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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
Terapia celular com células mesenquimais por via intracoronária: contributos do estudo invasivo da microcirculação coronária
Full text linkRESUMO: Introdução - A utilização de células e das suas propriedades para o tratamento das doenças cardiovasculares, é uma promessa para o futuro e talvez a única forma de ultrapassar algumas das insuficiências das terapêuticas atuais. A via de entrega das células mais utilizada na investigação tem sido a
intracoronária, ganhando a microcirculação especial relevância, por ser onde ocorre a primeira
interação com o tecido nativo. As células estaminais mesenquimais (CEM) têm propriedades que as
tornam particularmente aptas para a Terapia Celular, mas as suas dimensões, superiores ao diâmetro
dos capilares, tem motivado controvérsia quanto à sua entrega intracoronária. A cardiologia de
intervenção tem atualmente técnicas que permitem a avaliação em tempo real e in vivo do estado da
microcirculação coronária. A determinação do índice da resistência da microcirculação (IRM) fornece
informação sobre a circulação dos pequenos vasos, de forma independente da circulação coronária e
do estado hemodinâmico, mas a aplicabilidade clínica deste conhecimento encontra-se ainda por definir.
Objectivos Esclarecer o potencial do IRM no estudo dos efeitos do transplante de CEM por via intracoronária.
População e Métodos .
Estudo pré-clínico com modelo animal (suíno) desenvolvido em 3 fases.
Na Primeira Fase foram utilizados 8 animais saudáveis para estudar e validar a técnica de
determinação de estudo da microcirculação. Efetuou-se a determinação do IRM com duas doses
diferentes de papaverina para a indução da resposta hiperémica máxima (5 e 10 mg) e após a
disfunção da microcirculação com injeção intracoronária de microesferas de embozene com 40 μm de
diâmetro.
Na Segunda Fase foram utilizados 18 animais saudáveis, randomizados em grupo controlo e grupo
recetor de 30 x 106 CEM por via intracoronária. Foram avaliados de forma cega o IRM, a pressão
aórtica, o fluxo coronário epicárdico e a ocorrência de alterações electrocardiográficas.
Na Terceira Fase foram utilizados 18 animais, com enfarte agudo do miocárdio provocado (EAM),
randomizados em grupo controlo, grupo recetor de CEM expandidas de forma convencional e grupo
recetor de CEM expandidas com metodologia inovadora e de menores dimensões. Foi realizada uma
exploração da dose/efeito com infusão faseada de 10 x 106, 15 x 106 e 20 x 106 CEM, com
determinação do IRM, da pressão aórtica, do fluxo coronário epicárdico e da ocorrência de alterações
eletrocardiográficas. Quatro semanas após a entrega das células foi novamente avaliado o IRM e foi
efetuado o estudo anatomopatológico dos animais na procura de evidência de neoangiogénese e de
regeneração miocárdica, ou de um efeito positivo da resposta reparadora após o enfarte.
Resultados
Nas 3 fases todos os animais mantiveram estabilidade hemodinâmica e eletrocardiográfica, com
exceção da elevação de ST de V1-V3 verificada após a injeção das microesferas.
Na Primeira Fase as duas doses de papaverina induziram uma resposta hiperémica eficaz, sem
tradução com significado na determinação do IRM (variação da pressão distal de - 11,4 ± 5 e de - 10,6±
5 mmHg com as doses de 5 e 10 mg respetivamente (p=0,5). Com a injeção das microesferas o IRM
teve uma elevação média de 310 ± 190 %, para um valor médio de 41,3 ± 16 U (p = 0,001).
Na Segunda Fase não houve diferenças significativas dos parâmetros hemodinâmicos, do fluxo
epicárdico e da avaliação eletrocardiográfica entre os dois grupos. O IRM de base foi semelhante e
após a infusão intracoronária observou-se uma elevação expressiva do IRM nos animais que
receberam células em comparação com o grupo controlo (8,8 U ± 1 vs. 14,2 U ± 1,8, P=0,02) e quanto
ao seu valor de base (aumento de 112%, p=0,008).
