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Hamilton LD, Shelburne KB, Rullkoetter PJ, Barnes CL, Mannen EM. Kinematic Performance of Medial Pivot Total Knee Arthroplasty. J Arthroplasty 2024; 39:1595-1601.e7. [PMID: 38061399 PMCID: PMC11096005 DOI: 10.1016/j.arth.2023.11.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 11/16/2023] [Accepted: 11/27/2023] [Indexed: 12/30/2023] Open
Abstract
BACKGROUND Total knee arthroplasty (TKA) implants have continued to evolve to accommodate new understandings of knee mechanics. The medial-pivot implant is a newer design, which is intended to limit anterior-posterior translation in the medial compartment while allowing lateral compartment translation. However, evidence for a generalized medial-pivot characteristic across all activities is limited. The purpose of the study was to quantify and compare in vivo knee joint kinematics using high-speed stereo radiography during activities of daily living in patients who have undergone a TKA with a cruciate sacrificing medial-pivot implant to age-matched and sex-matched native controls. METHODS Fifteen participants (7 patients, 4 women, mean age 70 years and 8 nonsymptomatic controls, 4 women, mean age 64 years) performed 6 functional tasks in high-speed stereo radiography: deep-knee lunge, chair rise, step down, gait, gait with 90° turn, and seated knee extension. Translational differences between groups (surgical versus control) were assessed for the medial and lateral condyle, while pivot location was normalized to subject-specific tibial plateau geometry. RESULTS The surgical cohort displayed a more constrained medial condyle that provided greater stability of the medial compartment and did not result in the paradoxical anterior translation at mid-flexion angles during weight-bearing activities, but was associated with less condylar translation than native knees. Additionally, the transverse tibial pivot location occurs most commonly in the middle third of the tibial plateau and secondarily on the medial third. CONCLUSIONS Some variability in pivot location occurs between activities and is more in nonsymptomatic, native knee controls.
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Affiliation(s)
- Landon D Hamilton
- Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado
| | - Kevin B Shelburne
- Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado
| | - Paul J Rullkoetter
- Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado
| | - C Lowry Barnes
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Erin M Mannen
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Department of Mechanical and Biomedical Engineering, Boise State University, Boise, Idaho
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Hamilton LD, Binns S, McFann K, Nudell N, Dunn JA. A Direct Assessment of Noninvasive Continuous Blood Pressure Monitoring in the Emergency Department and Intensive Care Unit. J Emerg Nurs 2024:S0099-1767(24)00078-3. [PMID: 38639694 DOI: 10.1016/j.jen.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/07/2024] [Accepted: 03/08/2024] [Indexed: 04/20/2024]
Abstract
INTRODUCTION Noninvasive continuous blood pressure monitoring has the potential to improve patient treatment in the hospital setting. Such noninvasive devices can be applied earlier in the treatment process to empower nurses and clinicians to react more quickly to patient deterioration with the added benefit of eliminating the risks associated with invasive monitoring. However, emerging technologies must be capable of reproducing current clinical measures for medical decision making. METHODS This study aimed to determine the usability and willingness of nurses to implement a noninvasive continuous blood pressure monitoring device. The secondary aim directly compared the systolic blood pressure, diastolic blood pressure, and mean arterial pressure values recorded by the device (VitalStream; CareTaker Medical LLC, Charlottesville, VA) with the "gold standard" brachial cuff and arterial line measures recorded in the emergency department and intensive care unit settings. RESULTS VitalStream was similarly received by nurses in the emergency department and intensive care setting, but ultimately had greater promotion from emergency nurses. Despite some statistical similarity between measurement methodologies, all direct comparisons were found to not meet the Association for the Advancement of Medical Instrumentation 2008 and Association for the Advancement of Medical Instrumentation / European Society of Hypertension / International Organization for Standardization 2019 consensus statement criteria for acceptable blood pressure measure differences between the VitalStream and "gold standard" clinical measures. In all instances, the standard deviation of the Bland-Altman bias exceeded 8 mm Hg with less than 85% of paired differences falling within 10 mm Hg of the "gold standard." DISCUSSION Taken together, the tested device requires additional postprocessing for medical decision making in trauma or emergent care.
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Andreassen TE, Hume DR, Hamilton LD, Higinbotham SE, Shelburne KB. Automated 2D and 3D finite element overclosure adjustment and mesh morphing using generalized regression neural networks. Med Eng Phys 2024; 126:104136. [PMID: 38621835 PMCID: PMC11064159 DOI: 10.1016/j.medengphy.2024.104136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 02/21/2024] [Accepted: 02/25/2024] [Indexed: 04/17/2024]
Abstract
Computer representations of three-dimensional (3D) geometries are crucial for simulating systems and processes in engineering and science. In medicine, and more specifically, biomechanics and orthopaedics, obtaining and using 3D geometries is critical to many workflows. However, while many tools exist to obtain 3D geometries of organic structures, little has been done to make them usable for their intended medical purposes. Furthermore, many of the proposed tools are proprietary, limiting their use. This work introduces two novel algorithms based on Generalized Regression Neural Networks (GRNN) and 4 processes to perform mesh morphing and overclosure adjustment. These algorithms were implemented, and test cases were used to validate them against existing algorithms to demonstrate improved performance. The resulting algorithms demonstrate improvements to existing techniques based on Radial Basis Function (RBF) networks by converting to GRNN-based implementations. Implementations in MATLAB of these algorithms and the source code are publicly available at the following locations: https://github.com/thor-andreassen/femors; https://simtk.org/projects/femors-rbf; https://www.mathworks.com/matlabcentral/fileexchange/120353-finite-element-morphing-overclosure-reduction-and-slicing.
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Affiliation(s)
- Thor E Andreassen
- Center for Orthopaedic Biomechanics, Mechanical and Materials Engineering, University of Denver, Denver, CO, USA.
| | - Donald R Hume
- Center for Orthopaedic Biomechanics, Mechanical and Materials Engineering, University of Denver, Denver, CO, USA
| | - Landon D Hamilton
- Center for Orthopaedic Biomechanics, Mechanical and Materials Engineering, University of Denver, Denver, CO, USA
| | - Sean E Higinbotham
- Center for Orthopaedic Biomechanics, Mechanical and Materials Engineering, University of Denver, Denver, CO, USA
| | - Kevin B Shelburne
- Center for Orthopaedic Biomechanics, Mechanical and Materials Engineering, University of Denver, Denver, CO, USA
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Pollack AM, Hamilton LD, Jenkins NA, Lueders PC, Luckasen GJ. School screening programs to identify hypertension in Hispanic youth. Am J Prev Cardiol 2024; 17:100629. [PMID: 38293255 PMCID: PMC10825600 DOI: 10.1016/j.ajpc.2023.100629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 12/08/2023] [Accepted: 12/18/2023] [Indexed: 02/01/2024] Open
Abstract
Elevated blood pressure during childhood can lead to hypertension in adulthood and is associated with an increased risk of future cardiovascular disease with early identification as the best option for prevention. This study examines the prevalence of hypertension in Hispanic and White youths and reports the ability of a school-based program to identify hypertension in school-aged children. Approximately 3.5 % of students had hypertension while 7.5 % of students had elevated blood pressure. Elevated body mass index (BMI) was the most common predictor of hypertension in all three grade levels (elementary: 5th grade, middle: 7th grade, and high school: 10th grade). In the elementary school age group, the significant predictors of hypertension were an elevated BMI, sex, and height. In the middle school age group, the factors that were significant predictors of hypertension included ethnicity, an elevated BMI, and height. In high school age students, the only significant predictor of hypertension was elevated BMI; ethnicity alone was not a significant predictor. The only group that ethnicity was a significant predictor of hypertension was the middle school age. Given that at all three grade levels, the Hispanic students had a higher percentage with elevated BMIs compared to White students, they should be considered at higher risk of hypertension.
