Publications by authors named "Carl A Johnson"

Decompensated right ventricular failure (RVF) in pulmonary hypertension (PH) is fatal, with limited medical treatment options. Developing and testing novel therapeutics for PH requires a clinically relevant large animal model of increased pulmonary vascular resistance and RVF. This manuscript describes the method to induce an ovine PH-RVF model that utilizes left pulmonary artery (LPA) ligation, progressive main pulmonary artery (MPA) banding, and insertion of an RV pressure line for monitoring.

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Article Synopsis
  • Right heart failure is a leading cause of death in pulmonary hypertension, and lung transplants are limited due to the lack of donor lungs, highlighting the need for mechanical support for the right heart.
  • A study involved six sheep with chronic right heart failure using a wearable mechanical support system that combined a blood pump and a gas exchange unit, allowing some animals to move around freely while receiving support.
  • The system was effective, achieving similar blood flow levels to the heart and maintaining balanced blood gas levels, demonstrating potential for portable solutions in managing right heart failure.
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The interleukin-3 receptor α subunit, CD123, is expressed in many hematologic malignancies including acute myeloid leukemia (AML) and blastic plasmacytoid dendritic cell neoplasm (BPDCN). Tagraxofusp (SL-401) is a CD123-targeted therapy consisting of interleukin-3 fused to a truncated diphtheria toxin payload. Factors influencing response to tagraxofusp other than CD123 expression are largely unknown.

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Objective: Aortic root enlargement may be necessary to implant adequately sized valves to avoid patient-prosthetic mismatch. Our objective was to assess the feasibility of annular enlargement during aortic valve replacement via a right anterior minithoracotomy.

Methods: Twelve consecutive patients undergoing elective minimally invasive aortic valve replacement requiring annular enlargement over a 2-year period were retrospectively reviewed.

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Objective: Subaortic membrane is an anatomical intracardiac anomaly that may cause discrete subaortic stenosis and aortic insufficiency. Patients requiring subaortic membrane resection may benefit from a minimally invasive approach; however, subaortic membranes are typically resected through a median sternotomy. We present our initial clinical experience of adult patients who have undergone a mini-thoracotomy subaortic membrane resection.

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Objective: Bentall procedures are traditionally performed through a median sternotomy. The right mini-thoracotomy approach is increasingly used in aortic valve replacement. This approach has been shown to have decreased blood loss and hospital length of stay compared with sternotomy.

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Objective: The objective of this study was to investigate the feasibility of using titanium fasteners for securement of the inflow sewing ring during HeartMate 3 implantation. The secondary objective was to compare cardiopulmonary bypass and total operative times between the titanium fastener and hand-tied knot groups.

Methods: Clearance between the sewing ring and the HeartMate 3 device was assessed in vitro.

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Ovines are a common animal model for the study of cardiovascular devices, where consideration of blood biocompatibility is an essential design criterion. In the ovine model, tools to assess blood biocompatibility are limited and continued investigation to identify and apply additional assays is merited. Toward this end, the thrombelastograph, clinically utilized to assess hemostasis, was used to characterize normal ovine parameters.

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Focused research targeting an identified clinical problem may result in more rapid development of medical devices, technologies, and surgical techniques that directly impact patient care. These medical advances to improve patient care may be expedited by adopting an interactive translational research model in which inventors, designers, and engineers work in collaboration with surgeons. In addition, cadaveric simulation is a high-fidelity model that is bridging the translational and logistical gap to bring new surgical devices, technologies, and techniques to patients.

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Background: Optimal pain control continues to be a concern in cardiac surgery. Current strategies for postoperative pain management often yield suboptimal results. The superiority of Exparel (Pacira Pharmaceuticals, Inc, Parsippany, NJ) in providing postoperative pain control and opioid sparing is equivocal.

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Bentall procedures are traditionally performed through a median sternotomy. However, minimally invasive approaches are increasingly being utilized. A right mini-thoracotomy approach may improve postoperative recovery.

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Aortic valve replacement through minimally invasive access is increasing. These procedures have several advantages over conventional sternotomy including decreased intensive care unit and hospital length of stay and decreased ventilation time. The right anterior mini-thoracotomy (RAM) approach is potentially attractive in that it completely spares the sternum leading to improved cosmesis, reduced blood loss, and improved patient satisfaction.

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Aortic root replacement is typically performed through a median sternotomy. The right anterior mini-thoracotomy approach has been shown to decrease hospital length of stay in aortic valve surgery when compared to sternotomy. This approach is rare in ascending aortic surgery due to technical challenges which include exposure and annular suture placement.

