1,720,993 research outputs found
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
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
Selective mitochondrial Ca2+ uptake deficit in disease endstage vulnerable motoneurons of the SOD1G93A mouse model of amyotrophic lateral sclerosis
No full textKey points center dot So far, increased excitability and calcium handling problems have been discussed as causes for motoneuron death in amyotrophic lateral sclerosis (ALS) mainly on the basis of studies in juvenile presymptomatic mice. center dot We developed a brainstem preparation to analyse excitability and calcium handling during disease progression up to disease endstage of motoneurons in an ALS mouse model. center dot Increased excitability of motoneurons is not seen at disease endstage, challenging this factor as a direct cause for motoneuron death in ALS. center dot We show that calcium handling is remodelled during disease progression from mitochondrial uptake to mitochondrial uptake failure and increased plasma membrane extrusion, providing a compensatory mechanism that fails at disease endstage and might lead to a toxic calcium overload of the cells. center dot Supporting this newly described compensatory endeavour of the motoneurons might be a promising therapeutic strategy. Abstract Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that targets some somatic motoneuron populations, while others, e.g. those of the oculomotor system, are spared. The pathophysiological basis of this pattern of differential vulnerability, which is preserved in a transgenic mouse model of amyotrophic lateral sclerosis (SOD1G93A), and the mechanism of neurodegeneration in general are unknown. Hyperexcitability and calcium dysregulation have been proposed by others on the basis of data from juvenile mice that are, however, asymptomatic. No studies have been done with symptomatic mice following disease progression to the disease endstage. Here, we developed a new brainstem slice preparation for whole-cell patch-clamp recordings and single cell fura-2 calcium imaging to study motoneurons in adult wild-type and SOD1G93A mice up to disease endstage. We analysed disease-stage-dependent electrophysiological properties and intracellular Ca2+ handling of vulnerable hypoglossal motoneurons in comparison to resistant oculomotor neurons. Thereby, we identified a transient hyperexcitability in presymptomatic but not in endstage vulnerable motoneurons. Additionally, we revealed a remodelling of intracellular Ca2+ clearance within vulnerable but not resistant motoneurons at disease endstage characterised by a reduction of uniporter-dependent mitochondrial Ca2+ uptake and enhanced Ca2+ extrusion across the plasma membrane. Our study challenged the notion that hyperexcitability is a direct cause of neurodegeneration in SOD1G93A mice, but molecularly identified a Ca2+ clearance deficit in motoneurons and an adaptive Ca2+ handling strategy that might be targeted by future therapeutic strategies.Ulm University; BMBF/EU ProgramEranet Goettingen [01EW0912]; [SFB 815
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
Biophysical characterization of voltage-gated Ca2+ and A-type K+ currents in dopaminergic substantia nigra neurons reveals complex changes with age and in the A53T α-synuclein Parkinson’s disease mouse model
No full textParkinson's disease (PD) is an age-related disorder characterized by the formation of so-called Lewy bodies that mainly contain toxic α-synuclein aggregates and loss of dopaminergic (DA) midbrain neurons from the substantia nigra (SN) which causes its typical motor symptoms. SN DA neurons as well as neighboring less affected in PD ventral tegmental area (VTA) DA neurons are both pacemakers. Meaning these neurons show spontaneous activity even in full synaptic isolation. The electrical activity of SN DA neurons is followed by intracellular Ca2+ oscillations due to the activation of voltage-gated Ca2+ (Cav) currents, while this is not the case in VTA DA. Spontaneous activity of SN DA neurons, in combination with low cytosolic Ca2+ buffering, leads to fluctuations of intracellular Ca2+ levels which in the presence of PD risk factors such as aging or genetic mutations could increase neuronal oxidative stress and lead to degeneration of SN DA neurons. Cav currents and Ca2+ sensitive, voltage-gated A-type K+ (Kv4) channels are of particular interest, as both modulate the activity of SN DA neurons, and have been linked to PD pathophysiology. To identify mechanisms defining neuronal vulnerabilities with age and PD, I analyzed Cav currents in SN DA neurons in brain slices from both juvenile (~PN13) and adult (~3-6 months) wild-type (WT) mice, and in mice overexpressing a mutant human α-synuclein (A53T SNCA), causing familial forms of PD (PARK1). Within this work, we have established that low voltage-activated (LVA) Ca2+ currents increase and activate at more negative potentials with postnatal maturation/aging in SN DA neurons. SN DA neurons from adult mice had larger window currents that activated at more negative potentials compared to juveniles as well. LVA Ca2+ currents were fully blocked by T-type Cav inhibitors Z941/Z944 in SN DA neurons in juveniles as well as in adults. T-type Cav inhibition also reduced window currents and shifted them to more positive potentials. We did not observe significant changes in the amplitude and kinetics of high voltage-activated (HVA) Ca2+ currents in SN DA neurons with aging. Pharmacological isolation of different subtypes of HVA Ca2+ channels in juvenile and adult mice did not result in a significant difference between these two groups. HVA Ca2+ currents from adult A53T PD mouse model were smaller and their peak was shifted to more positive potentials compared to WT mice, while LVA Ca2+ currents were not affected. HVA Ca2+ currents from WT and A53T mice in L-type Cav channel blocker isradipine looked similar to A53T controls. Inhibition of Cav1 and Cav3 channels and genetic deletion of Cav2.3 channels had only a minor effect on A-type Kv4 currents. On other hand, A-type Kv4 currents were significantly affected by the inhibition of endoplasmic Ca2+ release and uptake in SN DA neurons. These findings indicate that Cav channel blockers are attractive targets in PD drug therapy. However, more studies should be done to understand the physiological functions of distinct Cav subtypes prior to developing suitable Cav inhibitors for neuroprotective PD therapy
Indikation und Ergebnisse der Kipptischuntersuchung unter Berücksichtigung der autonomen Kompetenz.
