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Search Results: 1 - 10 of 218088 matches for " James N. Palmer "
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Morphine has latent deleterious effects on the ventilatory responses to a hypoxic-hypercapnic challenge  [PDF]
Walter J. May, Fraser Henderson Jr., Ryan B. Gruber, Joseph F. Discala, Alex P. Young, James N. Bates, Lisa A. Palmer, Stephen J. Lewis
Open Journal of Molecular and Integrative Physiology (OJMIP) , 2013, DOI: 10.4236/ojmip.2013.33019
Abstract:

This study explored the concept that morphine has latent deleterious actions on the ventilatory control systems that respond to a hypoxic-hypercapnic challenge. In this study, we examined the ventilatory responses elicited by hypoxic-hypercapnic challenge in conscious rats at a time when the effects of morphine (10 mg/kg) on arterial blood-gas chemistry and minute ventilation had subsided. Morphine induced pronounced changes in arterial blood-gas chemistry (e.g., an increase in pCO2, decreases in pO2 and sO2) and decreases in minute ventilation. Despite the complete resolution of the morphine-induced changes in arterial blood-gas chemistry and minute ventilation and almost complete resolution of the effects on peak inspiratory flow and peak expiratory flow, subsequent exposure to hypoxic-hypercapnic challenge elicited markedly blunted increases in minute ventilation and in peak inspiratory and expiratory flows. These findings demonstrate that 1) the changes in arterial blood-gas chemistry elicited by morphine parallel changes in minute ventilation rather than PIF and PEF, and 2) morphine has latent untoward effects on the ventilatory responses to hypoxic-hypercapnic challenge. These novel findings raise the possibility that patients deemed to have recovered from the acute ventilatory depresssant effects of morphine may still be susceptible to the latent effects of this opioid analgesic. The mechanisms underlying these latent effects remain to be elucidated.

Implications of bacterial biofilms in chronic rhinosinusitis
Tamashiro, Edwin;Antunes, Marcelo B.;Palmer, James N.;Cohen, Noam A.;Anselmo-Lima, Wilma T.;
Brazilian Journal of Infectious Diseases , 2009, DOI: 10.1590/S1413-86702009000300015
Abstract: the recognition of sessile form of bacteria with particular features, known as biofilm, has given new insights to the understanding of pathogenesis of several chronic diseases, including chronic rhinosinusitis (crs). in this article we review the main characteristics of biofilms, describe the current methods used to demonstrate biofilms in chronic rhinosinusitis and discuss the future directions of research in the field.
Efeitos do cigarro sobre o epitélio respiratório e sua participa??o na rinossinusite cr?nica
Tamashiro, Edwin;Cohen, Noam A;Palmer, James N;Lima, Wilma Terezinha Anselmo;
Brazilian Journal of Otorhinolaryngology , 2009, DOI: 10.1590/S1808-86942009000600022
Abstract: the increasing consumption of cigarettes has aroused concerns about the development and worsening of diseases, particularly those related to the respiratory tract. aim: in this paper we review the evidence suggesting the effects of cigarette smoking on the respiratory epithelium and its role in the pathogenesis in chronic rhinosinusitis. conclusions: although there is evidence supporting a link between smoking and crs, studies suggest that there might be individual susceptibility to cigarette smoking causing the development and/or maintenance of crs. proper patient educations to quit smoking as well as reinforcement of antismoking campaigns are extremely important to control this disease of major socio-economic impact.
The Historical Context of Sierra Leonean Literature
Eustace James Palmer
Research in Sierra Leone Studies : Weave , 2013,
Abstract: This essay gives a survey of the history of Sierra Leone from the settlement of Freetown to more contemporary times and then proceeds to an accouont of the development of Sierra Leonean literature against this historical background.
