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Jucknischke U, Friebe S, Rehle M, Quast L, Schmidt SH. Antibody Profiling: Kinetics with Native Biomarkers for Diagnostic Assay and Drug Developments. Biosensors (Basel) 2023; 13:1030. [PMID: 38131790 PMCID: PMC10742008 DOI: 10.3390/bios13121030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/01/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023]
Abstract
Despite remarkable progress in applied Surface Plasmon Resonance (SPR)-based methods, concise monitoring of kinetic properties for native biomarkers from patient samples is still lacking. Not only are low concentrations of native targets in patient samples, often in the pM range, a limiting and challenging factor, but body fluids as complex matrices furthermore complicate measurements. The here-described method enables the determination of kinetic constants and resulting affinities for native antigens from patients' cerebrospinal fluid (CSF) and sera binding to antibodies. Using a significantly extended target-enrichment step, we modified a common sandwich-assay protocol, based on a primary and secondary antibody. We successfully analyze antibody kinetics of native targets from a variety of origins, with consistent results, independent of their source. Moreover, native neurofilament light chain (NFL) was investigated as an exemplary biomarker. Obtained data reveal antibodies recognizing recombinant NFL with high affinities, while showing no, or only significantly weakened binding to native NFL. The indicated differences for recombinant vs. native material demonstrate another beneficial application. Our assay is highly suitable for gaining valuable insights into characteristics of native biomarkers, thus impacting on the binder development of diagnostic reagents or pharmaceutical drugs.
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Affiliation(s)
- Ute Jucknischke
- Diagnostic Solutions, Reagent Research and Design, Department Antibody and Protein Technologies, (DSRRA) at Roche Diagnostics GmbH, Nonnenwald 2, 82377 Penzberg, Germany
| | | | | | | | - Sven H. Schmidt
- Diagnostic Solutions, Reagent Research and Design, Department Antibody and Protein Technologies, (DSRRA) at Roche Diagnostics GmbH, Nonnenwald 2, 82377 Penzberg, Germany
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Weng JH, Aoto PC, Lorenz R, Wu J, Schmidt SH, Manschwetus JT, Kaila-Sharma P, Silletti S, Mathea S, Chatterjee D, Knapp S, Herberg FW, Taylor SS. LRRK2 dynamics analysis identifies allosteric control of the crosstalk between its catalytic domains. PLoS Biol 2022; 20:e3001427. [PMID: 35192607 PMCID: PMC8863276 DOI: 10.1371/journal.pbio.3001427] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 01/14/2022] [Indexed: 12/12/2022] Open
Abstract
The 2 major molecular switches in biology, kinases and GTPases, are both contained in the Parkinson disease-related leucine-rich repeat kinase 2 (LRRK2). Using hydrogen-deuterium exchange mass spectrometry (HDX-MS) and molecular dynamics (MD) simulations, we generated a comprehensive dynamic allosteric portrait of the C-terminal domains of LRRK2 (LRRK2RCKW). We identified 2 helices that shield the kinase domain and regulate LRRK2 conformation and function. One helix in COR-B (COR-B Helix) tethers the COR-B domain to the αC helix of the kinase domain and faces its activation loop, while the C-terminal helix (Ct-Helix) extends from the WD40 domain and interacts with both kinase lobes. The Ct-Helix and the N-terminus of the COR-B Helix create a "cap" that regulates the N-lobe of the kinase domain. Our analyses reveal allosteric sites for pharmacological intervention and confirm the kinase domain as the central hub for conformational control.
