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Search Results: 1 - 10 of 228576 matches for " Robert D. Brown Jr. "
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Entecavir for treatment of chronic hepatitis B: A clinical update for the treatment of patients with decompensated cirrhosis  [PDF]
P. Patrick Basu, Robert S. Brown Jr.
Open Journal of Internal Medicine (OJIM) , 2012, DOI: 10.4236/ojim.2012.22012
Abstract: The introduction of nucleos(t)ide analogues for the treatment of chronic hepatitis B virus (HBV) infection was transformative in reducing morbidity and mortality. Entecavir, a potent selective nucleoside analogue first approved in 2005 for treatment of chronic HBV, is associated with significant antiviral, biochemical, serologic, and histologic responses. Rapid reductions in HBV DNA levels, low risk of resistance development, and a favorable adverse event profile have contributed to its clinical usefulness. Re-cent developments in the use of entecavir have increased its utility in the management of difficult-to-treat patients with chronic HBV, including those patients with decompensated liver disease. Recent studies in this population have demonstrated that entecavir 1.0 mg/d given for up to 48 weeks had superior antiviral activity when compared with adefovir and was generally safe and well tolerated. Long-term outcomes of entecavir in difficult-to-treat populations are eagerly anticipated.
Prognostic Value of Complete Blood Count and Electrolyte Panel during Emergency Department Evaluation for Acute Ischemic Stroke
Latha Ganti,Rachel M. Gilmore,Amy L. Weaver,Robert D. Brown Jr.
ISRN Stroke , 2013, DOI: 10.1155/2013/974236
Abstract: Objective. To determine whether routine laboratory parameters are predictors of early mortality after acute ischemic stroke (AIS). Methods. The cohort consisted of 522 consecutive patients with AIS presenting to the emergency department (ED) at a tertiary referral center during a 27-month period, residing within the surrounding ten counties. Serum laboratory values were obtained for all patients and categorized according to whether the levels were low, normal, or high. These laboratory results were evaluated as potential predictors of 90-day mortality using Cox proportional hazards models. The associations were summarized by calculating risk ratios (RRs) and 95% confidence intervals (CI). Results. The presence of elevated white blood cell count (RR 2.2, 95% CI 1.5–3.4), low bicarbonate (RR 4.2, 95% CI 2.6–6.7), low calcium (RR 2.9, 95% CI 1.4–5.9), and high glucose (RR 1.3, 95% 1.1–1.6) were each univariately associated with significantly higher mortality within the first 90 days. Based on fitting a multivariate Cox regression model, elevated white blood cell count, low bicarbonate, and high glucose were each identified as being jointly associated with early mortality ( ). Conclusion. Early leukocytosis, acidosis, and hyperglycemia and hypocalcemia in AIS appear to be associated with early mortality. Whether addressing these factors will impact survival remains to be investigated. 1. Introduction For patients who present with chief complaint of acute ischemic stroke, the American Stroke Association recommends a set of diagnostic studies [1] to be done at presentation, with the intent of optimizing and expediting the care of these patients. From the Emergency Physicians’ perspective many tests are simply part of a routine battery, often without direct impact on emergency department (ED) management, diagnostic or prognostic value. In this study, we sought to determine whether the routine complete blood count (CBC) and electrolyte panel include any components that are markers of early mortality in acute ischemic stroke. Specifically, the parameters of interest were those obtained as part of routine clinical investigation. 2. Methods 2.1. Study Design This study was an observational study using a consecutive sample of local residents presenting to the ED with acute ischemic stroke (AIS). The primary outcome measure was death at 90 days. This study was approved by the Mayo Clinic Institutional Review Board. 2.2. Study Population and Setting This study was conducted at the Saint Marys Hospital, a tertiary referral academic medical center with an annual ED
Cardioembolic but Not Other Stroke Subtypes Predict Mortality Independent of Stroke Severity at Presentation
Latha Ganti Stead,Rachel M. Gilmore,M. Fernanda Bellolio,Anunaya Jain,Alejandro A. Rabinstein,Wyatt W. Decker,Dipti Agarwal,Robert D. Brown Jr.
