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Lee S, Vander Roest AS, Blair CA, Kao K, Bremner SB, Childers MC, Pathak D, Heinrich P, Lee D, Chirikian O, Mohran SE, Roberts B, Smith JE, Jahng JW, Paik DT, Wu JC, Gunawardane RN, Ruppel KM, Mack DL, Pruitt BL, Regnier M, Wu SM, Spudich JA, Bernstein D. Incomplete-penetrant hypertrophic cardiomyopathy MYH7 G256E mutation causes hypercontractility and elevated mitochondrial respiration. Proc Natl Acad Sci U S A 2024; 121:e2318413121. [PMID: 38683993 PMCID: PMC11087781 DOI: 10.1073/pnas.2318413121] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 03/05/2024] [Indexed: 05/02/2024] Open
Abstract
Determining the pathogenicity of hypertrophic cardiomyopathy-associated mutations in the β-myosin heavy chain (MYH7) can be challenging due to its variable penetrance and clinical severity. This study investigates the early pathogenic effects of the incomplete-penetrant MYH7 G256E mutation on myosin function that may trigger pathogenic adaptations and hypertrophy. We hypothesized that the G256E mutation would alter myosin biomechanical function, leading to changes in cellular functions. We developed a collaborative pipeline to characterize myosin function across protein, myofibril, cell, and tissue levels to determine the multiscale effects on structure-function of the contractile apparatus and its implications for gene regulation and metabolic state. The G256E mutation disrupts the transducer region of the S1 head and reduces the fraction of myosin in the folded-back state by 33%, resulting in more myosin heads available for contraction. Myofibrils from gene-edited MYH7WT/G256E human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exhibited greater and faster tension development. This hypercontractile phenotype persisted in single-cell hiPSC-CMs and engineered heart tissues. We demonstrated consistent hypercontractile myosin function as a primary consequence of the MYH7 G256E mutation across scales, highlighting the pathogenicity of this gene variant. Single-cell transcriptomic and metabolic profiling demonstrated upregulated mitochondrial genes and increased mitochondrial respiration, indicating early bioenergetic alterations. This work highlights the benefit of our multiscale platform to systematically evaluate the pathogenicity of gene variants at the protein and contractile organelle level and their early consequences on cellular and tissue function. We believe this platform can help elucidate the genotype-phenotype relationships underlying other genetic cardiovascular diseases.
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Affiliation(s)
- Soah Lee
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Department of Biopharmaceutical Convergence, Sungkyunkwan University School of Pharmacy, Suwon, Gyeonggi-do16419South Korea
- School of Pharmacy, Sungkyunkwan University School of Pharmacy, Suwon, Gyeonggi-do16419, South Korea
| | - Alison S. Vander Roest
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA94305
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI48109
| | - Cheavar A. Blair
- Biological Engineering, University of California, Santa Barbara, CA93106
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY40536
| | - Kerry Kao
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Samantha B. Bremner
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Matthew C. Childers
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Divya Pathak
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
| | - Paul Heinrich
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Daniel Lee
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Orlando Chirikian
- Biological Engineering, University of California, Santa Barbara, CA93106
| | - Saffie E. Mohran
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | | | | | - James W. Jahng
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - David T. Paik
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Joseph C. Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | | | - Kathleen M. Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
| | - David L. Mack
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Beth L. Pruitt
- Biological Engineering, University of California, Santa Barbara, CA93106
| | - Michael Regnier
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Sean M. Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | - James A. Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
| | - Daniel Bernstein
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA94305