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Affiliation(s)
- Jui-Hung Weng
- Department of Pharmacology, University of California, San Diego, California, United States of America
| | - Phillip C. Aoto
- Department of Pharmacology, University of California, San Diego, California, United States of America
| | - Robin Lorenz
- Department of Biochemistry, University of Kassel, Kassel, Germany
| | - Jian Wu
- Department of Pharmacology, University of California, San Diego, California, United States of America
| | - Sven H. Schmidt
- Department of Biochemistry, University of Kassel, Kassel, Germany
| | | | - Pallavi Kaila-Sharma
- Department of Pharmacology, University of California, San Diego, California, United States of America
| | - Steve Silletti
- Department of Chemistry and Biochemistry, University of California, San Diego, California, United States of America
| | - Sebastian Mathea
- Institute for Pharmaceutical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Deep Chatterjee
- Institute for Pharmaceutical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Stefan Knapp
- Institute for Pharmaceutical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | | | - Susan S. Taylor
- Department of Pharmacology, University of California, San Diego, California, United States of America
- * E-mail:
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Taylor SS, Kaila-Sharma P, Weng JH, Aoto P, Schmidt SH, Knapp S, Mathea S, Herberg FW. Kinase Domain Is a Dynamic Hub for Driving LRRK2 Allostery. Front Mol Neurosci 2020; 13:538219. [PMID: 33122997 PMCID: PMC7573214 DOI: 10.3389/fnmol.2020.538219] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022] Open
Abstract
Protein kinases and GTPases are the two major molecular switches that regulate much of biology, and both of these domains are embedded within the large multi-domain Leucine-Rich Repeat Kinase 2 (LRRK2). Mutations in LRRK2 are the most common cause of familial Parkinson's disease (PD) and are also implicated in Crohn's disease. The recent Cryo-Electron Microscopy (Cryo-EM) structure of the four C-terminal domains [ROC COR KIN WD40 (RCKW)] of LRRK2 includes both of the catalytic domains. Although the important allosteric N-terminal domains are missing in the Cryo-EM structure this structure allows us to not only explore the conserved features of the kinase domain, which is trapped in an inactive and open conformation but also to observe the direct allosteric cross-talk between the two domains. To define the unique features of the kinase domain and to better understand the dynamic switch mechanism that allows LRRK2 to toggle between its inactive and active conformations, we have compared the LRRK2 kinase domain to Src, BRaf, and PKA. We also compare and contrast the two canonical glycine-rich loop motifs in LRRK2 that anchor the nucleotide: the G-Loop in protein kinases that anchors ATP and the P-Loop in GTPases that anchors GTP. The RCKW structure also provides a template for the cross-talk between the kinase and GTPase domains and brings new mechanistic insights into the physiological function of LRRK2 and how the kinase domain, along with key phosphorylation sites, can serve as an allosteric hub for mediating conformational changes.
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Affiliation(s)
- Susan S Taylor
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States.,Department of Chemistry and Biochemistry, University of California, San Diego, San Diego, CA, United States
| | - Pallavi Kaila-Sharma
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
| | - Jui-Hung Weng
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
| | - Phillip Aoto
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
| | - Sven H Schmidt
- Department of Biochemistry, Institute for Biology, University of Kassel, Kassel, Germany
| | - Stefan Knapp
- Institute of Pharmaceutical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany.,Structural Genomics Consortium, Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-University Frankfurt, Frankfurt, Germany
| | - Sebastian Mathea
- Institute of Pharmaceutical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany.,Structural Genomics Consortium, Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-University Frankfurt, Frankfurt, Germany
| | - Friedrich W Herberg
- Department of Biochemistry, Institute for Biology, University of Kassel, Kassel, Germany
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Knape MJ, Wallbott M, Burghardt NCG, Bertinetti D, Hornung J, Schmidt SH, Lorenz R, Herberg FW. Molecular Basis for Ser/Thr Specificity in PKA Signaling. Cells 2020; 9:cells9061548. [PMID: 32630525 PMCID: PMC7361990 DOI: 10.3390/cells9061548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/22/2020] [Accepted: 06/23/2020] [Indexed: 12/17/2022] Open
Abstract
cAMP-dependent protein kinase (PKA) is the major receptor of the second messenger cAMP and a prototype for Ser/Thr-specific protein kinases. Although PKA strongly prefers serine over threonine substrates, little is known about the molecular basis of this substrate specificity. We employ classical enzyme kinetics and a surface plasmon resonance (SPR)-based method to analyze each step of the kinase reaction. In the absence of divalent metal ions and nucleotides, PKA binds serine (PKS) and threonine (PKT) substrates, derived from the heat-stable protein kinase inhibitor (PKI), with similar affinities. However, in the presence of metal ions and adenine nucleotides, the Michaelis complex for PKT is unstable. PKA phosphorylates PKT with a higher turnover due to a faster dissociation of the product complex. Thus, threonine substrates are not necessarily poor substrates of PKA. Mutation of the DFG+1 phenylalanine to β-branched amino acids increases the catalytic efficiency of PKA for a threonine peptide substrate up to 200-fold. The PKA Cα mutant F187V forms a stable Michaelis complex with PKT and shows no preference for serine versus threonine substrates. Disease-associated mutations of the DFG+1 position in other protein kinases underline the importance of substrate specificity for keeping signaling pathways segregated and precisely regulated.