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Objective: Aortic cross-clamp and cardiopulmonary bypass times are independent predictors of postoperative morbidity and mortality. Reducing ischemic times with automated titanium fasteners may improve surgical outcomes. This study compared operative times and costs of titanium fasteners versus hand-tied knots for prosthesis securement in open aortic valve replacement.

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NOTCH1 is frequently mutated in adenoid cystic carcinoma (ACC). To test the idea that immunohistochemical (IHC) staining can identify ACCs with NOTCH1 mutations, we performed IHC for activated NOTCH1 (NICD1) in 197 cases diagnosed as ACC from 173 patients. NICD1 staining was positive in 194 cases (98%) in 2 major patterns: subset positivity, which correlated with tubular/cribriform histology; and diffuse positivity, which correlated with a solid histology.

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Introduction: Menthol cigarette smoking may increase the risk for tobacco smoke exposure and inhibit nicotine metabolism in the liver. Nicotine metabolism is primarily mediated by the enzyme CYP2A6 and the nicotine metabolite ratio (NMR = trans 3' hydroxycotinine/cotinine) is a phenotypic proxy for CYP2A6 activity. No studies have examined differences in this biomarker among young adult daily menthol and nonmenthol smokers.

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Current artificial lungs and respiratory assist devices designed for carbon dioxide removal (CO(2)R) are limited in their efficiency due to the relatively small partial pressure difference across gas exchange membranes. To offset this underlying diffusional challenge, bioactive hollow fiber membranes (HFMs) increase the carbon dioxide diffusional gradient through the immobilized enzyme carbonic anhydrase (CA), which converts bicarbonate to CO(2) directly at the HFM surface. In this study, we tested the impact of CA-immobilization on HFM CO(2) removal efficiency and thromboresistance in blood.

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Purpose: Compulsive Internet Use (CIU) has increasingly become an area of research among process addictions. Largely based on data from cross-sectional studies, a positive association between CIU and substance use has previously been reported. This study presents gender and country-specific longitudinal findings on the relationships between CIU and substance use.

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Ventricular assist devices (VADs) have significantly impacted the treatment of adult cardiac failure, but few options exist for pediatric patients. This has motivated our group to develop an implantable magnetically levitated rotodynamic VAD (PediaFlow®) for 3-20 kg patients. The second prototype design of the PediaFlow (PF2) is 56% smaller than earlier prototypes, and achieves 0.

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The Levitronix PediVAS is an extracorporeal magnetically levitated pediatric ventricular assist system with an optimal flow rate range of 0.3-1.5 L/min.

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The PediaFlow pediatric ventricular assist device (VAD) is a magnetically levitated turbodynamic pump under development for circulatory support of small children with a targeted flow rate range of 0.3-1.5 L/min.

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Hollow fiber membrane (HFM)-based artificial lungs can require a large blood-contacting membrane surface area to provide adequate gas exchange. However, such a large surface area presents significant challenges to hemocompatibility. One method to improve carbon dioxide (CO(2)) transfer efficiency might be to immobilize carbonic anhydrase (CA) onto the surface of conventional HFMs.

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The PediaFlow pediatric ventricular assist device is a miniature magnetically levitated mixed flow pump under development for circulatory support of newborns and infants (3-15 kg) with a targeted flow range of 0.3-1.5 L/min.

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Thrombosis and thromboembolism remain problematic for a large number of blood contacting medical devices and limit broader application of some technologies due to this surface bioincompatibility. In this study we focused on the covalent attachment of zwitterionic phosphorylcholine (PC) or sulfobetaine (SB) moieties onto a TiAl(6)V(4) surface with a single step modification method to obtain a stable blood compatible interface. Silanated PC or SB modifiers (PCSi or SBSi) which contain an alkoxy silane group and either PC or SB groups were prepared respectively from trimethoxysilane and 2-methacryloyloxyethyl phosphorylcholine (MPC) or N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (SMDAB) monomers by a hydrosilylation reaction.

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To improve the thromboresistance of a titanium alloy (TiAl(6)V(4)) surface which is currently utilized in several ventricular assist devices (VADs), a plasma-induced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) was carried out and poly(MPC) (PMPC) chains were covalently attached onto a TiAl(6)V(4) surface by a plasma induced technique. Cleaned TiAl(6)V(4) surfaces were pretreated with H(2)O-vapor-plasma and silanated with 3-methacryloylpropyltrimethoxysilane (MPS). Next, a plasma-induced graft polymerization with MPC was performed after the surfaces were pretreated with Ar plasma.

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