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Hureau TJ, Weavil JC, Sidhu SK, Thurston TS, Reese VR, Zhao J, Nelson AD, Birgenheier NM, Richardson RS, Amann M. Ascorbate attenuates cycling exercise-induced neuromuscular fatigue but fails to improve exertional dyspnea and exercise tolerance in COPD. J Appl Physiol (1985) 2021; 130:69-79. [PMID: 33151775 PMCID: PMC7944926 DOI: 10.1152/japplphysiol.00611.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 07/14/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 11/22/2022] Open
Abstract
We examined the effect of intravenous ascorbate (VitC) administration on exercise-induced redox balance, inflammation, exertional dyspnea, neuromuscular fatigue, and exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). Eight COPD patients completed constant-load cycling (∼80% of peak power output, 83 ± 10 W) to task failure after intravenous VitC (2 g) or saline (placebo, PL) infusion. All participants repeated the shorter of the two exercise trials (isotime) with the other infusate. Quadriceps fatigue was determined by pre- to postexercise changes in quadriceps twitch torque (ΔQtw, electrical femoral nerve stimulation). Corticospinal excitability before, during, and after exercise was assessed by changes in motor evoked potentials triggered by transcranial magnetic stimulation. VitC increased superoxide dismutase (marker for endogenous antioxidant capacity) by 129% and mitigated C-reactive protein (marker for inflammation) in the plasma during exercise but failed to alter the exercise-induced increase in lipid peroxidation (malondialdehyde) and free radicals [electron paramagnetic resonance (EPR)-spectroscopy]. Although VitC did, indeed, decrease neuromuscular fatigue (ΔQtw: PL -29 ± 5%, VitC -23 ± 6%, P < 0.05), there was no impact on corticospinal excitability and time to task failure (∼8 min, P = 0.8). Interestingly, in terms of pulmonary limitations to exercise, VitC had no effect on perceived exertional dyspnea (∼8.5/10) and its determinants, including oxygen saturation ([Formula: see text]) (∼92%) and respiratory muscle work (∼650 cmH2O·s·min-1) (P > 0.3). Thus, although VitC facilitated indicators for antioxidant capacity, diminished inflammatory markers, and improved neuromuscular fatigue resistance, it failed to improve exertional dyspnea and cycling exercise tolerance in patients with COPD. As dyspnea is recognized to limit exercise tolerance in COPD, the otherwise beneficial effects of VitC may have been impacted by this unaltered sensation.NEW & NOTEWORTHY We investigated the effect of intravenous vitamin C on redox balance, exertional dyspnea, neuromuscular fatigue, and exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. Acute vitamin C administration increased superoxide dismutase (marker of antioxidant capacity) and attenuated fatigue development but failed to improve exertional dyspnea and exercise tolerance. These findings suggest that a compromised redox balance plays a critical role in the development of fatigue in COPD but also highlight the significance of exertional dyspnea as an important symptom limiting the patients' exercise tolerance.
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Affiliation(s)
- Thomas J Hureau
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- EA 3072 Mitochondria, Oxidative Stress and Muscular Protection Laboratory, Department of Medicine, University of Strasbourg, Strasbourg, France
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Simranjit K Sidhu
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Van R Reese
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Jia Zhao
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | | | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Affairs Medical Center, Salt Lake City, Utah
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Markus Amann
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Affairs Medical Center, Salt Lake City, Utah
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
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2
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Trinity JD, Kwon OS, Broxterman RM, Gifford JR, Kithas AC, Hydren JR, Jarrett CL, Shields KL, Bisconti AV, Park SH, Craig JC, Nelson AD, Morgan DE, Jessop JE, Bledsoe AD, Richardson RS. The role of the endothelium in the hyperemic response to passive leg movement: looking beyond nitric oxide. Am J Physiol Heart Circ Physiol 2020; 320:H668-H678. [PMID: 33306447 DOI: 10.1152/ajpheart.00784.2020] [Citation(s) in RCA: 8] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Passive leg movement (PLM) evokes a robust and predominantly nitric oxide (NO)-mediated increase in blood flow that declines with age and disease. Consequently, PLM is becoming increasingly accepted as a sensitive assessment of endothelium-mediated vascular function. However, a substantial PLM-induced hyperemic response is still evoked despite nitric oxide synthase (NOS) inhibition. Therefore, in nine young healthy men (25 ± 4 yr), this investigation aimed to determine whether the combination of two potent endothelium-dependent vasodilators, specifically prostaglandin (PG) and endothelium-derived hyperpolarizing factor (EDHF), account for the remaining hyperemic response to the two variants of PLM, PLM (60 movements) and single PLM (sPLM, 1 movement), when NOS is inhibited. The leg blood flow (LBF, Doppler ultrasound) response to PLM and sPLM following the intra-arterial infusion of NG-monomethyl-l-arginine (l-NMMA), to inhibit NOS, was compared to the combined inhibition of NOS, cyclooxygenase (COX), and cytochrome P-450 (CYP450) by l-NMMA, ketorolac tromethamine (KET), and fluconazole (FLUC), respectively. NOS inhibition attenuated the overall LBF [area under the curve (LBFAUC)] response to both PLM (control: 456 ± 194, l-NMMA: 168 ± 127 mL, P < 0.01) and sPLM (control: 185 ± 171, l-NMMA: 62 ± 31 mL, P = 0.03). The combined inhibition of NOS, COX, and CYP450 (i.e., l-NMMA+KET+FLUC) did not further attenuate the hyperemic responses to PLM (LBFAUC: 271 ± 97 mL, P > 0.05) or sPLM (LBFAUC: 72 ± 45 mL, P > 0.05). Therefore, PG and EDHF do not collectively contribute to the non-NOS-derived NO-mediated, endothelium-dependent hyperemic response to either PLM or sPLM in healthy young men. These findings add to the mounting evidence and understanding of the vasodilatory pathways assessed by the PLM and sPLM vascular function tests.NEW & NOTEWORTHY Passive leg movement (PLM) evokes a highly nitric oxide (NO)-mediated hyperemic response and may provide a novel evaluation of vascular function. The contributions of endothelium-dependent vasodilatory pathways, beyond NO and including prostaglandins and endothelium-derived hyperpolarizing factor, to the PLM-induced hyperemic response to PLM have not been evaluated. With intra-arterial drug infusion, the combined inhibition of nitric oxide synthase (NOS), cyclooxygenase, and cytochrome P-450 (CYP450) pathways did not further diminish the hyperemic response to PLM compared with NOS inhibition alone.
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Affiliation(s)
- Joel D Trinity
- Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Oh Sung Kwon
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Ryan M Broxterman
- Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Jayson R Gifford
- Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise Science, Brigham Young University, Provo, Utah
| | - Andrew C Kithas
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Jay R Hydren
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Catherine L Jarrett
- Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Katherine L Shields
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Angela V Bisconti
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Soung Hun Park
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - David E Morgan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
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3
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Kithas AC, Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Hydren JR, Nelson AD, Jessop JE, Bledsoe AD, Morgan DE, Richardson RS. Nitric oxide synthase inhibition with N(G)-monomethyl-l-arginine: Determining the window of effect in the human vasculature. Nitric Oxide 2020; 104-105:51-60. [PMID: 32979497 DOI: 10.1016/j.niox.2020.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 07/20/2020] [Revised: 09/07/2020] [Accepted: 09/21/2020] [Indexed: 11/17/2022]
Abstract
Nitric oxide synthase (NOS) inhibition with N(G)-monomethyl-l-arginine (L-NMMA) is often used to assess the role of NO in human cardiovascular function. However, the window of effect for L-NMMA on human vascular function is unknown, which is critical for designing and interpreting human-based studies. This study utilized the passive leg movement (PLM) assessment of vascular function, which is predominantly NO-mediated, in 7 young male subjects under control conditions, immediately following intra-arterial L-NMMA infusion (0.24 mg⋅dl-1⋅min-1), and at 45-60 and 90-105 min post L-NMMA infusion. The leg blood flow (LBF) and leg vascular conductance (LVC) responses to PLM, measured with Doppler ultrasound and expressed as the change from baseline to peak (ΔLBFpeak and ΔLVCpeak) and area under the curve (LBFAUC and LVCACU), were assessed. PLM-induced robust control ΔLBFpeak (1135 ± 324 ml⋅min-1) and ΔLVCpeak (10.7 ± 3.6 ml⋅min-1⋅mmHg-1) responses that were significantly attenuated (704 ± 196 ml⋅min-1 and 6.7 ± 2 ml⋅min-1⋅mmHg-1) immediately following L-NMMA infusion. Likewise, control condition PLM ΔLBFAUC (455 ± 202 ml) and ΔLVCAUC (4.0 ± 1.4 ml⋅mmHg-1) were significantly attenuated (141 ± 130 ml and 1.3 ± 1.2 ml⋅mmHg-1) immediately following L-NMMA infusion. However, by 45-60 min post L-NMMA infusion all PLM variables were not significantly different from control, and this was still the case at 90-105 min post L-NMMA infusion. These findings reveal that the potent reduction in NO bioavailability afforded by NOS inhibition with L-NMMA has a window of effect of less than 45-60 min in the human vasculature. These data are particularly important for the commonly employed approach of pharmacologically inhibiting NOS with L-NMMA in the human vasculature.
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Affiliation(s)
- Andrew C Kithas
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Ryan M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA
| | - Joel D Trinity
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA
| | - Jayson R Gifford
- Department of Exercise Sciences, Brigham Young University, Provo, UT, USA
| | - Oh Sung Kwon
- Department of Kinesiology, University of Connecticut, Storrs, CT, USA
| | - Jay R Hydren
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - David E Morgan
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA.