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Affiliation(s)
| | | | | | | | | | | | - Robin Lorenz
- Correspondence: (R.L.); (F.W.H.); Tel.: +49-561-804-4539 (R.L.); +49-561-804-4511 (F.W.H.)
| | - Friedrich W. Herberg
- Correspondence: (R.L.); (F.W.H.); Tel.: +49-561-804-4539 (R.L.); +49-561-804-4511 (F.W.H.)
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Manschwetus JT, Wallbott M, Fachinger A, Obergruber C, Pautz S, Bertinetti D, Schmidt SH, Herberg FW. Binding of the Human 14-3-3 Isoforms to Distinct Sites in the Leucine-Rich Repeat Kinase 2. Front Neurosci 2020; 14:302. [PMID: 32317922 PMCID: PMC7155755 DOI: 10.3389/fnins.2020.00302] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 03/16/2020] [Indexed: 12/25/2022] Open
Abstract
Proteins of the 14-3-3 family are well known modulators of the leucine-rich repeat kinase 2 (LRRK2) regulating kinase activity, cellular localization, and ubiquitylation. Although binding between those proteins has been investigated, a comparative study of all human 14-3-3 isoforms interacting with LRRK2 is lacking so far. In a comprehensive approach, we quantitatively analyzed the interaction between the seven human 14-3-3 isoforms and LRRK2-derived peptides covering both, reported and putative 14-3-3 binding sites. We observed that phosphorylation is an absolute prerequisite for 14-3-3 binding and generated binding patterns of 14-3-3 isoforms to interact with peptides derived from the N-terminal phosphorylation cluster (S910 and S935), the Roc domain (S1444) and the C-terminus. The tested 14-3-3 binding sites in LRRK2 preferentially were recognized by the isoforms γ and η, whereas the isoforms ϵ and especially σ showed the weakest or no binding. Interestingly, the possible pathogenic mutation Q930R in LRRK2 drastically increases binding affinity to a peptide encompassing pS935. We then identified the autophosphorylation site T2524 as a so far not described 14-3-3 binding site at the very C-terminus of LRRK2. Binding affinities of all seven 14-3-3 isoforms were quantified for all three binding regions with pS1444 displaying the highest affinity of all measured singly phosphorylated peptides. The strongest binding was detected for the combined phosphosites S910 and S935, suggesting that avidity effects are important for high affinity interaction between 14-3-3 proteins and LRRK2.
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Affiliation(s)
| | | | | | | | | | | | | | - Friedrich W. Herberg
- Department of Biochemistry, Institute for Biology, University of Kassel, Kassel, Germany
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Flaherty BR, Ho TG, Schmidt SH, Herberg FW, Peterson DS, Kennedy EJ. Targeted Inhibition of Plasmodium falciparum Calcium-Dependent Protein Kinase 1 with a Constrained J Domain-Derived Disruptor Peptide. ACS Infect Dis 2019; 5:506-514. [PMID: 30746930 DOI: 10.1021/acsinfecdis.8b00347] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
To explore the possibility of constrained peptides to target Plasmodium-infected cells, we designed a J domain mimetic derived from Plasmodium falciparum calcium-dependent protein kinase 1 ( PfCDPK1) as a strategy to disrupt J domain binding and inhibit PfCDPK1 activity. The J domain disruptor (JDD) peptide was conformationally constrained using a hydrocarbon staple and was found to selectively permeate segmented schizonts and colocalize with intracellular merozoites in late-stage parasites. In vitro analyses demonstrated that JDD could effectively inhibit the catalytic activity of recombinant PfCDPK1 in the low micromolar range. Treatment of late-stage parasites with JDD resulted in a significant decrease in parasite viability mediated by a blockage of merozoite invasion, consistent with a primary effect of PfCDPK1 inhibition. To the best of our knowledge, this marks the first use of stapled peptides designed to specifically target a Plasmodium falciparum protein and demonstrates that stapled peptides may serve as useful tools for exploring potential antimalarial agents.