Expanded Endoscopic Endonasal Treatment of Primary Intracranial Tumors within the Paranasal Sinuses
Zarina S. Ali,Shih-Shan Lang,Nithin D. Adappa,Ariana Barkley,James N. Palmer,John Y. K. Lee
ISRN Minimally Invasive Surgery , 2013, DOI: 10.1155/2013/129780
Abstract: Objective. Meningiomas and schwannomas represent a subset of primary intracranial tumors that are rarely identified exclusively in the paranasal sinuses. Here, we describe our experience with minimally invasive endoscopic endonasal approaches for the treatment of these tumors. Methods. We retrospectively reviewed the clinical, surgical, and radiographic characteristics of adults with pathologically confirmed sinonasal meningiomas and schwannomas located within the paranasal sinuses that were resected via an expanded endoscopic endonasal approach. Results. Five patients (1 male, 4 females) underwent an endoscopic endonasal approach for resection of sinonasal tumor. Clinical symptomatology most commonly included nasal obstruction, in addition to headache, jaw pain, anosmia, and chronic rhinosinusitis. Tumors were located exclusively within the sinonasal cavity and were on average 2.2?cm (range 1.4–3.8?cm). Pathology revealed 2 cases of meningioma and 3 cases of schwannoma. No evidence of tumor recurrence occurred over average followup of 1.5 years (range 0.11–3.9 years). Conclusion. Our case series suggests that an expanded endoscopic endonasal approach with a combined neurosurgical-otorhinolaryngologic team for the resection of sinonasal meningiomas and schwannomas offers an effective treatment option. Further studies that include a larger number of patients over a longer follow-up period are required to compare outcomes between minimally invasive and open approaches. 1. Introduction Sinonasal schwannomas and meningiomas represent a rare subset of benign sinonasal tumors. Schwannomas originate from neural the crest-derived Schwann cells that line central nerve sheaths. In the head and neck, these tumors are located less than 4% of the time in the sinonasal cavity [1]. In contrast, meningiomas arise from arachnoid cap cells and are even less commonly associated with an extracranial origin (<2%), of which the sinonasal tract is most prevalent [2]. Traditional, transcranial approaches to these lesions are inherently morbid, due to significant brain retraction and complications associated with skin incision and craniotomy. Endoscopic endonasal approaches are becoming increasingly utilized to access these skull base pathologies. For these small, benign lesions extending into the paranasal sinuses, endoscopic approaches offer a minimally invasive approach to tumor resection and, in some cases, complete tumor resection. Endoscopic techniques provide a panoramic view of the lesion and associated anatomy not seen with the microscopic approach. In addition,
Petrographic and isotopic evidence for late-stage processes in sulfuric acid caves of the Guadalupe Mountains, New Mexico, USA
Palmer Arthur N.,Palmer Margaret V.
International Journal of Speleology , 2012,
Abstract: Caves of the Guadalupe Mountains have experienced many modifications since their final phase of sulfuric acid speleogenesis several million years ago. Petrographic and geochemical data reveal details of the change from H2SO4 to CO2-dominated reactions. The H2SO4 dissolution front acquired a coating of replacement gypsum with local pockets of anhydrite and by-products of altered clay, including Fe-Mn oxides. Alteration of bedrock beneath the gypsum produced a white micritized rind with small negative shifts in δ13C and δ18O. Solution basins contain records of the earliest post-speleogenetic processes: corroded bedrock, residual anhydrite, Fe-Mn oxides from fluctuating pH and Eh, mammillary calcite, and dolomitization. Later meteoric water removed or recrystallized much of the gypsum and early micrite, and replaced some gypsum with calcite. Mammillary crusts demonstrate fluctuating groundwater, with calcite layers interrupted by films of Fe-Mn oxides precipitated during periodic inflow of anoxic water. Condensation moisture (from local evaporation) absorbs CO2 from cave air, corroding earlier features and lowering their δ13C and δ18O. Drips of condensation water deposit minerals mainly by evaporation, which increases δ18O in the speleothems while δ13C remains nearly constant. By forcing calcite precipitation, evaporation raises the Mg content of remaining water and subsequent precipitates. Dolomite (both primary and replacive) is abundant. In areas of low air circulation, water on and within carbonate speleothems equilibrates with cave-air CO2, causing minerals to recrystallize with glassy textures. Fluorite on young evaporative speleothems suggests a recent release of deep-source HF gas and absorption by droplets of condensation water.
Speleogenesis in carbonate rocks
Palmer,A.N.
Speleogenesis and Evolution of Karst Aquifers , 2003,
Abstract: This paper outlines the current views on cave origin in carbonate rocks, combining ideas from a variety of sources. A typical dissolution cave develops in several stages that grade smoothly from one to the next: (1) Initial openings are slowly enlarged by water that is nearly at solutional equilibrium with the local bedrock. (2) As the early routes enlarge, those with the greatest amount of flow grow fastest. (3) These favoured routes eventually become wide enough that groundwater is able to retain most of its solutional aggressiveness throughout the entire distance to the spring outlets. This breakthrough time usually requires times on the order of 104 to 105 years and ends the inception phase of speleogenesis. (4) Discharge along these selected routes increases rapidly, allowing them to enlarge into cave passages rather uniformly over their entire length. Maximum enlargement rates are roughly 0.001-0.1 cm/yr, depending on the local water chemistry and lithology. (5) The cave acquires a distinct passage pattern that depends on the nature of groundwater recharge, the geologic setting, and the erosional history of the region. Branchwork patterns dominate in most carbonate aquifers. Maze caves are produced by any of the following: steep hydraulic gradients (e.g. during floods), short flow paths, uniform recharge to many openings, and mixing of waters that contrast in chemistry. (6) Enlargement rate usually decreases as passages become air-filled, owing to loss of aggressiveness as carbon dioxide escapes through openings to the surface. (7) The cave typically evolves by diversion of water to new and lower routes as the fluvial base level drops. (8) The cave is eventually destroyed by roof collapse and by intersection of passages by surface erosion. At any given time, different parts of the same cave may be experiencing different stages in this sequence.