Stroke Research and Treatment , 2011, DOI: 10.4061/2011/281496
Abstract: Introduction. Etiology of acute ischemic stroke (AIS) is known to significantly influence management, prognosis, and risk of recurrence. Objective. To determine if ischemic stroke subtype based on TOAST criteria influences mortality. Methods. We conducted an observational study of a consecutive cohort of patients presenting with AIS to a single tertiary academic center. Results. The study population consisted of 500 patients who resided in the local county or the surrounding nine-county area. No patients were lost to followup. Two hundred and sixty one (52.2%) were male, and the mean age at presentation was 73.7 years (standard deviation, SD = 14.3). Subtypes were as follows: large artery atherosclerosis 97 (19.4%), cardioembolic 144 (28.8%), small vessel disease 75 (15%), other causes 19 (3.8%), and unknown 165 (33%). One hundred and sixty patients died: 69 within the first 30 days, 27 within 31–90 days, 29 within 91–365 days, and 35 after 1 year. Low 90-, 180-, and 360-day survival was seen in cardioembolic strokes (67.1%, 65.5%, and 58.2%, resp.), followed for cryptogenic strokes (78.0%, 75.3%, and 71.1%). Interestingly, when looking into the cryptogenic category, those with insufficient information to assign a stroke subtype had the lowest survival estimate (57.7% at 90 days, 56.1% at 180 days, and 51.2% at 1 year). Conclusion. Cardioembolic ischemic stroke subtype determined by TOAST criteria predicts long-term mortality, even after adjusting for age and stroke severity. 1. Introduction Etiology of acute ischemic stroke (AIS) is known to significantly influence management, prognosis, and risk of recurrence. Certain stroke subtypes are associated with higher stroke severity at the time of presentation, which may account for the higher mortality seen. In 1993 the TOAST (Trail of ORG 10172 in Acute Stroke Treatment) investigators described a classification of AIS based on etiology, which is now the most commonly used etiological classification [1]. Comparison of clinical characteristics, functional outcomes, and mortality rates for specific ischemic stroke mechanisms may allow clinicians to identify those patients who are at higher risk and to evaluate treatment strategies more definitely. We conducted an observational study of all patients who presented to the emergency department (ED) with AIS and determined if ischemic stroke subtype (ISS) influences mortality even after correcting for stroke severity on initial presentation. 2. Methods This study was conducted at a tertiary care academic medical center, with an annual ED census of approximately
The energy partitioning of non-thermal particles in a plasma: or the Coulomb logarithm revisited
Robert L. Singleton Jr.,Lowell S. Brown
Physics , 2008, DOI: 10.1088/0741-3335/50/12/124016
Abstract: The charged particle stopping power in a highly ionized and weakly to moderately coupled plasma has been calculated to leading and next-to-leading order by Brown, Preston, and Singleton (BPS). After reviewing the main ideas behind this calculation, we use a Fokker-Planck equation derived by BPS to compute the electron-ion energy partitioning of a charged particle traversing a plasma. The motivation for this application is ignition for inertial confinement fusion -- more energy delivered to the ions means a better chance of ignition, and conversely. It is therefore important to calculate the fractional energy loss to electrons and ions as accurately as possible, as this could have implications for the Laser Megajoule (LMJ) facility in France and the National Ignition Facility (NIF) in the United States. The traditional method by which one calculates the electron-ion energy splitting of a charged particle traversing a plasma involves integrating the stopping power dE/dx. However, as the charged particle slows down and becomes thermalized into the background plasma, this method of calculating the electron-ion energy splitting breaks down. As a result, the method suffers a systematic error of order T/E0, where T is the plasma temperature and E0 is the initial energy of the charged particle. In the case of DT fusion, for example, this can lead to uncertainties as high as 10% or so. The formalism presented here is designed to account for the thermalization process, and in contrast, it provides results that are near-exact.
