Publications by authors named "J Jeffrey Carr"

2,354 Publications

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Quantitation of Regulatory Activity for the Complement Alternative PathwayUsing an Adaptation of the AP Assay.

Bio Protoc 2018 Dec 20;8(24):e3116. Epub 2018 Dec 20.

College of Medicine and Public Health, Flinders University, Bedford Park, Adelaide, South Australia.

Complement pathways function to identify and remove pathogens and infected cells. There are three complement pathways: the classical, lectin and alternative pathway (AP). While all pathways are activated following pathogen stimuli, the AP is constitutively active and tightly controlled by activators (, Factor B, Factor D) and negative regulators (, Factor H). Complement activity can be measured by well-established methods that are often used in a diagnostic setting to determine the CH (50% complement hemolytic activity) or AP, specifically to measure AP activity. The protocol here has adapted the traditional AP method designed to measure AP activity in human sera, to measure the positive or negative AP regulatory activity within a given test sample. The assay relies on the ability of AP components in human serum to lyse rabbit erythrocytes under conditions specific for the AP with subsequent release of hemoglobin that is quantitated by measurement of optical density. Our method has added test substances, such as cell culture media with defined changes in individual complement components and determined the ability to either promote or inhibit AP activity . Thus, this protocol reflects the overall functional ability of a sample to effect AP activity and can be used in the research laboratory to determine AP regulatory activity in a complex biological sample, or to test the ability of drugs or novel biomolecules to regulate AP activity.
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http://dx.doi.org/10.21769/BioProtoc.3116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8342107PMC
December 2018

Editorial Commentary: Platelet-Rich Plasma Shows Promise for Improving Shoulder Tendinopathy.

Authors:
James B Carr

Arthroscopy 2021 09;37(9):2754-2755

West Palm Beach, Florida.

Platelet-rich plasma (PRP) injections continue to be used at increasing rates to treat common musculoskeletal conditions. PRP has a low-risk profile and emerging in vitro evidence to support its positive effects on soft-tissue healing. PRP has been shown to be of benefit for knee osteoarthritis, but less has been published regarding the shoulder. PRP delivers a high concentration of growth factors, cytokines, and other important inflammatory modulators. Its use is appealing for treating partial-thickness rotator cuff tears, subacromial bursitis, and rotator cuff tendinopathy since rotator cuff tendons often have poor healing capacity due to intrinsic degeneration. PRP has been shown to increase cell proliferation and matrix synthesis in tenocytes, which may aid tendon regeneration and healing. Adult tendons also contain a small amount of tendon progenitor cells, which can be induced to an active state by PRP. In addition, PRP is an autologous biologic agent and easy to acquire and administer in an outpatient clinical setting. Clinical studies continue to lag and are often heterogenous in quality and in results. PRP can vary widely based on multiple intrinsic and extrinsic factors, including patient age, sex, activity level, centrifugation speed, and number of centrifugation cycles. Thus, quality research methods should include reporting using the PAW (platelets/activation/white blood cells) system. Clinicians should remain cautiously optimistic about the future role of PRP injections in the shoulder.
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http://dx.doi.org/10.1016/j.arthro.2021.05.045DOI Listing
September 2021

Automated segmentation of biventricular contours in tissue phase mapping using deep learning.

NMR Biomed 2021 Sep 2:e4606. Epub 2021 Sep 2.

Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.

Tissue phase mapping (TPM) is an MRI technique for quantification of regional biventricular myocardial velocities. Despite its potential, clinical use is limited due to the requisite labor-intensive manual segmentation of cardiac contours for all time frames. The purpose of this study was to develop a deep learning (DL) network for automated segmentation of TPM images, without significant loss in segmentation and myocardial velocity quantification accuracy compared with manual segmentation. We implemented a multi-channel 3D (three dimensional; 2D + time) dense U-Net that trained on magnitude and phase images and combined cross-entropy, Dice, and Hausdorff distance loss terms to improve the segmentation accuracy and suppress unnatural boundaries. The dense U-Net was trained and tested with 150 multi-slice, multi-phase TPM scans (114 scans for training, 36 for testing) from 99 heart transplant patients (44 females, 1-4 scans/patient), where the magnitude and velocity-encoded (V , V , V ) images were used as input and the corresponding manual segmentation masks were used as reference. The accuracy of DL segmentation was evaluated using quantitative metrics (Dice scores, Hausdorff distance) and linear regression and Bland-Altman analyses on the resulting peak radial and longitudinal velocities (V and V ). The mean segmentation time was about 2 h per patient for manual and 1.9 ± 0.3 s for DL. Our network produced good accuracy (median Dice = 0.85 for left ventricle (LV), 0.64 for right ventricle (RV), Hausdorff distance = 3.17 pixels) compared with manual segmentation. Peak V and V measured from manual and DL segmentations were strongly correlated (R ≥ 0.88) and in good agreement with manual analysis (mean difference and limits of agreement for V and V were -0.05 ± 0.98 cm/s and -0.06 ± 1.18 cm/s for LV, and -0.21 ± 2.33 cm/s and 0.46 ± 4.00 cm/s for RV, respectively). The proposed multi-channel 3D dense U-Net was capable of reducing the segmentation time by 3,600-fold, without significant loss in accuracy in tissue velocity measurements.
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http://dx.doi.org/10.1002/nbm.4606DOI Listing
September 2021

