506 research outputs found
New Perspectives on Amyloid-β Dynamics After Acute Brain Injury
No full textThe links between traumatic brain injury and Alzheimer disease have been of great interest for many years. However, the importance of amyloid-β- related neurodegenerative pathophysiologic processes after traumatic brain injury is still unknown. In this review, we present a brief overview of the scientific evidence regarding traumatic brain injury as a contributor to Alzheimer disease and describe recent results showing significant changes in brain extracellular amyloid-β dynamics in patients with severe brain injury. We then discuss the clinical significance of these findings with their implications for translational neurobiology and conclude with further directions for traumatic brain injury and Alzheimer disease research. ©2010 American Medical Association. All rights reserved
Clavicular osteomyelitis: A rare complication after surgery for head and neck cancer.
No full textClavicular osteomyelitis (COM) is a rarely described disease entity, occurring especially after head and neck surgery. We herein report the ninth case according to the English language literature and describe the pertinent diagnostic and therapeutic measures to treat this complication. A 63-year-old Caucasian male underwent total laryngectomy and partial pharyngectomy for a post-radiotherapy recurrence of a T2 hypopharyngeal cancer. He presented multiple systemic (cardiovascular problems, previous pneumonectomy, malnutrition) and local-regional (previous radiotherapy, neck dissection, tracheostomy) factors favoring postoperative complications. Sixteen days after surgery, he developed a painful swelling with overlying erythematous skin at the level of the medial portion of the left clavicle. A purulent discharge from the adjacent stomal dehiscence was also noted. COM, suspected on the base of patient's history and clavicular inspection, was confirmed by CT scan. Surgical debridement allowed for definitive diagnosis, ruling out any possible suspicion of stomal recurrence or secondary localization to the clavicle. Cultures from the debrided bone sequestra grew Streptococcus pyogenes Group A and allowed for proper targeting of antibiotic therapy, which was carried out for 4 weeks after surgery. Four years after surgery the patient is tumor-free and does not show any sequela related to the COM or its treatment. COM is a rarely encountered complication after major head and neck surgery. Nevertheless, prompt diagnosis and treatment are mandatory due to the potential life-threatening evolution of this condition
ASO Author Reflections: Is Breast-Conserving Surgery a Safe Treatment Option for High-Risk Breast Cancer?
No full textReply to: Is serum uric acid a pretty accurate prognostic predictor of ST elevated acute coronary syndrome? Author: Alexander E. Berezin
No full textRuins of the past: the use and perception of abandoned structures in the Maya lowlands
No full textTravix W. Stanton and Aline Magnoni, editors.Includes bibliographical references and index.From the Formative to the present, Maya peoples have continuously built, altered, abandoned, and re-used structures, imbuing them with new meanings at each transformation. Ruins of the Past is the first volume to focus on how previously built structures in the Maya Lowlands were used and perceived by later peoples, exploring the topic through concepts of landscape, place, and memory.--Book jacket.Foreword / Wendy Ashmore -- Places of remembrance: the use and perception of abandoned structures in the Maya lowlands / Travis W. Stanton and Aline Magnoni -- Forgotten structures, haunted houses, and occupied hearts: ancient perspectives and contemporary interpretations of abandoned sites and buildings in the Mirador Basin, Guatemala / Richard D. Hansen, Wayne K. Howell, and Stanley P. Guenter -- The transformation of abandoned architecture at Piedras Negras / Mark B. Child and Charles W. Golden -- Structure abandonment and landscape transformation: examples from the Three Rivers region / Lauren A. Sullivan [and others] -- Manipulating memory in the wake of dynastic decline at El Perú-Waka': termination deposits at abandoned structure M13-1 / Olivia C. Navarro Farr, David A. Freidel, and Ana Lucía Arroyave Prera -- Establishing and reusing sacred place: a diachronic perspective from Blackman Eddy, Belize / M. Kathryn Brown and James F. Garber -- Anatomy of a post-collapse society: identity and interaction in early postclassic Copán / T. Kam Manahan -- Landscape transformations and changing perceptions at Chunchucmil, Yucatán / Aline Magnoni, Scott R. Hutson, and Travis W. Stanton -- Edzná: a lived place through time / Antonio Benavides C. -- Memories, meanings, and historical awareness: post-abandonment behaviors among the lowland Maya / Marcello A. Canuto and Anthony P. Andrews -- Afterword / Denise Fay Brown
A Portable Dual-input Multichannel Analyzer with Large Onboard Memory for Dual Isotope Diagnostic Techniques
No full textN12-16
PAC learning of probability distributions over a discrete domain
No full textWe investigate learning of classes of distributions over a discrete domain in a PAC context. We introduce two paradigms of PAC learning, namely absolute PAC learning, which is independent of the representation of the class of hypotheses, and PAC learning wrt the indexes, which heavily depends on such representations. We characterize non-computable learnability in both contexts. Then we investigate efficient learning strategies which are simulated by a polynomial-time Turing machine. One strategy is the frequentist one. According to this strategy, the learner conjectures a hypothesis which is as close as possible to the distribution given by the frequency relative to the examples. We characterize the classes of distributions which are absolutely PAC learnable by means of this strategy, and we relate frequentist learning wrt the indexes to the NP = RP problem. Finally, we present another strategy for learning wrt the indexes, namely learning by tests
L-Type Calcium Channels are Modified in Rat Hippocampus by Short-Term Experimental Ischemia
No full text Increasing evidence suggests a role for calcium ions in the pathophysiology of ischemic brain damage. The major mechanism allowing calcium entry from the extracellular compartment is the opening of voltage-operated calcium channels. In this line, we have explored the hypothesis that the characteristics of central L-type voltage-dependent calcium channels, labeled by the dihydropyridine ligand 3H-PN 200-110, may be modified by experimental ischemia. The results show that short-term mild ischemia, produced in the rat by 1 h of right carotid ligation, induces an increase in the number of 3H-PN 200-110 binding sites in the hippocampus ipsilateral to the side of carotid occlusion, accompanied by an increase in the dissociation constant value, whereas no changes in the kinetic parameters of the binding were observed in the other areas examined, i.e., the cortex and the striatum. The changes in hippocampus are transient: 96 h after the occlusion, binding parameters return to the control range. The modifications of the binding characteristics in the hippocampus may be related to alterations of Ca2+ fluxes through L-type calcium channels. </jats:p
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