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4
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Craig JC, Broxterman RM, La Salle DT, Cerbie J, Ratchford SM, Gifford JR, Bunsawat K, Nelson AD, Bledsoe AD, Morgan DE, Wray DW, Richardson RS, Trinity JD. The role of endothelin A receptors in peripheral vascular control at rest and during exercise in patients with hypertension. J Physiol 2019; 598:71-84. [PMID: 31705661 DOI: 10.1113/jp279077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [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: 10/02/2019] [Accepted: 11/01/2019] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Exercise in patients with hypertension can be accompanied by an abnormal cardiovascular response that includes attenuated blood flow and an augmented pressor response. Endothelin-1, a very potent vasoconstrictor, is a key modulator of blood flow and pressure during in health and has been implicated as a potential cause of the dysfunction in hypertension. We assessed the role of endothelin-1, acting through endothelin A (ETA ) receptors, in modulating the central and peripheral cardiovascular responses to exercise in patients with hypertension via local antagonism of these receptors during exercise. ETA receptor antagonism markedly increased leg blood flow, vascular conductance, oxygen delivery, and oxygen consumption during exercise; interestingly, these changes occurred in the presence of reduced leg perfusion pressure, indicating that these augmentations were driven by changes in vascular resistance. These data indicate that ETA receptor antagonism could be a viable therapeutic approach to improve blood flow during exercise in hypertension. ABSTRACT Patients with hypertension can exhibit impaired muscle blood flow and exaggerated increases in blood pressure during exercise. While endothelin (ET)-1 plays a role in regulating blood flow and pressure during exercise in health, little is known about the role of ET-1 in the cardiovascular response to exercise in hypertension. Therefore, eight volunteers diagnosed with hypertension were studied during exercise with either saline or BQ-123 (ETA receptor antagonist) infusion following a 2-week withdrawal of anti-hypertensive medications. The common femoral artery and vein were catheterized for drug infusion, blood collection and blood pressure measurements, and leg blood flow was measured by Doppler ultrasound. Patients exercised at both absolute (0, 5, 10, 15 W) and relative (40, 60, 80% peak power) intensities. BQ-123 increased blood flow at rest (79 ± 87 ml/min; P = 0.03) and augmented the exercise-induced hyperaemia at most intensities (80% saline: Δ3818±1222 vs. BQ-123: Δ4812±1469 ml/min; P = 0.001). BQ-123 reduced leg MAP at rest (-8 ± 4 mmHg; P < 0.001) and lower intensities (0-10 W; P < 0.05). Systemic diastolic blood pressure was reduced (0 W, 40%; P < 0.05), but systemic MAP was defended by an increased cardiac output. The exercise pressor response (ΔMAP) did not differ between conditions (80% saline: 25 ± 10, BQ-123: 30 ± 7 mmHg; P = 0.17). Thus, ET-1, acting through the ETA receptors, contributes to the control of blood pressure at rest and lower intensity exercise in these patients. Furthermore, the finding that ET-1 constrains the blood flow response to exercise suggests that ETA receptor antagonism could be a therapeutic approach to improve blood flow during exercise in hypertension.
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Affiliation(s)
- Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Ryan M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah, USA
| | - D Taylor La Salle
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
| | - James Cerbie
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
| | - Stephen M Ratchford
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah, USA
| | - Jayson R Gifford
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah, USA
| | - Kanokwan Bunsawat
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Ashley D Nelson
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, USA
| | - David E Morgan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, USA
| | - D Walter Wray
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
| | - Joel D Trinity
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
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5
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Broxterman RM, Nelson AD, Lawrenson L, Poole JG, Hoff J, Wagner PD, Richardson RS. Determinants of Peak Oxygen Uptake in Patients with Chronic Obstructive Pulmonary Disease: Looking Beyond the Lungs. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.696.9] [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: 11/11/2022]
Affiliation(s)
- Ryan M Broxterman
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical Center (GRECC)Salt Lake City VAMCSalt Lake CityUT
| | | | | | | | - Jan Hoff
- Circulation and Medical ImagingNorwegian University of Science and TechnologyTrondheimNorway
| | | | - Russell S Richardson
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical Center (GRECC)Salt Lake City VAMCSalt Lake CityUT
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6
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Craig JC, Broxterman RM, La Salle DT, Cerbie J, Ratchford SM, Gifford JR, Bunsawat K, Nelson AD, Bledsoe AD, Morgan DE, Wray DW, Richardson RS, Trinity JD. The Role of Endothelin‐1 in Exercising Blood Flow and Blood Pressure Regulation in Patients with Hypertension. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.696.11] [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: 11/11/2022]
Affiliation(s)
| | - Ryan M Broxterman
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
| | - D Taylor La Salle
- Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - James Cerbie
- Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Stephen M Ratchford
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
| | - Jayson R Gifford
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
| | | | | | | | | | - D Walter Wray
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
| | - Russell S Richardson
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
| | - Joel D Trinity
- Internal MedicineUniversity of UtahSalt Lake CityUT
- Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- Geriatric Research, Education, and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
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7
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Barrett-O'Keefe Z, Lee JF, Ives SJ, Trinity JD, Witman MAH, Rossman MJ, Groot HJ, Sorensen JR, Morgan DE, Nelson AD, Stehlik J, Richardson RS, Wray DW. α-Adrenergic receptor regulation of skeletal muscle blood flow during exercise in heart failure patients with reduced ejection fraction. Am J Physiol Regul Integr Comp Physiol 2019; 316:R512-R524. [PMID: 30789790 DOI: 10.1152/ajpregu.00345.2018] [Citation(s) in RCA: 14] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Patients suffering from heart failure with reduced ejection fraction (HFrEF) experience impaired limb blood flow during exercise, which may be due to a disease-related increase in α-adrenergic receptor vasoconstriction. Thus, in eight patients with HFrEF (63 ± 4 yr) and eight well-matched controls (63 ± 2 yr), we examined changes in leg blood flow (Doppler ultrasound) during intra-arterial infusion of phenylephrine (PE; an α1-adrenergic receptor agonist) and phentolamine (Phen; a nonspecific α-adrenergic receptor antagonist) at rest and during dynamic single-leg knee-extensor exercise (0, 5, and 10 W). At rest, the PE-induced reduction in blood flow was significantly attenuated in patients with HFrEF (-15 ± 7%) compared with controls (-36 ± 5%). During exercise, the controls exhibited a blunted reduction in blood flow induced by PE (-12 ± 4, -10 ± 4, and -9 ± 2% at 0, 5, and 10 W, respectively) compared with rest, while the PE-induced change in blood flow was unchanged compared with rest in the HFrEF group (-8 ± 5, -10 ± 3, and -14 ± 3%, respectively). Phen administration increased leg blood flow to a greater extent in the HFrEF group at rest (+178 ± 34% vs. +114 ± 28%, HFrEF vs. control) and during exercise (36 ± 6, 37 ± 7, and 39 ± 6% vs. 13 ± 3, 14 ± 1, and 8 ± 3% at 0, 5, and 10 W, respectively, in HFrEF vs. control). Together, these findings imply that a HFrEF-related increase in α-adrenergic vasoconstriction restrains exercising skeletal muscle blood flow, potentially contributing to diminished exercise capacity in this population.
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Affiliation(s)
| | - Joshua F Lee
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah
| | - Stephen J Ives
- Department of Exercise and Sport Science, University of Utah , Salt Lake City, Utah
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - Melissa A H Witman
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Kinesiology and Applied Physiology, University of Delaware , Newark, Delaware
| | - Matthew J Rossman
- Department of Exercise and Sport Science, University of Utah , Salt Lake City, Utah
| | - H Jon Groot
- Department of Exercise and Sport Science, University of Utah , Salt Lake City, Utah
| | - Jacob R Sorensen
- Department of Exercise and Sport Science, University of Utah , Salt Lake City, Utah
| | - David E Morgan
- Department of Anesthesiology, University of Utah , Salt Lake City, Utah
| | - Ashley D Nelson
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Josef Stehlik
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - D Walter Wray
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
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8
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Weavil JC, Hureau TJ, Thurston TS, Sidhu SK, Garten RS, Nelson AD, McNeil CJ, Richardson RS, Amann M. Impact of age on the development of fatigue during large and small muscle mass exercise. Am J Physiol Regul Integr Comp Physiol 2018; 315:R741-R750. [PMID: 29995457 DOI: 10.1152/ajpregu.00156.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To examine the impact of aging on neuromuscular fatigue following cycling (CYC; large active muscle mass) and single-leg knee-extension (KE; small active muscle mass) exercise, 8 young (25 ± 4 years) and older (72 ± 6 years) participants performed CYC and KE to task failure at a given relative intensity (80% of peak power output). The young also matched CYC and KE workload and duration of the old (iso-work comparison). Peripheral and central fatigue were quantified via pre-/postexercise decreases in quadriceps twitch torque (∆Qtw, electrical femoral nerve stimulation) and voluntary activation (∆VA). Although young performed 77% and 33% more work during CYC and KE, respectively, time to task failure in both modalities was similar to the old (~9.5 min; P > 0.2). The resulting ΔQtw was also similar between groups (CYC ~40%, KE ~55%; P > 0.3); however, ∆VA was, in both modalities, approximately double in the young (CYC ~6%, KE ~9%; P < 0.05). While causing substantial peripheral and central fatigue in both exercise modalities in the old, ∆Qtw in the iso-work comparison was not significant (CYC; P = 0.2), or ~50% lower (KE; P < 0.05) in the young, with no central fatigue in either modality ( P > 0.4). Based on iso-work comparisons, healthy aging impairs fatigue resistance during aerobic exercise. Furthermore, comparisons of fatigue following exercise at a given relative intensity mask the age-related difference observed following exercise performed at the same workload. Finally, although active muscle mass has little influence on the age-related difference in the rate of fatigue at a given relative intensity, it substantially impacts the comparison during exercise at a given absolute intensity.