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Babcock CD, Volk VL, Zeng W, Hamilton LD, Shelburne KB, Fitzpatrick CK. Neural-driven activation of 3D muscle within a finite element framework: exploring applications in healthy and neurodegenerative simulations. Comput Methods Biomech Biomed Engin 2023:1-11. [PMID: 37966863 PMCID: PMC11093887 DOI: 10.1080/10255842.2023.2280772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/02/2023] [Indexed: 11/16/2023]
Abstract
This paper presents a novel computational framework for neural-driven finite element muscle models, with an application to amyotrophic lateral sclerosis (ALS). The multiscale neuromusculoskeletal (NMS) model incorporates physiologically accurate motor neurons, 3D muscle geometry, and muscle fiber recruitment. It successfully predicts healthy muscle force and tendon elongation and demonstrates a progressive decline in muscle force due to ALS, dropping from 203 N (healthy) to 155 N (120 days after ALS onset). This approach represents a preliminary step towards developing integrated neural and musculoskeletal simulations to enhance our understanding of neurodegenerative and neurodevelopmental conditions through predictive NMS models.
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Affiliation(s)
- Colton D. Babcock
- Mechanical and Biomedical Engineering, Boise State University, Boise, ID
| | - Victoria L. Volk
- Mechanical and Biomedical Engineering, Boise State University, Boise, ID
| | - Wei Zeng
- Department of Mechanical Engineering, New York Institute of Technology, New York, NY
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Hamilton LD, Andreassen TE, Myers CA, Shelburne KB, Clary CW, Rullkoetter PJ. Knee pivot location in asymptomatic older adults. J Biomech 2023; 149:111487. [PMID: 36868041 PMCID: PMC10080542 DOI: 10.1016/j.jbiomech.2023.111487] [Citation(s) in RCA: 1] [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: 07/11/2022] [Revised: 01/28/2023] [Accepted: 02/06/2023] [Indexed: 02/11/2023]
Abstract
Representative data of asymptomatic, native-knee kinematics is important when studying changes in knee function across the lifespan. High-speed stereo radiography (HSSR) provides a reliable measure of knee kinematics to <1 mm of translation and 1° of rotation, but studies often have limited statistical power to make comparisons between groups or measure the contribution of individual variability. The purpose of this study is to examine in vivo condylar kinematics to quantify the transverse center-of-rotation, or pivot, location across the flexion range and challenge the medial-pivot paradigm in asymptomatic knee kinematics. We quantified the pivot location during supine leg press, knee extension, standing lunge, and gait for 53 middle-aged and older adults (27 men; 26 women: 50.8 ± 7.0 yrs, 1.75 ± 0.1 m, 79.1 ± 15.4 kg). A central- to medial-pivot location was identified for all activities with increased knee flexion associated with posterior translation of the center-of-rotation. The association between knee angle and anterior-posterior center-of-rotation location was not as strong as the relation between medial-lateral and anterior-posterior location, excluding gait. The Pearson's correlation for gait was stronger between knee angle and anterior-posterior center-of-rotation location (P < 0.001) than medial-lateral and anterior-posterior location (P = 0.0122). Individual variability accounted for a measurable proportion in variance explained of center-of-rotation location. Unique to gait, the lateral translation of center-of-rotation location resulted in the anterior translation of center-of-rotation at <10° knee flexion. Furthermore, no association between vertical ground-reaction force and center-of-rotation was identified.
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Affiliation(s)
| | | | - Casey A Myers
- University of Denver, Denver, CO, USA; Ortho Haus, LLC, CO, USA
| | | | - Chadd W Clary
- University of Denver, Denver, CO, USA; Ortho Haus, LLC, CO, USA
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Schmidt JC, Huang DD, Fleming AM, Brockman V, Hennessy EA, Magnotti LJ, Schroeppel T, McFann K, Hamilton LD, Dunn JA. Missed blunt cerebrovascular injuries using current screening criteria - The time for liberalized screening is now. Injury 2023; 54:1342-1348. [PMID: 36841698 DOI: 10.1016/j.injury.2023.02.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/18/2023] [Accepted: 02/07/2023] [Indexed: 02/27/2023]
Abstract
Diagnostic Criteria Study BACKGROUND: The morbidity and mortality associated with ischemic stroke attributable to blunt cerebrovascular injury (BCVI) warrant aggressive screening. The Denver Criteria (DC) and Expanded Denver Criteria (eDC) have imprecise elements that can be difficult and subjective in application and can delay or prevent screening. We hypothesize these screening criteria lack adequate ability to consistently identify BCVI and that the use of a liberalized screening approach with CT angiography (CTA) is superior without increasing risk of acute kidney injury (AKI). METHODS This was a multi-institutional retrospective cohort study of trauma patients who presented between 2015-2020 with radiographically confirmed BCVI diagnosed using each institutions' liberalized screening protocol, defined as automatic CTA of the head and neck for all patients undergoing head and neck CT. Outcomes of interest included AKI, stroke, and death due to BCVI. Outcomes were reported as frequency, percent, and 95% confidence interval as calculated by the Clopper-Pearson method. Incidence of medical follow-up within 1 year of first medical visit was quantified as the median and inter-quartile range of days to follow-up visit. RESULTS We identified 433 BCVI patients with a mean age of 45.2 (standard deviation 18.9) years, 256 men and 177 women, 1.73 m (0.10) tall, and weighed 80.3 kg (20.3). Forty-one patients had strokes (9.5% [95% confidence interval 6.9, 12.6] and 12 patients (2.8% [1.4, 4.5]) had mortality attributable to BCVI. Of 433 total cases, 132 (30.5% [26.2, 35.1]) would have been missed by DC and 150 (34.6% [30.2, 39.3]) by eDC. Incidence of AKI in our BCVI population was 6 (1.4% [0.01, 3.0]). CONCLUSIONS BCVI would be missed over 30% of the time using the DC and eDC compared to liberalized use of screening CTA. Risk of AKI due to CTA did not occur at a clinically meaningful level, supporting liberal CTA screening.
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Affiliation(s)
- Julia C Schmidt
- UCHealth North Medical Center of the Rockies, 2500 Rocky Mountain Avenue, Loveland, CO 80538, USA
| | - Dih-Dih Huang
- University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Andrew M Fleming
- University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Valerie Brockman
- UCHealth Memorial Hospital Central, 1400 Boulder Street, Colorado Springs, CO 80909, USA
| | - Elizabeth A Hennessy
- UCHealth Memorial Hospital Central, 1400 Boulder Street, Colorado Springs, CO 80909, USA
| | - Louis J Magnotti
- University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Thomas Schroeppel
- UCHealth Memorial Hospital Central, 1400 Boulder Street, Colorado Springs, CO 80909, USA
| | - Kim McFann
- UCHealth North Medical Center of the Rockies, 2500 Rocky Mountain Avenue, Loveland, CO 80538, USA
| | - Landon D Hamilton
- UCHealth North Medical Center of the Rockies, 2500 Rocky Mountain Avenue, Loveland, CO 80538, USA
| | - Julie A Dunn
- UCHealth North Medical Center of the Rockies, 2500 Rocky Mountain Avenue, Loveland, CO 80538, USA.
