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One Theory (one + theory)
Selected AbstractsCould chronic pain and spread of pain sensation be induced and maintained by glial activation?ACTA PHYSIOLOGICA, Issue 1-2 2006E. Hansson Abstract An injury often starts with acute physiological pain, which becomes inflammatory or neuropathic, and may sometimes become chronic. It has been proposed recently that activated glial cells, astrocytes and microglia within the central nervous system could maintain the pain sensation even after the original injury or inflammation has healed, and convert it into chronic by altering neuronal excitability. Glial cell activation has also been proposed to be involved in the phenomenon of spread of pain sensation ipsilaterally or to the contralateral side (i.e. mirror image pain). Substance P and calcitonin gene-related peptide, released due to an inflammatory process, interact with the endothelial cells of the blood,spinal cord and blood,brain barriers. The barriers open partially and substances may influence adjacent glial cells. Such substances are also released from neurones carrying the ,pain message' all the way from the injury to the cerebral cortex. Pro-inflammatory cytokines may be released from the microglial cells, and astroglial Ca2+ -transients or oscillations may spread within the astroglial networks. One theory is that Ca2+ -oscillations could facilitate the formation of new synapses. These new synapses could establish neuronal contacts for maintaining and spreading the pain sensation. If this theory holds true, it is possible that Ca2+ waves, production of cytokines and growth factors could be modified by selective anti-inflammatory drugs to achieve a balance in the activities of the different intercellular and intracellular processes. This paper reviews current knowledge about glial mechanisms underlying the phenomena of chronic pain and spread of the pain sensation. [source] A systematic review and quantitative appraisal of fMRI studies of verbal fluency: Role of the left inferior frontal gyrusHUMAN BRAIN MAPPING, Issue 10 2006Sergi G. Costafreda Abstract The left inferior frontal gyrus (LIFG) has consistently been associated with both phonologic and semantic operations in functional neuroimaging studies. Two main theories have proposed a different functional organization in the LIFG for these processes. One theory suggests an anatomic parcellation of phonologic and semantic operations within the LIFG. An alternative theory proposes that both processes are encompassed within a supramodal executive function in a single region in the LIFG. To test these theories, we carried out a systematic review of functional magnetic resonance imaging studies employing phonologic and semantic verbal fluency tasks. Seventeen articles meeting our pre-established criteria were found, consisting of 22 relevant experiments with 197 healthy subjects and a total of 41 peak activations in the LIFG. We determined 95% confidence intervals of the mean location (x, y, and z coordinates) of peaks of blood oxygenation level-dependent (BOLD) responses from published phonologic and semantic verbal fluency studies using the nonparametric technique of bootstrap analysis. Significant differences were revealed in dorsal,ventral (z -coordinate) localizations of the peak BOLD response: phonologic verbal fluency peak BOLD response was significantly more dorsal to the peak associated with semantic verbal fluency (confidence interval of difference: 1.9,17.4 mm). No significant differences were evident in antero,posterior (x -coordinate) or medial,lateral (y -coordinate) positions. The results support distinct dorsal,ventral locations for phonologic and semantic processes within the LIFG. Current limitations to meta-analytic integration of published functional neuroimaging studies are discussed. Hum Brain Mapp, 2006. © 2006 Wiley-Liss, Inc. [source] Applying Prochaska's model of change to needs assessment, programme planning and outcome measurementJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 4 2001Kathryn Parker MA Abstract A major goal of continuing medical education (CME) is to enhance the performance of the learner. In order to accomplish this goal, careful consideration and expertise must be applied to the three primary ingredients of CME planning: assessing learner needs, programme design and outcome measurement. Traditional methods used to address these three components seldom result in CME initiatives that change performance, even in the presence of sophisticated CME formats and capable learners. In part, performance may not change because the learner is not ,ready to change'. Planners of CME are aware of this concept but have been unable to measure ,readiness to change' or employ it in assessing learner needs, and planning and evaluating CME. One theory that focuses on an individual's readiness to change is Prochaska's model, which postulates that change is a gradual process proceeding through specific stages, each of which has key characteristics. This paper examines the applicability of this model to all components of CME planning. To illustrate the importance of this model, this paper provides examples of these three components conducted both with and without implementation of this model. [source] Sexual selection is not the origin of long necks in giraffesJOURNAL OF ZOOLOGY, Issue 4 2009G. Mitchell Abstract The evolutionary origin of the long neck of giraffes is enigmatic. One theory (the ,sexual selection' theory) is that their shape evolved because males use their necks and heads to achieve sexual dominance. Support for this theory would be that males invest more in neck and head growth than do females. We have investigated this hypothesis in 17 male and 21 female giraffes with body masses ranging from juvenile to mature animals, by measuring head mass, neck mass, neck and leg length and the neck length to leg length ratio. We found no significant differences in any of these dimensions between males and females of the same mass, although mature males, whose body mass is significantly (50%) greater than that of mature females, do have significantly heavier (but not longer) necks and heavier heads than mature females. We conclude that morphological differences between males and females are minimal, that differences that do exist can be accounted for by the larger final mass of males and that sexual selection is not the origin of a long neck in giraffes. [source] The autonomic control of accommodation and implications for human myopia development: a reviewOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2003Jennifer C. Chen Abstract Prolonged nearwork has