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Affiliation(s)
- Joshua C Weavil
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center , Salt Lake City, Utah
| | - Thomas J Hureau
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Taylor S Thurston
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Simranjit K Sidhu
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Ryan S Garten
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center , Salt Lake City, Utah
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Chris J McNeil
- School of Health and Exercise Sciences, University of British Columbia , Kelowna , Canada
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center , Salt Lake City, Utah
| | - Markus Amann
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Anesthesiology, University of Utah , Salt Lake City, Utah
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9
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Trinity JD, Broxterman RM, Gifford JR, Kwon OS, Hydren JR, Kithas AC, Nelson AD, Morgan DE, Jessop JE, Bledsoe A, Richardson RS. Mechanisms of Age‐related Compensatory Vasodilation: Insight from Passive Leg Movement. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.726.7] [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: 11/11/2022]
Affiliation(s)
- Joel D. Trinity
- Geriatric ResearchEducation and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
- Nutrition and Integrative PhysiologyUniversity of UtahSaltUT
- Internal MedicinceUniversity of UtahSaltUT
| | - Ryan M. Broxterman
- Geriatric ResearchEducation and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
| | - Jayson R. Gifford
- Geriatric ResearchEducation and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
| | | | - Jay R. Hydren
- Nutrition and Integrative PhysiologyUniversity of UtahSaltUT
| | | | | | | | | | | | - Russell S. Richardson
- Geriatric ResearchEducation and Clinical CenterSalt Lake City VAMCSalt Lake CityUT
- Nutrition and Integrative PhysiologyUniversity of UtahSaltUT
- Internal MedicinceUniversity of UtahSaltUT
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10
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Bunsawat K, Ratchford SM, Clifton HL, Theisen JK, Barrett‐O'Keefe Z, Broxterman RM, Gifford JR, Hydren J, Rossman MJ, Ives SJ, Trinity JD, Witman MA, Garten RS, Morgan DE, Nelson AD, Richardson RS, Wray DW. Sex Differences in the Sympathetic Restraint of Skeletal Muscle Blood Flow in the Human Leg Vasculature. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.594.4] [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: 11/11/2022]
Affiliation(s)
- Kanokwan Bunsawat
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Stephen M. Ratchford
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Heather L. Clifton
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Jeremy K. Theisen
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | | | - Ryan M. Broxterman
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Jayson R. Gifford
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Exercise SciencesBrigham Young UniversityProvoUT
| | - Jay Hydren
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Matthew J. Rossman
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Stephen J. Ives
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
| | - Joel D. Trinity
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
| | - Melissa A.H. Witman
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Kinesiology and Applied PhysiologyUniversity of DelawareNewarkDE
| | - Ryan S. Garten
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - David E. Morgan
- Department of AnesthesiologyUniversity of UtahSalt Lake CityUT
| | - Ashley D. Nelson
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
| | - Russell S. Richardson
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
| | - D. Walter Wray
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineDivision of GeriatricsUniversity of UtahSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
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11
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Gifford JR, Trinity JD, Kwon OS, Layec G, Garten RS, Park SY, Nelson AD, Richardson RS. Altered skeletal muscle mitochondrial phenotype in COPD: disease vs. disuse. J Appl Physiol (1985) 2018; 124:1045-1053. [PMID: 29357496 PMCID: PMC5972462 DOI: 10.1152/japplphysiol.00788.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [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: 09/01/2017] [Revised: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 11/22/2022] Open
Abstract
Patients with chronic obstructive pulmonary disease (COPD) exhibit an altered skeletal muscle mitochondrial phenotype, which often includes reduced mitochondrial density, altered respiratory function, and elevated oxidative stress. As this phenotype may be explained by the sedentary lifestyle that commonly accompanies this disease, the aim of this study was to determine whether such alterations are still evident when patients with COPD are compared to control subjects matched for objectively measured physical activity (PA; accelerometry). Indexes of mitochondrial density [citrate synthase (CS) activity], respiratory function (respirometry in permeabilized fibers), and muscle oxidative stress [4-hydroxynonenal (4-HNE) content] were assessed in muscle fibers biopsied from the vastus lateralis of nine patients with COPD and nine PA-matched control subjects (CON). Despite performing similar levels of PA (CON: 18 ± 3, COPD: 20 ± 7 daily minutes moderate-to-vigorous PA; CON: 4,596 ± 683, COPD: 4,219 ± 763 steps per day, P > 0.70), patients with COPD still exhibited several alterations in their mitochondrial phenotype, including attenuated skeletal muscle mitochondrial density (CS activity; CON 70.6 ± 3.8, COPD 52.7 ± 6.5 U/mg, P < 0.05), altered mitochondrial respiration [e.g., ratio of complex I-driven state 3 to complex II-driven state 3 (CI/CII); CON: 1.20 ± 0.11, COPD: 0.90 ± 0.05, P < 0.05), and oxidative stress (4-HNE; CON: 1.35 ± 0.19, COPD: 2.26 ± 0.25 relative to β-actin, P < 0.05). Furthermore, CS activity ( r = 0.55), CI/CII ( r = 0.60), and 4-HNE ( r = 0.49) were all correlated with pulmonary function, assessed as forced expiratory volume in 1 s ( P < 0.05), but not PA ( P > 0.05). In conclusion, the altered mitochondrial phenotype in COPD is present even in the absence of differing levels of PA and appears to be related to the disease itself. NEW & NOTEWORTHY Chronic obstructive pulmonary disease (COPD) is associated with debilitating alterations in the function of skeletal muscle mitochondria. By comparing the mitochondrial phenotype of patients with COPD to that of healthy control subjects who perform the same amount of physical activity each day, this study provides evidence that many aspects of the dysfunctional mitochondrial phenotype observed in COPD are not merely due to reduced physical activity but are likely related to the disease itself.
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Affiliation(s)
- Jayson R Gifford
- Department of Exercise Sciences, Brigham Young University , Provo, Utah
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Medical Center , Salt Lake City, Utah
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Medical Center , Salt Lake City, Utah
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Oh-Sung Kwon
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Medical Center , Salt Lake City, Utah
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Gwenael Layec
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Medical Center , Salt Lake City, Utah
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Ryan S Garten
- Department of Exercise Science, Health, and Movement Science, Virginia Commonwealth University , Richmond, Virginia
| | - Song-Young Park
- School of Health and Kinesiology, University of Nebraska , Omaha, Nebraska
| | - Ashley D Nelson
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Medical Center , Salt Lake City, Utah
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Salt Lake City Department of Veterans Medical Center , Salt Lake City, Utah
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
- Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
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12
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Theisen JL, Ratchford SM, Clifton HL, Bunsawat K, Barret‐O'keefe Z, Broxterman RM, Gifford JR, Hydren J, Rossman MJ, Ives SJ, Witman MA, Trinity JD, Garten RJ, Morgan DE, Nelson AD, Richardson RS, Wray DW. Role of Alpha‐1 Adrenergic Vasoconstriction in Regulating Skeletal Muscle Blood Flow during Single Leg Knee Extension Exercise with Advancing Age. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.594.5] [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: 11/11/2022]
Affiliation(s)
- Jeremy L. Theisen
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Stephen M. Ratchford
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
| | | | - Kanokwan Bunsawat
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
| | | | - Ryan M. Broxterman
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
| | - Jayson R. Gifford
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
- Department of Exercise SciencesBrigham Young UniversityProvoUT
| | - Jay Hydren
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Matthew J. Rossman
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - Steve J. Ives
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
| | - Melissa A.H. Witman
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
- Department of Applied KinesiologyUniversity of DelawareNewarkDE
| | - Joel D. Trinity
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
| | - Ryan J. Garten
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
| | - David E. Morgan
- Department of AnesthesiologyUniversity of UtahSalt Lake CityUT
| | - Ashley D. Nelson
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
| | - Russel S. Richardson
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
| | - D Walter Wray
- Geriatric Research, Educationand Clinical CenterVAMCSalt Lake CityUT
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUT
- Department of Internal MedicineUniversity of UtahSalt Lake CityUT
- University of Utah Center on AgingSalt Lake CityUT
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13
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Hureau TJ, Weavil JC, Thurston TS, Broxterman RM, Nelson AD, Bledsoe AD, Jessop JE, Richardson RS, Wray DW, Amann M. Identifying the role of group III/IV muscle afferents in the carotid baroreflex control of mean arterial pressure and heart rate during exercise. J Physiol 2018; 596:1373-1384. [PMID: 29388218 DOI: 10.1113/jp275465] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [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: 10/23/2017] [Accepted: 01/29/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS We investigated the contribution of group III/IV muscle afferents to carotid baroreflex resetting during electrically evoked (no central command) and voluntary (requiring central command) isometric knee extension exercise. Lumbar intrathecal fentanyl was used to attenuate the central projection of μ-opioid receptor-sensitive group III/IV leg muscle afferent feedback. Spontaneous carotid baroreflex control was assessed by loading and unloading the carotid baroreceptors with a variable pressure neck chamber. Group III/IV muscle afferents did not influence spontaneous carotid baroreflex responsiveness at rest or during exercise. Afferent feedback accounted for at least 50% of the exercise-induced increase in the carotid baroreflex blood pressure and heart rate operating points, adjustments that are critical for an appropriate cardiovascular response to exercise. These findings suggest that group III/IV muscle afferent feedback is, independent of central command, critical for the resetting of the carotid baroreflex blood pressure and heart rate operating points, but not for spontaneous baroreflex responsiveness. ABSTRACT This study sought to comprehensively investigate the role of metabolically and mechanically sensitive group III/IV muscle afferents in carotid baroreflex responsiveness and resetting during both electrically evoked (EVO, no central command) and voluntary (VOL, requiring central command) isometric single-leg knee-extension (15% of maximal voluntary contraction; MVC) exercise. Participants (n = 8) were studied under control conditions (CTRL) and following lumbar intrathecal fentanyl injection (FENT) to inhibit μ-opioid receptor-sensitive lower limb muscle afferents. Spontaneous carotid baroreflex control of mean arterial pressure (MAP) and heart rate (HR) were assessed following rapid 5 s pulses of neck pressure (NP, +40 mmHg) or suction (NS, -60 mmHg). Resting MAP (87 ± 10 mmHg) and HR (70 ± 8 bpm) were similar between CTRL and FENT conditions (P > 0.4). In terms of spontaneous carotid baroreflex responsiveness, FENT did not alter the change in MAP or HR responses to NP (+13 ± 5 mmHg, P = 0.85; +9 ± 3 bpm; P = 0.99) or NS (-13 ± 5 mmHg, P = 0.99; -24 ± 11 bpm; P = 0.49) at rest or during either exercise protocol, which were of a remarkably similar magnitude to rest. In contrast, FENT administration reduced the exercise-induced resetting of the operating point for MAP and HR during both EVO (116 ± 10 mmHg to 100 ± 15 mmHg and 93 ± 14 bpm to 82 ± 10 bpm) and VOL (107 ± 13 mmHg to 100 ± 17 mmHg and 89 ± 10 bpm to 72 ± 10 bpm) exercise bouts. Together, these findings document that group III/IV muscle afferent feedback is critical for the resetting of the carotid baroreflex MAP and HR operating points, independent of exercise-induced changes in central command, but not for spontaneous carotid baroreflex responsiveness.