Na terceira Fase não houve novamente diferenças significativas dos parâmetros hemodinâmicos, do
fluxo epicárdico e da avaliação eletrocardiográfica entre os três grupos. Houve uma elevação do IRM
nos animais que receberam células a partir da 2ª dose (72% nas células convencionai e 108% nas
células inovadoras) e que se manteve com a 3ª dose (100% nas células convencionais e 88% nas
inovadoras) com significado estatístico em comparação com o grupo controlo (p=0,034 com a 2ªdose e
p=0,024 com a 3ª dose). Quatro semanas após a entrega das CEM observou-se a descida do IRM nos
dois grupos que receberam células, para valores sobreponíveis aos do grupo controlo e aos valores
pós-EAM. Na avaliação anatomopatológica e histológica dos corações explantados não houve
diferenças entre os três grupos.
Conclusões
O IRM permite distinguir alterações da microcirculação coronária motivadas pela entrega intracoronária
de CEM, na ausência de alterações de outros parâmetros clínicos da circulação coronária utilizados em
tempo real. As alterações do IRM são progressivas e passíveis de avaliar o efeito/dose, embora não
tenha sido possível determinar diferenças com os dois tipos de CEM. No nosso modelo a injeção
intracoronária não se associou a evidência de efeito benéfico na reparação ou regeneração miocárdica
após o EAM.---------------------------- ABSTRACT: ABSTRACT
Introduction
The use of cells for the treatment of cardiovascular disease is a promise for the future and perhaps the
only option to overcome some of the shortcomings of current therapies. The strategy for the delivery of
cells most often used in current research has been the intracoronary route and due to this
microcirculation gains special relevance, mainly because it is the first interaction site of transplanted
cells with the native tissue. Mesenchymal stem cells (MSC) have properties that make them suitable for
Cell Therapy, but its dimensions, larger than the diameter of capillaries, have prompted controversy
about the safety of intracoronary delivery. The interventional cardiology currently has techniques that
allow for real-time and in vivo assessment of coronary microcirculation state. The determination of the
index of microcirculatory resistance index (IMR) provides information about small vessels, independently
of the coronary circulation and hemodynamic status, but the clinical applicability of this knowledge is yet
to be defined.
Objectives
To clarify the potential use of IMR in the study of the effects of MSC through intracoronary
transplantation.
Population and Methods
Preclinical study with swine model developed in three phases.
In Phase One 8 healthy animals were used to study and validate the IMR assessment in our animal
model. IMR was assessed with two different doses of papaverine for inducing the maximal hyperaemic
response (5 and 10 mg) and microcirculation dysfunction was achieved after intracoronary injection with
embozene microspheres with 40 μm in diameter.
In Phase Two we randomized 18 healthy animals divided between the control group and the one
receiving 30 x 106 MSC through an intracoronary infusion. There we blindly evaluated IMR, the aortic
pressure, the epicardial coronary flow and the occurrence of ECG changes.
In Phase Three we used 18 animals with a provoked acute myocardial infarction (AMI), randomized into
a control group, a MSC expanded conventionally receiver group and a MSC expanded with an
innovative methodology receiver group. There was a stepwise infusion with doses of 10 x 106, 15 x 106
and 20 x 106 MSC with determination of IMR, the aortic pressure, the epicardial coronary flow and
occurrence of electrocardiographic abnormalities. Four weeks after cell delivery we again measured the
IMR and proceeded with the pathological study of animals in the search for evidence of
neoangiogenesis and myocardial regeneration, or a positive effect in the reparative response following
the infarction.
Results
All animals remained hemodynamically stable and with no electrocardiographic abnormalities, except for
the ST elevation in V1-V3 observed after injection of the microspheres.
In Phase One the two doses of papaverine achieved an hyperemic and effective response without
significant differences in IMR (variation of the distal pressure -11.4 ± 5 and -10.6 ± 5 mmHg with the
doses of 5 and 10 mg respectively (p = 0.5). With the injection of the microspheres the IMR had an
average increase of 310 ± 190% for an average value of 41.3 ± 16 U (p = 0.001).
