1,720,961 research outputs found
Body weight changes and incidence of cachexia after stroke.
Full text linkBACKGROUND
Body weight loss is a frequent complication after stroke, and its adverse effect on clinical outcome has been shown in several clinical trials. The purpose of this prospective longitudinal single-centre observational study was to investigate dynamical changes of body composition and body weight after ischemic stroke and an association with functional outcome.
METHODS
Sixty-seven consecutive patients (age 69 ± 11 years, body mass index 27.0 ± 4.1 kg/m , 42% female patient, mean ± SD) with acute ischemic stroke with mild to moderate neurological deficit (National Institute of Health Stroke Scale median 4, ranged 0-12) were analysed in the acute phase (4 ± 2 days) and at 12 months (389 ± 26 days) follow-up. Body composition was examined by dual energy X-ray absorptiometry. Cachexia was defined according to the consensus definition by body weight loss ≥5% within 1 year and additional clinical signs. Lean tissue wasting was considered if a ratio of upper and lower limbs lean mass sum to squared height (kg/m ) was ≤5.45 kg/m for female patient and ≤7.25 kg/m for male patient.
RESULTS
According to the body weight changes after 12 months, 42 (63%) patients had weight gain or stable weight, 11 (16%) patients had moderate weight loss, and 14 (21%) patients became cachectic. A relative decline of 19% of fat tissue and 6.5% of lean tissue was observed in cachectic patients, while no changes of lean tissue were observed in non-cachectic patients after 12 months. The modified Rankin Scale was 48% higher (2.1 ± 1.6, P < 0.05), Barthel Index was 22% lower (71 ± 39, P < 0.01), and handgrip strength was 34% lower (21.9 ± 13.0, P < 0.05) in cachectic compared to non-cachectic patients after 12 months. The low physical performance if defined by Barthel Index <60 points was linked to the lean tissue wasting (OR 44.8, P < 0.01), presence of cachexia (OR 20.8, P < 0.01), and low body mass index <25 kg/m (OR 11.5, P < 0.05). After adjustment for cofounders, lean tissue wasting remained independently associated with the low physical performance at 12 months follow-up (OR 137.9, P < 0.05).
CONCLUSIONS
In this cohort study, every fifth patient with ischemic stroke fulfilled the criteria of cachexia within 12 months after index event. The incidence of cachexia was 21%. Cachectic patients showed the lowest functional and physical capacity
Mechanisms of appetitive classical conditioning and extinction in healthy human subjects
Full text linkDie appetitiven Pawlow’schen Lernmechanismen der Konditionierung, Extinktion und des Reinstatements sind von entscheidender Bedeutung für das Verständnis der Entstehung, Aufrechterhaltung, Therapie und Rückfallphänomene von Abhängigkeitserkrankungen. Bislang mangelt es an Studien, die appetitive Konditionierungs- und Extinktionsprozesse im Humanmodell untersuchen, während Reinstatement-Effekte gänzlich unerforscht sind. Dieser Mangel wird gewöhnlich auf die Schwierigkeit zurückgeführt, ein geeignetes psychophysiologisches Maß zu finden, das sensitiv konditionierte Reaktionen beim Menschen erfasst. Die vorliegende Dissertation zielte daher darauf ab, die behavioralen, physiologischen und neuronalen Korrelate appetitiver Pawlow’scher Lernprozesse in gesunden Probanden zu erkunden.
Studie I untersuchte die Eignung von Eyetracking-Maßen zur Abbildung konditionierter Reaktionen in appetitiven Lernparadigmen und verglich diese mit weiteren psychophysiologischen Maßen. Zusätzlich wurde geprüft, ob sich Lernprozesse anhand des Pupillenverhaltens mit Hilfe computationaler Modellierung ableiten lassen. Konditionierte Reaktionen zeigten sich durch stärkere Pupillendilatation, längere Blickverweildauer und eine kürzere Lidschlagdauer auf den belohnungsankündigenden Stimulus. Das Pearce-Hall-Modell mit aufmerksamkeitsgewichtetem Prädiktionsfehler konnte die Pupillenreaktion am besten vorhersagen.
In Studie II wurde untersucht, ob sich der appetitive Reinstatement-Effekt als Modell des Rückfallgeschehens psychophysiologisch abbilden lässt und welche neuronalen Strukturen diesem Lernprozess zugrunde liegen. Ein erfolgreiches Reinstatement konnte anhand der Hautleitfähigkeitsreaktion festgestellt werden und wurde auf neuronaler Ebene durch eine erhöhte Amygdala-Aktivierung gezeigt. Die vmPFC-Aktivität korrelierte negativ mit dem beobachteten Reinstatement-Effekt der Hautleitfähigkeit.
Diese Ergebnisse belegen den Wert von Eyetracking-Maßen als robuste und sensitive Indizes appetitiver Konditionierungsprozesse und weisen der Amygdala und dem vmPFC gegenläufige Funktionen bei Pawlow’schen Rückfallprozessen zu. Damit tragen die Ergebnisse zu einem größeren Verständnis von appetitiven Lernprozessen beim Menschen bei und liefern wertvolle neue Maße und Erkenntnisse, um Abhängigkeitserkrankungen besser zu untersuchen und zu verstehen.Appetitive Pavlovian learning mechanisms like conditioning, extinction and reinstatement are of fundamental importance for the understanding of the etiology, maintenance, treatment and relapse of addiction disorders. The investigation of appetitive conditioning and extinction in humans remains sparse, while reinstatement has thus far never been successfully modeled in humans. This paucity is commonly attributed to the lack of an adequate psychophysiological measure that sensitively reflects conditioned responding. The aim of this thesis was to explore the behavioral, physiological and neural correlates of appetitive Pavlovian learning processes in healthy participants.
Study I evaluated the applicability of eye-tracking measures for representing conditioned responding and compared them to further psychophysiological measures. Additionally, this study investigated whether learning mechanisms could be inferred from the pupil response using computational modeling techniques. Conditioned responding was reflected through greater pupil dilation, longer gaze duration and shorter eye blink duration on the reward-predicting stimulus. A Pearce-Hall attention-weighted model most accurately predicted the trial-by-trial pupil response.
Study II examined whether appetitive reinstatement could be psychophysiologically modeled in humans and what neural structures underlie this learning process. Successful reinstatement was indicated through an enhanced skin conductance response and correlated positively with amygdala activation, while vmPFC activation correlated negatively with the reinstatement effect observed in the skin conductance response.
These results emphasize the value of eye-tracking measures as robust and sensitive indices for measuring appetitive conditioning processes and assign amygdala and vmPFC opposing roles in the return of Pavlovian reinstatement processes. These results thereby contribute to our knowledge of appetitive learning mechanisms in humans and provide valuable new measures and insights for exploring and understanding addiction disorders
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mechanismen der appetitiven klassischen Konditionierung und Extinktion bei gesunden Probanden = Mechanisms of appetitive classical conditioning and extinction in healthy human subjects
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