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Affiliation(s)
- Briana R. Flaherty
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 345 Coverdell Center, Athens, Georgia 30602, United States
- Center for Tropical and Emerging Global Diseases, University of Georgia, 345 Coverdell Center, Athens, Georgia 30602, United States
| | - Tienhuei G. Ho
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, 240 W. Green Street, Athens, Georgia 30602, United States
| | - Sven H. Schmidt
- Department of Biochemistry, University of Kassel, Heinrich-Plett Strasse 40, Kassel 34132, Germany
| | - Friedrich W. Herberg
- Department of Biochemistry, University of Kassel, Heinrich-Plett Strasse 40, Kassel 34132, Germany
| | - David S. Peterson
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 345 Coverdell Center, Athens, Georgia 30602, United States
- Center for Tropical and Emerging Global Diseases, University of Georgia, 345 Coverdell Center, Athens, Georgia 30602, United States
| | - Eileen J. Kennedy
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, 240 W. Green Street, Athens, Georgia 30602, United States
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Hermans HJE, Schmidt SH. [A blind bicycle repair man at the Stedelijk Museum: the exhibition and congress 'labour for the disabled' of 1928]. Gewina 2003; 25:226-40. [PMID: 12683366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
In the 1920's concern about the rising number of disabled unemployed urban poor led to the founding of the AVO (Dutch organization for labour care for the disabled) in 1927. The AVO presented the problem of the vulnerability of the physically and mentally disabled in the labour market as a matter of collective responsibility. At the Amsterdam AVO congress of 1928 expert contributors discussed the economic, social and medical aspects of disability and work. Simultaneously, a museum exhibition aimed at arousing the interest of the general public and at promoting a more understanding attitude towards the disabled. Though the twofold AVO manifestation raised an immediate favourable general response and the subject was put on the political agenda, the subsequent economic recession and war forestalled concrete measures. Essentially it was the first public debate on disability in the Netherlands.
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Affiliation(s)
- H J E Hermans
- AMC, Afdeling Sociale Geneeskunde, Universiteit van Amsterdam
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Schmidt SH. Comparison of tympanic membranes. Arch Otolaryngol Head Neck Surg 2001; 127:468-9. [PMID: 11296066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Schmidt SH, Oort-Marburger D, Meijman TF. Employment after rehabilitation for musculoskeletal impairments: the impact of vocational rehabilitation and working on a trial basis. Arch Phys Med Rehabil 1995; 76:950-4. [PMID: 7487437 DOI: 10.1016/s0003-9993(95)80073-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To investigate to what extent vocational rehabilitation and working on a trial basis have an impact on employment after rehabilitation. DESIGN Follow-up survey, conducted in 1991, among all patients, aged 14 to 64, who were treated between 1984 and 1987. SETTING An out-clinic department of a rehabilitation center in the west of The Netherlands. SUBJECTS 395 patients (59% of the original sample) participated in the study. They suffer from musculoskeletal impairments due to back pain (41%), brain injury (20%), neurological disorder (12%), trauma to the upper and/or lower extremities (8%), rheumatoid arthritis (7%), or other disorders (12%). No differences were found between those who did and those who did not respond with regard to age, gender, marital status, disorder, work experience, and participation in vocational rehabilitation. MAIN OUTCOME MEASURE Odds ratio of having a paid job after rehabilitation. RESULTS Participation in vocational rehabilitation and working on a trial basis depends on age, gender, work experience, and disorder. When statistically controlled for these variables vocational rehabilitation (odds ratio 1.96; 95% confidence interval 1.12 to 3.42) and working on a trial basis (odds ratio 3.26; 95% confidence interval 1.74 to 6.11) proved to have a significant impact on employment after rehabilitation. CONCLUSIONS The findings suggest that rehabilitation programs that aim specifically at promoting employment for people with disabilities are effective, in particular when they take place in both a laboratory and a natural setting. The validity of this suggestion must be further tested by means of an experimental design.