long been associated with myopia development, however, there is no well described linking mechanism. One theory suggests that if accommodation accuracy during nearwork is not maintained, the defocused retinal image leads to myopia development. Here we review the findings of research aimed at determining whether the autonomic inputs to the ciliary smooth muscle are involved in this type of environmental myopia. We examine whether an autonomic imbalance could be a precursor to axial elongation and the resulting myopia. Accommodation responses, such as tonic accommodation and nearwork-induced accommodative adaptation, as a function of refractive error, are described in relation to an autonomic imbalance model. The collective results of this research point to anomalous accommodation responses, possibly as a result of underlying anomalous autonomic input to the ciliary muscle, being involved in myopia development and progression. [source] Cellular and humoral autoimmunity directed at bile duct epithelia in murine biliary atresia,,HEPATOLOGY, Issue 5 2006Cara L. Mack Biliary atresia is an inflammatory fibrosclerosing lesion of the bile ducts that leads to biliary cirrhosis and is the most frequent indication for liver transplantation in children. The pathogenesis of biliary atresia is not known; one theory is that of a virus-induced, subsequent autoimmune-mediated injury of bile ducts. The aim of this study was to determine whether autoreactive T cells and autoantibodies specific to bile duct epithelia are present in the rotavirus (RRV)- induced murine model of biliary atresia and whether the T cells are sufficient to result in bile duct inflammation. In vitro analyses showed significant increases in IFN-,,producing T cells from RRV-diseased mice in response to bile duct epithelial autoantigen. Adoptive transfer of the T cells from RRV-diseased mice into naïve syngeneic SCID recipients resulted in bile duct,specific inflammation. This induction of bile duct pathology occurred in the absence of detectable virus, indicating a definite response to bile duct autoantigens. Furthermore, periductal immunoglobulin deposits and serum antibodies reactive to bile duct epithelial protein were detected in RRV-diseased mice. In conclusion, both cellular and humoral components of autoimmunity exist in murine biliary atresia, and the progressive bile duct injury is due in part to a bile duct epithelia,specific T cell,mediated immune response. The role of cellular and humoral autoimmunity in human biliary atresia and possible interventional strategies therefore should be the focus of future research. (HEPATOLOGY 2006;44:1231,1239.) [source] Which links in which theories shall we evaluate?NEW DIRECTIONS FOR EVALUATION, Issue 87 2000Carol Hirschon Weiss If there is little consensus about the assumptions underlying a program, theory-based evaluators can collect data relevant to more than one theory, selecting for study the specific links in those theories that answer key questions. [source] Emotivism and Deflationary TruthPACIFIC PHILOSOPHICAL QUARTERLY, Issue 3 2002Kyle S. Swan The paper investigates different ways to understand the claim that non,cognitivists theories of morality are incoherent. According to the claim, this is so because, on one theory of truth, non,cognitivists are not able to deny objective truth to moral judgments without taking a substantive normative position. I argue that emotivism is not self,defeating in this way. The charge of incoherence actually only amounts to a claim that emotivism is incompatible with deflationary truth, but this claim is based upon a mistake. It relies upon a problematic understanding of both emotivism and the deflationary theory of truth. [source] A guide to knowledge translation theoryTHE JOURNAL OF CONTINUING EDUCATION IN THE HEALTH PROFESSIONS, Issue 1 2006Carole A. Estabrooks RN Abstract Despite calls over several decades for theory development, there remains no overarching knowledge-translation theory. However, a range of models and theoretical perspectives focused on narrower and related areas have been available for some time. We provide an overview of selected perspectives that we believe are particularly useful for developing testable and useful knowledge-translation interventions. In addition, we discuss adjuvant theories necessary to complement these perspectives. We draw from organizational innovation, health, and social sciences literature to illustrate the similarities and differences of various theoretical perspectives related to the knowledge-translation field. A variety of theoretical perspectives useful to knowledge translation exist. They are often spread across disciplinary boundaries, making them difficult to locate and use. Poor definitional clarity, discipline-specific terminology, and implicit assumptions often hinder the use of complementary perspectives. Health care environments are complex, and assessing the setting prior to selecting a theory should be the first step in knowledge-translation initiatives. Finding a fit between setting (context) and theory is important for knowledge-translation initiatives to succeed. Because one theory will not fit all contexts, it is helpful to understand and use several different theories. Although there are often barriers associated with combining theories from different disciplines, such obstacles can be overcome, and to do so will increase the likelihood that knowledge-translation initiatives will succeed. [source] A Decision Theoretic Model of Public Opinion: Guns, Butter, and European Common DefenseAMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 2 2004Clifford J. Carrubba Why do individuals support the public policies they do? We argue that individuals can have quite sophisticated policy preferences and that not correctly modeling those preferences can lead to critically misspecified empirical models. To substantiate this position we derive and test a decision-theoretic model that relies upon three critical assumptions: (1) policies affect the provision of multiple goods about which individuals care; (2) individuals have diminishing returns to scale in those goods; and (3) preferences over at least some subset of those goods are correlated. Using this model, we demonstrate that arbitrarily small secondary policy effects can confound predictions over primary policy effects. Thus, not considering even arbitrarily small policy effects can cause one to conclude that evidence is consistent with one's theory when in fact it is inconsistent or vice versa. Testing this theory on support for forming a European common defense, we find evidence consistent with our model. [source] | ||||||||||||||||