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Pinton S, Vacchi E, Chiaro G, Raimondi A, Tzankov A, Gerber B, Gobbi C, Kaelin-Lang A, Melli G. Amyloid detection and typing yield of skin biopsy in systemic amyloidosis and polyneuropathy. Ann Clin Transl Neurol 2023; 10:2347-2359. [PMID: 37849451 PMCID: PMC10723241 DOI: 10.1002/acn3.51924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/26/2023] [Accepted: 09/28/2023] [Indexed: 10/19/2023] Open
Abstract
OBJECTIVE Disease-modifying therapies are available for amyloidosis but are ineffective if end-organ damage is severe. As small fiber neuropathy is an early and common feature of amyloidosis, we assessed detection and typing yield of skin biopsy for amyloid in patients with confirmed systemic amyloidosis and neuropathic symptoms. METHODS In this case-control study, patients with transthyretin and light chain amyloidosis (ATTRv, ATTRwt, and AL) were consecutively recruited. They were sex and age-matched to three control groups (1) non-neuropathic controls (NNC), (2) monoclonal gammopathy of undetermined significance (MGUS), and (3) other neuropathic disease controls (ONC). Patients underwent a double 3 mm skin biopsy in proximal and distal leg. Amyloid index and burden, protein typing by immuno-electron microscopy, intraepidermal nerve fiber density, electroneuromyography, and clinical characteristics were analyzed. RESULTS We studied 15 subjects with confirmed systemic amyloidosis, 20 NNC, 18 MGUS, and 20 ONC. Amyloid was detected in 100% of patients with amyloidosis (87% in ankle and 73% in thigh). It was not detected in any of the control groups. A small fiber neuropathy was encountered in 100% of amyloidosis patients, in 80% of MGUS, and in 78% of ONC. Amyloid burden was higher in ATTRv, followed by AL and ATTRwt. The ultrastructural examination allowed the identification of the precursor protein by immunotyping in most of the cases. INTERPRETATION Skin biopsy is a minimally invasive test with optimal sensitivity for amyloid. It allows amyloid typing by electron microscope to identify the precursor protein. The diagnostic work up of systemic amyloidosis should include a skin biopsy.
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Affiliation(s)
- Sandra Pinton
- Neurology Department, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Lugano, Switzerland
- Neurodegenerative disorders lab, Laboratories for Translational Research, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
| | - Elena Vacchi
- Neurology Department, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Lugano, Switzerland
- Neurodegenerative disorders lab, Laboratories for Translational Research, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
| | - Giacomo Chiaro
- Neurology Department, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Lugano, Switzerland
- Neurodegenerative disorders lab, Laboratories for Translational Research, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
| | - Andrea Raimondi
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
- Experimental Imaging Centre, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Alexandar Tzankov
- Histopathology, Institute of Medical Genetics and Pathology, University Hospital Basel, Basel, Switzerland
| | - Bernhard Gerber
- Clinic of Hematology, Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Claudio Gobbi
- Neurology Department, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Lugano, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
| | - Alain Kaelin-Lang
- Neurology Department, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Lugano, Switzerland
- Neurodegenerative disorders lab, Laboratories for Translational Research, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
- Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Giorgia Melli
- Neurology Department, Neurocenter of Southern Switzerland, Ente Ospedaliero Cantonale, Lugano, Switzerland
- Neurodegenerative disorders lab, Laboratories for Translational Research, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
- Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
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Cazzaniga G, Bolognesi MM, Stefania MD, Mascadri F, Eccher A, Alberici F, Mescia F, Smith A, Fraggetta F, Rossi M, Gambaro G, Pagni F, L'Imperio V. Congo Red Staining in Digital Pathology: The Streamlined Pipeline for Amyloid Detection Through Congo Red Fluorescence Digital Analysis. J Transl Med 2023; 103:100243. [PMID: 37634845 DOI: 10.1016/j.labinv.2023.100243] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/04/2023] [Accepted: 08/21/2023] [Indexed: 08/29/2023] Open
Abstract
Renal amyloidosis is a rare condition caused by the progressive accumulation of misfolded proteins within glomeruli, vessels, and interstitium, causing functional decline and requiring prompt treatment due to its significant morbidity and mortality. Congo red (CR) stain on renal biopsy samples is the gold standard for diagnosis, but the need for polarized light is limiting the digitization of this nephropathology field. This study explores the feasibility and reliability of CR fluorescence on virtual slides (CRFvs) in evaluating the diagnostic accuracy and proposing an automated digital pipeline for its assessment. Whole-slide images from 154 renal biopsies with CR were scanned through a Texas red fluorescence filter (NanoZoomer S60, Hamamatsu) at the digital Nephropathology Center of the Istituto di Ricovero e Cura a Carattere Scientifico San Gerardo, Monza, Italy, and evaluated double-blinded for the detection and quantification through the amyloid score and a custom ImageJ pipeline was built to automatically detect amyloid-containing regions. Interobserver agreement for CRFvs was optimal (k = 0.90; 95% CI, 0.81-0.98), with even better concordance when consensus-based CRFvs evaluation was compared to the standard CR birefringence (BR) (k = 0.98; 95% CI, 0.93-1). Excellent performance was achieved in the assessment of amyloid score overall by CRFvs (weighted k = 0.70; 95% CI, 0.08-1), especially within the interstitium (weighted k = 0.60; 95% CI, 0.35-0.84), overcoming the misinterpretation of interstitial and capsular collagen BR. The application of an automated digital pathology pipeline (Streamlined Pipeline for Amyloid detection through CR fluorescence Digital Analysis, SPADA) further increased the performance of pathologists, leading to a complete concordance with the standard BR. This study represents an initial step in the validation of CRFvs, demonstrating its general reliability in a digital nephropathology center. The computational method used in this study has the potential to facilitate the integration of spatial omics and artificial intelligence tools for the diagnosis of amyloidosis, streamlining its detection process.