Temperature equilibration in a fully ionized plasma: electron-ion mass ratio effects
Lowell S. Brown,Robert L. Singleton Jr
Physics , 2009, DOI: 10.1103/PhysRevE.79.066407
Abstract: Brown, Preston, and Singleton (BPS) produced an analytic calculation for energy exchange processes for a weakly to moderately coupled plasma: the electron-ion temperature equilibration rate and the charged particle stopping power. These precise calculations are accurate to leading and next-to-leading order in the plasma coupling parameter, and to all orders for two-body quantum scattering within the plasma. Classical molecular dynamics can provide another approach that can be rigorously implemented. It is therefore useful to compare the predictions from these two methods, particularly since the former is theoretically based and the latter numerically. An agreement would provide both confidence in our theoretical machinery and in the reliability of the computer simulations. The comparisons can be made cleanly in the purely classical regime, thereby avoiding the arbitrariness associated with constructing effective potentials to mock up quantum effects. We present here the classical limit of the general result for the temperature equilibration rate presented in BPS. We examine the validity of the m_electron/m_ion --> 0 limit used in BPS to obtain a very simple analytic evaluation of the long-distance, collective effects in the background plasma.
Temperature Equilibration Rate with Fermi-Dirac Statistics
Lowell S. Brown,Robert L. Singleton Jr
Physics , 2007, DOI: 10.1103/PhysRevE.76.066404
Abstract: We calculate the electron-ion temperature equilibration rate in a fully ionized, weakly to moderately coupled plasma, using an exact treatment of the Fermi-Dirac electrons. The temperature is sufficiently high so that the quantum-mechanical Born approximation to the scattering is valid. At the heart of this calculation lies the method of dimensional continuation, a technique that we borrow from quantum field theory and use in a novel fashion to regulate the kinetic equations in a consistent manner. We can then perform a systematic perturbation expansion and thereby obtain a finite first-principles result to leading and next-to-leading order. Unlike model building, this systematic calculation yields an estimate of its own error and thus prescribes its domain of applicability. The calculational error is small for a weakly to moderately coupled plasma, for which our result is nearly exact. It should also be emphasized that our calculation becomes unreliable for a strongly coupled plasma, where the perturbative expansion that we employ breaks down, and one must then utilize model building and computer simulations. Besides providing new and potentially useful results, we use this calculation as an opportunity to explain the method of dimensional continuation in a pedagogical fashion. Interestingly, in the regime of relevance for many inertial confinement fusion experiments, the degeneracy corrections are comparable in size to the subleading quantum correction below the Born approximation. For consistency, we therefore present this subleading quantum-to-classical transition correction in addition to the degeneracy correction.
Effect of Vitamin E and Alpha Lipoic Acid in Nonalcoholic Fatty Liver Disease: A Randomized, Placebo-Controlled, Open-Label, Prospective Clinical Trial (VAIN Trial)  [PDF]
Patrick P. Basu, Niraj J. Shah, Mark M. Aloysius, Robert S. Brown Jr.
Open Journal of Gastroenterology (OJGas) , 2014, DOI: 10.4236/ojgas.2014.45030
Abstract: Objective: Antioxidants, including alpha lipoic acid (ALA) and vitamin E, are efficacious for the treatment of nonalcoholic fatty liver disease (NAFLD). The objective was to evaluate the effects of ALA and vitamin E alone or combined as therapy for patients with NAFLD and nonalcoholic steatohepatitis (NASH). Design: Placebo-controlled, open-label, prospective study in which patients with NAFLD and NASH were randomized to treatment with ALA 300 mg (n = 40), vitamin E 700 IU (n = 40), ALA 300 mg plus vitamin E 700 IU (n = 40), or placebo (n = 35) daily for 6 months. Body mass index, homeostasis model assessment scores, fibrosis and steatosis markers, and diagnostic laboratory tests were assessed at baseline and at the end of the study. Results: Treatment with ALA and vitamin E alone or in combination, improved inflammatory cytokine levels, steatosis scores, homeostasis model assessment scores, and triglyceride levels after 6 months relative to baseline. Conclusion: Alpha lipoic acid and vitamin E, either alone or in combination, were effective treatments for patients with NAFLD and NASH.
