ends. This work shows that S1 confers to the ribosome dynamic properties to initiate translation of a large set of mRNAs with diverse structural features.
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http://dx.doi.org/10.1371/journal.pbio.1001731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3858243PMC
December 2013

Tuning a riboswitch response through structural extension of a pseudoknot.

Proc Natl Acad Sci U S A 2013 Aug 12;110(35):E3256-64. Epub 2013 Aug 12.

Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria.

Structural and dynamic features of RNA folding landscapes represent critical aspects of RNA function in the cell and are particularly central to riboswitch-mediated control of gene expression. Here, using single-molecule fluorescence energy transfer imaging, we explore the folding dynamics of the preQ1 class II riboswitch, an upstream mRNA element that regulates downstream encoded modification enzymes of queuosine biosynthesis. For reasons that are not presently understood, the classical pseudoknot fold of this system harbors an extra stem-loop structure within its 3'-terminal region immediately upstream of the Shine-Dalgarno sequence that contributes to formation of the ligand-bound state. By imaging ligand-dependent preQ1 riboswitch folding from multiple structural perspectives, we reveal that the extra stem-loop strongly influences pseudoknot dynamics in a manner that decreases its propensity to spontaneously fold and increases its responsiveness to ligand binding. We conclude that the extra stem-loop sensitizes this RNA to broaden the dynamic range of the ON/OFF regulatory switch.
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http://dx.doi.org/10.1073/pnas.1304585110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3761628PMC
August 2013

Folding and ligand recognition of the TPP riboswitch aptamer at single-molecule resolution.

Proc Natl Acad Sci U S A 2013 Mar 25;110(11):4188-93. Epub 2013 Feb 25.

Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020 Innsbruck, Austria.

Thiamine pyrophosphate (TPP)-sensitive mRNA domains are the most prevalent riboswitches known. Despite intensive investigation, the complex ligand recognition and concomitant folding processes in the TPP riboswitch that culminate in the regulation of gene expression remain elusive. Here, we used single-molecule fluorescence resonance energy transfer imaging to probe the folding landscape of the TPP aptamer domain in the absence and presence of magnesium and TPP. To do so, distinct labeling patterns were used to sense the dynamics of the switch helix (P1) and the two sensor arms (P2/P3 and P4/P5) of the aptamer domain. The latter structural elements make interdomain tertiary contacts (L5/P3) that span a region immediately adjacent to the ligand-binding site. In each instance, conformational dynamics of the TPP riboswitch were influenced by ligand binding. The P1 switch helix, formed by the 5' and 3' ends of the aptamer domain, adopts a predominantly folded structure in the presence of Mg(2+) alone. However, even at saturating concentrations of Mg(2+) and TPP, the P1 helix, as well as distal regions surrounding the TPP-binding site, exhibit an unexpected degree of residual dynamics and disperse kinetic behaviors. Such plasticity results in a persistent exchange of the P3/P5 forearms between open and closed configurations that is likely to facilitate entry and exit of the TPP ligand. Correspondingly, we posit that such features of the TPP aptamer domain contribute directly to the mechanism of riboswitch-mediated translational regulation.
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http://dx.doi.org/10.1073/pnas.1218062110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3600479PMC
March 2013

New insights into gene regulation--high-resolution structures of cobalamin riboswitches.

Angew Chem Int Ed Engl 2013 Feb 7;52(7):1874-7. Epub 2013 Jan 7.

Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, Center for Chemistry and Biomedicine, 6020 Innsbruck, Austria.

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http://dx.doi.org/10.1002/anie.201208167DOI Listing
February 2013

A powerful approach for the selection of 2-aminopurine substitution sites to investigate RNA folding.

J Am Chem Soc 2011 Oct 14;133(40):16161-7. Epub 2011 Sep 14.

Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.

A precise tertiary structure must be adopted to allow the function of many RNAs in cells. Accordingly, increasing resources have been devoted to the elucidation of RNA structures and the folding of RNAs. 2-Aminopurine (2AP), a fluorescent nucleobase analogue, can be substituted in strategic positions of DNA or RNA molecules to act as site-specific probe to monitor folding and folding dynamics of nucleic acids. Recent studies further demonstrated the potential of 2AP modifications in the assessment of folding kinetics during ligand-induced secondary and tertiary RNA structure rearrangements. However, an efficient way to unambiguously identify reliable positions for 2AP sensors is as yet unavailable and would represent a major asset, especially in the absence of crystallographic or NMR structural data for a target molecule. We report evidence of a novel and direct correlation between the 2'-OH flexibility of nucleotides, observed by selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) probing and the fluorescence response following nucleotide substitutions by 2AP. This correlation leads to a straightforward method, using SHAPE probing with benzoyl cyanide, to select appropriate nucleotide sites for 2AP substitution. This clear correlation is presented for three model RNAs of biological significance: the SAM-II, adenine (addA), and preQ(1) class II (preQ(1)cII) riboswitches.
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http://dx.doi.org/10.1021/ja2063583DOI Listing
October 2011

The dynamic nature of RNA as key to understanding riboswitch mechanisms.

