1,721,029 research outputs found
Severe bilateral isolated coronary ostial lesions as a rare manifestation of radiation-induced cardiac disease A case report
No full textRationale: With advances in contemporary radiotherapy techniques, and as cancer survival improves, severe isolated coronary ostial disease may develop many years following mediastinal radiotherapy, even in the absence of classical cardiovascular risk factors.
Patient concerns: We describe the case of a 73-year-old woman with previous chest radiotherapy for breast cancer who underwent coronary artery bypass graft surgery for severe bilateral coronary ostial lesions.
Diagnoses: Coronary angiography demonstrated severe, isolated bilateral coronary ostial lesions.
Interventions: The patient underwent urgent coronary artery bypass graft surgery to treat her critical coronary artery disease.
Outcomes: Intra-operatively, internal mammary arteries were not amenable to harvesting due to very dense mediastinal adhesions. Therefore, saphenous vein grafts were performed to the left anterior descending, distal left circumflex, obtuse marginal and distal right coronary arteries. The patient made a satisfactory in-hospital recovery, and was subsequently discharged back to her local hospital for rehabilitation.
Lessons: Patients successfully treated with mediastinal radiotherapy require careful long-term follow-up for the assessment of radiation-induced coronary artery disease. Importantly, mediastinal irradiation may preclude internal mammary artery utilization, and thus alter the strategy for surgical myocardial revascularization
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
Zusammenhang von Struktur und Funktion im Myokard bei Patienten mit hochgradiger Aortenstenose und erhaltener systolischer Herzfunktion unter besonderer Berücksichtigung der B-Typ natriuretischen Peptide
Full text linkDie valvuläre Aortenstenose ist die häufigste erworbene Klappenerkrankung in der westlichen Welt. Als Folge der Stenosierung der linksventrikulären Ausflussbahn entwickelt sich durch die chronische Druckbelastung des Herzens eine pathologische kardiale Hypertrophie und eine Herzinsuffizienz. Im Verlauf dieser Entwicklung findet ein kardiales Remodeling mit strukturellen Veränderungen der Herzmuskelzellen und Fibrose statt.Die Korrektur dieses Herzklappenfehlers erfolgt bei den meisten Patienten mittels eines standardisierten herzchirurgischen Eingriffs. Frühere Arbeiten konnten jedoch zeigen, dass die myokardialen strukturellen Veränderungen auch nach Ersatz der erkrankten Herzklappe nicht vollständig reversibel sind. Allerdings waren Untersuchungen an Patienten mit erhaltener systolischer Herzfunktion bei Aortenstenose in dieser Form noch nicht Gegenstand der Forschung.Aus diesem Grund war das Ziel der vorliegenden Studie zweigliedrig: Erstens sollten myokardiale Strukturen bei Patienten mit schwergradiger Aortenstenose aber erhaltener Ejektionsfraktion untersucht werden, zweitens sollten diese strukturellen Veränderungen im Gewebe mit Biomarkern der diagnostischen Routine korreliert werden.Mittels immunhistochemischer Methoden konnte die spezifische Zusammensetzung der myokardialen Extrazellularmatrix quantifiziert werden. Der gefundene Grad der Fibrose des Herzmuskels war signifikant erhöht. Der myokardiale interstitielle Raum im Gewebe der Studiengruppe war signifikant gegenüber der Kontrolle vergrößert (21,9 % versus 12,74 % Kontrolle). Spezifische Messungen ergaben signifikant erhöhte Werte für Kollagen I (8,51 % versus 1,98% Kontrolle), Kollagen III (16,67 % versus 7,62 % Kontrolle) und für Kollagen VI (26,61 % versus 14,6 % Kontrolle). Kollagenstoffwechselprodukte, wie Prokollagen-I- Propeptid (18,71 % versus 8,58 % Kontrolle) und Prokollagen-III-Propeptid (16,1 % versus 9,48 % Kontrolle) waren ebenfalls signifikant verstärkt nachweisbar.Zur Darstellung von strukturellen Veränderungen der Myozyten wurden mit zwei verschiedenen Alpha-Aktinin-Antikörpern spezifisch angefärbt. Das im glatten Muskel vorkommende ACTN-1 (BM 75.2) wurde in Biopsien von zehn Patienten in Form von klusterartigen Ansammlungen nachgewiesen. Desorganisation der sarkomerischen Struktur der Myozyten anhand des Nachweises von dysmorphem ACTN-2 (EA 53.3) gelang bei 25 Patienten.Wir konnten präoperativ eine Erhöhung der Serumkonzentration der B-Typ natriuretischen Peptide nachweisen. Immunhistochemisch gelang der Nachweis von BNP bei 16 Patienten, der ventrikuläre ANP-Nachweis in fünf Fällen. Eine signifikante Korrelation konnte zwischen erhöhten NTproBNP Serumwerten und dem Nachweis von ACTN-1, nicht aber für ACTN-2 gezeigt werden. Erhöhte NTproBNP Konzentration korrelierten nicht mit einem positiven zytoplasmatischen BNP-Nachweis im Gewebe. Eine Korrelation zwischen NTproBNP im Serum und der Extrazellularmatrix blieb aus, womöglich begründet