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Hamilton LD, Andreassen TE, Myers C, Shelburne KB, Clary C, Rullkoetter PJ. Supine leg press as an alternative to standing lunge in high-speed stereo radiography. J Biomech 2022; 138:111118. [PMID: 35576630 PMCID: PMC10863335 DOI: 10.1016/j.jbiomech.2022.111118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 03/21/2022] [Accepted: 04/29/2022] [Indexed: 10/18/2022]
Abstract
The standing lunge is an activity commonly used to quantify in-vivo knee kinematics with fluoroscopy. The ability to perform the standing lunge varies between subjects and can necessitate movement accommodations to successfully complete the desired range of motion. We proposed a supine leg press as an alternative to the standing lunge that aimed to provide a similar evaluation of knee motion while increasing the measured range of motion. Tibiofemoral kinematics of 53 non-symptomatic adults (27 men, 26 women, 50.8 ± 7.0 yrs.) were calculated from the tracked high-speed stereo radiography (HSSR) images for supine leg press and standing lunge using CT-segmented bony geometries of the right lower limb. The supine leg press proved to be a useful alternative to the standing lunge while providing 46.2° greater range of motion in knee flexion. The difference in angle-matched kinematics across a 100° flexion range between the leg press and lunge was 0.70° in varus-valgus rotation, 1.5° in internal-external rotation, 1.0 mm in medial-lateral translation, 2.3 mm in anterior-posterior translation, and 0.46 mm in superior-inferior translation for men. The angle-matched difference for women across 100° was 0.58° in varus-valgus rotation, 2.4° internal-external rotation, 0.70 mm medial-lateral translation, 2.1 mm anterior-posterior translation, and 0.78 mm superior-inferior translation. The similar kinematics, while having a greater range of motion, and control of the applied load makes the supine leg press an alternative for quantifying in-vivo knee kinematics.
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Affiliation(s)
| | | | - Casey Myers
- University of Denver, Denver, CO, USA; Ortho Haus, LLC, CO, USA
| | | | - Chadd Clary
- University of Denver, Denver, CO, USA; Ortho Haus, LLC, CO, USA
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Kefala V, Ali AA, Hamilton LD, Mannen EM, Shelburne KB. Effects of Weight-Bearing on Tibiofemoral, Patellofemoral, and Patellar Tendon Kinematics in Older Adults. Front Bioeng Biotechnol 2022; 10:820196. [PMID: 35497367 PMCID: PMC9048742 DOI: 10.3389/fbioe.2022.820196] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/08/2022] [Indexed: 11/26/2022] Open
Abstract
Quantification of natural knee kinematics is essential for the assessment of joint function in the diagnosis of pathologies. Combined measurements of tibiofemoral and patellofemoral joint kinematics are necessary because knee pathologies, such as progression of osteoarthritis and patellar instability, are a frequent concern in both articulations. Combined measurement of tibiofemoral and patellofemoral kinematics also enables calculation of important quantities, specifically patellar tendon angle, which partly determines the loading vector at the tibiofemoral joint and patellar tendon moment arm. The goals of this research were to measure the differences in tibiofemoral and patellofemoral kinematics, patellar tendon angle (PTA), and patellar tendon moment arm (PTMA) that occur during non-weight-bearing and weight-bearing activities in older adults. Methods: High-speed stereo radiography was used to measure the kinematics of the tibiofemoral and patellofemoral joints in subjects as they performed seated, non-weight-bearing knee extension and two weight-bearing activities: lunge and chair rise. PTA and PTMA were extracted from the subject’s patellofemoral and tibiofemoral kinematics. Kinematics and the root mean square difference (RMSD) between non-weight-bearing and weight-bearing activities were compared across subjects and activities. Results: Internal rotation increased with weight-bearing (mean RMSD from knee extension was 4.2 ± 2.4° for lunge and 3.6 ± 1.8° for chair rise), and anterior translation was also greater (mean RMSD from knee extension was 2.2 ± 1.2 mm for lunge and 2.3 ± 1.4 mm for chair rise). Patellar tilt and medial–lateral translation changed from non-weight-bearing to weight-bearing. Changes of the patellar tendon from non-weight-bearing to weight-bearing were significant only for PTMA. Conclusions: While weight-bearing elicited changes in knee kinematics, in most degrees of freedoms, these differences were exceeded by intersubject differences. These results provide comparative kinematics for the evaluation of knee pathology and treatment in older adults.
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Affiliation(s)
- Vasiliki Kefala
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, United States
| | - Azhar A Ali
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, United States
- Stryker Orthopedics, Kalamazoo, MI, United States
| | - Landon D Hamilton
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, United States
| | - Erin M Mannen
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, United States
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, United States
| | - Kevin B Shelburne
- Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, United States
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Andreassen TE, Hamilton LD, Hume D, Higinbotham SE, Behnam Y, Clary C, Shelburne KB. Apparatus for In Vivo Knee Laxity Assessment Using High-Speed Stereo Radiography. J Med Device 2021; 15:041004. [PMID: 34721751 DOI: 10.1115/1.4051834] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 06/02/2021] [Indexed: 11/08/2022] Open
Abstract
Computational modeling is of growing importance in orthopedics and biomechanics as a tool to understand differences in pathology and predict outcomes from surgical interventions. However, the computational models of the knee have historically relied on in vitro data to create and calibrate model material properties due to the unavailability of accurate in vivo data. This work demonstrates the design and use of a custom device to quantify anterior-posterior (AP) and internal-external (IE) in vivo knee laxity, with an accuracy similar to existing in vitro methods. The device uses high-speed stereo radiography (HSSR) tracking techniques to accurately measure the resulting displacements of the femur, tibia, and patella bones during knee laxity assessment at multiple loads and knee flexion angles. The accuracy of the knee laxity apparatus was determined by comparing laxity data from two cadaveric specimens between the knee laxity apparatus and an existing in vitro robotic knee joint simulator. The accuracy of the knee laxity apparatus was within 1 mm (0.04 in.) for AP and 2.5 deg for IE. Additionally, two living subjects completed knee laxity testing to confirm the laboratory use of the novel apparatus. This work demonstrates the ability to use custom devices in HSSR to collect accurate data, in vivo, for calibration of computational models.