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Affiliation(s)
- Giorgio Cazzaniga
- Department of Medicine and Surgery, Pathology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione San Gerardo dei Tintori, University of Milano-Bicocca, Monza, Italy
| | - Maddalena Maria Bolognesi
- Department of Medicine and Surgery, Pathology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione San Gerardo dei Tintori, University of Milano-Bicocca, Monza, Italy
| | - Matteo Davide Stefania
- Department of Medicine and Surgery, Pathology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione San Gerardo dei Tintori, University of Milano-Bicocca, Monza, Italy
| | - Francesco Mascadri
- Department of Medicine and Surgery, Pathology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione San Gerardo dei Tintori, University of Milano-Bicocca, Monza, Italy
| | - Albino Eccher
- Department of Pathology and Diagnostics, University and Hospital Trust of Verona, Verona, Italy; Department of Medical and Surgical Sciences for Children and Adults, University of Modena and Reggio Emilia, University Hospital of Modena, Modena, Italy
| | - Federico Alberici
- Nephrology Unit, Spedali Civili Hospital, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili di Brescia, Brescia, Italy; Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
| | - Federica Mescia
- Nephrology Unit, Spedali Civili Hospital, Azienda Socio Sanitaria Territoriale (ASST) Spedali Civili di Brescia, Brescia, Italy; Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy
| | - Andrew Smith
- Department of Medicine and Surgery, Proteomics and Metabolomics Unit, University of Milano-Bicocca, Monza, Italy
| | - Filippo Fraggetta
- Pathology Unit, Azienda Sanitaria Provinciale (ASP) Catania, "Gravina" Hospital, Caltagirone, Italy
| | - Mattia Rossi
- Division of Nephrology, Department of Medicine, University of Verona, Verona, Italy
| | - Giovanni Gambaro
- Division of Nephrology, Department of Medicine, University of Verona, Verona, Italy
| | - Fabio Pagni
- Department of Medicine and Surgery, Pathology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione San Gerardo dei Tintori, University of Milano-Bicocca, Monza, Italy
| | - Vincenzo L'Imperio
- Department of Medicine and Surgery, Pathology, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione San Gerardo dei Tintori, University of Milano-Bicocca, Monza, Italy.
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Pinedo Pichilingue A, Thayyil A, Dai DF, Rastogi P. Diagnostic performance of fluorescence microscopy with a tetramethylrhodamine isothiocyanate filter in identifying renal amyloidosis. Histopathology 2023; 83:722-732. [PMID: 37501637 DOI: 10.1111/his.15014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/14/2023] [Accepted: 07/10/2023] [Indexed: 07/29/2023]
Abstract
BACKGROUND Renal amyloidosis (RA) has a worldwide incidence of 5-13 cases per million person-years and is expected to rise in upcoming years due to growing awareness, plus improvement of diagnostic modalities. Diagnosing RA remains challenging, especially when encountering very small, focal, or early amyloid deposits. Since delays in diagnosis portends poor prognosis, high morbidity, and mortality, it is crucial to evaluate the performance of commonly used diagnostic modalities. This is the first study that presents a full picture of the diagnostic performance of fluorescence microscopy (FM) with a tetramethylrhodamine isothiocyanate (TRITC) filter to diagnose RA in general and stratified by compartments. MATERIALS AND METHODS A retrospective double-blind diagnostic accuracy study of FM-TRITC filter was performed. The presence or absence of amyloid in the vascular, interstitial, and glomerular compartments was established in 316 representative Congo red-stained core biopsies with an FM-TRITC filter. This was contrasted with polarized microscopy (PM) showing apple-green birefringence as the gold standard. Sensitivity, specificity, positive and negative predictive values, likelihood ratios, and the receiver operating characteristic (ROC) curve were obtained using STATA13. RESULTS The prevalence of RA was 6.01%, comparable with that reported in the literature. Reciprocity with regard to the location and pattern of fluorescence and birefringence between the two diagnostic modalities was seen. The FM-TRITC filter has a sensitivity of 100%, specificity of 97.64%, and a positive and negative predictive value of 73.08% and 100%, respectively. The positive likelihood ratio was 42.37, and the negative was 0.00. Overall accuracy was 97.78%. The area under the ROC curve was 0.98. The Diagnostic performance of the FM-TRITC filter stratified by compartments is shown in Table 1. The area under the ROC curve was 0.99, 0.98, and 0.99 for the vascular, interstitial, and glomerular compartment, respectively. All patients with RA (n = 19) were correctly identified; this included one new case, one case with small and focal amyloid, and two early cases with less dense amyloid where birefringence was ambiguous by PM. DISCUSSION The FM-TRITC filter is a highly accurate, sensitive, specific, with excellent predictive values, time-efficient, easy to perform, and suitable to reproduce diagnostic modality for RA. It can accurately rule out RA in all compartments, and in most cases concomitant use of PM should not be indispensable. The diagnosis of vascular, interstitial, and glomerular amyloid deposits can be done using only the FM-TRITC filter with Congo red-stained slides. Exceptionally, a few cases of interstitial amyloidosis could be overdiagnosed due to interferences (e.g. artefacts), these cases could be further assessed with a second diagnostic modality if positive fluorescence is seen. Routine use of the FM-TRITC filter can aid in the diagnosis of early RA, even when the deposits are inconspicuous by PM.