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Lee S, Roest ASV, Blair CA, Kao K, Bremner SB, Childers MC, Pathak D, Heinrich P, Lee D, Chirikian O, Mohran S, Roberts B, Smith JE, Jahng JW, Paik DT, Wu JC, Gunawardane RN, Spudich JA, Ruppel K, Mack D, Pruitt BL, Regnier M, Wu SM, Bernstein D. Multi-scale models reveal hypertrophic cardiomyopathy MYH7 G256E mutation drives hypercontractility and elevated mitochondrial respiration. bioRxiv 2023:2023.06.08.544276. [PMID: 37333118 PMCID: PMC10274883 DOI: 10.1101/2023.06.08.544276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Rationale Over 200 mutations in the sarcomeric protein β-myosin heavy chain (MYH7) have been linked to hypertrophic cardiomyopathy (HCM). However, different mutations in MYH7 lead to variable penetrance and clinical severity, and alter myosin function to varying degrees, making it difficult to determine genotype-phenotype relationships, especially when caused by rare gene variants such as the G256E mutation. Objective This study aims to determine the effects of low penetrant MYH7 G256E mutation on myosin function. We hypothesize that the G256E mutation would alter myosin function, precipitating compensatory responses in cellular functions. Methods We developed a collaborative pipeline to characterize myosin function at multiple scales (protein to myofibril to cell to tissue). We also used our previously published data on other mutations to compare the degree to which myosin function was altered. Results At the protein level, the G256E mutation disrupts the transducer region of the S1 head and reduces the fraction of myosin in the folded-back state by 50.9%, suggesting more myosins available for contraction. Myofibrils isolated from hiPSC-CMs CRISPR-edited with G256E (MYH7 WT/G256E ) generated greater tension, had faster tension development and slower early phase relaxation, suggesting altered myosin-actin crossbridge cycling kinetics. This hypercontractile phenotype persisted in single-cell hiPSC-CMs and engineered heart tissues. Single-cell transcriptomic and metabolic profiling demonstrated upregulation of mitochondrial genes and increased mitochondrial respiration, suggesting altered bioenergetics as an early feature of HCM. Conclusions MYH7 G256E mutation causes structural instability in the transducer region, leading to hypercontractility across scales, perhaps from increased myosin recruitment and altered crossbridge cycling. Hypercontractile function of the mutant myosin was accompanied by increased mitochondrial respiration, while cellular hypertrophy was modest in the physiological stiffness environment. We believe that this multi-scale platform will be useful to elucidate genotype-phenotype relationships underlying other genetic cardiovascular diseases.
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Tanner BCW, Awinda PO, Agonias KB, Attili S, Blair CA, Thompson MS, Walker LA, Kampourakis T, Campbell KS. Sarcomere length affects Ca2+ sensitivity of contraction in ischemic but not non-ischemic myocardium. J Gen Physiol 2023; 155:213800. [PMID: 36633584 PMCID: PMC9859763 DOI: 10.1085/jgp.202213200] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 11/18/2022] [Accepted: 12/22/2022] [Indexed: 01/13/2023] Open
Abstract
In healthy hearts, myofilaments become more sensitive to Ca2+ as the myocardium is stretched. This effect is known as length-dependent activation and is an important cellular-level component of the Frank-Starling mechanism. Few studies have measured length-dependent activation in the myocardium from failing human hearts. We investigated whether ischemic and non-ischemic heart failure results in different length-dependent activation responses at physiological temperature (37°C). Myocardial strips from the left ventricular free wall were chemically permeabilized and Ca2+-activated at sarcomere lengths (SLs) of 1.9 and 2.3 µm. Data were acquired from 12 hearts that were explanted from patients receiving cardiac transplants; 6 had ischemic heart failure and 6 had non-ischemic heart failure. Another 6 hearts were obtained from organ donors. Maximal Ca2+-activated force increased at longer SL for all groups. Ca2+ sensitivity increased with SL in samples from donors (P < 0.001) and patients with ischemic heart failure (P = 0.003) but did not change with SL in samples from patients with non-ischemic heart failure. Compared with donors, troponin I phosphorylation decreased in ischemic samples and even more so in non-ischemic samples; cardiac myosin binding protein-C (cMyBP-C) phosphorylation also decreased with heart failure. These findings support the idea that troponin I and cMyBP-C phosphorylation promote length-dependent activation and show that length-dependent activation of contraction is blunted, yet extant, in the myocardium from patients with ischemic heart failure and further reduced in the myocardium from patients with non-ischemic heart failure. Patients who have a non-ischemic disease may exhibit a diminished contractile response to increased ventricular filling.