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Affiliation(s)
- Thomas J Hureau
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Joshua C Weavil
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Ryan M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - D Walter Wray
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
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14
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Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Kithas AC, Hydren JR, Nelson AD, Morgan DE, Jessop JE, Bledsoe AD, Richardson RS. Single passive leg movement assessment of vascular function: contribution of nitric oxide. J Appl Physiol (1985) 2017; 123:1468-1476. [PMID: 28860173 DOI: 10.1152/japplphysiol.00533.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [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: 11/22/2022] Open
Abstract
Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Kithas AC, Hydren JR, Nelson AD, Morgan DE, Jessop JE, Bledsoe AD, Richardson RS. Single passive leg movement assessment of vascular function: contribution of nitric oxide. J Appl Physiol 123: 1468-1476, 2017. First published August 31, 2017; doi:10.1152/japplphysiol.00533.2017.-The assessment of passive leg movement (PLM)-induced leg blood flow (LBF) and vascular conductance (LVC) is a novel approach to assess vascular function that has recently been simplified to only a single PLM (sPLM), thereby increasing the clinical utility of this technique. As the physiological mechanisms mediating the robust increase in LBF and LVC with sPLM are unknown, we tested the hypothesis that nitric oxide (NO) is a major contributor to the sPLM-induced LBF and LVC response. In nine healthy men, sPLM was performed with and without NO synthase inhibition by intra-arterial infusion of NG-monomethyl-l-arginine (l-NMMA). Doppler ultrasound and femoral arterial pressure were used to determine LBF and LVC, which were characterized by the peak change (ΔLBFpeak and ΔLVCpeak) and area under the curve (LBFAUC and LVCAUC). l-NMMA significantly attenuated ΔLBFpeak [492 ± 153 (l-NMMA) vs. 719 ± 238 (control) ml/min], LBFAUC [57 ± 34 (l NMMA) vs. 147 ± 63 (control) ml], ΔLVCpeak [4.7 ± 1.1 (l-NMMA) vs. 8.0 ± 3.0 (control) ml·min-1·mmHg-1], and LVCAUC [0.5 ± 0.3 (l-NMMA) vs. 1.6 ± 0.9 (control) ml/mmHg]. The magnitude of the NO contribution to LBF and LVC was significantly correlated with the magnitude of the control responses ( r = 0.94 for ΔLBFpeak, r = 0.85 for LBFAUC, r = 0.94 for ΔLVCpeak, and r = 0.95 for LVCAUC). These data establish that the sPLM-induced hyperemic and vasodilatory response is predominantly (~65%) NO-mediated. As such, sPLM appears to be a promising, simple, in vivo assessment of NO-mediated vascular function and NO bioavailability. NEW & NOTEWORTHY Passive leg movement (PLM), a novel assessment of vascular function, has been simplified to a single PLM (sPLM), thereby increasing the clinical utility of this technique. However, the role of nitric oxide (NO) in mediating the robust sPLM hemodynamic responses is unknown. This study revealed that sPLM induces a hyperemic and vasodilatory response that is predominantly NO-mediated and, as such, appears to be a promising simple, in vivo, clinical assessment of NO-mediated vascular function and, therefore, NO bioavailability.
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Affiliation(s)
- Ryan M Broxterman
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - Jayson R Gifford
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Oh Sung Kwon
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Andrew C Kithas
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - Jay R Hydren
- Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah , Salt Lake City, Utah
| | - David E Morgan
- Department of Anesthesiology, University of Utah , Salt Lake City, Utah
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah , Salt Lake City, Utah
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah , Salt Lake City, Utah
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center , Salt Lake City, Utah.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah , Salt Lake City, Utah
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15
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Nelson AD, Camilleri M, Acosta A, Boldingh A, Busciglio I, Burton D, Ryks M, Zinsmeister AR. A single-center, prospective, double-blind, sham-controlled, randomized study of the effect of a vibrating capsule on colonic transit in patients with chronic constipation. Neurogastroenterol Motil 2017; 29. [PMID: 28177172 DOI: 10.1111/nmo.13034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 12/23/2016] [Indexed: 01/12/2023]
Abstract
BACKGROUND In an open-label study of 26 patients with IBS-C and chronic constipation, treatment with a vibrating (VIBRANT) capsule twice a week for 7.5 weeks resulted in 88.5% responders. Effects on colonic transit are unclear. We aimed to compare effects of VIBRANT and sham capsule treatment on colonic transit in patients with functional constipation. METHODS Patients with functional constipation (Rome III criteria) were randomized to VIBRANT or sham capsule treatment for 8 weeks and underwent scintigraphic colonic transit measurements during week 8. We estimated the overall rate of colonic transit from the slope of progression of colonic geometric center over 48 hours. The capsule was activated 8 hours after ingestion, and the vibration sequence included 240 cycles. KEY RESULTS There were no significant group differences in overall colonic transit [GC48, 2.76 (IQR 2.42-4.03) for sham group and 3.46 (2.55-4.61) for active treatment group (P=.13)]. Additionally, the progression of the isotope through the colon was numerically faster, though not significantly different (slope, P=.14) in the VIBRANT capsule group compared to the sham group. Three participants in the VIBRANT capsule group had accelerated colonic transit at 32 hours and faster colonic transit slope compared to the 95th percentile of the sham group. CONCLUSIONS AND INFERENCES Although there were no group differences between VIBRANT and sham capsule treatment on colonic transit, at least one (and possibly three) of 12 patients receiving the VIBRANT capsule had faster colonic transit. The vibration parameters to accelerate colonic transit in patients with functional constipation require further optimization.
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Affiliation(s)
- A D Nelson
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - M Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - A Acosta
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - A Boldingh
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - I Busciglio
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - D Burton
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - M Ryks
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - A R Zinsmeister
- Division of Biomedical Statistics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
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16
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Gifford JR, Nelson AD, Trinity JD, Broxterman RM, Layec G, Weavil JC, Richardson RS. The Age-related Decline In Vo2max. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000519459.45983.f6] [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: 11/21/2022]
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17
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Kithas AC, Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Hydren JR, Nelson AD, Jessop JE, Bledsoe AD, Morgan DE, Richardson RS. Determining The Window Of Effect In The Human Vasculature For The Nitric Oxide Synthase Inhibitor N(G)-monomethyl-L-arginine (L-NMMA). Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000519224.07620.d2] [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: 11/21/2022]
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18
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Khemani D, Camilleri M, Roldan A, Nelson AD, Park SY, Acosta A, Zinsmeister AR. Opioid analgesic use among patients presenting with acute abdominal pain and factors associated with surgical diagnoses. Neurogastroenterol Motil 2017; 29:10.1111/nmo.13000. [PMID: 28019066 PMCID: PMC5393942 DOI: 10.1111/nmo.13000] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 10/26/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND The prevalence of chronic opioid use among non-cancer patients presenting with acute abdominal pain (AAP) is unknown. The aim was to characterize opioid use, constipation, diagnoses, and risk factors for surgical diagnoses among non-cancer patients presenting with AAP to an emergency department (ED). METHODS We performed a retrospective, observational cohort study of all (n=16,121) adult patients (88% from MN, IA and WI) presenting during 2014 with AAP. We used electronic medical records, and focused on 2352 adults with AAP who underwent abdominal CT scan within 24 hours of presentation. We determined odds ratios of association with constipation and features predicting conditions that may require surgery (surgical diagnosis). KEY RESULTS There were 2352 eligible patients; 18.8% were opioid users. Constipation was more frequent in opioid (35.1%) compared to non-opioid users [OR 2.88 (95% CI 2.28, 3.62)]. Prevalence of surgical diagnosis in the opioid and non-opioid users was 35.3% and 41.7% respectively (P=.019). By univariate analysis, age and neutrophil count independently predicted increased risk, and chronic opioid use decreased risk of surgical diagnosis. Internal validation of logistic models using a randomly selected validation subset (25% of entire cohort, 587/2352) showed receiver operating characteristic (ROC) curves for the validation and full cohorts were similar. CONCLUSIONS AND INFERENCES Approximately 19% of adults presenting with AAP were opioid users; constipation is almost three times as likely in opioid users compared to non-opioid users presenting with AAP. Factors significantly associated with altered risk of surgical diagnoses were age, opioid use, and neutrophil count.
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Affiliation(s)
- D Khemani
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - M Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - A Roldan
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - A D Nelson
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - S-Y Park
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - A Acosta
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
| | - A R Zinsmeister
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
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19
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Affiliation(s)
- Jayson R. Gifford
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC Salt Lake City, Utah
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah; and
| | - Joshua C. Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC Salt Lake City, Utah
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Ashley D. Nelson
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC Salt Lake City, Utah
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah; and
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Mangum TS, Hureau TJ, Weavil JC, Sidhu SK, Thurston TS, Nelson AD, Richardson RS, Amann M. Ascorbate Attenuates the Development of Fatigue During Exercise in Patients with Chronic Obstructive Pulmonary Disease. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000485853.57265.c4] [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: 11/21/2022]
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21
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Lee JF, Barrett-O'Keefe Z, Nelson AD, Garten RS, Ryan JJ, Nativi-Nicolau JN, Richardson RS, Wray DW. Impaired skeletal muscle vasodilation during exercise in heart failure with preserved ejection fraction. Int J Cardiol 2016; 211:14-21. [PMID: 26970959 DOI: 10.1016/j.ijcard.2016.02.139] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 02/28/2016] [Indexed: 01/25/2023]
Abstract
BACKGROUND Exercise intolerance is a hallmark symptom of heart failure patients with preserved ejection fraction (HFpEF), which may be related to an impaired ability to appropriately increase blood flow to the exercising muscle. METHODS We evaluated leg blood flow (LBF, ultrasound Doppler), heart rate (HR), stroke volume (SV), cardiac output (CO), and mean arterial blood pressure (MAP, photoplethysmography) during dynamic, single leg knee-extensor (KE) exercise in HFpEF patients (n=21; 68 ± 2 yrs) and healthy controls (n=20; 71 ± 2 yrs). RESULTS HFpEF patients exhibited a marked attrition during KE exercise, with only 60% able to complete the exercise protocol. In participants who completed all exercise intensities (0-5-10-15 W; HFpEF, n=13; Controls, n=16), LBF was not different at 0 W and 5 W, but was 15-25% lower in HFpEF compared to controls at 10 W and 15 W (P<0.001). Likewise, leg vascular conductance (LVC), an index of vasodilation, was not different at 0 W and 5 W, but was 15-20% lower in HFpEF compared to controls at 10 W and 15 W (P<0.05). In contrast to these peripheral deficits, exercise-induced changes in central variables (HR, SV, CO), as well as MAP, were similar between groups. CONCLUSIONS These data reveal a marked reduction in LBF and LVC in HFpEF patients during exercise that cannot be attributed to a disease-related alteration in central hemodynamics, suggesting that impaired vasodilation in the exercising skeletal muscle vasculature may play a key role in the exercise intolerance associated with this patient population.