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Affiliation(s)
| | - Abdullah Thayyil
- Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | - Dao-Fu Dai
- Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | - Prerna Rastogi
- Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
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Zayas‐Santiago A, Martínez‐Montemayor MM, Colón‐Vázquez J, Ortiz‐Soto G, Cirino‐Simonet JG, Inyushin M. Accumulation of amyloid beta (Aβ) and amyloid precursor protein (APP) in tumors formed by a mouse xenograft model of inflammatory breast cancer. FEBS Open Bio 2022; 12:95-105. [PMID: 34592066 PMCID: PMC8727955 DOI: 10.1002/2211-5463.13308] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/16/2021] [Accepted: 10/29/2021] [Indexed: 02/06/2023] Open
Abstract
Accumulation of amyloid in breast cancer is a well-known phenomenon, but only immunoglobulin light-chain amyloidosis (AL) or transthyretin (TTR) amyloid had been detected in human breast tumor samples previously. We recently reported that another amyloidogenic peptide, amyloid beta (Aβ), is present in an aggregated form in animal and human high-grade gliomas and suggested that it originates systemically from the blood, possibly generated by platelets. To study whether breast cancers are also associated with these Aβ peptides and in what form, we used a nude mouse model inoculated with triple-negative inflammatory breast cancer cell (SUM-149) xenografts, which develop noticeable tumors. Immunostaining with two types of specific antibodies for Aβ identified the clear presence of Aβ peptides associated with (a) carcinoma cells and (b) extracellular aggregated amyloid (also revealed by Congo red and thioflavin S staining). Aβ peptides, in both cells and in aggregated amyloid, were distributed in clear gradients, with maximum levels near blood vessels. We detected significant presence of amyloid precursor protein (APP) in the walls of blood vessels of tumor samples, as well as in carcinoma cells. Finally, we used ELISA to confirm the presence of elevated levels of mouse-generated Aβ40 in tumors. We conclude that Aβ in inflammatory breast cancer tumors, at least in a mouse model, is always present and is concentrated near blood vessels. We also discuss here the possible pathways of Aβ accumulation in tumors and whether this phenomenon could represent the specific signature of high-grade cancers.
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Affiliation(s)
| | | | | | | | | | - Mikhail Inyushin
- Department of PhysiologyUniversidad Central del CaribeBayamónPRUSA
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Lee AYS, Bayly A, Lin MW. Evaluation of Polarized Light and Fluorescence Microscopy of Congo Red Stain in the Diagnosis of Renal Amyloidosis. Lab Med 2021; 52:574-577. [PMID: 33929031 DOI: 10.1093/labmed/lmab022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Amyloidosis is a devastating multisystemic disease resulting from organ deposition of misfolded proteins and subsequent organ dysfunction. An accurate diagnosis relies frequently on biopsies and microscopy techniques to detect amyloid deposition. We evaluated the diagnostic performance of Congo red staining using polarized light (PM) and fluorescence microscopy (FM) techniques in renal amyloidosis. METHODS We performed a retrospective and prospective analysis of all renal biopsies submitted at a large quarternary hospital in Sydney, Australia, that had undergone PM and FM evaluation using Congo red staining. Identification of amyloid fibrils on electron microscopy was considered the reference method. RESULTS PM and FM displayed very high sensitivity and specificity in correctly identifying amyloid deposits in renal biopsies that tested positive via Congo red staining. Comparison of the diagnostic statistics revealed that they are diagnostically equivalent. CONCLUSION In the diagnosis of renal amyloidosis on biopsy, evaluation of Congo red staining may be reliably performed via PM or FM.
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Affiliation(s)
- Adrian Y S Lee
- ICPMR and NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.,Sydney Medical School, The University of Sydney, Westmead, NSW, Australia
| | - Angela Bayly
- ICPMR and NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia
| | - Ming-Wei Lin
- ICPMR and NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.,Sydney Medical School, The University of Sydney, Westmead, NSW, Australia
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Javed I, Zhang Z, Adamcik J, Andrikopoulos N, Li Y, Otzen DE, Lin S, Mezzenga R, Davis TP, Ding F, Ke PC. Accelerated Amyloid Beta Pathogenesis by Bacterial Amyloid FapC. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2001299. [PMID: 32999841 PMCID: PMC7509637 DOI: 10.1002/advs.202001299] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/10/2020] [Indexed: 05/03/2023]
Abstract
The gut-brain axis has attracted increasing attention in recent years, fueled by accumulating symptomatic, physiological, and pathological findings. In this study, the aggregation and toxicity of amyloid beta (Aβ), the pathogenic peptide associated with Alzheimer's disease (AD), seeded by FapC amyloid fragments (FapCS) of Pseudomonas aeruginosa that colonizes the gut microbiome through infections are examined. FapCS display favorable binding with Aβ and a catalytic capacity in seeding the peptide amyloidosis. Upon seeding, twisted Aβ fibrils assume a much-shortened periodicity approximating that of FapC fibrils, accompanied by a 37% sharp rise in the fibrillar diameter, compared with the control. The robust seeding capacity for Aβ by FapCS and the biofilm fragments derived from P. aeruginosa entail abnormal behavior pathology and immunohistology, as well as impaired cognitive function of zebrafish. Together, the data offer the first concrete evidence of structural integration and inheritance in peptide cross-seeding, a crucial knowledge gap in understanding the pathological correlations between different amyloid diseases. The catalytic role of infectious bacteria in promoting Aβ amyloidosis may be exploited as a potential therapeutic target, while the altered mesoscopic signatures of Aβ fibrils may serve as a prototype for molecular assembly and a biomarker for screening bacterial infections in AD.