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Affiliation(s)
- Bertrand C W Tanner
- Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, WA, USA
| | - Peter O Awinda
- Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, WA, USA
| | - Keinan B Agonias
- Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, WA, USA
| | - Seetharamaiah Attili
- Randall Centre for Cell and Molecular Biophysics, King's College London , London, UK
| | - Cheavar A Blair
- Department of Physiology, University of Kentucky , Lexington, KY, USA
| | - Mindy S Thompson
- Department of Physiology, University of Kentucky , Lexington, KY, USA
| | - Lori A Walker
- Division of Cardiology, Department of Medicine, University of Colorado Anschutz Medical Campus , Aurora, CO, USA
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, King's College London , London, UK
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky , Lexington, KY, USA.,Division of Cardiovascular Medicine, University of Kentucky , Lexington, KY, USA
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Lane KV, Dow LP, Larson SR, Blair CA, Pruitt BL. Dual-protein patterning to investigate effects of cell-cell adhesions on hiPSC-CM maturity. Biophys J 2023; 122:24a. [PMID: 36783228 DOI: 10.1016/j.bpj.2022.11.353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Kerry V Lane
- University of California Santa Barbara, Santa Barbara, CA, USA
| | - Liam P Dow
- University of California Santa Barbara, Santa Barbara, CA, USA
| | | | - Cheavar A Blair
- University of California Santa Barbara, Santa Barbara, CA, USA
| | - Beth L Pruitt
- University of California Santa Barbara, Santa Barbara, CA, USA
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Blair CA, Pruitt B, Feinstein SD. The polyamine spermidine enhances contractile function and sarcomere dynamics post-doxorubicin treatment. Biophys J 2023; 122:148a. [PMID: 36782682 DOI: 10.1016/j.bpj.2022.11.1016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Cheavar A Blair
- Bioengineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Beth Pruitt
- Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA; Biomolecular Science and Engineering, University of California Santa Barbara, Santa Barbara, CA, USA; Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
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6
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Vikhorev PG, Vikhoreva NN, Yeung W, Li A, Lal S, dos Remedios CG, Blair CA, Guglin M, Campbell KS, Yacoub MH, de Tombe P, Marston SB. Titin-truncating mutations associated with dilated cardiomyopathy alter length-dependent activation and its modulation via phosphorylation. Cardiovasc Res 2020; 118:241-253. [PMID: 33135063 PMCID: PMC8752363 DOI: 10.1093/cvr/cvaa316] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 10/20/2020] [Indexed: 12/18/2022] Open
Abstract
Abstract
Aims
Dilated cardiomyopathy (DCM) is associated with mutations in many genes encoding sarcomere proteins. Truncating mutations in the titin gene TTN are the most frequent. Proteomic and functional characterizations are required to elucidate the origin of the disease and the pathogenic mechanisms of TTN-truncating variants.
Methods and results
We isolated myofibrils from DCM hearts carrying truncating TTN mutations and measured the Ca2+ sensitivity of force and its length dependence. Simultaneous measurement of force and adenosine triphosphate (ATP) consumption in skinned cardiomyocytes was also performed. Phosphorylation levels of troponin I (TnI) and myosin binding protein-C (MyBP-C) were manipulated using protein kinase A and λ phosphatase. mRNA sequencing was employed to overview gene expression profiles. We found that Ca2+ sensitivity of myofibrils carrying TTN mutations was significantly higher than in myofibrils from donor hearts. The length dependence of the Ca2+ sensitivity was absent in DCM myofibrils with TTN-truncating variants. No significant difference was found in the expression level of TTN mRNA between the DCM and donor groups. TTN exon usage and splicing were also similar. However, we identified down-regulation of genes encoding Z-disk proteins, while the atrial-specific regulatory myosin light chain gene, MYL7, was up-regulated in DCM patients with TTN-truncating variants.
Conclusion
Titin-truncating mutations lead to decreased length-dependent activation and increased elasticity of myofibrils. Phosphorylation levels of TnI and MyBP-C seen in the left ventricles are essential for the length-dependent changes in Ca2+ sensitivity in healthy donors, but they are reduced in DCM patients with TTN-truncating variants. A decrease in expression of Z-disk proteins may explain the observed decrease in myofibril passive stiffness and length-dependent activation.
