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The Role of Inflammatory Mediators in the Pathogenesis of Otitis Media and Sequelae
Steven K. Juhn,정민교,Mark D. Hoffman,Brian R. Drew,Diego A. Preciado,Nicholas J. Sausen,Timothy T.K. Jung,Bo Hyung Kim,박상유,Jizhen Lin,Frank G. Ondrey,David R. Mains,Tina Huang 대한이비인후과학회 2008 Clinical and Experimental Otorhinolaryngology Vol.1 No.3
This review deals with the characteristics of various inflammatory mediators identified in the middle ear during otitis media and in cholesteatoma. The role of each inflammatory mediator in the pathogenesis of otitis media and cholesteatoma has been discussed. Further, the relation of each inflammatory mediator to the pathophysiology of the middle and inner ear along with its mechanisms of pathological change has been described. The mechanisms of hearing loss including sensorineural hearing loss (SNHL) as a sequela of otitis media are also discussed. The passage of inflammatory mediators through the round window membrane into the scala tympani is indicated. In an experimental animal model, an application of cytokines and lipopolysaccharide (LPS), a bacterial toxin, on the round window membrane induced sensorineural hearing loss as identified through auditory brainstem response threshold shifts. An increase in permeability of the blood-labyrinth barrier (BLB) was observed following application of these inflammatory mediators and LPS. The leakage of the blood components into the lateral wall of the cochlea through an increase in BLB permeability appears to be related to the sensorineural hearing loss by hindering K+ recycling through the lateral wall disrupting the ion homeostasis of the endolymph. Further studies on the roles of various inflammatory mediators and bacterial toxins in inducing the sensorineumral hearing loss in otitis media should be pursued.
An integro-differential equation model for alignment and orientational aggregation
Kang, K.,Perthame, B.,Stevens, A.,Velazquez, J.J.L. Academic Press 2009 Journal of differential equations Vol.246 No.4
We study an integro-differential equation modeling angular alignment of interacting bundles of cells or filaments. A bifurcation analysis of the related stationary problem was done by Geigant and Stoll in [E. Geigant, M. Stoll, Bifurcation analysis of an orientational aggregation model, J. Math. Biol. 46 (6) (2003) 537-563]. Here we analyze the time-dependent problem and prove that the type of alignment (one- or multi-directional) depends on the initial distribution, the interaction potential, and the preferred optimal orientation of the bundles of cells or filaments. Our main technical tool is the analysis of the evolution of suitable functionals for the cell density, which allows to also specify the direction(s) where the final alignment takes place.
Persistent near-tropical warmth on the Antarctic continent during the early Eocene epoch
Pross, J철rg,Contreras, Lineth,Bijl, Peter K.,Greenwood, David R.,Bohaty, Steven M.,Schouten, Stefan,Bendle, James A.,R철hl, Ursula,Tauxe, Lisa,Raine, J. Ian,Huck, Claire E.,van de Flierdt, Tina,Jamieso Nature Publishing Group, a division of Macmillan P 2012 Nature Vol.488 No.7409
The warmest global climates of the past 65 million years occurred during the early Eocene epoch (about 55 to 48 million years ago), when the Equator-to-pole temperature gradients were much smaller than today and atmospheric carbon dioxide levels were in excess of one thousand parts per million by volume. Recently the early Eocene has received considerable interest because it may provide insight into the response of Earth??s climate and biosphere to the high atmospheric carbon dioxide levels that are expected in the near future as a consequence of unabated anthropogenic carbon emissions. Climatic conditions of the early Eocene ??greenhouse world??, however, are poorly constrained in critical regions, particularly Antarctica. Here we present a well-dated record of early Eocene climate on Antarctica from an ocean sediment core recovered off the Wilkes Land coast of East Antarctica. The information from biotic climate proxies (pollen and spores) and independent organic geochemical climate proxies (indices based on branched tetraether lipids) yields quantitative, seasonal temperature reconstructions for the early Eocene greenhouse world on Antarctica. We show that the climate in lowland settings along the Wilkes Land coast (at a palaeolatitude of about 70째 south) supported the growth of highly diverse, near-tropical forests characterized by mesothermal to megathermal floral elements including palms and Bombacoideae. Notably, winters were extremely mild (warmer than 10??째C) and essentially frost-free despite polar darkness, which provides a critical new constraint for the validation of climate models and for understanding the response of high-latitude terrestrial ecosystems to increased carbon dioxide forcing.
Electron microscopy of bismuth building blocks for self-assembled nanowires
K.J. Stevens,K.S. Cheong,D.M. Knowles,N.J. Laycock,A. Ayesh,J. Partridge,S.A. Brown,S.C. Hendy 한국물리학회 2006 Current Applied Physics Vol.6 No.3
Nanowires can be fabricated from bismuth nanoclusters. The structure of bismuth nanoclusters of 4060 nm diameter has beenobserved by high resolution transmission electron microscopy (HRTEM) and matched to multislice image simulations forB=[. 2,0, . 1] andB= [1,0,. 1,0]. The hexagonal structure matches that of bulk bismuth embedded in a 5 nm thick shell ofb-Bi2O3.
K. J. Stevens,A. Parbhu,J. Soltis 한국물리학회 2004 Current Applied Physics Vol.4 No.2-4
Magnetic force microscopy has been used to determine the origin and spatial distribution of changes in magnetic properties of anHPM alloy carburised by exposure in an ethylene production furnace. In higher activity carburising atmospheres at 400800.C,metal dusting can occur in which the exposed surface becomes carburised to such an extent that the tube alloy pits and literally turnsinto a dust of carbon, graphite and metallic particles. Metal dusting is a signicant ‘‘remaining life’’ and design issue in several large petrochemical plants in Australasia. Transmission electron microscopy is being used to observe the element segregation into car-bides, coke and graphite to clarify the mechanisms by which metal dusting occurs in 601 and 316 stainless steel alloys.