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Affiliation(s)
- Ibrahim Javed
- Australian Institute for Bioengineering and NanotechnologyUniversity of QueenslandBrisbaneQLD4072Australia
- ARC Centre of Excellence in Convergent Bio‐Nano Science and TechnologyMonash Institute of Pharmaceutical SciencesMonash University381 Royal ParadeParkvilleVIC3052Australia
| | - Zhenzhen Zhang
- Department of Physics and AstronomyClemson UniversityClemsonSC29634USA
| | - Jozef Adamcik
- Food & Soft MaterialsDepartment of Health Science & TechnologyETH ZurichSchmelzbergstrasse 9, LFO, E23Zurich8092Switzerland
| | - Nicholas Andrikopoulos
- ARC Centre of Excellence in Convergent Bio‐Nano Science and TechnologyMonash Institute of Pharmaceutical SciencesMonash University381 Royal ParadeParkvilleVIC3052Australia
| | - Yuhuan Li
- ARC Centre of Excellence in Convergent Bio‐Nano Science and TechnologyMonash Institute of Pharmaceutical SciencesMonash University381 Royal ParadeParkvilleVIC3052Australia
| | - Daniel E. Otzen
- Interdisciplinary Nanoscience Center (iNANO)University of AarhusAarhus CAarhus8000Denmark
| | - Sijie Lin
- College of Environmental Science and EngineeringBiomedical Multidisciplinary Innovation Research InstituteShanghai East HospitalShanghai Institute of Pollution Control and Ecological SecurityTongji University1239 Siping RoadShanghai200092China
| | - Raffaele Mezzenga
- Food & Soft MaterialsDepartment of Health Science & TechnologyETH ZurichSchmelzbergstrasse 9, LFO, E23Zurich8092Switzerland
| | - Thomas P. Davis
- Australian Institute for Bioengineering and NanotechnologyUniversity of QueenslandBrisbaneQLD4072Australia
- ARC Centre of Excellence in Convergent Bio‐Nano Science and TechnologyMonash Institute of Pharmaceutical SciencesMonash University381 Royal ParadeParkvilleVIC3052Australia
| | - Feng Ding
- Department of Physics and AstronomyClemson UniversityClemsonSC29634USA
| | - Pu Chun Ke
- ARC Centre of Excellence in Convergent Bio‐Nano Science and TechnologyMonash Institute of Pharmaceutical SciencesMonash University381 Royal ParadeParkvilleVIC3052Australia
- Zhongshan HospitalFudan University111 Yixueyuan Rd, Xuhui DistrictShanghai200032China
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Dapson RW. Amyloid from a histochemical perspective. A review of the structure, properties and types of amyloid, and a proposed staining mechanism for Congo red staining. Biotech Histochem 2018; 93:543-556. [PMID: 30403893 DOI: 10.1080/10520295.2018.1528385] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Amyloid is a diverse group of unrelated peptides or proteins that have positive functionality or are associated with various pathologies. Despite vast differences, all amyloids share several features that together uniquely define the group. 1) All amyloids possess a characteristic cross-ß pattern with X-ray diffraction typical of ß-sheet secondary protein structures. 2) All amyloids are birefringent and dichroic under polarizing microscopy after staining with Congo red, which indicates a crystalline-like (ordered) structure. 3) All amyloids cause a spectral shift in the peak wavelength of Congo red with conventional light microscopy due to perturbation of π electrons of the dye. 4) All amyloids show heightened intensity of fluorescence with Congo red, which suggests an unusual degree of packing of the dye onto the substrate. The ß portion of amyloid molecules, the only logical substrate for specific Congo red staining under histochemical conditions, consists of a stack of ß-sheets laminated by hydrophilic and hydrophobic interactions between adjacent pairs. Only the first and last ß-sheets are accessible to dyes. Each sheet is composed of numerous identical peptides running across the width of the sheet and arranged in parallel with side chains in register over the length of the fibril. Two sets of grooves are bordered by side chains. X grooves run perpendicular to the long axis of the fibril; these grooves are short (the width of the sheet) and number in the hundreds or thousands. Y grooves are parallel with the long axis. Each groove runs the entire length of the fibril, but there are very few of them. While Congo red is capable of ionic bonding with proteins via two sulfonic acid groups, physical constraints on the staining solution preclude ionic interactions. Hydrogen bonding between dye amine groups and peptide carbonyls is the most likely primary bonding mechanism, because all ß-sheets possess backbone carbonyls. Various amino acid residues may form secondary bonds to the dye via any of three van der Waals forces. It is possible that Congo red binds within the Y grooves, but that would not produce the characteristic staining features that are the diagnostic hallmarks of amyloid. Binding in the X grooves would produce a tightly packed series of dye molecules over the entire length of the fibril. This would account for the signature staining of amyloid by Congo red: dichroic birefringence, enhanced intensity of fluorescence and a shift in visible absorption wavelength.
