Publications by authors named "Timothy S Johnson"

Background: As machine learning becomes increasingly utilized in orthopaedic clinical research, the application of machine learning methodology to cohort data from the Multicenter ACL Revision Study (MARS) presents a valuable opportunity to translate data into patient-specific insights.

Purpose: To apply novel machine learning methodology to MARS cohort data to determine a predictive model of revision anterior cruciate ligament reconstruction (rACLR) graft failure and features most predictive of failure.

Study Design: Cohort study; Level of evidence, 3.

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Background: Revision anterior cruciate ligament (ACL) reconstruction has been documented to have inferior outcomes compared with primary ACL reconstruction. The reasons why remain unknown.

Purpose: To determine whether surgical factors performed at the time of revision ACL reconstruction can influence a patient's outcome at 6-year follow-up.

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Pulmonary fibrosis is an interstitial scarring disease of the lung characterized by poor prognosis and limited treatment options. Tissue transglutaminase 2 (TG2) is believed to promote lung fibrosis by crosslinking extracellular matrix components and activating latent TGFβ. This study assessed physiologic pulmonary function and metabolic alterations in the mouse bleomycin model with TG2 genetic deletion.

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Fibrotic remodeling is the primary driver of functional loss in chronic kidney disease, with no specific anti-fibrotic agent available for clinical use. Transglutaminase 2 (TG2), a wound response enzyme that irreversibly crosslinks extracellular matrix proteins causing dysregulation of extracellular matrix turnover, is a well-characterized anti-fibrotic target in the kidney. We describe the humanization and characterization of two anti-TG2 monoclonal antibodies (zampilimab [hDC1/UCB7858] and BB7) that inhibit crosslinking by TG2 in human in vitro and rabbit/cynomolgus monkey in vivo models of chronic kidney disease.

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Introduction: After undergoing breast reconstructive surgery, patients are typically prescribed opioids. Smoking tobacco increases rate of opioid metabolism and is associated with development of opioid use disorder (OUD). The aim of this study was to determine whether patients who smoke have an increased risk of OUD after breast reconstructive surgery.

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Objective: Fibrotic tissues are characterized by excessive crosslinking between extracellular matrix (ECM) proteins, rendering them more resistant to degradation. Although increased crosslinking of ECM is thought to play an important role for progression of tissue fibrosis, enhanced ECM crosslinking has not yet been targeted therapeutically in systemic sclerosis (SSc). Here, we investigated the role of transglutaminase 2 (TG2), a central crosslinking enzyme, in the activation of SSc fibroblasts.

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Introduction: With an increasing focus on multimodal pain control to reduce opioid requirements, regional and local anesthesia techniques have been investigated in bilateral reduction mammaplasty with variable results. The purpose of this study is to compare tumescent anesthesia with pectoral nerve block II (PECS II) in patients undergoing bilateral reduction mammaplasty with respect to postoperative pain and nausea, opioid consumption, length of stay, and cost.

Methods: A retrospective review of patients undergoing bilateral reduction mammaplasty for macromastia between November 2020 and December 2021 was performed.

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Background: Meniscal and chondral damage is common in the patient undergoing revision anterior cruciate ligament (ACL) reconstruction.

Purpose: To determine if meniscal and/or articular cartilage pathology at the time of revision ACL surgery significantly influences a patient's outcome at 6-year follow-up.

Study Design: Cohort study; Level of evidence, 3.

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Article Synopsis
  • The study investigates the differences in preoperative characteristics, intraoperative findings, and outcomes after two years for patients undergoing revision ACL reconstruction (rACLR) with and without bone grafting.
  • Out of 1,234 patients analyzed, 159 (13%) required bone grafting, with variables including the type of grafting (1-stage or 2-stage) affecting preoperative quality of life and activity levels.
  • Patients needing 2-stage grafting had undergone more previous ACL surgeries and were less likely to have used certain types of grafts in their initial surgeries compared to those who did not require grafting.
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Background: The role sex plays in surgical leadership positions is heavily discussed in the literature; however, there is an absence of research looking at plastic surgery program director (PD) demographics and the differences between male and female PDs.

Methods: A cross sectional study of publicly available online resources of all integrated plastic surgery residency programs was performed. Demographic and academic data of integrated plastic surgery PDs was analyzed focusing on the differences in PDs based on sex.

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Background: Patients with anterior cruciate ligament (ACL) revision report lower outcome scores on validated knee questionnaires postoperatively compared to cohorts with primary ACL reconstruction. In a previously active population, it is unclear if patient-reported outcomes (PROs) are associated with a return to activity (RTA) or vary by sports participation level (higher level vs. recreational athletes).

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Renal clinical chemistry only detects kidney dysfunction after considerable damage has occurred and is imperfect in predicting long term outcomes. Consequently, more sensitive markers of early damage and better predictors of progression are being urgently sought, to better support clinical decisions and support shorter clinical trials. Transglutaminase 2 (TG2) is strongly implicated in the fibrotic remodeling that drives chronic kidney disease (CKD).