Patterns of dissolutional porosity in carbonate rocks
Palmer,A.N.
Speleogenesis and Evolution of Karst Aquifers , 2003,
Abstract: This paper reviews the hydrochemical processes that determine the patterns of caves and other solutional features within carbonate rocks. The model presented relies on the functional relationships expressed by chemical mass balances, flow equations, and kinetic expressions for dissolution rate. Although it shares many aspects of purely conceptual models and is backed by field evidence, its quantitative basis places it into the realm of analytical models. The conclusions merely summarize earlier work (mainly Palmer, 1981, 1991). Solutional enlargement of caves and other karst features is highly selective in water that is close to equilibrium with dissolved carbonate minerals, enlarging only the most favorable openings – i.e. those that transmit the greatest discharge. This is characteristic of long flow paths within a typical karst aquifer. In contrast, solutional enlargement will be rather uniform along many competing flow paths where there is (1) high discharge, (2) sustained steep hydraulic gradients, (3) short flow paths, or (4) local renewal of aggressiveness by mixing, oxidation of sulfides, etc. These conditions produce maze caves and epikarstic networks. In general, this condition prevails if Q/rL > 0.001 cm/sec (tubes), or /bL > 0.001 cm/sec (fissures), where Q = discharge, r = tube radius, b = long dimension of fissure cross section, and L = distance of flow from where the initial aggressive solution comes in contact with the carbonate rock.
Dynamics of cave development by allogenic water
Palmer,A.N.
Speleogenesis and Evolution of Karst Aquifers , 2003,
Abstract: Streams that drain from non karstic surfaces tend to have great discharge fluctuations and low concentrations of dissolved solids. Where these streams encounter karstic rocks they can form caves with hydraulic and chemical dynamics quite different from those fed by autogenic recharge (e.g. through dolines). In either case, caves form only along those paths in which the discharge can increase with time. Only a few favorable paths achieve this goal, while the others stagnate with small and diminishing enlargement rates. Caves in carbonate rocks that are fed by allogenic streams have a relatively short inception period, after which the mean annual rate of dissolutional wall retreat is typically about 0.01 cm/yr. Most of the annual growth takes place during a few major floods that occupy only a small fraction of the year. Local growth rates can be enhanced by abrasion from sediment. During floods, highly aggressive water is delivered rapidly to points deep within the karst aquifer. As flood discharge increases, cave streams become ponded by constrictions caused by detrital sediment, insoluble beds, or collapse material. The head loss across a constriction varies with the fifth power of the diameter ratio under pipe full conditions. Head loss also increases with the square of the discharge. Because the discharge during a flood rises by several orders of magnitude, the head loss across constrictions can increase enormously, causing water to fill parts of the cave under considerable pressure. This highly aggressive water is injected into all available openings in the surrounding bedrock, enlarging them at a rapid and nearly uniform rate. Depending on the structural nature of the bedrock, a dense array of blind fissures, pockets, anastomoses, or spongework is formed. Many such caves develop traversable mazes that serve either as bypass routes around constrictions, or as "karst annexes", which store and later release floodwaters. Many features that are sometimes attributed to slow phreatic flow or mixing corrosion are actually generated by ponded floodwaters. In caves that experience severe flooding, adjacent fissures or bypass routes with initial widths at least 0.01 cm can grow to traversable size within 10,000 years.
Puntos de encuentro de las mujeres en el Madrid del siglo XIX
Simón Palmer, Carmen
Revista de Dialectología y Tradiciones Populares , 2001,
Abstract: In the 19th century, scores of middle class women from Madrid joined social life through different kinds of associations: social gatherings, charities and educational, masonic and religious societies. The author gives an outline of the most important of these associations and their links with one another. En el siglo XIX un elevado número de mujeres madrile as de la burguesía se incorporaron a la vida social a través de diferentes tipos de asociaciones: tertulias, sociedades de beneficencia, educativas, masónicas y religiosas. Se ofrece aquí un breve esbozo de las principales y sus vinculaciones.
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