In the second phase there were no significant differences in hemodynamic parameters, epicardial flow
and electrocardiographic assessment between the two groups. The baseline IMR was similar and after
intracoronary infusion there was a significant increase in animals receiving cells compared with the
control group (8.8 ± U 1 vs. 14.2 ± 1.8, p = 0.02) and with their baseline (112% increase, p = 0.008).
In the third phase again there were no significant differences in hemodynamic parameters, the epicardial
flow and electrocardiographic evaluation between the three groups. There was a significant increase in
IMR in animals that received cells from the 2nd dose (72% in conventional cells and 108% in the
innovative cells) that remained with the 3rd dose (100% in conventional cells and 88% in the innovative)
with statistical significance compared with the control group (p = 0.034 with 2nd dose, p = 0.024 with 3rd
dose). Four weeks after delivery of the MSC we observed the fall of the IMR in the two groups that
received cells with values overlapping those of the control group. In pathological and histological
evaluation of removed hearts there were no differences among the three groups.
Conclusions
The IMR allows for the differentiation of changes in coronary microcirculation motivated by intracoronary
delivery of MSC in the absence of modification in other clinical parameters. IMR changes are
progressive and enable the evaluation of the effect / dose, though it has not been possible to determine
differences in the two types of MSC. In our model, intracoronary injection of MSC was not associated
with evidence of repair or myocardial regeneration after AMI
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
European multicentre validation study of the accuracy of E/e' ratio in estimating invasive left ventricular filling pressure: EURO-FILLING study.
Full text linkpeer reviewedAIMS: The non-invasive estimation of left ventricular filling pressures (LVFPs) represents a main goal in the clinical setting. Current recommendations encourage the use of pulsed-wave Tissue Doppler for calculating the ratio between the preload-dependent transmitral E velocity and the average of septal and lateral early diastolic velocities (e') of the mitral annulus. Despite its wide use, real utility of the E/e' ratio has been recently challenged in patients with either very advanced heart failure or preserved left ventricular (LV) ejection fraction. However, only few studies performed the invasive and non-invasive estimation of LVFP simultaneously. The EURO-FILLING Study will validate the E/e' ratio (and additional non-invasive estimates) against simultaneously measured LVFP obtained by left heart catheterization in a multicentre study involving reference European echo laboratories collecting a wide population sample size of cardiac patients with and without heart failure. METHODS AND RESULTS: The EURO-FILLING study is a large, prospective observational study in which simultaneous assessment of invasive and non-invasive measurements of LVFP will be acquired in eight reference European centres. Centralized reading of the collected parameters will be performed in a core laboratory. Not only standardized echo Doppler measurements but also novel echo parameters such as LV global longitudinal strain and global atrial strain (obtainable by two-dimensional speckle tracking echocardiography) will be tested for predicting invasive measurements of LVFP. CONCLUSIONS: The EURO-FILLING study is expected to provide important information on non-invasive assessment of LVFP and to contribute to the standardization of this assessment in clinical practice
Ultrasonographic vascular mechanics: feasibility, usefulness, and clinical applications
No full textTese de doutoramento em Ciências da Saúde, na especialidade de Medicina, apresentada à Faculdade de Medicina da Universidade de CoimbraThe development of accurate non-invasive methods of early diagnosis of vascular degenerative changes is of considerable clinical interest, given that cardiovascular disease remains the leading cause of death worldwide and large artery damage is a major contributor to cardiovascular disease. Ultrasound delivers dynamic images of the heart and central arteries. Two-dimensional speckle tracking echocardiography (2D-STE) is a semi automated analysis based on frame-by-frame tracking of tiny echo-dense speckles within the myocardium, from which deformation variables such as strain, strain rate, velocity and displacement can be studied. Initial attempts to study cardiac mechanics were focused on the left ventricular chamber, but its usage has been expanded and validated for the right ventricle, as well as the thin-walled atrial chambers. Later, direct vessel-wall tracking has been achievable through 2D-STE. The focus on previous vascular mechanics studies was the circumferential expansion and recoil of the vessel wall, which enabled the assessment of a positive systolic strain plus a positive and negative strain rate. Vascular mechanics assessment with 2D-STE has been validated with sonomicrometry studies and an association with vascular mechanics and the collagen content of vascular wall has also demonstrated, promoting vascular mechanics with 2D-STE as a new imaging surrogate of vascular stiffening.
