Publications by authors named "McClellan R"

The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties.

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Study Design: Prospective cross-sectional survey.

Objective: To identify timelines for when athletes may be considered safe to return to varying athletic activities after sustaining cervical spine fractures.

Background: While acute management and detection of cervical spine fractures have been areas of comprehensive investigation, insight into timelines for when athletes may return to different athletic activities after sustaining such fractures is limited.

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Background: The mechanisms of AF development and progression are still not completely understood. Despite the relative efficacy of ablation, the risk of AF recurrence is substantial, particularly in patients with persistent AF (perAF). At present we do not have any reliable intra-procedural electrophysiologic predictors of long-term success of AF ablation other than pulmonary vein isolation.

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Article Synopsis
  • Genetic testing is essential for diagnosing long QT syndrome (LQTS) and can provide valuable information for patients and their families, but about 25% of patients show no identifiable genetic variants despite having significant symptoms.
  • The prognosis for these patients mirrors that of those with known genetic variants, highlighting the need to investigate various potential causes of QT interval prolongation beyond genetic factors, including environmental influences and exercise-related issues.
  • Continuous advancements in genetics may reveal new risk factors and causal genes for LQTS, emphasizing the importance of expert cardiogenetic clinics in effectively managing and counseling affected patients, especially those with unclear genetic test results.
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The mechanisms of particle-induced pathogenesis in the lung remain poorly understood. Neutrophilic inflammation and oxidative stress in the lung are hallmarks of toxicity. Some investigators have postulated that oxidative stress from particle surface reactive oxygen species (psROS) on the dust produces the toxicopathology in the lungs of dust-exposed animals.

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Targeted delivery of nucleic acid therapeutics to the lungs could transform treatment options for pulmonary disease. We have previously developed oligomeric charge-altering releasable transporters (CARTs) for in vivo mRNA transfection and demonstrated their efficacy for use in mRNA-based cancer vaccination and local immunomodulatory therapies against murine tumors. While our previously reported glycine-based CART-mRNA complexes (mRNA) show selective protein expression in the spleen (mouse, >99%), here, we report a new lysine-derived CART-mRNA complex mRNA that, without additives or targeting ligands, shows selective protein expression in the lungs (mouse, >90%) following systemic IV administration.

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The proton is one of the main building blocks of all visible matter in the Universe. Among its intrinsic properties are its electric charge, mass and spin. These properties emerge from the complex dynamics of its fundamental constituents-quarks and gluons-described by the theory of quantum chromodynamics.

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When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure, and mapping out the strength and the isospin structure (neutron-proton (np) versus proton-proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements.

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Background: The relationship between inflammation and corrected QT (QTc) interval prolongation is currently not well defined in patients with COVID-19.

Objective: This study aimed to assess the effect of marked interval changes in the inflammatory marker C-reactive protein (CRP) on QTc interval in patients hospitalized with COVID-19.

Methods: In this retrospective cohort study of hospitalized adult patients admitted with COVID-19 infection, we identified 85 patients who had markedly elevated CRP levels and serial measurements of an ECG and CRP during the same admission.

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The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio.

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Humans will set foot on the Moon again soon. The lunar dust (LD) is potentially reactive and could pose an inhalation hazard to lunar explorers. We elucidated LD toxicity and investigated the toxicological impact of particle surface reactivity (SR) using three LDs, quartz, and TiO.

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Three-dimensional (3D) culture systems have been developed that can re-capitulate organ level responses, simulate compound diffusion through complex structures, and assess cellular heterogeneity of tissues, making them attractive models for advanced in vitro research and discovery. Organoids are a unique subtype of 3D cell culture that are grown from stem cells, are self-organizing, and closely replicate in vivo pathophysiology. Organoids have been used to understand tissue development, model diseases, test drug sensitivity and toxicity, and advance regenerative medicine.

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We report a case series of 4 patients with transient marked QTc prolongation and ventricular arrhythmias in the setting of inflammation with very high ferritin levels. Three patients were positive for coronavirus disease-2019. In the setting of an acute rise in inflammatory markers, electrocardiography screening for QTc prolongation is warranted.

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Background: Implantable cardioverter-defibrillators (ICDs) are an effective treatment in some patients with inherited heart disease, including inherited channelopathies, yet they have also been shown to impact patients' psychological health.

Objective: We sought to improve understanding of the level of anxiety and depression as well as device acceptance among inherited channelopathy patients with an ICD.

Methods: Eligible patients seen at Johns Hopkins Hospital were sent a survey, which included the Hospital Anxiety and Depression Scale (HADS), Cardiac Anxiety Questionnaire (CAQ), and the Florida Patient Acceptance Survey (FPAS).

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The fundamental building blocks of the proton-quarks and gluons-have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as its spin. The two up quarks and the single down quark that comprise the proton in the simplest picture account only for a few per cent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force.

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Osteobiologics are defined as a group of natural and synthetic materials used to augment bone healing. The selection of the most appropriate osteobiologic from the growing list of available options can be a challenging task. In selecting a material, surgeons should weigh a variety of considerations, including the indication for their use (the when), the most suitable substance (the what), and the correct mode of application (the how).

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We report the first measurement of the (e,e^{'}p) three-body breakup reaction cross sections in helium-3 (^{3}He) and tritium (^{3}H) at large momentum transfer [⟨Q^{2}⟩≈1.9  (GeV/c)^{2}] and x_{B}>1 kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta 40≤p_{miss}≤500  MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon.

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Background: It is estimated that less than 10% of cases of familial hypercholesterolemia (FH) in the United States have been diagnosed. Low rates of diagnosis may in part be attributable to affected patients not meeting the clinical diagnostic criteria of the Dutch Lipid Clinic Network (DLCN), Simon Broome, or US MEDPED diagnostic criteria.

Objective: The objective of this study was to assess the utility of incorporating genetic testing into a patient's evaluation for FH.

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Purpose: To systemically describe posterior bone defects in the setting of posterior shoulder instability based on several parameters, including surface area, slope and version, defect height from the base of the glenoid, and extent of bone loss at equal intervals along the long axis of the fossa.

Methods: A total of 40 young, active individuals with recurrent posterior shoulder instability and a bony injury confirmed on either computed tomography (n = 18; mean age, 26.3 ± 4.

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The US Transuranium and Uranium Registries is a human tissue program that collects tissues posthumously from former nuclear workers and radiochemically analyzes them for actinides such as plutonium, americium, and uranium. It was established in 1968 with the goal of advancing science and improving the safety of future workers. Roundtable participants recalled various aspects of this multidisciplinary research program, from establishing consistent autopsy protocols to comparing the registries' findings to those of other programs, such as the historical beagle dog studies and the Russian Radiobiological Human Tissue Repository.

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RNA technology is transforming life science research and medicine, but many applications are limited by the accessibility, cost, efficacy, and tolerability of delivery systems. Here we report the first members of a new class of dynamic RNA delivery vectors, oligo(serine ester)-based charge-altering releasable transporters (Ser-CARTs). Composed of lipid-containing oligocarbonates and cationic oligo(serine esters), Ser-CARTs are readily prepared (one flask) by a mild ring-opening polymerization using thiourea anions and, upon simple mixing with mRNA, readily form complexes that degrade to neutral serine-based products, efficiently releasing their mRNA cargo.

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