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Affiliation(s)
- Joshua F Lee
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States
| | - Zachary Barrett-O'Keefe
- Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States; Department of Exercise & Sport Science, University of Utah, Salt Lake City, UT, United States
| | - Ashley D Nelson
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Ryan S Garten
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States
| | - John J Ryan
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Jose N Nativi-Nicolau
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Russell S Richardson
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States; Department of Exercise & Sport Science, University of Utah, Salt Lake City, UT, United States
| | - D Walter Wray
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, UT, United States; Department of Exercise & Sport Science, University of Utah, Salt Lake City, UT, United States.
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22
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Nelson AD, Rossman MJ, Witman MA, Barrett-O'Keefe Z, Groot HJ, Garten RS, Richardson RS. Nitric oxide-mediated vascular function in sepsis using passive leg movement as a novel assessment: a cross-sectional study. J Appl Physiol (1985) 2016; 120:991-9. [PMID: 26869709 DOI: 10.1152/japplphysiol.00961.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [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: 11/10/2015] [Accepted: 02/05/2016] [Indexed: 02/08/2023] Open
Abstract
Post-cuff occlusion flow-mediated dilation (FMD) is a proposed indicator of nitric oxide (NO) bioavailability and vascular function. FMD is reduced in patients with sepsis and may be a marker of end organ damage and mortality. However, FMD likely does not solely reflect NO-mediated vasodilation, is technically challenging, and often demonstrates poor reproducibility. In contrast, passive leg movement (PLM), a novel methodology to assess vascular function, yields a hyperemic response that is predominately NO-dependent, reproducible, and easily measured. This study evaluated PLM as an approach to assess NO-mediated vascular function in patients with sepsis. We hypothesized that PLM-induced hyperemia, quantified by the increase in leg blood flow (LBF), would be attenuated in sepsis. In a cross-sectional study, 17 subjects in severe sepsis or septic shock were compared with 16 matched healthy controls. Doppler ultrasound was used to assess brachial artery FMD and the hyperemic response to PLM in the femoral artery. FMD was attenuated in septic compared with control subjects (1.1 ± 1.7% vs. 6.8 ± 1.3%; values are means ± SD). In terms of PLM, baseline LBF (196 ± 33 ml/min vs. 328 ± 20 ml/min), peak change in LBF from baseline (133 ± 28 ml/min vs. 483 ± 86 ml/min), and the LBF area under the curve (16 ± 8.3 vs. 143 ± 33) were all significantly attenuated in septic subjects. Vascular function, as assessed by both FMD and PLM, is attenuated in septic subjects compared with controls. These data support the concept that NO bioavailability is attenuated in septic subjects, and PLM appears to be a novel and feasible approach to assess NO-mediated vascular function in sepsis.
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Affiliation(s)
- Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah;
| | - Matthew J Rossman
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah; Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah; and
| | - Melissa A Witman
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Zachary Barrett-O'Keefe
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah; Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah; and
| | - H Jonathan Groot
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah; Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah; and
| | - Ryan S Garten
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah; Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah; Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah; and
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23
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Gifford JR, Garten RS, Nelson AD, Trinity JD, Layec G, Witman MAH, Weavil JC, Mangum T, Hart C, Etheredge C, Jessop J, Bledsoe A, Morgan DE, Wray DW, Rossman MJ, Richardson RS. Symmorphosis and skeletal muscle V̇O2 max : in vivo and in vitro measures reveal differing constraints in the exercise-trained and untrained human. J Physiol 2016; 594:1741-51. [PMID: 26614395 DOI: 10.1113/jp271229] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 11/10/2015] [Indexed: 01/15/2023] Open
Abstract
The concept of symmorphosis postulates a matching of structural capacity to functional demand within a defined physiological system, regardless of endurance exercise training status. Whether this concept applies to oxygen (O2 ) supply and demand during maximal skeletal muscle O2 consumption (V̇O2 max ) in humans is unclear. Therefore, in vitro skeletal muscle mitochondrial V̇O2 max (Mito V̇O2 max , mitochondrial respiration of fibres biopsied from vastus lateralis) was compared with in vivo skeletal muscle V̇O2 max during single leg knee extensor exercise (KE V̇O2 max , direct Fick by femoral arterial and venous blood samples and Doppler ultrasound blood flow measurements) and whole-body V̇O2 max during cycling (Body V̇O2 max , indirect calorimetry) in 10 endurance exercise-trained and 10 untrained young males. In untrained subjects, during KE exercise, maximal O2 supply (KE Q̇O2max ) exceeded (462 ± 37 ml kg(-1) min(-1) , P < 0.05) and KE V̇O2 max matched (340 ± 22 ml kg(-1) min(-1) , P > 0.05) Mito V̇O2 max (364 ± 16 ml kg(-1) min(-1) ). Conversely, in trained subjects, both KE Q̇O2max (557 ± 35 ml kg(-1) min(-1) ) and KE V̇O2 max (458 ± 24 ml kg(-1) min(-1) ) fell far short of Mito V̇O2 max (743 ± 35 ml kg(-1) min(-1) , P < 0.05). Although Mito V̇O2 max was related to KE V̇O2 max (r = 0.69, P < 0.05) and Body V̇O2 max (r = 0.91, P < 0.05) in untrained subjects, these variables were entirely unrelated in trained subjects. Therefore, in untrained subjects, V̇O2 max is limited by mitochondrial O2 demand, with evidence of adequate O2 supply, whereas, in trained subjects, an exercise training-induced mitochondrial reserve results in skeletal muscle V̇O2 max being markedly limited by O2 supply. Taken together, these in vivo and in vitro measures reveal clearly differing limitations and excesses at V̇O2 max in untrained and trained humans and challenge the concept of symmorphosis as it applies to O2 supply and demand in humans.
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Affiliation(s)
- Jayson R Gifford
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA
| | - Ryan S Garten
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Ashley D Nelson
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Gwenael Layec
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Melissa A H Witman
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA
| | - Tyler Mangum
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA
| | - Corey Hart
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA
| | - Cory Etheredge
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA
| | - Jake Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Amber Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - David E Morgan
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - D Walter Wray
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Matthew J Rossman
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, UT, USA.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
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24
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Lee JF, Barrett-O'Keefe Z, Garten RS, Nelson AD, Ryan JJ, Nativi JN, Richardson RS, Wray DW. Evidence of microvascular dysfunction in heart failure with preserved ejection fraction. Heart 2015; 102:278-84. [PMID: 26567228 DOI: 10.1136/heartjnl-2015-308403] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 10/15/2015] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE While vascular dysfunction is well defined in patients with heart failure (HF) with reduced ejection fraction (HFrEF), disease-related alterations in the peripheral vasculature of patients with HF with preserved ejection fraction (HFpEF) are not well characterised. Thus, we sought to test the hypothesis that patients with HFpEF would demonstrate reduced vascular function, at the conduit artery and microvascular levels, compared with controls. METHODS We examined conduit artery function via brachial artery flow-mediated dilation (FMD) and microvascular function via reactive hyperaemia (RH) following 5 min of ischaemia in 24 patients with Class II-IV HFpEF and 24 healthy controls matched for age, sex and brachial artery diameter. RESULTS FMD was reduced in patients with HFpEF compared with controls (HFpEF: 3.1±0.7%; CONTROLS 5.1±0.5%, p=0.03). However, shear rate at time of peak brachial artery dilation was lower in patients with HFpEF compared with controls (HFpEF: 42 070±4018/s; CONTROLS 69 018±9509/s, p=0.01), and when brachial artery FMD was normalised for the shear stimulus, cumulative area-under-the-curve (AUC) at peak dilation, the between-group differences were eliminated (HFpEF: 0.11±0.03%/AUC; CONTROLS 0.09±0.01%/AUC, p=0.58). RH, assessed as AUC, was lower in patients with HFpEF (HFpEF: 454±35 mL; CONTROLS 660±63 mL, p<0.01). CONCLUSIONS Collectively, these data suggest that maladaptations at the microvascular level contribute to the pathophysiology of HFpEF, while conduit artery vascular function is not diminished beyond that which occurs with healthy aging.
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Affiliation(s)
- Joshua F Lee
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, Utah, USA
| | - Zachary Barrett-O'Keefe
- Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, Utah, USA Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah, USA
| | - Ryan S Garten
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, Utah, USA
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - John J Ryan
- Division of Cardiovascular Medicine, Department of Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Jose N Nativi
- Division of Cardiovascular Medicine, Department of Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, Utah, USA Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah, USA
| | - D Walter Wray
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA Geriatric Research, Education, and Clinical Center, VA Medical Center, Salt Lake City, Utah, USA Department of Exercise & Sport Science, University of Utah, Salt Lake City, Utah, USA
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25
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Nelson AD, Mouchli MA, Valentin N, Deyle D, Pichurin P, Acosta A, Camilleri M. Ehlers Danlos syndrome and gastrointestinal manifestations: a 20-year experience at Mayo Clinic. Neurogastroenterol Motil 2015; 27:1657-66. [PMID: 26376608 DOI: 10.1111/nmo.12665] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/01/2015] [Indexed: 02/06/2023]
Abstract
BACKGROUND Gastrointestinal (GI) manifestations are found in Ehlers Danlos syndrome (EDS) hypermobility subtype (HM). We aimed to assess associations between EDS HM and other EDS subtypes with GI manifestations. METHODS We reviewed medical records of EDS patients evaluated at Mayo Clinic's Medical Genetics Clinic 1994-2013. We extracted information regarding EDS subtypes, GI manifestations, and treatments. KEY RESULTS We identified 687 patients; 378 (56%) had associated GI manifestations (female 86.8%, diagnosis mean age 29.6 years). Of the patients identified, 58.9% (43/73) had EDS classic, 57.5% (271/471) EDS HM, 47.3% (27/57) EDS vascular subtypes. In addition, 86 patients had EDS that could not be classified in any of those three subtypes. Commonest GI symptoms were: abdominal pain (56.1%), nausea (42.3%), constipation (38.6%), heartburn (37.6%), and irritable bowel syndrome-like symptoms (27.5%). Many GI symptoms were commoner in EDS HM than the other subtypes together. Among 37.8% of the 378 patients who underwent esophagogastroduodenoscopy, the commonest abnormalities were gastritis, hiatal hernia and reflux esophagitis. Abnormal gastric emptying was observed in 22.3% (17/76): 11.8% delayed and 10.5% accelerated. Colonic transit was abnormal in 28.3% (13/46): 19.6% delayed and 8.7% accelerated. Rectal evacuation disorder was confirmed in 18/30 patients who underwent anorectal manometry. Angiography showed aneurysms in abdominal vessels in EDS vascular type. Proton pump inhibitors (38%) and drugs for constipation (23%) were the most commonly used medications. A minority underwent colectomy (2.9%) or small bowel surgery (4%). CONCLUSIONS & INFERENCES EDS HM and other subtypes should be considered in patients with chronic functional GI symptoms and abdominal vascular lesions.