We used 2D-STE to study aortic mechanics in patients with aortic stenosis (AS), with hypertension, and atrial fibrillation (AF), in order to assess i) the methodology feasibility and reproducibility; ii) to study the variability of vascular mechanics; iii) to assess the association of vascular mechanics and vascular stiffness.
In the first part of our research we studied 45 patients with moderate to severe AS (aortic valve area ≤ 0.85 cm2/m2) with 2D-STE at the level of the thoracic ascending aorta. We demonstrated that the left ventricular stroke volume index was the most important variable to explain aortic strain variability. Moreover, the vascular rigidity assessed with the aortic β1 stiffness index was useful to explain the aortic strain rate variability. As an exploratory results, we have showed that aortic mechanics were associated with mortality.
Subsequently we used 2D-STE to study vascular mechanics at the level of the aortic arch. We enrolled a cohort of 61 apparently healthy participants, and we reported normal values. In this study we have also included a group of 46 hypertensive patients that had lower values of aortic mechanics than the healthy group (strain: 6.3±2.0% vs 11.2±3.2% and strain rate: 1.0±0.3 vs 1.5±0.4 s-1, respectively, both P<0.01). We have demonstrated that aortic arch mechanics correlated with the gold standard method used to study vascular stiffness (pulse wave velocity, with the Complior® method) and finally we have also identified that parameters of vascular mechanics were associated with left ventricular relaxation. After adjustments for age and pulse pressure, aortic arch strain was significantly lower in hypertensive patients, when compared to healthy subjects.
Finally, we studied aortic mechanics at the level of the descending aorta in a cohort of 44 patients with non-valvular AF who needed cardioversion and were referred for transesophageal echocardiography (TEE). We concluded for a positive association of vascular mechanics and the left atrial appendage function. Moreover, as the CHA2DS2VASc score increased both the vascular strain (r=-0.38, P=0.01) and the vascular strain rate (r=-0.42, P<0.01) decreased. Aortic strain remained independently associated with a past history of stroke after adjustment for the CHA2DS2VASc score.
The feasibility values for vascular mechanics with 2D-STE ranged from 85% to 95% for the selected patients included in the three studies. Of the total 1176 segments included in the studies, we extracted 2D-STE data for 1075 aortic wall segments. Regarding reproducibility, data was considered adequate, in particular for the assessment of global strain and strain rate.
In conclusion, it was possible to study vascular mechanics with 2D-STE at three different aortic levels. Our worked contributed to promote vascular mechanics as an imaging vascular risk marker. The usefulness of aortic strain and strain rate was established to identify higher risk subgroups of patients with degenerative AS and non-valvular AF. Aortic arch strain remained significantly lower for hypertensive patients, when compared to healthy subjects.O desenvolvimento de métodos não-invasivos para o diagnostico de alterações degenerativas vasculares é de considerável interesse clínico, dado que a doença cardiovascular permanece a principal causa de morte em todo o mundo. A ecocardiografia com speckle-tracking é um método de análise da imagem ecográfica semi–automatizado, baseado no seguimento de pontos ecodensos da parede do miocárdio ao longo do ciclo cardiaco. A integração informática do movimento dos segmentos miocárdicos, permite a determinação da velocidade, do deslocamento, da deformação (strain) e da taxa de deformação (strain-rate) dos segmentos miocárdicos. O estudo da mecânica cardiaca por speckle-tracking foi inicialmente focado na câmara ventricular esquerda, mas a sua utilização foi alargada e validada para o ventrículo direito, bem como para as câmaras auriculares, que apresentam uma espessura de parede mais reduzida. Recentemente, foi analisada a deformação da parede vascular com a metodologia de speckle-tracking. A atenção tem sido centrada na expansão circunferencial e no recuo da parede vascular. Tal conduz a um padrão de deformação vascular característico, com um pico sistólico positivo de deformação (strain) circunferencial e um pico positivo da taxa de deformação (strain rate) vascular. A avaliação da mecânica vascular com speckle-tracking foi validada com estudos de sonomicrometria, e uma associação entre a mecânica vascular e o conteúdo de colágeno da parede vascular foi também demonstrada. Desta forma foi sugerida a utilização da mecânica vascular por speckle-tracking como um marcador imagiólógico da rigidez vascular.