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Affiliation(s)
- Thor E Andreassen
- Department of Mechanical and Materials Engineering, The University of Denver, 2155 E. Wesley Ave., Denver, CO 80210
| | - Landon D Hamilton
- Department of Mechanical and Materials Engineering, The University of Denver, 2155 E. Wesley Ave., Denver, CO 80210
| | - Donald Hume
- Department of Mechanical and Materials Engineering, The University of Denver, 2155 E. Wesley Ave., Denver, CO 80210
| | - Sean E Higinbotham
- Department of Mechanical and Materials Engineering, The University of Denver, 2155 E. Wesley Ave., Denver, CO 80210
| | - Yashar Behnam
- Department of Mechanical and Materials Engineering, The University of Denver, 2155 E. Wesley Ave., Denver, CO 80210
| | - Chadd Clary
- Department of Mechanical and Materials Engineering, The University of Denver, 2155 E. Wesley Ave., Denver, CO 80210
| | - Kevin B Shelburne
- Department of Mechanical and Materials Engineering, The University of Denver, 2155 E. Wesley Ave., Denver, CO 80210
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Volk VL, Hamilton LD, Hume DR, Shelburne KB, Fitzpatrick CK. Integration of neural architecture within a finite element framework for improved neuromusculoskeletal modeling. Sci Rep 2021; 11:22983. [PMID: 34836986 PMCID: PMC8626416 DOI: 10.1038/s41598-021-02298-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 11/10/2021] [Indexed: 11/12/2022] Open
Abstract
Neuromusculoskeletal (NMS) models can aid in studying the impacts of the nervous and musculoskeletal systems on one another. These computational models facilitate studies investigating mechanisms and treatment of musculoskeletal and neurodegenerative conditions. In this study, we present a predictive NMS model that uses an embedded neural architecture within a finite element (FE) framework to simulate muscle activation. A previously developed neuromuscular model of a motor neuron was embedded into a simple FE musculoskeletal model. Input stimulation profiles from literature were simulated in the FE NMS model to verify effective integration of the software platforms. Motor unit recruitment and rate coding capabilities of the model were evaluated. The integrated model reproduced previously published output muscle forces with an average error of 0.0435 N. The integrated model effectively demonstrated motor unit recruitment and rate coding in the physiological range based upon motor unit discharge rates and muscle force output. The combined capability of a predictive NMS model within a FE framework can aid in improving our understanding of how the nervous and musculoskeletal systems work together. While this study focused on a simple FE application, the framework presented here easily accommodates increased complexity in the neuromuscular model, the FE simulation, or both.
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Affiliation(s)
- Victoria L Volk
- Micron School of Materials Science and Engineering, Boise State University, Boise, ID, USA.,Mechanical and Biomedical Engineering, Boise State University, 1910 University Drive, MS-2085, Boise, ID, 83725-2085, USA
| | - Landon D Hamilton
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, USA
| | - Donald R Hume
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, USA
| | - Kevin B Shelburne
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, USA
| | - Clare K Fitzpatrick
- Mechanical and Biomedical Engineering, Boise State University, 1910 University Drive, MS-2085, Boise, ID, 83725-2085, USA.
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Davis LA, Allen SP, Hamilton LD, Grabowski AM, Enoka RM. Differences in postural sway among healthy adults are associated with the ability to perform steady contractions with leg muscles. Exp Brain Res 2020; 238:487-497. [PMID: 31960103 DOI: 10.1007/s00221-019-05719-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [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: 07/08/2019] [Accepted: 12/30/2019] [Indexed: 12/13/2022]
Abstract
Upright standing involves small displacements of the center of mass about the base of support. These displacements are often quantified by measuring various kinematic features of the center-of-pressure trajectory. The plantar flexors have often been identified as the key muscles for the control of these displacements; however, studies have suggested that the hip abductor and adductors may also be important. The purpose of our study was to determine the association between the force capabilities of selected leg muscles and sway-area rate across four balance conditions in young (25 ± 4 years; 12/19 women) and older adults (71 ± 5 years; 5/19 women). Due to the marked overlap in sway-area rate between the two age groups, the data were collapsed, and individuals were assigned to groups of low- and high-sway area rates based on a k-medoid cluster analysis. The number of participants assigned to each group varied across balance conditions and a subset of older adults was always included in the low-sway group for each balance condition. The most consistent explanatory variable for the variance in sway-area rate was force control of the hip abductors and ankle dorsiflexors as indicated by the magnitude of the normalized force fluctuations (force steadiness) during a submaximal isometric contraction. The explanatory power of the regression models varied across conditions, thereby identifying specific balance conditions that should be examined further in future studies of postural control.
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Affiliation(s)
- Leah A Davis
- Department of Integrative Physiology, University of Colorado Boulder, Campus Box 354, Boulder, CO, 80309, USA.
| | - Stephen P Allen
- Department of Integrative Physiology, University of Colorado Boulder, Campus Box 354, Boulder, CO, 80309, USA
| | - Landon D Hamilton
- Center for Orthopedic Biomechanics, Ritchie School of Mechanical Engineering and Computer Science, University of Denver, 2155 E. Wesley Ave., Denver, CO, 80210, USA
| | - Alena M Grabowski
- Department of Integrative Physiology, University of Colorado Boulder, Campus Box 354, Boulder, CO, 80309, USA
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado Boulder, Campus Box 354, Boulder, CO, 80309, USA
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Hamilton LD, Mazzo MR, Petrigna L, Ahmed AA, Enoka RM. Poor estimates of motor variability are associated with longer grooved pegboard times for middle-aged and older adults. J Neurophysiol 2018; 121:588-601. [PMID: 30540504 DOI: 10.1152/jn.00543.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Goal-directed movements that involve greater motor variability are performed with an increased risk that the intended goal will not be achieved. The ability to estimate motor variability during such actions varies across individuals and influences how people decide to move about their environment. The purpose of our study was to identify the decision-making strategies used by middle-aged and older adults when performing two goal-directed motor tasks and to determine if these strategies were associated with the time to complete the grooved pegboard test. Twenty-one middle-aged (48 ± 6 yr; range 40-59 yr, 15 women) and 20 older adults (73 ± 4 yr; range 65-79 yr, 8 women) performed two targeted tasks, each with two normalized target options. Decision-making characteristics were not associated with time to complete the test of manual dexterity when the analysis included all participants, but slower pegboard times were associated with measures of greater movement variability during the target-directed actions. When the data were clustered on the basis of pegboard time rather than age, relatively longer times for the faster group were associated with greater motor variability during the prescribed tasks, whereas longer times for the slower group were associated with increased risk-seeking behavior (α) and greater variability in the targeted actions. NEW & NOTEWORTHY This study was the first to examine the association between decision-making choices and an NIH Toolbox test of manual dexterity (grooved pegboard test) performed by middle-aged and older adults. Significant associations were observed between decision-making choices and time to complete the test when the analyses were based on pegboard times rather than chronological age. This result indicates that decision-making choices of middle-aged and older adults, independent of age, were associated with time to complete a test of manual dexterity.