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Affiliation(s)
- Petr G Vikhorev
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Natalia N Vikhoreva
- Heart Science Centre, Magdi Yacoub Institute, Harefield Hospital, London UB9 6JH, UK
| | - WaiChun Yeung
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Amy Li
- Department of Pharmacy and Biomedical Sciences, La Trobe University, Bendigo, VIC 3550, Australia
| | - Sean Lal
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, NSW 2006, Australia
| | - Cristobal G dos Remedios
- Division of Molecular Cardiology and Biophysics, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Cheavar A Blair
- Division of Cardiovascular Medicine, Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Maya Guglin
- Division of Cardiovascular Medicine, Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Kenneth S Campbell
- Division of Cardiovascular Medicine, Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Magdi H Yacoub
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Pieter de Tombe
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
- Heart Science Centre, Magdi Yacoub Institute, Harefield Hospital, London UB9 6JH, UK
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Steven B Marston
- National Heart and Lung Institute, Imperial College London, Du Cane Road, London W12 0NN, UK
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Blair CA, Brundage EA, Thompson KL, Stromberg A, Guglin M, Biesiadecki BJ, Campbell KS. Heart Failure in Humans Reduces Contractile Force in Myocardium From Both Ventricles. JACC Basic Transl Sci 2020; 5:786-798. [PMID: 32875169 PMCID: PMC7452203 DOI: 10.1016/j.jacbts.2020.05.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 05/18/2020] [Accepted: 05/18/2020] [Indexed: 01/01/2023]
Abstract
Contractile assays were performed using multicellular preparations isolated from the left and right ventricles of organ donors and patients with heart failure. Heart failure reduced maximum force and power by approximately 30% in the myocardium from both ventricles. Heart failure increased the Ca2+ sensitivity of contraction, but the effect was bigger in right ventricular tissue than in left ventricular samples. The changes in Ca2+ sensitivity may reflect ventricle-specific post-translational modifications to sarcomeric proteins.
This study measured how heart failure affects the contractile properties of the human myocardium from the left and right ventricles. The data showed that maximum force and maximum power were reduced by approximately 30% in multicellular preparations from both ventricles, possibly because of ventricular remodeling (e.g., cellular disarray and/or excess fibrosis). Heart failure increased the calcium (Ca2+) sensitivity of contraction in both ventricles, but the effect was bigger in right ventricular samples. The changes in Ca2+ sensitivity were associated with ventricle-specific changes in the phosphorylation of troponin I, which indicated that adrenergic stimulation might induce different effects in the left and right ventricles.
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Key Words
- Ca2+ sensitivity
- Ca2+, calcium
- Fact, maximum Ca2+-activated force
- Fpas, passive force
- LV, left ventricle
- MyBP-C, myosin binding protein-C
- PKA, protein kinase A
- Pmax, maximum power output
- RLC, regulatory light chain
- RV, right ventricle
- TnI, troponin I
- Vmax, maximum shortening velocity
- heart failure
- human myocardium
- ktr, rate of force recovery
- myofilament proteins
- nH, Hill coefficient
- ventricular function
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Affiliation(s)
- Cheavar A Blair
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology and The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | | | - Arnold Stromberg
- Department of Statistics, University of Kentucky, Lexington, Kentucky
| | - Maya Guglin
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology and The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky, Lexington, Kentucky.,Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky
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Blair CA, Pruitt BL. Mechanobiology Assays with Applications in Cardiomyocyte Biology and Cardiotoxicity. Adv Healthc Mater 2020; 9:e1901656. [PMID: 32270928 PMCID: PMC7480481 DOI: 10.1002/adhm.201901656] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 12/19/2022]
Abstract
Cardiomyocytes are the motor units that drive the contraction and relaxation of the heart. Traditionally, testing of drugs for cardiotoxic effects has relied on primary cardiomyocytes from animal models and focused on short-term, electrophysiological, and arrhythmogenic effects. However, primary cardiomyocytes present challenges arising from their limited viability in culture, and tissue from animal models suffers from a mismatch in their physiology to that of human heart muscle. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) can address these challenges. They also offer the potential to study not only electrophysiological effects but also changes in cardiomyocyte contractile and mechanical function in response to cardiotoxic drugs. With growing recognition of the long-term cardiotoxic effects of some drugs on subcellular structure and function, there is increasing interest in using hiPSC-CMs for in vitro cardiotoxicity studies. This review provides a brief overview of techniques that can be used to quantify changes in the active force that cardiomyocytes generate and variations in their inherent stiffness in response to cardiotoxic drugs. It concludes by discussing the application of these tools in understanding how cardiotoxic drugs directly impact the mechanobiology of cardiomyocytes and how cardiomyocytes sense and respond to mechanical load at the cellular level.