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Affiliation(s)
- S H Schmidt
- Institute of Social Medicine/Institute for Work and Health, University of Amsterdam, The Netherlands
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Abstract
The etiology of cholesteatoma is still enigmatic. Of the current theories, none has been confirmed with adequately convincing evidence. A completely suitable animal model has not hitherto been available and there is still a need for further experimental studies of this entity. As a possible experimental model we suggest dimethyl-benzanthracene induced cholesteatoma in the rat.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/adverse effects
- Animals
- Cholesteatoma, Middle Ear/chemically induced
- Cholesteatoma, Middle Ear/pathology
- Disease Models, Animal
- Ear Canal/drug effects
- Ear Canal/pathology
- Ear, Middle/drug effects
- Ear, Middle/pathology
- Epithelium/drug effects
- Epithelium/pathology
- Eustachian Tube/drug effects
- Eustachian Tube/pathology
- Keratins/drug effects
- Otitis Media, Suppurative/chemically induced
- Otitis Media, Suppurative/pathology
- Rats
- Rats, Sprague-Dawley
- Tympanic Membrane/drug effects
- Tympanic Membrane/pathology
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Affiliation(s)
- S H Schmidt
- Department of Otorhinolaryngology, University of Umeå, Sweden
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Schmidt SH, Meijman TF, Scholten A, van Oel CJ, Oort-Marburger D. Factors contributing to job satisfaction following rehabilitation for musculoskeletal impairments. J Occup Rehabil 1993; 3:213-222. [PMID: 24243436 DOI: 10.1007/bf01097431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The study investigates whether changing jobs is related to work-related well-being of people with musculoskeletal impairments. In order to assess this relationship subjects who began new jobs after rehabilitation (N=52) were compared with subjects who returned to their former employment (N=63). Work-related well-being was measured by means of the scales "job satisfaction" and "need to recover after work." After controlling for individual characteristics (gender, age, working hours per week, and pain complaints) and job characteristics (job demands and decision latitude), job satisfaction could be predicted by job change. Recovery need after work was predicted by pain complaints, job demands, and decision latitude, but not by job change.
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Affiliation(s)
- S H Schmidt
- Institute of Social Medicine/Research Centre "Work and Health," Faculty of Medicine, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands
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Schmidt SH, Hellström S. Phenol anesthesia of the tympanic membrane in purulent otitis media: a structural analysis in the rat. Eur Arch Otorhinolaryngol 1993; 249:470-2. [PMID: 8442942 DOI: 10.1007/bf00168857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In the present study, local anesthetics were applied to the tympanic membrane (TM) of rats following experimentally evoked purulent otitis media (POM). The structure of the TM was evaluated 24 h, 2 weeks and 3 months after application of phenol to a discrete are of the right TM. The left ear was used as a control. POM induced swelling of all tissue layers of the pears tensa. The tissues were invaded by inflammatory cells and disintegrated. The fibrous layer also dissolved, leaving spontaneous perforations. However, phenol on inflamed TMs did not further alter the TM structure. These findings infer that the injurious effect of topical anesthesia on the intact TM is more or less negligible when applied to diseased TMs.
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Affiliation(s)
- S H Schmidt
- Department of Otorhinolaryngology & Head and Neck Surgery, University of Umeå, Sweden
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Abstract
In recent years, the rat has attracted increasing interest as an experimental animal in otological research. In the present study, the structure of the rat tympanic membrane (TM) is compared with that of a traditional experimental animal, the guinea pig, and with the human TM. The normal guinea pig TM consists mainly of a single layer of coarse fiber bundles, in contrast to the more solid layers of radial and circular fibers in man and rat. The investigation reveals similar architectural features in the rat and human TM, whereas the guinea pig TM differs structurally.
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Affiliation(s)
- S H Schmidt
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Umeå, Sweden
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Schmidt SH, Anniko M, Hellström S. Electrophysiological effects of the clinically used local anesthetics lidocaine, lidocaine-prilocaine and phenol on the rat's inner ear. Eur Arch Otorhinolaryngol 1990; 248:87-94. [PMID: 2282220 DOI: 10.1007/bf00240226] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Local anesthetics, even if applied to the outer ear canal, may still enter the middle ear, running the risk of penetrating the round window. To elucidate the effect of certain topical anesthetics on the inner ear, the round window niche in the laboratory rat's middle ear was exposed separately to lidocaine, lidocaine-prilocaine and phenol. Auditory brain-stem responses (ABR) were recorded at 2, 4, 6, 8, 12, 16, 20, and 31.5 kHz before the application, and 24 h, 3 weeks, 2 months and 6 months after exposure. After terminating the 6-month ABR measurements, the animal were sacrificed and the temporal bones fixed and decalcified for light microscopic analysis. All three drugs affected the ABR thresholds and the cochlear morphology with a pattern characteristic for each drug. At 24 h, all three substances caused severe impairment of ABR thresholds, followed by a period of restitution lasting up to 2 months. Even 6 months after exposure, the ABR thresholds at and above 12 kHz were impaired, as compared with the pretreatment level, for all substances tested. In the lower frequencies the original ABR threshold was reached in the order: (1) lidocaine, (2) lidocaine-prilocaine, (3) phenol. The cochlear structures were unaffected by lidocaine, whereas lidocaine-prilocaine and phenol caused morphological damage which was most pronounced after exposure to phenol. The heterogeneity of the changes in the ABR thresholds suggests differences in the mechanism of action of each type of local anesthetic investigated. The effects following lidocaine were transient. However, clinicians must be aware of the ototoxic potential of both lidocaine and phenol.