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Affiliation(s)
- Landon D Hamilton
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Melissa R Mazzo
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Luca Petrigna
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado.,PhD Program in Health Promotion and Cognitive Sciences, Sport and Exercise Sciences Research Unit, University of Palermo , Palermo , Italy
| | - Alaa A Ahmed
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado.,Department of Mechanical Engineering, University of Colorado , Boulder, Colorado
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
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Hamilton LD, Mani D, Almuklass AM, Davis LA, Vieira T, Botter A, Enoka RM. Electrical nerve stimulation modulates motor unit activity in contralateral biceps brachii during steady isometric contractions. J Neurophysiol 2018; 120:2603-2613. [PMID: 30156959 DOI: 10.1152/jn.00235.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [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: 12/12/2022] Open
Abstract
The purpose of our study was to compare the influence of five types of electrical nerve stimulation delivered through electrodes placed over the right biceps brachii on motor unit activity in the left biceps brachii during an ongoing steady isometric contraction. The electrical stimulation protocols comprised different combinations of pulse duration (0.2 and 1.0 ms), stimulus frequency (50 and 90 Hz), and stimulus current (greater or less than motor threshold). The electrical nerve stimulation protocols were applied over the muscle of the right elbow flexors of 13 participants (26 ± 3 yr) while they performed voluntary contractions with the left elbow flexors to match a target force set at 10% of maximum. All five types of electrical nerve stimulation increased the absolute amplitude of the electromyographic (EMG) signal recorded from the left biceps brachii with high-density electrodes. Moreover, one stimulation condition (1 ms, 90 Hz) had a consistent influence on the centroid location of the EMG amplitude distribution and the average force exerted by the left elbow flexors. Another stimulation condition (0.2 ms, 90 Hz) reduced the coefficient of variation for force during the voluntary contraction, and both low-frequency conditions (50 Hz) increased the duration of the mean interspike interval of motor unit action potentials after the stimulation had ended. The findings indicate that the contralateral effects of electrical nerve stimulation on the motor neuron pool innervating the homologous muscle can be influenced by both stimulus pulse duration and stimulus frequency. NEW & NOTEWORTHY Different types of electrical nerve stimulation delivered through electrodes placed over the right biceps brachii modulated the ongoing motor unit activity in the left biceps brachii. Although the effects varied with stimulus pulse duration, frequency, and current, all five types of electrical nerve stimulation increased the amplitude of the electromyographic activity in the left biceps brachii. Moreover, most of the effects in the left arm occurred after the electrical nerve stimulation of the right arm had been terminated.
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Affiliation(s)
- Landon D Hamilton
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Diba Mani
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Awad M Almuklass
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado.,College of Medicine, King Saud bin Abdulaziz University for Health Sciences , Riyadh , Saudi Arabia
| | - Leah A Davis
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Taian Vieira
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Torino , Italy
| | - Alberto Botter
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Torino , Italy
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
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Mani D, Almuklass AM, Hamilton LD, Vieira TM, Botter A, Enoka RM. Motor unit activity, force steadiness, and perceived fatigability are correlated with mobility in older adults. J Neurophysiol 2018; 120:1988-1997. [PMID: 30044670 DOI: 10.1152/jn.00192.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The purpose of our study was to examine the associations between the performance of older adults on four tests of mobility and the physical capabilities of the lower leg muscles. The assessments included measures of muscle strength, muscle activation, and perceived fatigability. Muscle activation was quantified as the force fluctuations-a measure of force steadiness-and motor unit discharge characteristics of lower leg muscles during submaximal isometric contractions. Perceived fatigability was measured as the rating of perceived exertion achieved during a test of walking endurance. Twenty participants (73 ± 4 yr) completed one to four evaluation sessions that were separated by at least 3 wk. The protocol included a 400-m walk, a 10-m walk at maximal and preferred speeds, a chair-rise test, and the strength, force steadiness, and discharge characteristics of motor units detected by high-density electromyography of lower leg muscles. Multiple-regression analyses yielded statistically significant models that explained modest amounts of the variance in the four mobility tests. The variance explained by the regression models was 39% for 400-m walk time, 33% for maximal walk time, 42% for preferred walk time, and 27% for chair-rise time. The findings indicate that differences in mobility among healthy older adults were partially associated with the level of perceived fatigability (willingness of individuals to exert themselves) achieved during the test of walking endurance and the discharge characteristics of soleus, medial gastrocnemius, and tibialis anterior motor units during steady submaximal contractions with the plantar flexor and dorsiflexor muscles. NEW & NOTEWORTHY Differences among healthy older adults in walking endurance, walking speed, and ability to rise from a chair can be partially explained by the performance capabilities of lower leg muscles. Assessments comprised the willingness to exert effort (perceived fatigability) and the discharge times of action potentials by motor units in calf muscles during submaximal isometric contractions. These findings indicate that the nervous system contributes significantly to differences in mobility among healthy older adults.
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Affiliation(s)
- Diba Mani
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Awad M Almuklass
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado.,College of Medicine, King Saud bin Abdulaziz University for Health Sciences , Riyadh , Saudi Arabia
| | - Landon D Hamilton
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Taian M Vieira
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Turin , Italy
| | - Alberto Botter
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Turin , Italy
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
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Almuklass AM, Feeney DF, Mani D, Hamilton LD, Enoka RM. Peg-manipulation capabilities of middle-aged adults have a greater influence on pegboard times than those of young and old adults. Exp Brain Res 2018; 236:2165-2172. [PMID: 29785485 DOI: 10.1007/s00221-018-5294-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 01/15/2018] [Accepted: 05/16/2018] [Indexed: 11/30/2022]
Abstract
Declines in manual dexterity are frequently quantified as the time it takes to complete the grooved pegboard test. The test requires individuals to manipulate 25 pegs, one at a time, by removing them from a well and inserting them into a prescribed hole. The manipulation of each peg involves four phases: selection, transport, insertion, and return. The purpose of our study was to compare the times to complete the four phases of peg manipulation and the forces applied to the pegboard during peg insertion as young, middle-aged, and old adults performed the grooved pegboard test. The relative significance of the peg-manipulation attributes for 30 young (24.0 ± 4.4 years), 15 middle-aged (46.5 ± 6.5 years), and 15 old (70.4 ± 4.0 years) adults was assessed with a multiple-regression analysis. The grooved pegboard test was performed on a force plate. Pegboard times for the old adults (81 ± 17 s) were longer than those for young (56 ± 7 s) and middle-aged (58 ± 11 s) adults. Regression analysis indicated that the explanatory variables for the pegboard times of young (R2 = 0.33) and middle-aged (R2 = 0.78) adults were the times for the peg insertion and return phases, whereas the predictors for old adults (R2 = 0.49) were the times for the peg selection and transport phases. The relative influence of peg-manipulation capabilities on a pegboard test of manual dexterity was greater for middle-aged adults than for young and old adults.
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Affiliation(s)
- Awad M Almuklass
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA. .,College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.
| | - Daniel F Feeney
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
| | - Diba Mani
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
| | - Landon D Hamilton
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
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Almuklass AM, Davis L, Hamilton LD, Hebert JR, Alvarez E, Enoka RM. Pulse Width Does Not Influence the Gains Achieved With Neuromuscular Electrical Stimulation in People With Multiple Sclerosis: Double-Blind, Randomized Trial. Neurorehabil Neural Repair 2018; 32:84-93. [PMID: 29366377 DOI: 10.1177/1545968317753681] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [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: 11/15/2022]
Abstract
BACKGROUND Multiple sclerosis (MS) eventually compromises the walking ability of most individuals burdened with the disease. Treatment with neuromuscular electrical stimulation (NMES) can restore some functional abilities in persons with MS, but its effectiveness may depend on stimulus-pulse duration. OBJECTIVE To compare the effects of a 6-week intervention with narrow- or wide-pulse NMES on walking performance, neuromuscular function, and disability status of persons with relapsing-remitting MS. METHODS Individuals with MS (52.6 ± 7.4 years) were randomly assigned to either the narrow-pulse (n = 13) or wide-pulse (n = 14) group. The NMES intervention was performed on the dorsiflexor and plantar flexor muscles of both legs (10 minutes each muscle, 4 s on and 12 s off) at a tolerable level for 18 sessions across 6 weeks. Outcomes were obtained before (week 0) and after (week 7) the intervention and 4 weeks later (week 11). RESULTS There was no influence of stimulus-pulse duration on the outcomes ( P > .05); thus, the data were collapsed across groups. The NMES intervention improved ( P < .05) gait speed and walking endurance, dorsiflexor strength in the more-affected leg, plantar flexor strength in the less-affected leg, force control for plantar flexors in the less-affected leg, and self-reported levels of fatigue and walking limitations. CONCLUSION There was no influence of stimulus-pulse duration on the primary outcomes (gait speed and walking endurance). The 6-week NMES intervention applied to the lower leg muscles of persons with mild to moderate levels of disability can improve their walking performance and provide some symptom relief.