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Yang X, Li Z, Xiao H, Wang N, Li Y, Xu X, Chen Z, Tan H, Li J. A Universal and Ultrastable Mineralization Coating Bioinspired from Biofilms. ADVANCED FUNCTIONAL MATERIALS 2018. [DOI: 10.1002/adfm.201802730] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Xiao Yang
- College of Polymer Science and Engineering; State Key Laboratory of Polymer Materials Engineering; Sichuan University; No. 24, South Section One of Yinhuan Road Chengdu 610065 P. R. China
| | - Zhenhua Li
- State Key Laboratory of Supramolecular Structure and Materials; Institute of Theoretical Chemistry; Jilin University; 2699 Qianjin Street Changchun 130012 P. R. China
| | - Hong Xiao
- Department of Pain Management; West China Hospital; Sichuan University; No. 37, GuoXue Xiang Chengdu 610041 P. R. China
| | - Ning Wang
- Regenerative Medicine Research Center; West China Hospital; Sichuan University; No. 37, GuoXue Xiang Chengdu 61004 P. R. China
| | - Yanpu Li
- College of Polymer Science and Engineering; State Key Laboratory of Polymer Materials Engineering; Sichuan University; No. 24, South Section One of Yinhuan Road Chengdu 610065 P. R. China
| | - Xinyuan Xu
- College of Polymer Science and Engineering; State Key Laboratory of Polymer Materials Engineering; Sichuan University; No. 24, South Section One of Yinhuan Road Chengdu 610065 P. R. China
| | - Zhijun Chen
- State Key Laboratory of Supramolecular Structure and Materials; Institute of Theoretical Chemistry; Jilin University; 2699 Qianjin Street Changchun 130012 P. R. China
| | - Hong Tan
- College of Polymer Science and Engineering; State Key Laboratory of Polymer Materials Engineering; Sichuan University; No. 24, South Section One of Yinhuan Road Chengdu 610065 P. R. China
| | - Jianshu Li
- College of Polymer Science and Engineering; State Key Laboratory of Polymer Materials Engineering; Sichuan University; No. 24, South Section One of Yinhuan Road Chengdu 610065 P. R. China
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Praveschotinunt P, Dorval Courchesne NM, den Hartog I, Lu C, Kim JJ, Nguyen PQ, Joshi NS. Tracking of Engineered Bacteria In Vivo Using Nonstandard Amino Acid Incorporation. ACS Synth Biol 2018; 7:1640-1650. [PMID: 29791796 PMCID: PMC6415965 DOI: 10.1021/acssynbio.8b00135] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The rapidly growing field of microbiome research presents a need for better methods of monitoring gut microbes in vivo with high spatial and temporal resolution. We report a method of tracking microbes in vivo within the gastrointestinal tract by programming them to incorporate nonstandard amino acids (NSAA) and labeling them via click chemistry. Using established machinery constituting an orthogonal translation system (OTS), we engineered Escherichia coli to incorporate p-azido-l-phenylalanine (pAzF) in place of the UAG (amber) stop codon. We also introduced a mutant gene encoding for a cell surface protein (CsgA) that was altered to contain an in-frame UAG codon. After pAzF incorporation and extracellular display, the engineered strains could be covalently labeled via copper-free click reaction with a Cy5 dye conjugated to the dibenzocyclooctyl (DBCO) group. We confirmed the functionality of the labeling strategy in vivo using a murine model. Labeling of the engineered strain could be observed using oral administration of the dye to mice several days after colonization of the gastrointestinal tract. This work sets the foundation for the development of in vivo tracking microbial strategies that may be compatible with noninvasive imaging modalities and are capable of longitudinal spatiotemporal monitoring of specific microbial populations.