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Affiliation(s)
- Cheavar A. Blair
- Department of mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
- Biomolecular Science and Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Beth L. Pruitt
- Department of mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
- Biomolecular Science and Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
- Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
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Papadaki M, Holewinski RJ, Previs SB, Martin TG, Stachowski MJ, Li A, Blair CA, Moravec CS, Van Eyk JE, Campbell KS, Warshaw DM, Kirk JA. Diabetes with heart failure increases methylglyoxal modifications in the sarcomere, which inhibit function. JCI Insight 2018; 3:121264. [PMID: 30333300 DOI: 10.1172/jci.insight.121264] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 09/04/2018] [Indexed: 12/27/2022] Open
Abstract
Patients with diabetes are at significantly higher risk of developing heart failure. Increases in advanced glycation end products are a proposed pathophysiological link, but their impact and mechanism remain incompletely understood. Methylglyoxal (MG) is a glycolysis byproduct, elevated in diabetes, and modifies arginine and lysine residues. We show that left ventricular myofilament from patients with diabetes and heart failure (dbHF) exhibited increased MG modifications compared with nonfailing controls (NF) or heart failure patients without diabetes. In skinned NF human and mouse cardiomyocytes, acute MG treatment depressed both calcium sensitivity and maximal calcium-activated force in a dose-dependent manner. Importantly, dbHF myocytes were resistant to myofilament functional changes from MG treatment, indicating that myofilaments from dbHF patients already had depressed function arising from MG modifications. In human dbHF and MG-treated mice, mass spectrometry identified increased MG modifications on actin and myosin. Cosedimentation and in vitro motility assays indicate that MG modifications on actin and myosin independently depress calcium sensitivity, and mechanistically, the functional consequence requires actin/myosin interaction with thin-filament regulatory proteins. MG modification of the myofilament may represent a critical mechanism by which diabetes induces heart failure, as well as a therapeutic target to avoid the development of or ameliorate heart failure in these patients.
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Affiliation(s)
- Maria Papadaki
- Loyola University Chicago, Department of Cell and Molecular Physiology, Chicago, Illinois, USA
| | | | - Samantha Beck Previs
- University of Vermont, Department of Molecular Physiology and Biophysics, Burlington, Vermont, USA
| | - Thomas G Martin
- Loyola University Chicago, Department of Cell and Molecular Physiology, Chicago, Illinois, USA
| | - Marisa J Stachowski
- Loyola University Chicago, Department of Cell and Molecular Physiology, Chicago, Illinois, USA
| | - Amy Li
- University of Vermont, Department of Molecular Physiology and Biophysics, Burlington, Vermont, USA
| | - Cheavar A Blair
- University of Kentucky, Department of Physiology, Lexington, Kentucky, USA
| | - Christine S Moravec
- The Cleveland Clinic, Department of Molecular Cardiology, Cleveland, Ohio, USA
| | - Jennifer E Van Eyk
- Cedars-Sinai Medical Center, Heart Institute, Los Angeles, California, USA
| | - Kenneth S Campbell
- University of Kentucky, Department of Physiology, Lexington, Kentucky, USA
| | - David M Warshaw
- University of Vermont, Department of Molecular Physiology and Biophysics, Burlington, Vermont, USA
| | - Jonathan A Kirk
- Loyola University Chicago, Department of Cell and Molecular Physiology, Chicago, Illinois, USA
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Tanner BC, Awinda PO, Blair CA, Guglin MA, Campbell KS. Length-Dependent Activation is Reduced in Myocardium from Patients with Non-ischemic Heart Failure. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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11
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Papadaki M, Holewinski RJ, Smolin N, Stachowski MJ, Blair CA, Campbell KS, Robia SL, Kirk JA. Methylglyoxal Modifications are Elevated in the Myofilament of Diabetic Cardiomyopathy Patients and Reduce Myofilament Function. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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12
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Vikhorev PG, Smoktunowicz N, Munster AB, Copeland O, Kostin S, Montgiraud C, Messer AE, Toliat MR, Li A, Dos Remedios CG, Lal S, Blair CA, Campbell KS, Guglin M, Richter M, Knöll R, Marston SB. Abnormal contractility in human heart myofibrils from patients with dilated cardiomyopathy due to mutations in TTN and contractile protein genes. Sci Rep 2017; 7:14829. [PMID: 29093449 PMCID: PMC5665940 DOI: 10.1038/s41598-017-13675-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 09/26/2017] [Indexed: 11/29/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is an important cause of heart failure. Single gene mutations in at least 50 genes have been proposed to account for 25–50% of DCM cases and up to 25% of inherited DCM has been attributed to truncating mutations in the sarcomeric structural protein titin (TTNtv). Whilst the primary molecular mechanism of some DCM-associated mutations in the contractile apparatus has been studied in vitro and in transgenic mice, the contractile defect in human heart muscle has not been studied. In this study we isolated cardiac myofibrils from 3 TTNtv mutants, and 3 with contractile protein mutations (TNNI3 K36Q, TNNC1 G159D and MYH7 E1426K) and measured their contractility and passive stiffness in comparison with donor heart muscle as a control. We found that the three contractile protein mutations but not the TTNtv mutations had faster relaxation kinetics. Passive stiffness was reduced about 38% in all the DCM mutant samples. However, there was no change in maximum force or the titin N2BA/N2B isoform ratio and there was no titin haploinsufficiency. The decrease in myofibril passive stiffness was a common feature in all hearts with DCM-associated mutations and may be causative of DCM.