Com a presente tese tivemos como objetivos a utilização da metodologia de speckle-tracking para estudar a mecânica vascular da aorta torácica em doentes com estenose aortica (EA) degenerativa, com hipertensão arterial, e com fibrilhação auricular (FA) não-valvular, a fim de avaliar i) a exequibilidade e reprodutibilidade da metodologia; ii) estudar a variabilidade da mecânica vascular; iii) avaliar a associação da mecânica vasculares à rigidez vascular.
Nos primeiros dois estudos foram incluídos 45 doentes com EA degenerativa moderada a grave (área valvular aórtica ≤ 0,85 cm2/m2). Foi analisada a mecânica da aorta torácica ascendente, por ecocardiografia transtoracica e por speckle-tracking. Foi demonstrado que o volume ejeção do ventrículo esquerdo indexado foi a variável mais importante para explicar a variabilidade do strain da aorta torácica ascendente. Em contraste, a rigidez vascular avaliada com o índice β1 foi útil para explicar a variabilidade do strain rate vascular da aorta torácica ascendente. Como um resultado exploratório foi possível associar a mecânica vascular da aorta torácica ascendente ao prognóstico.
Subsequentemente foi utilizada a mesma metodologia de speckle-tracking para estudar a mecânica vascular ao nível do arco aórtico. Foi incluída uma coorte de 61 participantes, aparentemente saudáveis, tendo sido apresentados os valores de normalidade para o strain e o strain rate vascular ao nível da crossa da aorta. Este estudo também incluiu um grupo de 46 doentes com hipertensão arterial, que apresentou valores mais reduzidos da mecânica da aorta do que o grupo saudável (strain: 6,3±2,0% vs 11,2±3,2% e strain rate: 1,0±0,3 vs 1,5±0,4 s-1, ambos com valor de P <0,01). Foi demonstrado que os valores da mecânica vascular do arco aortico se correlacionaram com a velocidade da onda de pulso (avaliada pelo método Complior®). Os parâmetros da mecânica vascular foram também associados à velocidade de relaxamento do miocárdio do ventrículo esquerdo. Após ajuste para idade e pressão de pulso, o strain vascular do arco aórtico foi significativamente menor no grupo de doentes hipertensos, quando comparado com o grupo de participantes saudáveis.
Por último, estudamos a mecânica vascular ao nível da aorta torácica descendente, numa coorte de 44 doentes com FA não-valvular, referenciada para cardioversão eléctrica e ecocardiografia transesofágica. Demonstramos uma correlação positiva entre mecânica vascular e a função do apêndice auricular esquerdo. Para além disso, como o aumento da pontuação do score CHA2DS2VASc foi observada uma redução do strain vascular (r=-0,38, P=0,01) e do strain rate vascular (r = -0,42, P <0,01). Após ajuste para o score CHA2DS2VASc, os valores mais reduzidos de strain da aorta torácica descendente permaneceram independentemente associados aos doentes com FA e história prévia de acidente vascular cerebral.
A exequibilidade da mecânica vascular por speckle tracking para os doentes selecionados nos referidos estudos variou entre 85 – 95%. Com a referida metodologia, de um total de 1176 segmentos foi possível analisar 1075 segmentos da circumferência da aorta. A reprodutibilidade foi considerada adequada particularmente para o valor global de strain e de strain rate vascular.
Em conclusão, foi possível analisar com a metodologia ecocardiográfica de speckle tracking a mecânica vascular da aorta, em três locais diferentes. O nosso trabalho é um contributo para a promoção da mecânica vascular como uma avaliação imagiológica da doença vascular. O strain e o strain rate vascular permitiram identificar sub-grupos de doentes com risco superior, quer no contexto da EA degenerativa e da FA não valvular. No que disse respeito à da doença hipertensiva, a mecânica vascular do arco aortico foi significativamente inferior para os doentes hipertensos em comparação com um grupo de indivíduos saudáveis
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
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