Acc Chem Res 2011 Dec 16;44(12):1339-48. Epub 2011 Jun 16.

Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, 6020 Innsbruck, Austria.

Riboswitches are gene regulation elements within RNA that recognize specific metabolites. They predominantly occur in the untranslated leader regions of bacterial messenger RNA (mRNA). Upon metabolite binding to the aptamer domain, a structural change in the adjoining downstream expression platform signals "on" or "off" for gene expression. Researchers have achieved much progress in characterizing ligand-bound riboswitch states at the molecular level; an impressive number of high-resolution structures of aptamer-ligand complexes is now available. These structures have significantly contributed toward our understanding of how riboswitches interact with their natural ligands and with structurally related analogues. In contrast, relatively little is known about the nature of the unbound (apo) form of riboswitches. Moreover, the details of how changes in the aptamer domain are transduced into conformational changes in the decision-making expression platform remain murky. In this Account, we report on recent efforts aimed at the characterization of free states, ligand recognition, and ligand-induced folding in riboswitches. Riboswitch action is best approached as a cotranscriptional process, which implies sequential folding and release of the aptamer prior to the signaling of the expression platform. Thus, a complex interplay of several factors has to be taken into account, such as speed of transcription, transcriptional pausing, kinetics and thermodynamics of RNA structure formation, and kinetics and thermodynamics of ligand binding. The response mechanism appears to be best described as a process in which ligand recognition critically dictates the folding pathway of the nascent mRNA during its expression; the resulting structures determine the interactions with the transcriptional or translational apparatus. We discuss experimental methods that offer insight into the dynamics of the free riboswitch state. These include probing experiments, such as in-line and selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) techniques, small-angle X-ray scattering (SAXS) analysis, NMR spectroscopy, and fluorescence spectroscopy, including single-molecule fluorescence resonance energy transfer (smFRET) imaging. One of our research contributions is an approach, termed 2ApFold, that incorporates noninvasive 2-aminopurine modifications in riboswitches. The fluorescence response of these moieties is used to delineate the order of secondary-tertiary structure formation and rearrangements taking place during ligand-induced folding. This information can be used to explore the kinetics of ligand recognition and to analyze the degree of structure preorganization of the free riboswitch state. Furthermore, we discuss a recent smFRET study on the SAM-II riboswitch; this report underscores the importance of choosing strategic labeling patterns that leave maximal conformational freedom to the regulatory interaction. Finally, we comment on how riboswitch ligand recognition appeals to the concepts of conformational selection and induced fit, and on the question of whether riboswitches act under thermodynamic or kinetic control. This Account highlights the fact that a thorough understanding of RNA dynamics in vitro is required to shed light on cellular riboswitch mechanisms. Elucidating these mechanisms will contribute not only to ongoing efforts to target riboswitches with antibiotics but also to attempts to engineer artificial cell regulation systems.
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http://dx.doi.org/10.1021/ar200035gDOI Listing
December 2011

Conformational capture of the SAM-II riboswitch.

Nat Chem Biol 2011 Jun 1;7(6):393-400. Epub 2011 May 1.

Institute of Organic Chemistry, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria.

Riboswitches are gene regulation elements in mRNA that function by specifically responding to metabolites. Although the metabolite-bound states of riboswitches have proven amenable to structure determination efforts, knowledge of the structural features of riboswitches in their ligand-free forms and their ligand-response mechanisms giving rise to regulatory control is lacking. Here we explore the ligand-induced folding process of the S-adenosylmethionine type II (SAM-II) riboswitch using chemical and biophysical methods, including NMR and fluorescence spectroscopy, and single-molecule fluorescence imaging. The data reveal that the unliganded SAM-II riboswitch is dynamic in nature, in that its stem-loop element becomes engaged in a pseudoknot fold through base-pairing with nucleosides in the 3' overhang containing the Shine-Dalgarno sequence. Although the pseudoknot structure is highly transient in the absence of its ligand, S-adenosylmethionine (SAM), it becomes conformationally restrained upon ligand recognition, through a conformational capture mechanism. These insights provide a molecular understanding of riboswitch dynamics that shed new light on the mechanism of riboswitch-mediated translational regulation.
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http://dx.doi.org/10.1038/nchembio.562DOI Listing
June 2011