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Affiliation(s)
- Awad M Almuklass
- 1 University of Colorado, Boulder, CO, USA.,2 King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Leah Davis
- 1 University of Colorado, Boulder, CO, USA
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Almuklass AM, Davis L, Hamilton LD, Vieira TM, Botter A, Enoka RM. Motor unit discharge characteristics and walking performance of individuals with multiple sclerosis. J Neurophysiol 2018; 119:1273-1282. [PMID: 29357453 DOI: 10.1152/jn.00598.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [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
Walking performance of persons with multiple sclerosis (MS) is strongly influenced by the activation signals received by lower leg muscles. We examined the associations between force steadiness and motor unit discharge characteristics of lower leg muscles during submaximal isometric contractions with tests of walking performance and disability status in individuals who self-reported walking difficulties due to MS. We expected that worse walking performance would be associated with weaker plantar flexor muscles, worse force steadiness, and slower motor unit discharge times. Twenty-three individuals with relapsing-remitting MS (56 ± 7 yr) participated in the study. Participants completed one to three evaluation sessions that involved two walking tests (25-ft walk and 6-min walk), a manual dexterity test (grooved pegboard), health-related questionnaires, and measurement of strength, force steadiness, and motor unit discharge characteristics of lower leg muscles. Multiple regression analyses were used to construct models to explain the variance in measures of walking performance. There were statistically significant differences (effect sizes: 0.21-0.60) between the three muscles in mean interspike interval (ISI) and ISI distributions during steady submaximal contractions with the plantar flexor and dorsiflexor muscles. The regression models explained 40% of the variance in 6-min walk distance and 47% of the variance in 25-ft walk time with two or three variables that included mean ISI for one of the plantar flexor muscles, dorsiflexor strength, and force steadiness. Walking speed and endurance in persons with relapsing-remitting MS were reduced in individuals with longer ISIs, weaker dorsiflexors, and worse plantar flexor force steadiness. NEW & NOTEWORTHY The walking endurance and gait speed of persons with relapsing-remitting multiple sclerosis (MS) were worse in individuals who had weaker dorsiflexor muscles and greater force fluctuations and longer times between action potentials discharged by motor units in plantar flexor muscles during steady isometric contractions. These findings indicate that the control of motor unit activity in lower leg muscles of individuals with MS is associated with their walking ability.
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Affiliation(s)
- Awad M Almuklass
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado.,College of Medicine, King Saud bin Abdulaziz University for Health Sciences , Riyadh , Saudi Arabia
| | - Leah Davis
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Landon D Hamilton
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
| | - Taian M Vieira
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Turin , Italy
| | - Alberto Botter
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Turin , Italy
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado , Boulder, Colorado
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Almuklass AM, Feeney DF, Mani D, Hamilton LD, Enoka RM. Peg-manipulation capabilities during a test of manual dexterity differ for persons with multiple sclerosis and healthy individuals. Exp Brain Res 2017; 235:3487-3493. [PMID: 28849332 DOI: 10.1007/s00221-017-5075-4] [Citation(s) in RCA: 7] [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: 05/26/2017] [Accepted: 08/22/2017] [Indexed: 11/25/2022]
Abstract
Manual dexterity declines with advancing age and the development of neurological disorders. Changes in manual dexterity are frequently quantified as the time it takes to complete the grooved pegboard test, which requires individuals to manipulate 25 pegs. The manipulation of each peg involves four phases: selection, transport, insertion, and return. The purpose of the study was to compare the times to complete the four phases of manipulating each peg and the forces applied to the pegboard during peg selection and insertion in persons with multiple sclerosis (MS) and age- and sex-matched healthy adults. Multiple-regression models that could explain the variance in pegboard times for each group of participants were compared to assess the relative significance of the peg-manipulation attributes. The performance of 17 persons with MS (52.2 ± 8.3 years) was compared with 17 control subjects (52.2 ± 11.5 years). The grooved pegboard test was performed on a force plate. Pegboard times for the MS group (104 ± 40 s) were longer than those for the Control group (61 ± 15 s). Regression analysis indicated that the pegboard times for the MS group could be predicted by the time for the peg-selection phase (R 2 = 0.78), whereas the predictors for Control group (R 2 = 0.77) were the times for the peg-transport (partial r = 0.80) and selection (partial r = 0.58) phases. The variance in the time it took the MS participants to complete the grooved pegboard test was strongly related to the time required to select each peg, whereas the pegboard times for the Control subjects depended mostly on the duration of the transport phase but also on the time to select each peg.
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Affiliation(s)
- Awad M Almuklass
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA.
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.
| | - Daniel F Feeney
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
| | - Diba Mani
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
| | - Landon D Hamilton
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado, Boulder, CO, 80309, USA
- Department of Mathematics, University of Colorado, Boulder, CO, USA
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Hamilton LD, Thomas E, Almuklass AM, Enoka RM. A framework for identifying the adaptations responsible for differences in pegboard times between middle-aged and older adults. Exp Gerontol 2017; 97:9-16. [PMID: 28688836 DOI: 10.1016/j.exger.2017.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [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: 04/12/2017] [Revised: 05/22/2017] [Accepted: 07/03/2017] [Indexed: 11/25/2022]
Abstract
Time to complete two tests of manual dexterity, the 9-hole Peg Test and Grooved Pegboard Test, increases with advancing age. However, the adaptations responsible for the differences in pegboard times between middle-aged and older adults are largely unknown. Potential mechanisms include neuromuscular characteristics, cognitive function, and cutaneous sensation. To provide a tractable framework to address these gaps in knowledge, the purpose of the current study was to identify the latent variables underlying age-associated differences in time to complete the 9-hole and grooved pegboard tests. The approach involved an independent component analysis that identified associations between the two pegboard times for the two groups of participants with two to six secondary outcomes. The common association across three of the four conditions (two groups and two pegboard tests) was features derived from force-matching tasks requiring submaximal isometric contraction. In addition, there were significant associations for older adults between age, measures of cognitive function, and pegboard times. Nonetheless, the significant associations were unique for each age group and pegboard test. The results provide a framework for subsequent mechanistic studies to identify the adaptations underlying age-associated declines in manual dexterity.
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Affiliation(s)
- Landon D Hamilton
- Department of Integrative Physiology, University of Colorado, 354 UCB, Boulder, CO 80309-0354, United States.
| | - Ewan Thomas
- Sports and Exercise Science Research Unit, University of Palermo, Palermo, Italy.
| | - Awad M Almuklass
- Department of Integrative Physiology, University of Colorado, 354 UCB, Boulder, CO 80309-0354, United States.
| | - Roger M Enoka
- Department of Integrative Physiology, University of Colorado, 354 UCB, Boulder, CO 80309-0354, United States; Department of Mathematics, University of Colorado, Boulder, CO.