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Affiliation(s)
- Petr G Vikhorev
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom.
| | - Natalia Smoktunowicz
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom
| | - Alex B Munster
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom
| | - O'Neal Copeland
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom
| | - Sawa Kostin
- Max-Planck-Institute for Heart and Lung Research, Ludwigstrasse 43, 61231, Bad Nauheim, 61231, Germany
| | - Cecile Montgiraud
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom
| | - Andrew E Messer
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom
| | - Mohammad R Toliat
- Cologne Center for Genomics, University of Cologne, Cologne, 50931, Germany
| | - Amy Li
- Discipline of Anatomy and Histology, Bosch Institute, University of Sydney, Sydney, NSW, 2006, Australia
| | - Cristobal G Dos Remedios
- Discipline of Anatomy and Histology, Bosch Institute, University of Sydney, Sydney, NSW, 2006, Australia
| | - Sean Lal
- Discipline of Anatomy and Histology, Bosch Institute, University of Sydney, Sydney, NSW, 2006, Australia
| | - Cheavar A Blair
- Division of Cardiovascular Medicine, Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Kenneth S Campbell
- Division of Cardiovascular Medicine, Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Maya Guglin
- Division of Cardiovascular Medicine, Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Manfred Richter
- Department of Cardiac Surgery, Kerckhoff-Clinic, Benekestrasse 2-8, Bad Nauheim, 61231, Germany
| | - Ralph Knöll
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom.,ICMC (Integrated Cardio Metabolic Centre), Myocardial Genetics, Karolinska Institutet, University Hospital, Heart and Vascular Theme, Novum, Hiss A, våning 7, Hälsovägen 7-9, Huddinge, 141 57, Sweden.,AstraZeneca R&D Gothenburg, R&D, Innovative Medicines & Early Development, Cardiovascular, Renal and Metabolic Diseases (CVRM), Pepparedsleden 1, SE-431 83, Mölndal, Sweden
| | - Steven B Marston
- National Heart and Lung Institute, Imperial College London, London, W12 0NN, United Kingdom.
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13
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Tanner BC, Awinda PO, Blair CA, Guglin ME, Campbell KS. Abstract 227: Skinned Myocardial Strips From Non-failing and Failing Human Hearts Produce More Force at Physiological Temperature. Circ Res 2017. [DOI: 10.1161/res.121.suppl_1.227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction:
Heart failure contributes to 1 in 9 deaths in the United States. Contractile deficits at the myofilament level may contribute to the heart inadequately pumping blood throughout the body. Few studies have investigated force production and myosin cross-bridge kinetics at physiological temperature in human myocardium from non-failing and failing hearts.
Hypothesis:
Myosin cross-bridge kinetics speed up with temperature, thereby altering contractility in non-failing and failing human myocardium.
Methods:
Skinned myocardial strips from the left ventricle free wall were Ca
2+
-activated at 2.3 μm sarcomere length. Isometric force production and cross-bridge attachment and detachment rates were measured at 17 and 37°C (4 non-failing hearts, 8 failing hearts; 4-6 strips tested at each condition).
Results:
Maximal Ca
2+
-activated, force was ~35% greater in non-failing vs. failing tissue at both 17 and 37°C (p<0.001 for condition effect). Moreover, increasing temperature from 17 to 37°C increased maximal force by roughly 30% and 40% in non-failing and failing myocardial strips, respectively (p<0.001 for temperature effect). Ca
2+
-sensitivity of the force-pCa relationship was reduced for non-failing vs. failing myocardial strips (p=0.03 for condition effect), with differences in pCa
50
being greatest at 17°C between non-failing and failing samples. These contractile differences between non-failing and failing myocardium, were not driven via differences in myosin cross-bridge kinetics, which were similar among non-failing and failing samples at each temperature. However, faster cross-bridge cycling rates accompanied greater force production at physiological temperature in both non-failing and failing samples.
Conclusions:
These findings suggest that heart failure compromises force production without significantly altering cross-bridge kinetics, both at sub-physiological and physiological temperatures in human myocardium.