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Affiliation(s)
- A D Nelson
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER) , Rochester, MN, USA
| | - M A Mouchli
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER) , Rochester, MN, USA
| | - N Valentin
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER) , Rochester, MN, USA
| | - D Deyle
- Division of Medical Genetics, Mayo Clinic, Rochester, MN, USA
| | - P Pichurin
- Division of Medical Genetics, Mayo Clinic, Rochester, MN, USA
| | - A Acosta
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER) , Rochester, MN, USA
| | - M Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER) , Rochester, MN, USA
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26
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Cannon JL, Mody PD, Blaine KM, Chen EJ, Nelson AD, Sayles LJ, Moore TV, Clay BS, Dulin NO, Shilling RA, Burkhardt JK, Sperling AI. CD43 interaction with ezrin-radixin-moesin (ERM) proteins regulates T-cell trafficking and CD43 phosphorylation. Mol Biol Cell 2011; 22:954-63. [PMID: 21289089 PMCID: PMC3069020 DOI: 10.1091/mbc.e10-07-0586] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [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] [Indexed: 01/19/2023] Open
Abstract
CD43 interaction with ERM proteins regulates CD43 phosphorylation and T-cell migration. CD43 phosphorylation can also drive CD43 localization in T-cells independently of ERM association. Cell polarization is a key feature of cell motility, driving cell migration to tissues. CD43 is an abundantly expressed molecule on the T-cell surface that shows distinct localization to the migrating T-cell uropod and the distal pole complex (DPC) opposite the immunological synapse via association with the ezrin-radixin-moesin (ERM) family of actin regulatory proteins. CD43 regulates multiple T-cell functions, including T-cell activation, proliferation, apoptosis, and migration. We recently demonstrated that CD43 regulates T-cell trafficking through a phosphorylation site at Ser-76 (S76) within its cytoplasmic tail. Using a phosphorylation-specific antibody, we now find that CD43 phosphorylation at S76 is enhanced by migration signals. We further show that CD43 phosphorylation and normal T-cell trafficking depend on CD43 association with ERM proteins. Interestingly, mutation of S76 to mimic phosphorylation enhances T-cell migration and CD43 movement to the DPC while blocking ERM association, showing that CD43 movement can occur in the absence of ERM binding. We also find that protein kinase Cθ can phosphorylate CD43. These results show that while CD43 binding to ERM proteins is crucial for S76 phosphorylation, CD43 movement and regulation of T-cell migration can occur through an ERM-independent, phosphorylation–dependent mechanism.
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Affiliation(s)
- J L Cannon
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
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Piper J, Shen G, Nelson AD, Nelson AS. SU-FF-I-92: Partial Volume Correction in PET Images: A Single Correction Method Applied for Multiple Source to Background Ratios. Med Phys 2009. [DOI: 10.1118/1.3181212] [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: 11/07/2022] Open
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Sodee DB, Faulhaber PF, Nelson AD, Bakale G. The Prognostic Significance of Indium-111–Capromab Penetide. J Clin Oncol 2004; 22:379-80; author reply 380-1. [PMID: 14722051 DOI: 10.1200/jco.2004.99.163] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Lee Z, Berridge MS, Nelson AD, Heald DL. The effect of scatter and attenuation on aerosol deposition as determined by gamma scintigraphy. J Aerosol Med 2002; 14:167-83. [PMID: 11681649 DOI: 10.1089/08942680152484108] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Gamma scintigraphy is often used to quantify deposition patterns from aerosol inhalers. The errors caused by scatter and tissue attenuation in planar Tc-99m gamma scintigraphy were investigated based on the data collected from four subjects in this study. Several error correction methods were tested. The results from two scatter correction methods, Jaszczak's method and factor analysis of dynamic sequences (FADS), were similar. Scatter accounted for 20% of raw data in the whole lung, 20% in the oropharynx, and 43% in the central airways and esophagus. Three attenuation correction methods were investigated and compared. These were: uniform attenuation correction (UAC), a known method used for inhalation drug imaging work; the broad-beam attenuation correction used for organ imaging in nuclear medicine; and a narrow-beam inhomogeneous tissue attenuation correction proposed in this study. The three methods differed significantly (p < 0.05), but all indicated that attenuation is a severe quantification problem. The narrow beam attenuation correction with scatter correction, showed that raw data underestimated tracer deposition by 44% in the lung, 137% in the oropharynx, and 153% in the trachea/esophageal region. To quantify aerosol lung deposition using planar scintigraphy even in relative terms, corrections are necessary. Much of the literature concerning quantified aerosol dose distributions measured by gamma scintigraphy needs to be interpreted carefully.
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Affiliation(s)
- Z Lee
- Nuclear Medicine, Radiology, University Hospitals of Cleveland, Ohio 44106, USA.
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30
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Muzic RF, Saidel GM, Zhu N, Nelson AD, Zheng L, Berridge MS. Iterative optimal design of PET experiments for estimating beta-adrenergic receptor concentration. Med Biol Eng Comput 2000; 38:593-602. [PMID: 11217875 DOI: 10.1007/bf02344863] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
To estimate in vivo myocardial beta-adrenergic receptor concentration with sufficient precision and to reduce the experimental complexities in positron emission tomography (PET), an iterative optimal design method is applied. An initial three-injection protocol, utilising [F-18]-labelled (R)- and (S)-fluorocarazolol and unlabelled (S)-fluorocarazolol, is optimised for ligand dosages and administration times to maximise the precision of all model parameters using the D-optimal criterion. Using this experimental protocol, PET data are collected in porcine studies, and model parameters are estimated. All model parameters are identified with satisfactory precision. The in vivo myocardial beta-receptor concentration is 7.5+/-0.6 pmol x ml(-1), which corresponds to the in vitro result of 10.1+/-1.3 pmol x ml(-1). With more accurate parameter values, a simplified two-injection protocol is optimally designed, utilising only radiolabelled and unlabelled (S)-fluorocarazolol, based on a new criterion to maximise the precision of the beta-receptor concentration. This revised optimum design predicts that the in vivo beta-receptor concentration can be estimated with good precision but reduced experiment complexity.
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Affiliation(s)
- R F Muzic
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
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Nelson AD, Elisens WJ. Polyploid evolution and biogeography in Chelone (Scrophulariaceae): morphological and isozyme evidence. Am J Bot 1999; 86:1487-1501. [PMID: 10523288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Chelone is a genus of perennial herbs comprising three diploid species (C. cuthbertii, C. glabra, and C. lyonii) and a fourth species (C. obliqua) that occurs as tetraploid and hexaploid races. To assess patterns of isozyme and morphological variation, and to test hypotheses of hybridization and allopolyploidy, we analyzed variation among 16 isozyme loci from 61 populations and 16 morphological characters from 33 populations representing all taxa and ploidy levels. Based on morphological analyses using clustering (unweighted pair group method using an arithmetic average) and ordination (principal components analysis and canonical variance analysis) methods, we recognize three diploid species without infraspecific taxa. Polyploids in the C. obliqua complex were most similar morphologically to diploid populations of C. glabra and C. lyonii. Patterns of isozyme variation among polyploids, which included fixed heterozygosity and recombinant profiles of alleles present in diploids, suggested polytopic origins of tetraploids and hexaploids. Our data indicate independent origins of polyploids in or near the southern Blue Ridge, Interior Highlands and Plains, and Atlantic Coastal Plain regions from progenitors most similar to C. glabra and C. lyonii. Extant tetraploids were not implicated in evolution of hexaploids, and plants similar to C. cuthbertii appeared unlikely as diploid progenitors for polyploids. We propose multiple differentiation and hybridization/polyploidization cycles in different geographic regions to explain the pattern of allopatry and inferred polytopic origins among polyploids.
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Affiliation(s)
- A D Nelson
- Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma 73019
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Chen CH, Muzic RF, Nelson AD, Adler LP. Simultaneous recovery of size and radioactivity concentration of small spheroids with PET data. J Nucl Med 1999; 40:118-30. [PMID: 9935067] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
UNLABELLED Quantification of tumor activity is used to predict prognosis and discriminate benign from malignant lesions identified by PET. Accurate quantitation of small lesions requires correction for the partial volume effects. Such a correction is often based on the recovery coefficient (RC), which depends on the lesion size, the object-to-background ratio (OBR) and physical properties of the media. The purpose of this investigation was to determine whether a model-based optimization method to simultaneously recover the size and the activity concentration of small spheroids could improve estimates of lesion radioactivity when object size is unknown. For reference, we compared our method with a widely used approach, RC correction, that requires the object size to be known. METHODS A three-dimensional, spatially varying, object size- and contrast-dependent Gaussian model of the point spread function (PSF) of an ECAT EXACT was developed. The observed dependence of the PSF on random coincidences and measured-peak/background activity were included in the PSF using three adjusting factors. Size and radioactivity concentration of a spheroid were estimated by adjusting size and concentration until model output best matched the image data. Elliptic and circular phantoms both containing seven hot spheroids, with OBRs ranging from 5.6 to 0 background, were evaluated. RESULTS The proposed quantification method reduced the activity error by 11%-63% of the error obtained without correction. The greatest error reduction occurred for small spheroids. The average error in radius estimation ranged from 2% to 48%, wherein the smallest spheroid produced the largest errors. For spheroids with diameters from 8 to 22 mm, Student t test (paired, one-tail) showed the proposed method significantly improved accuracy (P < 0.05) in comparison with the RC method and also in comparison with optimization without the three adjusting factors. CONCLUSION The model-based optimization method improved estimation of radioactivity concentration over that corrected by the RC method and that made without any correction. It also provided accurate estimation of size for spheroids larger than 6 mm in diameter.