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Hamilton LD, Thomas E, Enoka RM. Identification of Latent Variables Underlying Manual Dexterity In Middle-aged and Old Adults. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000519848.75640.00] [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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Hamilton LD, Thomas E, Derqaoui K, Almuklass A, Enoka RM. Determinants Of Manual Dexterity In Middle-aged And Older Adults. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000487472.43093.a4] [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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Fine JS, Cai XY, Justice L, Gommoll CP, Hamilton LD, Waters TA, Narula SK, Bober LA, Grace MJ. A specific stimulator of granulocyte colony-stimulating factor accelerates recovery from cyclophosphamide-induced neutropenia in the mouse. Blood 1997; 90:795-802. [PMID: 9226180] [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: 02/04/2023] Open
Abstract
We have identified a small molecular weight compound, SCH 14988, which specifically stimulates in vitro granulocyte-colony stimulating factor (G-CSF) production from activated human peripheral blood mononuclear cells and monocytes but not other cytokines or CSFs with hematoregulatory activity. In vivo administration of SCH 14988 to mice rendered neutropenic by cyclophosphamide treatment resulted in the accelerated recovery of the peripheral neutrophil compartment. This activity correlated with increased in vivo G-CSF levels and stimulation of marrow granulopoiesis, and was comparable to that of exogenously administered recombinant human G-CSF. No alterations to other leukocyte populations in peripheral blood, spleen, or the peritoneal cavity were observed. These findings suggest that SCH 14988 may be clinically useful to enhance neutrophil granulopoiesis, as well as to study the mechanisms involved in G-CSF gene regulation.
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Affiliation(s)
- J S Fine
- Schering-Plough Research Institute, Department of Immunology, Kenilworth, NJ 07033, USA
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Hamilton LD. Various approaches to damage assessment. Health Phys 1996; 70:859-867. [PMID: 8635912 DOI: 10.1097/00004032-199606000-00012] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
There are two main approaches used to assess the damage to human health from exposure to low-level ionizing radiation. The first is a realistic best-estimate approach. The second is performed in support of the development of radiation standards to protect workers and the public, and tends to overestimate risk. This paper reviews these approaches to damage assessments as they have been applied to the development of radiation protection standards and current estimates of risk. Technical issues affected by these two different approaches include use of the linear hypothesis, use of relative and absolute risk projection models, dose-rate effectiveness factor, appropriateness of data sets, and the transfer of risks between populations. The prudent approach may be justified for radiation protection purposes, but scientific estimates of risk should reflect the state-of-the-science and include estimates of uncertainty.
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Affiliation(s)
- L D Hamilton
- Biomedical and Environmental Assessment Group, Brookhaven National Laboratory, Upton, NY 11973, USA
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Abstract
Interleukin-10 (IL-10), originally identified as an inhibitor of cytokine and monokine synthesis [e.g., IL-2, interferon-gamma (IFN-gamma), and tumor necrosis factor (TNF-alpha)], modulates a wide range of immunologic activities. In the present study we have examined the induction of non-major histocompatibility complex-restricted cytolytic activity in human peripheral blood mononuclear cells (PBMCs). PBMCs incubated with human IL-10 for 3 days were used as effector cells in cytotoxicity (i.e., 51Cr release) assays against a panel of human tumor cells. In a concentration-dependent manner. IL-10 stimulated or potentiated lytic activity against several human tumor cell lines. Induction of cytolytic activities by IL-10 was neutralized by anti-IL-10 monoclonal antibodies but not by antibodies against IFN-gamma or TNF-alpha. Co-incubation of PB-MCs with IL-10 and IL-2 or IL-10 and IFN-alpha augmented cytolytic activity, in particular at lower effector-to-target ratios. IL-2-induced release of TNF-alpha was dramatically reduced by IL-10; however, the expression of lymphokine-activated killer (LAK) activity was not affected. PBMCs preactivated with IL-10 before addition of IL-2 displayed higher levels of LAK activity. Inhibition of IL-2-driven LAK activity by IL-4 is alleviated by IL-10. Finally, IL-10 is not affected by inhibitors of IL-2, such as IL-4 and transforming growth factor-beta. Potential application of IL-10 to anti-tumor therapies is discussed.
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Affiliation(s)
- M A Schwarz
- Immunology Department, Schering-Plough Research Institute, Kenilworth, New Jersey 07033
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Hamilton LD, Nagy J, Robinson CV. Response to "genetic effects of the atomic bombs: a reappraisal". Health Phys 1983; 44:435-437. [PMID: 6841109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Bond VP, Hamilton LD. Leukemia in the Nevada 'Smoky' bomb test. JAMA 1980; 244:1610. [PMID: 7420667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Abstract
Several technologies to convert coal to liquid and gaseous fuels are being developed in the United States, some with support from the Department of Energy. Substitution of these technologies for those currently being used will produce different health and environmental hazards. In this article, selected health and environmental effects of four coal conversion and four existing technologies are compared. For each technology, the emission estimates for complete fuel cycles, including all steps in fuel use from extraction to the end use of space and water heating by electricity or direct combustion, were prepared by means of the Brookhaven Energy System Network Simulator model. Quantitative occupational health and safety estimates are presented for the extraction, transportation, distribution, processing, and conversion activities associated with each technology; also included are some public health damage estimates arising from fuel transportation and air pollution impacts. Qualitative estimates of health damage due to polycyclic organic matter and reduced sulfur are discussed. In general, energy inefficiencies, environmental residuals, and hence implied environmental effects and health damage increase in the order: (i) direct combustion of natural gas and oil, (ii) direct combustion of synthetic gas and oil, (iii) central-station electric power produced from synthetic gas, (iv) central-station electric power produced from coal, and (v) central-station electric power produced by the combustion of synthetic liquid fuels. The compliance and conflict of these technologies with the amendments of the Clean Air Act and other legislation are discussed.
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Bozzo SR, Novak KM, Galdos F, Hakoopian R, Hamilton LD. Mortality, migration, income and air pollution: a comparative study. Soc Sci Med Med Geogr 1979; 13 D:95-109. [PMID: 494014 DOI: 10.1016/0160-8002(79)90056-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Abstract
The hard and soft acids and bases (HSAB) principle, which states that hard acids bind preferentially to hard bases and soft acids to soft bases, may serve to assess specific chemico-biological interactions. As living systems are composed mainly of "hard" elements, molecular events taking place within the cell are dominated by "hard-hard interactions". On this premise, it becomes likely that extraneous "soft" agents are particularly injurious to life. In the HSAB context a selected number of variegated phenomena are briefly discussed qualitatively; these include biocidal actions, heavy metal poisoning, chemical carcinogenesis, some enzymic reactions, and nucleic acid complexations. Although the HSAB principle cannot be used as a tool for mechanistic explanations of biochemical processes, it may provide clues to likely target molecules and the loci of action.