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14
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Blair CA, Davis J, Biesiadecki B, Campbell K. Engineered Troponins Modulate the Ca 2+ Sensitivity of the Failing Human Myocardium. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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15
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Swenson AM, Tang W, Blair CA, Fetrow CM, Unrath WC, Previs MJ, Campbell KS, Yengo CM. Omecamtiv Mecarbil Enhances the Duty Ratio of Human β-Cardiac Myosin Resulting in Increased Calcium Sensitivity and Slowed Force Development in Cardiac Muscle. J Biol Chem 2017; 292:3768-3778. [PMID: 28082673 DOI: 10.1074/jbc.m116.748780] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 01/05/2017] [Indexed: 01/10/2023] Open
Abstract
The small molecule drug omecamtiv mecarbil (OM) specifically targets cardiac muscle myosin and is known to enhance cardiac muscle performance, yet its impact on human cardiac myosin motor function is unclear. We expressed and purified human β-cardiac myosin subfragment 1 (M2β-S1) containing a C-terminal Avi tag. We demonstrate that the maximum actin-activated ATPase activity of M2β-S1 is slowed more than 4-fold in the presence of OM, whereas the actin concentration required for half-maximal ATPase was reduced dramatically (30-fold). We find OM does not change the overall actin affinity. Transient kinetic experiments suggest that there are two kinetic pathways in the presence of OM. The dominant pathway results in a slow transition between actomyosin·ADP states and increases the time myosin is strongly bound to actin. However, OM also traps a population of myosin heads in a weak actin affinity state with slow product release. We demonstrate that OM can reduce the actin sliding velocity more than 100-fold in the in vitro motility assay. The ionic strength dependence of in vitro motility suggests the inhibition may be at least partially due to drag forces from weakly attached myosin heads. OM causes an increase in duty ratio examined in the motility assay. Experiments with permeabilized human myocardium demonstrate that OM increases calcium sensitivity and slows force development (ktr) in a concentration-dependent manner, whereas the maximally activated force is unchanged. We propose that OM increases the myosin duty ratio, which results in enhanced calcium sensitivity but slower force development in human myocardium.
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Affiliation(s)
- Anja M Swenson
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Wanjian Tang
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Cheavar A Blair
- the Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, and
| | - Christopher M Fetrow
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - William C Unrath
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Michael J Previs
- the Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, Vermont 05405
| | - Kenneth S Campbell
- the Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, and
| | - Christopher M Yengo
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033,
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16
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Tang W, Blair CA, Walton SD, Málnási-Csizmadia A, Campbell KS, Yengo CM. Modulating Beta-Cardiac Myosin Function at the Molecular and Tissue Levels. Front Physiol 2017; 7:659. [PMID: 28119616 PMCID: PMC5220080 DOI: 10.3389/fphys.2016.00659] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [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: 09/01/2016] [Accepted: 12/15/2016] [Indexed: 01/10/2023] Open
Abstract
Inherited cardiomyopathies are a common form of heart disease that are caused by mutations in sarcomeric proteins with beta cardiac myosin (MYH7) being one of the most frequently affected genes. Since the discovery of the first cardiomyopathy associated mutation in beta-cardiac myosin, a major goal has been to correlate the in vitro myosin motor properties with the contractile performance of cardiac muscle. There has been substantial progress in developing assays to measure the force and velocity properties of purified cardiac muscle myosin but it is still challenging to correlate results from molecular and tissue-level experiments. Mutations that cause hypertrophic cardiomyopathy are more common than mutations that lead to dilated cardiomyopathy and are also often associated with increased isometric force and hyper-contractility. Therefore, the development of drugs designed to decrease isometric force by reducing the duty ratio (the proportion of time myosin spends bound to actin during its ATPase cycle) has been proposed for the treatment of hypertrophic cardiomyopathy. Para-Nitroblebbistatin is a small molecule drug proposed to decrease the duty ratio of class II myosins. We examined the impact of this drug on human beta cardiac myosin using purified myosin motor assays and studies of permeabilized muscle fiber mechanics. We find that with purified human beta-cardiac myosin para-Nitroblebbistatin slows actin-activated ATPase and in vitro motility without altering the ADP release rate constant. In permeabilized human myocardium, para-Nitroblebbistatin reduces isometric force, power, and calcium sensitivity while not changing shortening velocity or the rate of force development (ktr). Therefore, designing a drug that reduces the myosin duty ratio by inhibiting strong attachment to actin while not changing detachment can cause a reduction in force without changing shortening velocity or relaxation.