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Affiliation(s)
- S H Schmidt
- Department of Oto-Rhino-Laryngology, University of Umeå, Sweden
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Abstract
The effects of topically applied hydrocortisone on experimental tympanic membrane (TM) perforations in rats were evaluated by otomicroscopy and light microscopy. Standardized TM perforations, occupying the whole upper rear quadrant, were performed, and a 2% hydrocortisone suspension (CORT) was applied once daily for 10 consecutive days. Application of CORT caused a delayed healing pattern, and even at 1 month only 2 of 12 perforations had healed. The keratinizing squamous epithelial cells of the TM appeared hypertrophic, whereas hyperplasia, characterizing a nontreated healing TM perforation, was less prominent. The connective tissue layer of the CORT-treated TM was invaded by abundant inflammatory cells, mainly polymorphonuclear leukocytes. Also, when applied to an intact TM, CORT caused hypertrophy of the epidermal cells and an inflammatory reaction within the TM.
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Affiliation(s)
- O Spandow
- Department of Otorhinolaryngology & Head and Neck Surgery, University Hospital, Umeå, Sweden
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Carlsöö B, Franzén L, Henriksson R, Löfroth PO, Schmidt SH. Bilateral squamous cell carcinoma of the middle ear. Int J Radiat Oncol Biol Phys 1990; 19:506-7. [PMID: 2394631 DOI: 10.1016/0360-3016(90)90571-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Schmidt SH, Hellström S, Anniko M. Structural effects of the topical lidocaine-prilocaine anesthetic Emla on the tympanic membrane. Arch Otorhinolaryngol 1988; 245:136-41. [PMID: 3178560 DOI: 10.1007/bf00464014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A eutectic mixture of two anesthetic solutions is that of lidocaine and prilocaine, which is available commercially as Emla (eutectic mixture of local anesthetics). This solution is commonly used in clinics in superficial skin surgery and when inserting intravenous catheters, and we also wanted to determine its surface effects when applied onto the tympanic membranes (TM) of rats and guinea pigs as animal models. The animals were observed by otomicroscopy for 2 weeks up to 5 months after administrations of the anesthetic solution. Tissue specimens were then obtained for light microscopy and fine structural analysis. The application of Emla caused minor structural changes to the rat TM, but hardly any alterations to that of the guinea pig. The changes displayed were an overall increased thickness, with typical submucosal edema but only slight epithelial reaction. In comparison with previous results with lidocaine, phenol and Bonain's solution, Emla seemed to be harmless to the structure of the TM. However, the efficacy of Emla as a topical TM anesthetic remains to be proved in future clinical trials.
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Affiliation(s)
- S H Schmidt
- Department of Otorhinolaryngology and Head and Neck Surgery, University of Umeå, Sweden
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Abstract
Instillation of EMLA, a new local anesthetic, into the middle ear of the guinea pig caused severe morphological damage to the organ of Corti in the first 4 mm from the round window. Further up the cochlea, only derangements of the stereocilia were found. The extent of morphological damage was the same, whether the agent was administered once or several times. The ototoxic potential of EMLA was obvious and is probably due to direct damage in areas where present in high concentrations. Over a short distance of approximately 0.1 mm there is a transition from a total destruction of the organ of Corti to a completely normal morphology.