Structure of palladium nanoclusters for hydrogen gas sensors
K.J. Stevens,B. Ingham,M.F. Toney,S.A. Brown,A. Lassesson 한국물리학회 2008 Current Applied Physics Vol.8 No.3,4
Palladium nanoclusters produced by inert gas aggregation/magnetron sputtering are used as building blocks for the construction ofnano electronic devices with large surface to volume ratios that can be used as sensitive hydrogen gas sensors in fuel cells and in petro-chemical plants. X-ray diraction (XRD), extended X-ray absorption ne structure (EXAFS), and high resolution transmission electronmicroscopy (HRTEM) have been used to characterise the structure, lattice constant, particle diameter and oxide thickness of the palla-dium nanoclusters in order to understand the operation of these sensors. Grazing incidence XRD (GIXRD) of heat treated Pd clustershas shown that the palladanite structure forms at elevated temperatures.
( Simran K. Bhandari ),( Michael Batech ),( Jiaxiao Shi ),( Steven J. Jacobsen ),( John J. Sim ) 대한신장학회 2016 Kidney Research and Clinical Practice Vol.35 No.4
Background: We sought to evaluate plasma renin activity (PRA) levels and risk of mortality and cardiovascular events among individuals with elevated blood pressure [systolic blood pressure (SBP) ≥ 140 mmHg] and those with controlled blood pressure (SBP < 140 mmHg) in a large diverse population. Methods: A retrospective cohort study between January 1, 2007, and December 31, 2013, among adults (≥ 18 years) within an integrated health system was conducted. Subjects were categorized by SBP into 2 groups: SBP < 140 mmHg and SBP ≥ 140 mmHg and then further categorized into population-based PRA tertiles within each SBP group. Cox proportional hazard modeling was used to estimate hazard ratios for cardiovascular and mortality outcomes among tertiles of PRA levels. Results: Among 6,331 subjects, 32.6% had SBP ≥ 140 mmHg. Multivariable hazard ratios and 95% confidence interval for PRA tertiles T2 and T3 compared to T1 in subjects with SBP ≥ 140 mmHg were 1.42 (0.99-2.03) and 1.61 (1.12-2.33) for ischemic heart events; 1.40 (0.93-2.10) and 2.23 (1.53-3.27) for congestive heart failure; 1.10 (0.73-1.68) and 1.06 (0.68-1.66) for cerebrovascular accident; 1.23 (0.94-1.59) and 1.43 (1.10-1.86) for combined cardiovascular events; and 1.39 (0.97-1.99) and 1.35 (0.92-1.97) for all-cause mortality, respectively. Among the SBP < 140mmHg group, therewas no relationship between PRA levels and outcomes. Conclusion: Higher PRA levels demonstrated increased risk for ischemic heart events and congestive heart failure and a trend toward higher mortality among individuals with SBP ≥ 140 mmHg but not among those with SBP < 140 mmHg. Copyright ⓒ 2016. The Korean Society of Nephrology. Published by Elsevier. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Biomaterials in Spinal Implants: A Review
Andrew Warburton,Steven J. Girdler,Christopher M. Mikhail,Amy Ahn,Samuel K. Cho 대한척추신경외과학회 2020 Neurospine Vol.17 No.1
The aim to find the perfect biomaterial for spinal implant has been the focus of spinal research since the 1800s. Spinal surgery and the devices used therein have undergone a constant evolution in order to meet the needs of surgeons who have continued to further understand the biomechanical principles of spinal stability and have improved as new technologies and materials are available for production use. The perfect biomaterial would be one that is biologically inert/compatible, has a Young’s modulus similar to that of the bone where it is implanted, high tensile strength, stiffness, fatigue strength, and low artifacts on imaging. Today, the materials that have been most commonly used include stainless steel, titanium, cobalt chrome, nitinol (a nickel titanium alloy), tantalum, and polyetheretherketone in rods, screws, cages, and plates. Current advancements such as 3-dimensional printing, the ProDisc-L and ProDisc-C, the ApiFix, and the Mobi-C which all aim to improve range of motion, reduce pain, and improve patient satisfaction. Spine surgeons should remain vigilant regarding the current literature and technological advancements in spinal materials and procedures. The progression of spinal implant materials for cages, rods, screws and plates with advantages and disadvantages for each material will be discussed.
Reorganization of Southern Ocean Plankton Ecosystem at the Onset of Antarctic Glaciation
Houben, Alexander J. P.,Bijl, Peter K.,Pross, Jö,rg,Bohaty, Steven M.,Passchier, Sandra,Stickley, Catherine E.,Rö,hl, Ursula,Sugisaki, Saiko,Tauxe, Lisa,van de Flierdt, Tina,Olney, Matthew,San American Association for the Advancement of Scienc 2013 Science Vol.340 No.6130
<P><B>Southern Change</B></P><P>Antarctica has been mostly covered by ice since the inception of large-scale continental glaciation during the Oligocene, which profoundly altered the isotopic and mineralogical records of the sediments surrounding the continent. <B>Houben <I>et al.</I></B> (p. 341) found records of the corresponding living systems in the fossil marine dinoflagellate cysts, which revealed that a microplankton ecosystem, similar to the one that exists today, appeared simultaneously with the first major Antarctic glaciation approximately 34 million years ago.</P>