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Affiliation(s)
- Wanjian Tang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | - Cheavar A Blair
- Department of Physiology, University of Kentucky Lexington, KY, USA
| | - Shane D Walton
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | | | - Kenneth S Campbell
- Department of Physiology, University of KentuckyLexington, KY, USA; Division of Cardiovascular Medicine, University of KentuckyLexington, KY, USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
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17
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Blair CA, Haynes P, Campbell SG, Chung C, Mitov MI, Dennis D, Bonnell MR, Hoopes CW, Guglin M, Campbell KS. A Protocol for Collecting Human Cardiac Tissue for Research. VAD J 2016; 2. [PMID: 28042604 DOI: 10.13023/vad.2016.12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This manuscript describes a protocol at the University of Kentucky that allows a translational research team to collect human myocardium that can be used for biological research. We have gained a great deal of practical experience since we started this protocol in 2008, and we hope that other groups might be able to learn from our endeavors. To date, we have procured ~4000 samples from ~230 patients. The tissue that we collect comes from organ donors and from patients who are receiving a heart transplant or a ventricular assist device because they have heart failure. We begin our manuscript by describing the importance of human samples in cardiac research. Subsequently, we describe the process for obtaining consent from patients, the cost of running the protocol, and some of the issues and practical difficulties that we have encountered. We conclude with some suggestions for other researchers who may be considering starting a similar protocol.
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Affiliation(s)
- Cheavar A Blair
- Department of Physiology, University of Kentucky, Lexington, KY
| | - Premi Haynes
- Department of Pediatrics, Institute for Stem Cell & Regenerative Medicine, University of Washington, Seattle, WA
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, CT
| | - Charles Chung
- Department of Physiology, Wayne State University, Detroit, MI
| | - Mihail I Mitov
- Markey Cancer Center, University of Kentucky, Lexington, KY
| | - Donna Dennis
- Gill Heart Institute, University of Kentucky, Lexington, KY
| | | | - Charles W Hoopes
- University of Alabama Birmingham School of Medicine, Birmingham, AL
| | - Maya Guglin
- Gill Heart Institute, University of Kentucky, Lexington, KY; Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky, Lexington, KY; Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY
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18
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Blair CA, Guglin ME, Stromberg A, Campbell KS. Myocardium from the Left and Right Ventricles of Human Hearts have Similar Mechanical Properties. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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19
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Veith LR, Blair CA, Leonard NV, Bouma R, Pazda HH. Attorney-case manager collaboration in the conservatorship of older adults. J Case Manag 1996; 5:115-20. [PMID: 9257626] [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: 02/05/2023]
Abstract
The complex issues of long-term care are everchanging, with no one discipline having the corner on all the intricate options, regulations, and ethical choices that often confront an aging person. This is most critical when a person's incompetence requires the appointment of a conservator or guardian. When the probate court finds it necessary to appoint a conservator/guardian for an older adult, and family or other informal caregivers are unavailable or unable to assume the role, the responsibility is often delegated to an attorney. However, an attorney's expertise is in the field of law, not necessarily in the complex and intricate long-term health care system. Maintaining a mentally incompetent and functionally disabled person in the safest and least restrictive environment is demanding. It requires a thorough knowledge and understanding of the physical and emotional changes associated with the aging process, an area of expertise of long-term care case managers. Combining the clinical proficiency of the case manager with the legal and financial expertise of the attorney benefits the conserved older adult. This article illustrates this collaborative approach to long-term care through the use of several case histories.
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Affiliation(s)
- L R Veith
- National Case Management Partnership, Bristol, CT 06011-2360, USA
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20
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Abstract
Five kinds of coffee samples were prepared from a commercial drip-grind coffee in order to examine the mutagenicity of brewed coffee using the Ames test. The samples prepared were a thick coffee syrup, coffee solid residues, dichloromethane and ethanol extracts of solid residues, a dichloromethane extract of a distillate from normally heated brewed coffee and dichloromethane extracts of distillates from overheated (150-300 degrees C) brewed coffee. The samples were tested for mutagenicity towards Salmonella typhimurium strains TA98 and TA100 both with and without metabolic activation (S-9 mix). Only the extracts of the distillates obtained from coffee heated to 150 degrees or 300 degrees C exhibited mutagenicity towards strain TA98 with S-9 mix.
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