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Affiliation(s)
- Pichet Praveschotinunt
- Wyss Institute for Biologically Inspired Engineering , Harvard University , Boston , Massachusetts 02138 , United States
- John A. Paulson School of Engineering and Applied Sciences , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Noémie-Manuelle Dorval Courchesne
- Wyss Institute for Biologically Inspired Engineering , Harvard University , Boston , Massachusetts 02138 , United States
- Department of Chemical Engineering , McGill University , Montréal , Québec H3A 0C5 , Canada
| | - Ilona den Hartog
- Wyss Institute for Biologically Inspired Engineering , Harvard University , Boston , Massachusetts 02138 , United States
- Laboratory of Chemical Biology and Institute of Complex Molecular Systems, Department of Biomedical Engineering , Eindhoven University of Technology , 5612 AZ Eindhoven , The Netherlands
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research , Leiden University , 2311 EZ Leiden , The Netherlands
| | - Chaochen Lu
- Wyss Institute for Biologically Inspired Engineering , Harvard University , Boston , Massachusetts 02138 , United States
- Dr. von Hauner Children's Hospital , 80337 Munich , Germany
- Medical Center of the University of Munich , 80539 Munich , Germany
- Ludwig Maximilians University , 80539 Munich , Germany
| | - Jessica J Kim
- Harvard College , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Peter Q Nguyen
- Wyss Institute for Biologically Inspired Engineering , Harvard University , Boston , Massachusetts 02138 , United States
| | - Neel S Joshi
- Wyss Institute for Biologically Inspired Engineering , Harvard University , Boston , Massachusetts 02138 , United States
- John A. Paulson School of Engineering and Applied Sciences , Harvard University , Cambridge , Massachusetts 02138 , United States
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Nusrat S, Khan RH. Exploration of ligand-induced protein conformational alteration, aggregate formation, and its inhibition: A biophysical insight. Prep Biochem Biotechnol 2018; 48:43-56. [PMID: 29106330 DOI: 10.1080/10826068.2017.1387561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The association of protein aggregates with plentiful human diseases has fascinated studies regarding the biophysical characterization of protein misfolding and ultimately their aggregate formation mechanism. Protein-ligand interaction, their mechanism, conformational changes by ligands, and protein aggregate formation have been studied upon exploiting experimental techniques and computational methodologies. Such studies for the exploration of ligand-induced conformational changes in protein, misfolding and aggregation, has confirmed drastic progresses in the study of aggregate formation pathways. This review comprises of an inclusive description of contemporary experimental techniques as well as theoretical improvements in the interpretation of the conformational properties of protein. We have also discussed various factors responsible for the microenvironment change around protein that sequentially causes amyloidoses. Biophysical techniques and cell-based assays to gain comprehensive understandings of protein-ligand interaction, protein folding, and aggregation pathways have also been described. The promising therapeutic methods used to inhibit the protein fibrillogenesis have also been discussed.
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Affiliation(s)
- Saima Nusrat
- a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , Uttar Pradesh , India
| | - Rizwan Hasan Khan
- a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , Uttar Pradesh , India
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Wang M, Huang M, Zhang J, Ma Y, Li S, Wang J. A novel secretion and online-cleavage strategy for production of cecropin A in Escherichia coli. Sci Rep 2017; 7:7368. [PMID: 28779147 PMCID: PMC5544755 DOI: 10.1038/s41598-017-07411-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/23/2017] [Indexed: 01/08/2023] Open
Abstract
Antimicrobial peptides, promising antibiotic candidates, are attracting increasing research attention. Current methods for production of antimicrobial peptides are chemical synthesis, intracellular fusion expression, or direct separation and purification from natural sources. However, all these methods are costly, operation-complicated and low efficiency. Here, we report a new strategy for extracellular secretion and online-cleavage of antimicrobial peptides on the surface of Escherichia coli, which is cost-effective, simple and does not require complex procedures like cell disruption and protein purification. Analysis by transmission electron microscopy and semi-denaturing detergent agarose gel electrophoresis indicated that fusion proteins contain cecropin A peptides can successfully be secreted and form extracellular amyloid aggregates at the surface of Escherichia coli on the basis of E. coli curli secretion system and amyloid characteristics of sup35NM. These amyloid aggregates can be easily collected by simple centrifugation and high-purity cecropin A peptide with the same antimicrobial activity as commercial peptide by chemical synthesis was released by efficient self-cleavage of Mxe GyrA intein. Here, we established a novel expression strategy for the production of antimicrobial peptides, which dramatically reduces the cost and simplifies purification procedures and gives new insights into producing antimicrobial and other commercially-viable peptides.
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Affiliation(s)
- Meng Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China
| | - Minhua Huang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China
| | - Junjie Zhang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China
| | - Yi Ma
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China
| | - Shan Li
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China
| | - Jufang Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China.
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China.
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Hoepfner J, Kleinsorge M, Papp O, Alfken S, Heiringhoff R, Pich A, Sauer V, Zibert A, Göhring G, Schmidt H, Sgodda M, Cantz T. In vitro modelling of familial amyloidotic polyneuropathy allows quantitative detection of transthyretin amyloid fibril-like structures in hepatic derivatives of patient-specific induced pluripotent stem cells. Biol Chem 2017; 398:939-954. [DOI: 10.1515/hsz-2016-0258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 12/22/2016] [Indexed: 01/04/2023]
Abstract
Abstract
The transthyretin protein is thermodynamically destabilised by mutations in the transthyretin gene, promoting the formation of amyloid fibrils in various tissues. Consequently, impaired autonomic organ function is observed in patients suffering from transthyretin-related familial amyloidotic polyneuropathy (FAP). The influence of individual genetic backgrounds on fibril formation as a potential cause of genotype-phenotype variations needs to be investigated in order to ensure efficient patient-specific therapies. We reprogrammed FAP patient fibroblasts to induced pluripotent stem (iPS) cells and differentiated these cells into transthyretin-expressing hepatocyte-like cells (HLCs). HLCs differentiated from FAP iPS cells and healthy control iPS cells secreted the transthyretin protein in similar concentrations. Mass spectrometry revealed the presence of mutant transthyretin protein in FAP HLC supernatants. In comparison to healthy control iPS cells, we demonstrated the formation of transthyretin amyloid fibril-like structures in FAP HLC supernatants using the amyloid-specific dyes Congo red and thioflavin T. These dyes were also applicable for the quantitative determination of in vitro formed transthyretin fibril-like structures. Moreover, we confirmed the inhibition of fibril formation by the TTR kinetic stabiliser diclofenac. Thioflavin T fluorescence intensity measurements even allowed the quantification of amyloid fibril-like structures in 96-well plate formats as a prerequisite for patient-specific drug screening approaches.