Active Trafficking of Alpha 1 Antitrypsin across the Lung Endothelium
Angelia D. Lockett, Mary Beth Brown, Nieves Santos-Falcon, Natalia I. Rush, Houssam Oueini, Amber J. Oberle, Esther Bolanis, Miryam A. Fragoso, Daniela N. Petrusca, Karina A. Serban, Kelly S. Schweitzer, Robert G. Presson Jr., Michael Campos, Irina Petrache
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093979
Abstract: The homeostatic lung protective effects of alpha-1 antitrypsin (A1AT) may require the transport of circulating proteinase inhibitor across an intact lung endothelial barrier. We hypothesized that uninjured pulmonary endothelial cells transport A1AT to lung epithelial cells. Purified human A1AT was rapidly taken up by confluent primary rat pulmonary endothelial cell monolayers, was secreted extracellularly, both apically and basolaterally, and was taken up by adjacent rat lung epithelial cells co-cultured on polarized transwells. Similarly, polarized primary human lung epithelial cells took up basolaterally-, but not apically-supplied A1AT, followed by apical secretion. Evidence of A1AT transcytosis across lung microcirculation was confirmed in vivo by two-photon intravital microscopy in mice. Time-lapse confocal microscopy indicated that A1AT co-localized with Golgi in the endothelium whilst inhibition of the classical secretory pathway with tunicamycin significantly increased intracellular retention of A1AT. However, inhibition of Golgi secretion promoted non-classical A1AT secretion, associated with microparticle release. Polymerized A1AT or A1AT supplied to endothelial cells exposed to soluble cigarette smoke extract had decreased transcytosis. These results suggest previously unappreciated pathways of A1AT bidirectional uptake and secretion from lung endothelial cells towards the alveolar epithelium and airspaces. A1AT trafficking may determine its functional bioavailablity in the lung, which could be impaired in individuals exposed to smoking or in those with A1AT deficiency.
Charged Particle Motion in a Plasma: Electron-Ion Energy Partition
Lowell S. Brown,Dean L. Preston,Robert L. Singleton Jr
Physics , 2011, DOI: 10.1103/PhysRevE.86.016406
Abstract: A charged particle traversing a plasma loses its energy to both plasma electrons and ions. We compute the energy partition, the fractions $E_e/E_0$ and $E_\smI/E_0$ of the initial energy $E_0$ of this `impurity particle' that are deposited into the electrons and ions when it has slowed down into an equilibrium distribution that we shall determine. We use a well-defined Fokker-Planck equation for the phase space distribution of the charged impurity particles in a weakly to moderately coupled plasma. The Fokker-Planck equation holds to first sub-leading order in the dimensionless plasma coupling constant, which means we compute to order $n\ln n$ (leading) and $n$ (sub-leading) in the plasma density $n$. Previously, the order $n$ terms had been estimated, not calculated. Since the charged particle does not come to rest, the energy loss obtained by an integration of a $dE/dx$ has an ambiguity of order of the plasma temperature. Our Fokker-Planck formulation provides an unambiguous, precise definition of the energy fractions. For equal electron and ion temperatures, we find that our precise results agree well with a fit obtained by Fraley, Linnebur, Mason, and Morse. The case with differing electron and ion temperatures, a case of great importance for nuclear fusion, will be investigated in detail in the present paper. The energy partitions for this general case, partitions that have not been obtained before, will be presented. We find that now the proper solution of the Fokker-Planck equation yields a quasi-static equilibrium distribution to which fast particles relax that has neither the electron nor the ion temperature. This "schizophrenic" final ensemble of slowed particles gives a new mechanism to bring the electron and ion temperatures together. The rate at which this new mechanism brings the electrons and ions in the plasma into thermal equilibrium will be computed.
dE/dx to Subleading Order in the Plasma Density
Lowell S. Brown,Dean L. Preston,Robert L. Singleton Jr
Physics , 2005,
Abstract: Dimensional continuation is employed to compute the energy loss rate for a non-relativistic particle moving through a highly ionized plasma. No restriction is made on the charge, mass, or speed of this particle, but it is assumed that the plasma is not strongly coupled in that the dimensionless plasma coupling parameter g= e^2 \kappa_D/4\pi T is small, where \kappa_D is the Debye wave number. To leading order in this coupling, dE/dx is of the generic form g^2 \ln[g^2 C]. The prefactor of the logarithm is well known. We compute the constant C under the logarithm exactly. Our result differs from approximations given in the literature, with differences in the range of about 20% for cases relevant to inertial confinement fusion experiments.
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