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Affiliation(s)
- C H Chen
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
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Muzic RF, Berridge MS, Friedland RP, Zhu N, Nelson AD. PET quantification of specific binding of carbon-11-nicotine in human brain. J Nucl Med 1998; 39:2048-54. [PMID: 9867140] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
UNLABELLED Previous work on the PET measured uptake of (S)-[11C]nicotine presents conflicting findings as to whether it reflects specific binding. METHODS We studied the uptake of (R)-[11C]nicotine and (S)-[11C]nicotine in normal volunteers at baseline conditions and after a challenge with unlabeled (S)-nicotine to decrease the concentration of free binding sites or with CO2 to increase perfusion. We analyzed the data using two- and three-compartment models. RESULTS We found tissue pharmacokinetics of (R)- and (S)-[11C]nicotine are adequately described by the two-compartment model. (S)-nicotine challenge induced small but statistically significant reductions in distribution volume (DV) of both (R)- and (S)-[11C]nicotine. The changes in DV could not be attributed to perfusion changes because DV was not affected by CO2 challenge. Although the reduction in DV indicates sensitivity of [11C]nicotine to status of nicotinic binding sites, the small magnitude of the reduction suggests that most nicotine uptake is nonspecific. CONCLUSION Although differences in DV attributable to specific binding were detected, (R)- and (S)-[11C]nicotine are relatively poor tracers for studying nicotinic binding sites using PET.
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Affiliation(s)
- R F Muzic
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio, USA
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Bednarczyk EM, Remler B, Weikart C, Nelson AD, Reed RC. Global cerebral blood flow, blood volume, and oxygen metabolism in patients with migraine headache. Neurology 1998; 50:1736-40. [PMID: 9633719 DOI: 10.1212/wnl.50.6.1736] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.6] [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: 11/15/2022] Open
Abstract
OBJECTIVE Migraine headaches with and without aura are representative of vascular headache states traditionally thought to be mediated by alterations in vascular tone. Validation of this theory has been hampered in part by technical difficulties inherent in the measurement of cerebral blood flow (CBF). The purpose of this study was to compare CBF measured during migraine and migraine-free states using PET. METHODS Patients with a minimum of one migraine headache without aura per month (International Headache Society [IHS] criteria) underwent measurement of CBF, cerebral blood volume (CBV), oxygen extraction, and metabolism during an episode of spontaneous migraine headache. Imaging was repeated during a migraine-free period of at least 48 hours. PET radiotracers used were: CBF, H(2)15O; CBV, C15O; oxygen metabolism, 15O2. RESULTS In nine patients (seven female and two male), global CBF (mL/min/100 g [SD]) was measured as 52.70 (6.9) during migraine and 59.65 (10.6) in the migraine-free state; p=0.028. CBV (mL/100 g [SD]) was 3.6 (0.43) during the symptomatic state and 3.8 (0.55) after the migraine; p=0.047. Oxygen metabolism (mL/min/100 g [SD]) was 3.68 (0.9) during migraine and 3.38 (1.02) without headache; p=0.211. The oxygen extraction ratio was 0.48 (0.15) and 0.41 (0.12) during migraine and migraine-free states, respectively; p=0.132. CONCLUSIONS In patients experiencing migraine without aura, CBF and CBV are reduced during the headache phase. Cerebral oxygen metabolism and oxygen extraction are not significantly affected.
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Affiliation(s)
- E M Bednarczyk
- University Hospitals of Cleveland, Department of Medicine, Case Western Reserve University, OH, USA
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Muzic RF, Chen CH, Nelson AD. A method to correct for scatter, spillover, and partial volume effects in region of interest analysis in PET. IEEE Trans Med Imaging 1998; 17:202-213. [PMID: 9688152 DOI: 10.1109/42.700732] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Scatter and spatial resolution effects degrade the accuracy of radioactivity concentration estimates obtained from positron emission tomography (PET) data. We present and evaluate a methodology for region quantification which accounts for these degradations. The method is based on analysis of sinogram data and does not require dynamic data sequences to be reconstructed. Moreover, estimates of region variance are also produced which may be used to define weights for model analyses that use weighted least squares minimization in order to obtain unbiased parameter estimates. We evaluate the method using both simulation and measured data and find that, with an appropriate model of scatter and spatial resolution effects, it is unbiased and capable of quantifying myocardial concentration with no more than a 5% error in accuracy for myocardium as thin as 10 mm.
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Affiliation(s)
- R F Muzic
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA.
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Chen CH, Muzic RF, Nelson AD, Adler LP. A nonlinear spatially variant object-dependent system model for prediction of partial volume effects and scatter in PET. IEEE Trans Med Imaging 1998; 17:214-227. [PMID: 9688153 DOI: 10.1109/42.700733] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Accurate quantitation of small lesions with positron emission tomography (PET) requires correction for the partial volume effect. Traditional methods that use Gaussian models of the PET system were found to be insufficient. A new approach that models the non-Gaussian object-dependent scatter was developed. The model consists of eight simple functions with a total of 24 parameters. Images of line and disk sources in circular and elliptical cylinders, and an anthropomorphic chest phantom were used to determine the parameter values. Empirical rules to determine these parameter values for various objects based on those for a reference object, a 21.5-cm circular cylinder, were also proposed. For seven spheroids and a 3.4-cm cylinder, pixel values predicted by the model were compared with the measured values. The model-to-measurement-ratio was 1.03+/-0.07 near the center of the spheroids and 0.99+/-0.03 near the center of the 3.4-cm cylinder. In comparison, the standard single Gaussian model had corresponding ratios of 1.27+/-0.09 and 1.24+/-0.03, respectively, and the corresponding ratios for a double Gaussian model were 1.13+/-0.09 and 1.05+/-0.01. Scatter fraction (28.5%) for a line source in the 21.5-cm cylinder was correctly estimated by our model. Because of scatter, we found that errors in the measurement of activity in spheroids with diameters from 0.6 to 3.4 cm were more significant than previously appreciated.
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Affiliation(s)
- C H Chen
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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Nelson AD, Muswick GJ, Muzic RF, Descamps X. A robust edge detection method for gated radionuclide ventriculograms. J Nucl Med 1996; 37:685-9. [PMID: 8691267] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED We present a myocardial edge detection technique that was developed for fast, reproducible measurements of left ventricular ejection fraction in the clinical setting. METHODS This myocardial edge detection method compares three edge parameters--count amplitude and first and second count derivatives--in three consecutive locations along a radius to a predetermined template of these values. Each of the radii, defined at 10-degree intervals, has different template values that permit accurate edge detection even though adjacent structures, such as the left atrium and the right ventricle, alter edge parameters. The template for edge detection is based on either the average edge parameters determined from manually defined edges in 15 patients (automatic method) or an operator-defined edge in the first frame (semiautomatic method). RESULTS The edge detection methods were tested in 100 patients, and intraobserver variabilities as well as comparison with clinically obtained ejection fractions were calculated. The standard error of the estimate was less than 3.1% for all observer comparisons. In 15 patients with both high-count (400,000 counts per image) and low count (50,000 counts per image) studies, the mean absolute difference in ejection fraction was 2.6% for intraobserver comparisons. CONCLUSION A robust myocardial edge detection technique was developed that is applicable for routine clinical use.
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Affiliation(s)
- A D Nelson
- Department of Radiology, University Hospitals of Cleveland, Case Western Reserve University, School of Medicine, Ohio 44106, USA
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Muzic RF, Nelson AD, Saidel GM, Miraldi F. Optimal experiment design for PET quantification of receptor concentration. IEEE Trans Med Imaging 1996; 15:2-12. [PMID: 18215884 DOI: 10.1109/42.481436] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The mathematical models used to analyze positron emission tomography (PET) data obtained for receptor quantitation have many unknown parameters which must be estimated from the data. Obtaining unique and precise estimates of the model parameters from PET data is difficult as a result of the complex interdependence of the parameters. Here the authors address the task of estimating the concentration of myocardial beta-adrenergic receptors using unlabeled and (18)F-labeled S(-)-fluorocarazolol as the receptor ligand. For a three-injection study the authors have optimized the ligand injection times and dosages using the D-optimal criterion for estimating receptor concentration. They found that in optimizing a three-injection experimental design, the dose of ligand in the third injection approaches zero so that the optimal three-injection design is actually a two-injection experiment. Using this optimal experiment, the authors demonstrate estimates of receptor concentration that are almost five times as precise as compared to an empirically designed three-injection experiment.
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Affiliation(s)
- R F Muzic
- Dept. of Radiol., Univ. Hospitals of Cleveland, OH, USA
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Berridge MS, Nelson AD, Zheng L, Leisure GP, Miraldi F. Specific beta-adrenergic receptor binding of carazolol measured with PET. J Nucl Med 1994; 35:1665-76. [PMID: 7931670] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
UNLABELLED Carazolol is a promising high-affinity beta-adrenergic receptor ligand for the noninvasive determination of beta receptor status using PET. Earlier investigations demonstrated specific receptor binding of carazolol in mice. These PET studies with S(-)-[2"-11C]carazolol in pigs were performed to explore the utility of the tracer for PET receptor studies. METHODS Tracer uptake in the heart and lung was measured by PET as a function of time. Receptors were blocked with propranolol and different doses of ICI 118,551 to estimate specific binding. Fluorine-18-1"-Fluorocarazolol and the less active R-enantiomer of [11C]-carazolol were also studied. RESULTS Specific receptor binding was 75% of the total uptake in the heart, preventable and displaceable by propranolol. Dose-dependent competition showed that carazolol binds in vivo to beta 1 and to beta 2 subtypes. Uptake of the labeled R(+) enantiomer of carazolol was not receptor-specific. CONCLUSIONS Carazolol labeled with 11C or 18F is a strong candidate for use in receptor estimation with PET. The in vivo observations were consistent with its known high affinity and slow receptor dissociation rate. Its high specific receptor uptake and low metabolism allow existing kinetic models to be applied for receptor measurements. The 11C label is convenient for repeated administrations, though 18F allowed the long observation periods necessary for measurement of the receptor dissociation rate. If needed, nonspecific uptake can be estimated without pharmacologic intervention by using the labeled R enantiomer.
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Affiliation(s)
- M S Berridge
- Department of Radiology, Case Western Reserve University School of Medicine, Cleveland, Ohio
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Nelson AD, Miraldi F, Muzic RF, Leisure GP, Semple WE. Noninvasive arterial monitor for quantitative oxygen-15-water blood flow studies. J Nucl Med 1993; 34:1000-6. [PMID: 8509836] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A noninvasive monitor has been developed for monitoring arterial radioactivity in quantitative PET studies of blood flow. The significance of this probe is that quantitative blood flow studies can be performed without the use of arterial catheterization. The method employed is based on the flux of photons emanating from the superior lobe of the right lung following an intravenous bolus of H2(15)O. Calibration of the monitor is obtained by measuring the relationship between lung monitor counts and arterial radioactivity after arterial and venous radioactivity levels have equilibrated following inhalation of C15O. To determine the accuracy of the lung probe as a measure of arterial radioactivity, 44 brain blood flow determinations were made in 11 volunteers using arterial radioactivity measures based both on the lung probe and continuous sampling from a radial artery. Repeated measures analysis of variance found no differences between invasive and noninvasive estimates of blood flow. These results suggest that the lung monitor enables quantitation of cerebral blood flow yet avoids the trauma of an arterial puncture.