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Castellani C, Fedrigo M, Frigo AC, Barbera MD, Thiene G, Valente M, Adami F, Angelini A. Application of confocal laser scanning microscopy for the diagnosis of amyloidosis. Virchows Arch 2017; 470:455-463. [PMID: 28220300 DOI: 10.1007/s00428-017-2081-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 11/10/2016] [Accepted: 01/30/2017] [Indexed: 01/28/2023]
Abstract
We analysed specificity and sensitivity of confocal laser microscopy (CLSM) on tissue sections for a diagnosis of amyloidosis, in an attempt to reduce technical errors and better standardise pathological diagnosis. We first set up a protocol for the use of CLSM on this type of specimen, using a group of 20 amyloid negative and 20 positive samples. Of all specimens, 2, 4 and 8-μm sections were cut. Sections were stained with Congo red (CR) and thioflavin-T (ThT) and observed by cross-polarised light microscopy (CR-PL), epifluorescence microscopy (CRF-epiFM and ThT-epiFM) and CLSM (CRF-CLSM and ThT-CLSM). To validate the method in a diagnostic setting, we examined tissue samples from 116 consecutive patients with clinical suspicion of amyloidosis, selected from the period 2005 to 2014 from the database of the Pathology Unit of the University of Padua. The results were compared with those of transmission electron microscopy (TEM), which we consider as reference. We found that with CRF-CLSM, the false negative rate was reduced from 17 to 5%, while the sensitivity of detection increased to 12%. The results were in complete agreement with those of TEM ThT-CLSM; both sensitivity and specificity were 100%. Finally, ThT-CLSM results did not vary with section thickness, and small amounts of amyloid could even be detected in 2-μm sections. In conclusion, we found ThT-CLSM to be more sensitive as a screening method for amyloidosis than CR and ThT epifluorescence optical imaging. The method was easier to standardise, provided images with better resolution and resulted in more consistent pathologist diagnoses.
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Affiliation(s)
- Chiara Castellani
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via Gabelli 61, 35100, Padova, Italy
| | - Marny Fedrigo
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via Gabelli 61, 35100, Padova, Italy
| | - Anna Chiara Frigo
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via Gabelli 61, 35100, Padova, Italy
| | - Mila Della Barbera
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via Gabelli 61, 35100, Padova, Italy
| | - Gaetano Thiene
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via Gabelli 61, 35100, Padova, Italy
| | - Marialuisa Valente
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via Gabelli 61, 35100, Padova, Italy
| | - Fausto Adami
- Department of Clinical and Experimental Medicine, University of Padua, Padua, Italy
| | - Annalisa Angelini
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via Gabelli 61, 35100, Padova, Italy.
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Menter T, Bachmann M, Grieshaber S, Tzankov A. A More Accurate Approach to Amyloid Detection and Subtyping: Combining in situ Congo Red Staining and Immunohistochemistry. Pathobiology 2016; 84:49-55. [PMID: 27487341 DOI: 10.1159/000447304] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 05/30/2016] [Indexed: 11/19/2022] Open
Abstract
Amyloidosis is the result of various, differently approachable diseases. It is vital to subtype the amyloid deposits in order to establish and finally treat the underlying disease properly. Besides the classical staining with Congo red, further procedures like immunohistochemical staining are needed for classification. Here, we present a more accurate approach using Congo red/immunohistochemical double staining easily applicable in routine diagnostics. Modifications of the Congo red staining technique and the immunohistochemical procedures were needed in order to combine both staining procedures on one slide. The evaluation was done using conventional light and fluorescence microscopy. By shortening the staining time for Congo red to 10 s and by modification regarding endogenous peroxidase blockage, accurate results could be obtained for evaluating the Congo red/immunohistochemistry double staining using a fluorescence microscope. Sections of 2 μm instead of 4 μm thickness were superior for evaluation, since they increased staining specificity. The combination of Congo red and immunohistochemistry as in situ double staining on one slide is a feasible approach in the diagnosis of amyloidosis. It allows focusing on the fluorescent Congo red-positive areas when evaluating immunohistochemistry, thus avoiding signing out false-positive results. Additionally, it increases the signal-to-noise ratio of the immunohistochemically stained sections on conventional microscopy.
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Affiliation(s)
- Thomas Menter
- Institute of Pathology, University Hospital Basel, Basel, Switzerland
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Amyloid Arthropathy: When the Rheumatologist Meets the Hematologist. J Clin Rheumatol 2016; 22:285-6. [PMID: 27464780 DOI: 10.1097/rhu.0000000000000404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Stofer F, Barretto MF, Gouvea AL, Ribeiro M, Neves M, Gismondi RA, Mocarzel LO. A Rare Case of Ascites due to Peritoneal Amyloidosis. AMERICAN JOURNAL OF CASE REPORTS 2016; 17:439-43. [PMID: 27353538 PMCID: PMC4928597 DOI: 10.12659/ajcr.898357] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The clinical manifestations of amyloidosis depend on the type of insoluble protein as well as the location of amyloid deposits in tissues or organs. In the gastrointestinal tract, the small intestine is the most common site of amyloid deposits, whereas peritoneal involvement and ascites are rare. CASE REPORT We report on a case of ascites due to peritoneal amyloidosis. A 65-year-old patient was admitted to our institution due to anasarca and pulmonary congestion, mimicking heart failure. We started the patient on diuretics and vasodilators. Despite improvement in pulmonary congestion and peripheral edema, his ascites was not reduced. Echocardiogram revealed restrictive cardiomyopathy and a speckle-tracking pattern suggestive of cardiac amyloidosis. Subcutaneous and peritoneal biopsies revealed amyloidosis. CONCLUSIONS Amyloidosis is rare in the peritoneum and is usually asymptomatic. Ascites occurs in only 20% of patients with peritoneal amyloidosis. We searched PubMed using "ascites" and "amyloidosis" and identified only eight case reports of amyloidosis with ascites. Physicians should be particularly careful in heart failure and anasarca cases when ascites is disproportional or not responsive to diuretic treatment. To date, there is no specific treatment for peritoneal amyloidosis.