durch die geringe Anzahl an Studienpatienten (n=31).Die Prokollagen-I- und III-Propeptide im Serum waren gegenüber der Referenz nicht erhöht. Eine Korrelation von PIP und PIIIP im Serum mit der Extrazellularmatrix war nicht feststellbar. Es konnte eine signifikante Korrelation zwischen PIIIP und NTproBNP Serumkonzentration gezeigt werden, wohingegen eine Signifikanz für PIP versus NTproBNP im Serum fehlte.Diese Ergebnissen unterstützen den Einsatz der B-Typ natriuretischen Peptide bei Aortenklappenerkrankungen, wobei weitere Untersuchungen auf diesem Gebiet an einem größeren Patientenkollektiv folgen sollten.Der operative Aortenklappenersatz ist ein sicheres und gut etabliertes Verfahren zur Behandlung einer valvulären Aortenstenose. Hierbei ist der Zeitpunkt zu Intervention durch Leitlinien der medizinischen Fachgesellschaften weitgehend vorgegeben. Die Daten der vorliegenden Arbeit zeigen jedoch, dass bereits im Zustand der erhaltenen Herzfunktion strukturelle Veränderungen bestehen. Weiterführende und umfangreiche Untersuchungen auf diesem Gebiet sollten folgen.Aortic valve stenosis is the most common acquired valvular heart disease in the Western world. The stenosis causes chronic pressure overload of the left ventricle, which leads to cardiac hypertrophy and heart failure. During the development of pathological cardiac hypertrophy cardiac remodeling occurs including alterations of the extracellular matrix resulting in fibrosis and in structural deterioration of the myocytes.Correction of the valvular defect by open-heart-surgery is commonly and successfully performed in most patients. However, several studies in patients with with severely reduced function preoperatively have shown that the symptoms of structural impairment of the left ventricle tissue do not completely disappear after valve replacement. Investigations in patients with aortic stenosis and preserved cardiac function have not been carried out yet.Therefore, the aim of the study was twofold: 1. To study the myocardial structure in patients with severe aortic stenosis and preserved ejection fraction and 2. To orrelate the structural alterations of the interstitium and the myocytes with biomarkers commonly used in clinical diagnostic routine.Using immunohistochemical procedures we recorded and quantified the specific composition of the myocardial extracellular matrix and found myocardial fibrosis. The interstitial space indicated by fibronectin staining was significantly increased as compared to control (21.9 % vs. 12.74 %). Measurements also showed significantly increased levels of collagen I (8.51 % vs. 1.98 % control), collagen III (16.67 % vs. 7.62 % control) and collagen VI (26.62 % vs. 14.6 % control). Indicators of collagen metabolism such as procollagen-propeptide I (18.71 % vs. 8.58 % control) and procollagen-propeptide III (16.1 % vs. 9.48 % control) were increased as well.For myocyte deterioration, we used staining with 2 different alpha-actinin antibodies, EA 53.3 for the cardiac specific alpha-actinin 2 (ACTN-2) and BM 75.2 for smooth muscle cell alpha- actinin 1 (ACTN-1). Disorganization of the sarcomeric structure was found in 25 patients. The presence of ACTN-1 in clusters, which normally is absent from ventricular myocytes, was found in 10 patients.In the present study, a close connection existed between structural impairment observed in cardiomyocytes and the B-type natriuretic peptides, clinically suitable biomarkers for cardiacdisorders. A weak correlation was found between the elevated biomarker NTproBNP and sarcomeric disorganization, whereas the correlation was significant for ACTN-1.On the one hand, our results support the active use of the biomarkers B-type natriuretic peptides as indicators of myocardial structural degeneration in patients with aortic valve disease. It seems, therefore, worthwhile to carry out further investigations concerning this issue in a larger patient cohort.On the other hand, a correlation between the procollagen-propeptide serum concentration and the degree of structural deterioration or myocardial fibrosis was absent, probably caused by the small number of patients (n=31) involved in this study.Aortic valve replacement is a safe and well understood procedure for treating aortic stenosis and the determination of the optimal time point for of the intervention (AVR) follows the topic guidelines for valve disease of the international medical societies.However, the present data show, that in patients, which still possess a reserved systolic cardiac function, structural alterations are already present and that these might be irreversible. Therefore, studies in a larger patient cohort might be useful to determine the optimal time point for AVR
Variations 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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