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Affiliation(s)
- A D Nelson
- Department of Radiology, University Hospitals of Cleveland
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Muzic RF, Nelson AD, Miraldi F. Temporal alignment of tissue and arterial data and selection of integration start times for the H(2)(15)O autoradiographic CBF model in PET. IEEE Trans Med Imaging 1993; 12:393-398. [PMID: 18218431 DOI: 10.1109/42.241866] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A technique has been developed and tested that provides an automated method of temporally aligning the PET tissue activity curve with the arterial activity curve for quantification of cerebral blood flow using the H(2)(15)O autoradiographic model. This technique not only determines the relative time delay between the two curves, but also provides the start time of integration. Variability in computing global cerebral blood flow using this technique is shown to be less than that obtained by trained observers manually selecting parameters and at least as good as that obtained by using another automated alignment technique.
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Affiliation(s)
- R F Muzic
- Dept. of Biomed. Eng., Case Western Reserve Univ., Cleveland, OH
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Abstract
Progress in understanding genetic regulatory controls in the Actinomycetes has been rate limited by the properties of in vivo transcriptional probes. We have developed a set of plasmid- and transposon-based promoter-probe vectors that employ the Vibrio harveyi luciferase-encoding luxAB cassette as a reporter of transcription. The primary advantages of luciferase (Lux) over other reporter gene products are: (i) unsurpassed sensitivity; (ii) utility during stationary-phase gene expression; and (iii) the ability to localize promoter activity spatially within developing colonies. We have used these vectors to screen for Streptomyces coelicolor promoters that exhibit developmental phenotypes or that are induced by various environmental stimuli. The plasmid-based probes have proved invaluable for identifying cis- and trans-acting elements that are required for stationary-phase expression of the S. coelicolor sapA gene. A collection of novel bld and whi insertion mutants has been obtained by use of the Lux-encoding transposon, Tn5353.
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Affiliation(s)
- C D Sohaskey
- Department of Microbiology, University of Texas, Austin 78712
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Miraldi F, Nelson AD, Jones WT, Thompson S, Kursh ED. A dual-radioisotope technique for the evaluation of penile blood flow during tumescence. J Nucl Med 1992; 33:41-6. [PMID: 1730993] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A technique is described for concomitant study of both arterial and venous penile blood flow during tumescence. Dual-isotope acquisition is started after labeling red cells in vivo with 99mTc. Xenon-133 in saline is then injected into the corpus cavernosum followed with vasoactive drugs to induce an erection. The resulting xenon and technetium time-activity curves are inputs for a one-compartment model. In 14 subjects, the average peak arterial flow rate (PAF) for normal males was calculated as 13.0 +/- 1.28 ml/min (avg +/- s.d.) compared to 16.1 +/- 5.14 and 5.02 +/- 1.78 ml/min for patients with venous leak (VL) or arterial insufficiency (AI), respectively. Peak venous flows (PVF) were 4.25 +/- 1.17, 12.1 +/- 3.75, and 3.78 +/- 1.00 ml/min for normal, VL and AL respectively. Al patients have significantly lower PAF than normal (p = 0.002) or VL patients (p = 0.018), and VL patients had significantly higher PVF than normal (p = 0.012) or Al (p = 0.018). The technique may be helpful in the study of impotence.
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Affiliation(s)
- F Miraldi
- Department of Radiology, CWRU, School of Medicine, Cleveland, Ohio
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Berridge MS, Adler LP, Nelson AD, Cassidy EH, Muzic RF, Bednarczyk EM, Miraldi F. Measurement of human cerebral blood flow with [15O]butanol and positron emission tomography. J Cereb Blood Flow Metab 1991; 11:707-15. [PMID: 1874804 DOI: 10.1038/jcbfm.1991.127] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Although H2(15)O is widely used for CBF measurement by positron tomography, it underestimates CBF, especially at elevated flow rates. Several tracers, including butanol, overcome this problem, but the short half-life of 15O provides advantages that cause water to remain the tracer of choice. We report the first use and evaluation of 15O-labeled butanol for CBF measurement. Flow measurements made in a similar fashion with water and butanol at 10-min intervals were compared in normal volunteers under resting and hypercapnic conditions. Regional analysis showed good agreement between the tracers at low flows, and significant underestimation of flow by water relative to butanol in regions of elevated flow. The observed relationship between the tracers and the curve-fitted permeability-surface area product for water (133 ml.100 g-1.min-1) follow the known relationship between water and true flow. These observations indicate that [15O]-butanol provided accurate measurements of human regional CBF under conditions of elevated perfusion. We conclude that butanol is a convenient and accurate method for routine CBF determination by positron emission tomography.
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Affiliation(s)
- M S Berridge
- Department of Radiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio
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Bednarczyk EM, Green JA, Nelson AD, Leisure GA, Little D, Adler LP, Berridge MS, Panacek EA, Miraldi FD. Comparison of the effect of temafloxacin, ciprofloxacin, or placebo on cerebral blood flow, glucose, and oxygen metabolism in healthy subjects by means of positron emission tomography. Clin Pharmacol Ther 1991; 50:165-71. [PMID: 1868678 DOI: 10.1038/clpt.1991.121] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
STUDY OBJECTIVE To determine the cause of the central nervous system effect of the fluorinated quinolones temafloxacin and ciprofloxacin by measuring cerebral blood flow and metabolism by use of positron emission tomography. DESIGN This was a prospective, randomized, double-blind, placebo-controlled study. PATIENTS The patients were 13 healthy, nonsmoking volunteers whose ages ranged from 18 to 40 years. RESULTS We measured brain blood flow and metabolism by use of positron emission tomography before and after a five-dose course of 750 mg ciprofloxacin, 600 mg temafloxacin, or placebo given every 12 hours. Quinolone administration produced no significant effect on visual (qualitative) reading of the positron emission tomography scans. CONCLUSIONS We conclude that short-term administration of temafloxacin, ciprofloxacin, or placebo does not significantly alter cerebral glucose or oxygen metabolism. Subjects treated with ciprofloxacin demonstrated a significant decrease in brain blood flow compared with baseline and with temafloxacin- or placebo-treated subjects.
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Affiliation(s)
- E M Bednarczyk
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio
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Abstract
The Tn3-like transposon Tn4556 (and its derivatives Tn4560 and Tn4563) has been used for insertion mapping of genetic loci cloned on plasmids, but it has been difficult to obtain chromosomal insertions, largely because of the lack of a strong selection against transposon donor molecules. In this communication, we report two efficient selection techniques for transposition and their use in the isolation of chromosomal insertion mutations. A number of independent Streptomyces coelicolor morphological mutants (bld and whi) were obtained. Two of the bld mutations were mapped to locations on the chromosome by SCP1-mediated conjugation; at least one mutation, bld-5m1, appears to define a novel locus involved in control of S. coelicolor morphogenesis and antibiotic production.
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Affiliation(s)
- A T Schauer
- Department of Microbiology, University of Texas, Austin 78712-1095
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Abstract
Cerebral blood flow (CBF), glucose (FDG), and oxygen metabolism (OM) were evaluated by positron emission tomography (PET) in 18 healthy volunteers who were randomized to a 72-hour course of either 600 mg/d of fleroxacin or placebo. Such studies attempted to assess potentially serious, yet unexplained, central nervous system adverse effects of the fluorinated quinolone class. Baseline and postplacebo values for CBF (mL/min/100 g) and FDG (mg/min/100 g) were: 53 +/- 6 and 5.7 +/- 1.8; and 49.6 +/- 4.4, and 5.2 +/- 1.2, respectively. Identical values for fleroxacin were: 53.9 +/- 4.8 and 6.3 +/- 1.1; and 54.4 +/- 2.2 and 6.8 +/- 1.5, respectively. The differences between fleroxacin and placebo were not significant. There was also no effect seen in OM between placebo and the active drug. The authors conclude that short-term administration of fleroxacin does not alter CBF, FDG, or OM in healthy volunteers.
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Affiliation(s)
- S F Gardner
- Division of Cardiology, University Hospitals of Cleveland, OH 44106
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Abstract
The positron emission tomography (PET) H(2)(15)O bolus injection model for cerebral blood flow (CBF) requires calculation of a certain double integral that, when calculated, provides the pixel values of a reconstructed image (PET number) in terms of the tissue flow, the arterial input function, a decay constant for (15)O, the partition coefficient and a camera calibration constant that relates the flow-dependent integrated tissue activity to the measured PET number (cts/pixel). The tissue activity is assumed to be zero at the time of injection. A mathematical simplification, changing the order of integration, enabled the integration with respect to time to be performed analytically before the integration of the arterial input function. As a result of this simplification, only single integrals remain to be calculated numerically; cubic spline integration was used to calculate numerically these remaining integrals. This technique increases the accuracy and speed of evaluating blood flow without making simplifying assumptions. Similar simplifications may be applicable to other physiological models.
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Affiliation(s)
- R F Muzic
- Dept. of Biomed. Eng., Case Western Reserve Univ., Cleveland, OH
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Alfidi RJ, Masaryk TJ, Haacke EM, Lenz GW, Ross JS, Modic MT, Nelson AD, LiPuma JP, Cohen AM. MR angiography of peripheral, carotid, and coronary arteries. AJR Am J Roentgenol 1987; 149:1097-109. [PMID: 3318337 DOI: 10.2214/ajr.149.6.1097] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- R J Alfidi
- Department of Radiology, University Hospitals of Cleveland, Case Western Reserve University, School of Medicine, OH 44106
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Abstract
This note explains and illustrates a technique of reducing artifacts produced by periodic motion without using physiologic gating. The method is simple and can be applied on any standard MRI unit. For periodic motion, effective gating can be attained by setting the product of the number of acquisitions (at each phase-encoding step), N, times the repeat time, TR, equal to the period of the motion, T. This pseudo-gating can be used with any TR but, if changes in the period occur, is most robust with short TR values. The method is also applicable to multislice and volume imaging. For fast field echo methods, the above rule can be used if the period of the motion is smaller than the total scan time. Otherwise, the scan need only be repeated N times to avoid artifacts and improve signal-to-noise. The method has been implemented to remove both respiratory and/or cardiac motion artifacts.
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