Association of Pitch Timing and Throwing Arm Kinetics in High School and Professional Pitchers.

Am J Sports Med 2021 Aug 18:3635465211031853. Epub 2021 Aug 18.

Sports Medicine Institute Hospital for Special Surgery, New York, New York, USA.

Background: Understanding the relationship between the temporal phases of the baseball pitch and subsequent joint loading may improve our understanding of optimal pitching mechanics and contribute to injury prevention in baseball pitchers.

Purpose: To investigate the temporal phases of the pitching motion and their associations with ball velocity and throwing arm kinetics in high school (HS) and professional (PRO) baseball pitchers.

Study Design: Descriptive laboratory study.

Methods: PRO (n = 317) and HS (n = 54) baseball pitchers were evaluated throwing 8 to 12 fastball pitches using 3-dimensional motion capture (480 Hz). Four distinct phases of the pitching motion were evaluated based on timing of angular velocities: (1) Foot-Pelvis, (2) Pelvis-Torso, (3) Torso-Elbow, and (4) Elbow-Ball. Peak elbow varus torque, shoulder internal rotation torque, and shoulder distraction force were also calculated and compared between playing levels using 2-sample tests. Linear mixed-effect models with compound symmetry covariance structures were used to correlate pitch velocity and throwing arm kinetics with the distinct temporal phases of the pitching motion.

Results: PRO pitchers had greater weight and height, and faster ball velocities than HS pitchers ( < .001). There was no difference in total pitch time between groups ( = .670). PRO pitchers spent less time in the Foot-Pelvis ( = .010) and more time in the Pelvis-Torso ( < .001) phase comparatively. Shorter time spent in the earlier phases of the pitching motion was significantly associated with greater ball velocity for both PRO and HS pitchers (Foot-Pelvis: B = -6.4 and B = -11.06, respectively; Pelvis-Torso: B = -6.4 and B = -11.4, respectively), while also associated with increased shoulder proximal force (Pelvis-Torso: B = -76.4 and B = -77.5, respectively). Decreased time in the Elbow-Ball phase correlated with greater shoulder proximal force for both cohorts (B = -1150 and B = -645, respectively) with no significant correlation found for ball velocity.

Conclusion: Significant differences in temporal phases exist between PRO and HS pitchers. For all pitchers, increased time spent in the final phase of the pitching motion has the potential to decrease shoulder distraction force with no significant loss in ball velocity.

Clinical Relevance: Identifying risk factors for increased shoulder and elbow kinetics, acting as a surrogate for loading at the respective joints, has potential implications in injury prevention.
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http://dx.doi.org/10.1177/03635465211031853DOI Listing
August 2021

A multifaceted quality improvement intervention to improve management of alcohol withdrawal on a general medicine ward: impact on benzodiazepine use.

J Addict Dis 2021 Aug 6:1-4. Epub 2021 Aug 6.

Division of General Internal Medicine, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA.

Objective: To measure the effects of a quality improvement intervention on length of stay and benzodiazepine use among patients admitted for alcohol use disorder.

Methods: This retrospective cohort study was performed at the Salt Lake City Veterans Affairs Medical Center. Patients 18 years and older admitted to a general medical ward with a diagnosis of alcohol related disorders who were treated for alcohol withdrawal were included. The baseline cohort included patients admitted over 12 months. The post-intervention cohort included patients admitted over 12 months. Primary outcomes were total benzodiazepine dose and length of stay. Secondary outcomes included episodes of delirium tremens and seizures.

Results: Total benzodiazepine dose decreased significantly over the intervention period. Length of stay also decreased. No episodes of delirium tremens or seizures were observed.

Conclusions: A quality improvement intervention directed at general medicine inpatients admitted for alcohol withdrawal was associated with reductions in total benzodiazepine administration and length of stay.
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http://dx.doi.org/10.1080/10550887.2021.1960121DOI Listing
August 2021
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