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Abstract
Excision repair of UV-damaged Bacillus subtilis transforming DNA has been carried out by a sequential enzyme system in vitro. Incision adjacent to the pyrimidine dimer in the DNA strand by correndonuclease II-initiated excision of the damage by the 5' in equilibrium 3'-directed exonuclease of the Micrococcus luteus DNA polymerase. Reinsertion of nucleotides into the gap in the strand by the DNA polymerase at 10 degrees C terminated in a single-strand break which was sealed by a polynucleotide ligase, thereby repairing the DNA strand. This restored biological activity to damaged DNA up to doses resulting in 60% inactivation of transforming activity. At higher doses, less repair was achieved, due to the development of double-strand breaks during the in vitro incision and excision steps.
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Kim CW, Jamuar MP, Hamilton LD. Trichinella spiralis: effect of synthetic double-stranded polyribonucleotides. Exp Parasitol 1974; 35:92-101. [PMID: 4815021 DOI: 10.1016/0014-4894(74)90011-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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33
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Teng CT, Chen MC, Hamilton LD. Poly(inosinic acid)-poly(cytidylic acid) inhibition of DNA synthesis in synchronized HeLa cells. Proc Natl Acad Sci U S A 1973; 70:3904-8. [PMID: 4521216 PMCID: PMC427354 DOI: 10.1073/pnas.70.12.3904] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Inhibition by double-stranded polyribonucleotides of DNA synthesis in synchronized HeLa cultures is dose- and time-dependent. Inhibition by poly(I.C) primarily affected late G(1) and early S phases of the cell cycle. Single-stranded polynucleotides, native calf-thymus DNA, and yeast RNA had no effect. Radioautography showed that after 2-hr exposure the synthetic polyribonucleotides were predominantly inside the nucleus. The results extend the spectrum of action of double-stranded RNA.
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35
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McVicar JW, Richmond JY, Campbell CH, Hamilton LD. Observations of cattle, goats and pigs after administration of synthetic interferon inducers and subsequent exposure to foot and mouth disease virus. Can J Comp Med 1973; 37:362-8. [PMID: 4356316 PMCID: PMC1319793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Polyriboinosinic-polyribocytidylic acid (poly [rI.rC]) was administered intravenously to 11 cattle and 13 goats in doses of 0.25 to 4.0, and 1.0 to 5.0 mg/kg, respectively. Subsequent exposure of these and untreated control animals to foot and mouth disease virus (FMDV) failed to demonstrate any differences in either the course or severity of the disease. Serum interferon was detected in cattle one hour after the intravenous administration of poly (rI.rC). Six pigs given 4, 20, or 100 mg/kg of itaconic-acrylic acid copolymer (IAA, HMW) intraperitoneally reacted clinically the same as six untreated control pigs after contact exposure to FMDV. Three pigs given 50, 100, or 200 mg/kg of divinyl ether-maleic anhydride copolymer (DVE/MA, pyran) intraperitoneally similarly failed to show any difference in clinical reaction from three untreated control pigs after intranasal instillation of FMDV. Three pigs given 100, 200 or 400 mg/kg of DVE/MA intraperitoneally developed rapid diffuse peritonitis causing the death of one in 48 hours.
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Morahan PS, Munson AE, Regelson W, Commerford SL, Hamilton LD. Antiviral activity and side effects of polyriboinosinic-cytidylic acid complexes as affected by molecular size. Proc Natl Acad Sci U S A 1972; 69:842-6. [PMID: 4337241 PMCID: PMC426577 DOI: 10.1073/pnas.69.4.842] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The decrease of the molecular size of poly(I.C) to less than 10(6) decreases its ability to induce interferon, protect mice against virus, or enhance the immune response. Immune adjuvant activity appeared more sensitive to molecular weight than the other protective activities. The composition of the complex-the molecular size of the individual homopolymers when one was large and the other small-did not affect antiviral activity; the activity of a complex made from large poly(I) and small poly(C) was similar to one made from small poly(I) and large poly(C). Molecular size of the complex did not profoundly alter the side effects of poly(I.C). At 2 mg/kg, none of the complexes markedly altered phagocytic function. Only the largest complex sensitized the mouse to endotoxin. However, all of the complexes studied profoundly inhibited drug metabolism by the liver microsomal enzymes between 24 and 72 hr after their inoculation. Decreasing the molecular weight did not alter this inhibition.
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Kim CW, Jamuar MP, Hamilton LD. Transformation of lymphocytes from animals sensitized to Trichinella spiralis. J Immunol 1971; 107:1382-9. [PMID: 4256095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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41
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Zedeck MS, Marquardt H, Sternberg SS, Fleisher M, Hamilton LD. Role of adrenal cortical function in toxicity of polyriboinosinic-polyribocytidylic acid and its component homopolymers. Proc Natl Acad Sci U S A 1970; 67:180-4. [PMID: 5272311 PMCID: PMC283185 DOI: 10.1073/pnas.67.1.180] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Adrenalectomized rats are 1000 times more sensitive to lethal effects of the double-stranded complex polyriboinosinic.polyribocytidylic acid than intact rats. They are protected from such lethal effects by corticosterone. The complex can rapidly induce diffuse, severe necrosis of villous epithelium in small intestine without damage in crypts. Injection of the individual homopolymers, polyriboinosinic acid and polyribocytidylic acid, separately but in rapid succession is at least as lethal as injection of the complex.
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42
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Kim CW, Jamuar MP, Hamilton LD. Delayed hypersensitivity to Trichinella spiralis. 3. Effect of repeated sensitizations in donors and recipients. J Immunol 1970; 105:175-86. [PMID: 4246565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Abstract
The X-ray diffraction patterns of DNA do not support a four-stranded helical structure.
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Hamilton LD, Babcock VI, Southam CM. Inhibition of herpes simplex virus by synthetic double-stranded RNA (polyriboadenylic and polyribouridylic acids and polyriboinosinic and polyribocytidylic acids). Proc Natl Acad Sci U S A 1969; 64:878-83. [PMID: 4313333 PMCID: PMC223316 DOI: 10.1073/pnas.64.3.878] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Two-stranded polyriboadenylic and polyribouridylic acids and polyriboinosinic and polyribocytidylic acids protect against herpes simplex virus-induced cytopathogenicity in HEp 2 cultures, systemic herpes simplex virus infection in mice, and herpes simplex virus-induced keratoconjunctivitis in rabbits.
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Richmond JY, Hamilton LD. Foot-and-mouth disease virus inhibition induced in mice by synthetic double-stranded RNA (polyriboinosinic and polyribocytidylic acids). Proc Natl Acad Sci U S A 1969; 64:81-6. [PMID: 4312754 PMCID: PMC286129 DOI: 10.1073/pnas.64.1.81] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Synthetic 2-stranded RNA-a helical complex formed by duplexing homopolymers of polyriboinosinic and polyribocytidylic acids (poly I:C)-induced host resistance to foot-and-mouth disease virus when microgram quantities were injected into mice. There was a graded response as shown by titrations of polynucleotide complex or virus. Protection was effective for >48 hours after a single injection of polynucleotide complex. Survival and serum interferon titers were directly related.
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Hamilton LD. A nurse's aide program for youthful dropouts. Am J Nurs 1969; 69:518-20. [PMID: 5189794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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49
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50
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Jamuar MP, Kim CW, Hamilton LD. Fine structure of lymphocytes sensitized to Trichinella spiralis antigen. J Immunol 1968; 100:329-37. [PMID: 5639701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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