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Affiliation(s)
- Fernanda Stofer
- Department of Clinical Medicine, Fluminense Federal University, Niterói, Brazil
| | | | - Ana Luisa Gouvea
- Department of Pathology, Fluminense Federal University, Niterói, Brazil
| | - Mario Ribeiro
- Department of Clinical Medicine, Fluminense Federal University, Niterói, Brazil
| | - Marcio Neves
- Department of Clinical Medicine, Fluminense Federal University, Niterói, Brazil
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Programmable biofilm-based materials from engineered curli nanofibres. Nat Commun 2014; 5:4945. [DOI: 10.1038/ncomms5945] [Citation(s) in RCA: 231] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/08/2014] [Indexed: 12/18/2022] Open
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Chimileski S, Franklin MJ, Papke RT. Biofilms formed by the archaeon Haloferax volcanii exhibit cellular differentiation and social motility, and facilitate horizontal gene transfer. BMC Biol 2014; 12:65. [PMID: 25124934 PMCID: PMC4180959 DOI: 10.1186/s12915-014-0065-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 07/31/2014] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Archaea share a similar microbial lifestyle with bacteria, and not surprisingly then, also exist within matrix-enclosed communities known as biofilms. Advances in biofilm biology have been made over decades for model bacterial species, and include characterizations of social behaviors and cellular differentiation during biofilm development. Like bacteria, archaea impact ecological and biogeochemical systems. However, the biology of archaeal biofilms is only now being explored. Here, we investigated the development, composition and dynamics of biofilms formed by the haloarchaeon Haloferax volcanii DS2. RESULTS Biofilms were cultured in static liquid and visualized with fluorescent cell membrane dyes and by engineering cells to express green fluorescent protein (GFP). Analysis by confocal scanning laser microscopy showed that H. volcanii cells formed microcolonies within 24 h, which developed into larger clusters by 48 h and matured into flake-like towers often greater than 100 μm in height after 7 days. To visualize the extracellular matrix, biofilms formed by GFP-expressing cells were stained with concanavalin A, DAPI, Congo red and thioflavin T. Stains colocalized with larger cellular structures and indicated that the extracellular matrix may contain a combination of polysaccharides, extracellular DNA and amyloid protein. Following a switch to biofilm growth conditions, a sub-population of cells differentiated into chains of long rods sometimes exceeding 25 μm in length, compared to their planktonic disk-shaped morphology. Time-lapse photography of static liquid biofilms also revealed wave-like social motility. Finally, we quantified gene exchange between biofilm cells, and found that it was equivalent to the mating frequency of a classic filter-based experimental method. CONCLUSIONS The developmental processes, functional properties and dynamics of H. volcanii biofilms provide insight on how haloarchaeal species might persist, interact and exchange DNA in natural communities. H. volcanii demonstrates some biofilm phenotypes similar to bacterial biofilms, but also has interesting phenotypes that may be unique to this organism or to this class of organisms, including changes in cellular morphology and an unusual form of social motility. Because H. volcanii has one of the most advanced genetic systems for any archaeon, the phenotypes reported here may promote the study of genetic and developmental processes in archaeal biofilms.
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Clement CG, Truong LD. An evaluation of Congo red fluorescence for the diagnosis of amyloidosis. Hum Pathol 2014; 45:1766-72. [PMID: 24935061 DOI: 10.1016/j.humpath.2014.04.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 04/23/2014] [Accepted: 04/25/2014] [Indexed: 10/25/2022]
Abstract
Congo red stain apple-green birefringence under polarized light is the most popular method for detecting amyloid; however, it has limitations. The goal of this study was to evaluate if examination of Congo red stain by fluorescent microscopy (FM) significantly enhances the diagnostic yield. Congo red-stained tissue sections were retrospectively and prospectively examined by light microscopy (LM) with and without polarizer and by FM using the Texas red filter and results by each method compared. Congo red-stained amyloid recognized by LM was unequivocally and easily identified by FM in each of 48 cases. In 22 of them, FM either confirmed the presence of a small amount of amyloid or lead to a definitive diagnosis, which was otherwise missed. Eight cases with Congo red-negative by LM were also negative by FM. In 8 cases with a false-positive Congo red stain, FM still detected the signal in 5, but it was absent in 3 cases. In conclusion, Congo red fluorescence improves the diagnostic yield of LM for both positive and negative cases.
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Affiliation(s)
- Cecilia G Clement
- Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, TX 77030
| | - Luan D Truong
- Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, TX 77030; Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065.
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