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Background: Chronic kidney disease (CKD) has a high global prevalence and large unmet need. Central to developing new CKD therapies are in vivo models in CKD. However, next-generation antibody, protein, and gene therapies are highly specific, meaning some do not cross-react with rodent targets.

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Background And Purpose: Transglutaminase type 2 (TG2) catalyses formation of ε-(γ-glutamyl)-lysine bonds between proteins, including those of the extracellular matrix (ECM). Elevated extracellular TG2 leads to accelerated ECM deposition and reduced clearance that underlies tissue scarring and fibrosis. Many transglutaminase inhibitors exist and allowed for proof-of-concept studies in disease models, but their lack of specificity for the TG2 isoform, and/or poor pharmacokinetic/pharmacodynamic properties have limited their clinical application.

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Background:  Head and neck free flap reconstructions are complex procedures requiring extensive resources, and have the potential to be highly morbid. As such, it is imperative that they should be performed in an appropriate setting, optimizing outcomes while limiting morbidity. The aim of this study is to identify any disparities in the treatment outcomes of patients undergoing head and neck free flap reconstruction by a single surgeon in an academic versus a community hospital setting.

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Background: Although graft choice may be limited in the revision setting based on previously used grafts, most surgeons believe that graft choice for anterior cruciate ligament (ACL) reconstruction is an important factor related to outcome.

Hypothesis: In the ACL revision setting, there would be no difference between autograft and allograft in rerupture rate and patient-reported outcomes (PROs) at 6-year follow-up.

Study Design: Cohort study; Level of evidence, 2.

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Breeding crops for improved flavor is challenging due to the high cost of sensory evaluation and the difficulty of connecting sensory experience to chemical composition. The main goal of this study was to identify the chemical drivers of sweetness and consumer liking for fresh strawberries (Fragaria × ananassa). Fruit of 148 strawberry samples from cultivars and breeding selections were grown and harvested over seven years and were subjected to both sensory and chemical analyses.

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Ubiquinone (Coenzyme Q) is a vital respiratory cofactor and antioxidant in eukaryotes. The recent discovery that kaempferol serves as a precursor for ubiquinone's benzenoid moiety both challenges the conventional view of flavonoids as specialized metabolites, and offers new prospects for engineering ubiquinone in plants. Here, we present evidence that Arabidopsis thaliana mutants lacking kaempferol 3-O-rhamnosyltransferase (ugt78d1) and kaempferol 3-O-glucosyltransferase (ugt78d2) activities display increased de novo biosynthesis of ubiquinone and increased ubiquinone content.

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Mosquito larvicides are an effective tool for reducing numbers of adult females that bite and potentially spread pathogenic organisms. Methionine, an essential amino acid in humans, has been previously demonstrated to be a highly effective larvicide against four (4) mosquito species in three (3) genera, Anopheles, Culex and Aedes. The aim of the present study was to determine the potential impact on non-target aquatic organisms of methionine applied as a mosquito larvicide.

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Background: Risk for venous thromboembolism formation and the relationship to postoperative free flap venous congestion and flap failure have not been adequately evaluated in a trauma population. The authors aim to use the Caprini Risk Assessment Model to evaluate the association between venous thromboembolism risk and postoperative flap venous congestion following lower extremity free tissue transfer.

Methods: A retrospective analysis was conducted of all patients who underwent lower extremity free flap reconstruction of traumatic defects at a single institution between 2007 and 2016.

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Infection is a rare occurrence after revision anterior cruciate ligament reconstruction (rACLR). Because of the low rates of infection, it has been difficult to identify risk factors for infection in this patient population. The purpose of this study was to report the rate of infection following rACLR and assess whether infection is associated with patient- and surgeon-dependent risk factors.

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Background: Meniscal preservation has been demonstrated to contribute to long-term knee health. This has been a successful intervention in patients with isolated tears and tears associated with anterior cruciate ligament (ACL) reconstruction. However, the results of meniscal repair in the setting of revision ACL reconstruction have not been documented.

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Plants produce a range of volatile organic compounds (VOCs), some of which are perceived by the human olfactory system, contributing to a myriad flavors. Despite the importance of flavor for consumer preference, most plant breeding programs have neglected it, mainly because of the costs of phenotyping and the complexity of disentangling the role of VOCs in human perception. To develop molecular breeding tools aimed at improving fruit flavor, we carried out target genotyping of and VOC extraction from a blueberry population.

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Plants have evolved the ability to derive the benzenoid moiety of the respiratory cofactor and antioxidant, ubiquinone (coenzyme Q), either from the β-oxidative metabolism of p-coumarate or from the peroxidative cleavage of kaempferol. Here, isotopic feeding assays, gene co-expression analysis and reverse genetics identified Arabidopsis 4-COUMARATE-COA LIGASE 8 (4-CL8; At5g38120) as a contributor to the β-oxidation of p-coumarate for ubiquinone biosynthesis. The enzyme is part of the same clade (V) of acyl-activating enzymes than At4g19010, a p-coumarate CoA ligase known to play a central role in the conversion of p-coumarate into 4-hydroxybenzoate.

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