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Affiliation(s)
- M Anniko
- Department of Oto-Rhino-Laryngology-Head and Neck Surgery, Umeå University Hospital, Sweden
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20
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Anniko M, Hellström S, Schmidt SH, Spandow O. Toxic effects on inner ear of noxious agents passing through the round window membrane. Acta Otolaryngol Suppl 1988; 457:49-56. [PMID: 2648756 DOI: 10.3109/00016488809138884] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects on inner ear of Xylocain, EMLA, phenol, endotoxin and hydrocortisone were analysed before treatment and 24 h-6 months after instillation of each drug into the round window (RW) niche, where the substance was left. Inner ear function was determined by repeated auditory brainstem recordings (ABR). All cochleae were analysed morphologically at the light microscopic level. Hydrocortisone, Xylocain and endotoxin caused functional changes without morphological correlates, even at long-term follow-up. In contrast, phenol and EMLA caused both functional impairment and graded morphological damage to the organ of Corti in the basal coil. Outer hair cells (OHC) were more vulnerable than inner hair cells (IHC).
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Affiliation(s)
- M Anniko
- Department of Oto-Rhino-Laryngology and Head and Neck Surgery, University Hospital, Umeå, Sweden
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21
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Schmidt SH, Spithoven AH. [The aged and job perspectives. An exploration]. Tijdschr Gerontol Geriatr 1986; 17:183-9. [PMID: 2947352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The expulsion of older people from the labour market is observed with some resignation by policy-makers. One of the consequences is the lack of opportunities for older people to participate in social life. This process of expulsion started as far back as the mid-sixties. Initially the Disablement Acts, and more recently the Unemployment Acts and Early Retirement measures were used to this end. After describing these processes, attention is paid to the rehabilitation activities for the older people who are entitled to payments according to the Disablement Acts. Some empirical data are presented. It is shown that hardly any activities have been undertaken that result in the rehabilitation of older disabled people. This situation has contributed to create an atmosphere in which the opinion prevails that older people are superfluous in the labour market. Taking into account the development of employment in agriculture, manufacturing and services, there are perspectives for older people to work in the service sector.
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22
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Abstract
With the rat tympanic membrane used as a model, various topical anesthetics in current clinical use (phenol, Bonain's liquid, and Xylocaine spray) were tested. Structural changes were observed for up to five months from the time of anesthetic application. The most protracted changes affect the lamina propria, which exhibits a pronounced thickening. The extent of the changes, however, differs according to the agent used; for example, phenol applied to discrete areas exhibited the least widespread changes. In the tympanic portion of the lamina propria, the connective tissue was loosely packed with less regularly arranged collagen fibers, while a tightly packed fiber bundle existed on the meatal side. It is inferred that the submucosal connective tissue layer is the portion of the connective tissue layer where the remodeling and reconstruction of the fibrous layer occur.
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23
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Abstract
The tympanic membrane of the rat was studied ultrastructurally after application of a local anaesthetic--lidocaine spray. Already after 10 min, degenerative changes--or even necrosis--were observed on both epithelial surfaces of the eardrum. Later on, a marked hyperplasia of the epidermal layer was most characteristic, as was a proliferation of the fibroblasts of the subepithelial connective tissue. After 3 weeks the eardrum had not regained its normal appearance. No perforations were encountered and only minute substructural changes could be detected within the fibrous layer.
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24
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Abstract
Topical agents used in office procedures for tympanic membrane anaesthesia have been considered to cause damage to the membrane. Four different anaesthetic agents have been compared as regards their histopathological effects for a period of up to 2 weeks after application. An etching effect is obvious when using these clinically potent agents, but it seems reversible and does not leave remaining structural changes.
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25
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Schmidt SH, Hellström S, Carlsöö B. Short-term effects of local anaesthetic agents on the structure of the rat tympanic membrane. Arch Otorhinolaryngol 1984; 240:159-66. [PMID: 6477294 DOI: 10.1007/bf00453474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Four different local anaesthetic agents were tested on the tympanic membrane of the rat in order to detect any structural changes. Specimens were obtained for examination under the light microscope 10 min, 24 h, 1 week, and 2 weeks after exposure to each anaesthetic. The histological changes observed were, in general, rather similar for all agents tested, although certain differences were noted. The initial change observed was damage of the outer epithelial layers, later also accompanied by changes in the corresponding endothelial cover. No perforations were observed macroscopically. The healing process was characterized by hyperplasia of the connective tissue layers of the drum. However, the most prominent feature of this process was the hyperplastic epithelium, ingrowing from the periphery of the membrane to cover denuded areas. During certain stages of the healing process the thickness of the membrane amounted to 40 times that of the normal drum. The initial changes appeared severe both with the clinically more potent and effective anaesthetics (phenol and Bonain's liquid), and with Xylocaine spray.
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