No full textEinleitung:
Die Kipptischuntersuchung (KTU) ist ein seit 50 Jahren verwendeter Test zur Abklärung von Synkopen und wurde in den Leitlinien der European Society of Cardiology zur Abklärung von Synkopen von 2018 von Klasse I auf Klasse IIa/b herabgestuft.
Die wichtige Fragestellung dieser retrospektiven Kohortenstudie war es festzustellen, ob und wie sich die Indikationen für die KTU bereits vor der Aktualisierung der Leitlinien im 2018 verändert haben und welche Auswirkungen es auf die Relevanz dieser Untersuchung gegeben hat. Es wurden außerdem die Unterschiede in der Anamnese sowie Ergebnissen der KTU zwischen Patientengruppen analysiert.
Patienten und Methoden:
Eingeschlossen wurden alle Patienten, die zwischen 2014 und 2018 an der Klinik Landstraße Wien einer Kipptischuntersuchung unterzogen wurden, das waren 205 Patienten, 100 Frauen und 105 Männer, im Durchschnittsalter von 52 Jahren. Es wurden Informationen aus den Arztbriefen, Ambulanzakten und dem Krankenhaus-Informationssystem herangezogen.
Ergebnisse:
Die Indikationen waren orthostatische Hypotonie (OH) bei 53 Patienten, Reflexsynkope bei 98 Patienen und Synkopen unklarer Genese bei 54 Patienten.
Im gesamten Zeitraum hatten 61% der Patienten einen positiven Untersuchungsbefund. Ein positives Ergebnis hatten 66% der Patienten mit Indikation OH, 62% mit Indikation Reflexsynkope und 54% mit Synkopen unklarer Genese.
Durch die KTU wurde die Diagnose OH bei 32 %, die Diagnose Reflexsynkope bei 27 % und die Diagnose posturales Tachykardiesyndrom (POTS) bei 16 % gestellt.
Es fand sich ein Anstieg in der Rate an positiven Befunden im untersuchten Zeitraum, was wahrscheinlich durch den Rückgang in der Häufigkeit der Indikation Synkopen unklarer Genese zwischen 2014 und 2018 (33 vs. 14 %, p=.039) bedingt ist. Darüber hinaus zeigte sich im untersuchten Zeitraum bei Indikation OH ein positiver Trend (22 % vs. 41 %).
Im Vergleich zu Patienten mit Indikation Reflexsynkope litten Patienten mit Synkopen unklarer Genese häufiger unter koronaren Herzkrankheiten (KHK) (19 vs. 5 %, p = 0,011) und Arrhythmien (24 vs. 10 %, p = 0,032), sie nahmen häufiger Betablocker ein (26 vs. 7 %, p = 0,002) und hatten häufiger ST-Segment-Anomalien (11 vs. 1 %, p = 0,008). Verglichen zu Patienten mit Indikation OH hatten Patienten mit Synkopen unklarer Genese häufiger Palpitationen (11 vs. 8 %, p = 0,0024).
Im Vergleich zu Patienten mit Indikation Reflexsynkope wiesen Patienten mit Indikation OH mehr Komorbiditäten wie KHK (17 vs. 5 %, p = 0,036), Bluthochdruck (45 vs. 18 %, p = 0,01), Diabetes mellitus (25 vs. 3 %, p = 0,0) und Synukleinopathien (6 vs. 0 %, p = 0,042) auf und nahmen mehr Glukose-senkende (23 vs. 4 %, p = 0,001) und antithrombotische Mittel (42 vs. 12 %, p = 0,001) sowie Diuretika (15 vs. 2 %, p = 0,004), Betablocker (23 vs. 7 %, p = 0,009), anfallssuppressive Mittel (6 vs. 0 %, p = 0,042), Antiparkinsonmittel (6). vs. 0 %, p=0,042), Antidepressiva (26 vs. 11 %, p=0,022) und Statine (26 vs. 8 %, p=0,004) ein. Patienten mit Indikation Reflexsynkope hatten verglichen zu Patienten mit Indikation OH häufiger Prodromi wie Hitzegefühl (17 vs. 2 %, p = 0,001) und Übelkeit (33 vs. 8 %, p = 0,004).
Zusammenfassung:
Die KTU weist für entsprechende Indikationen eine hohe diagnostische Wertigkeit auf.
Der Vergleich der drei Indikationen zeigte komplexe signifikante Korrelationen zu den erfassten Parametern, was bei der Betreuung von Patineten mit Synkopen behilflich sein kann.
Des Weiteren bestätigte meine Studie die Ergebnisse anderer Studien, dass Synkopen unklarer Genese eine zugrundeliegende kardiale Genese ihrer Synkope haben können.Introduction:
The tilt table examination (TTT) is a diagnostic test that has been used to investigate the syncope for over 50 years. Although the TTT was downgraded for the evaluation of syncope from class I to IIa/b in 2018 in the Guidelines of the European Society of Cardiology (ESC), the test still offers a high diagnostic value and has advantages over other tests.
Purpose:
The purpose of this work was to determine whether there was a change in the frequency of referrals for TTT in the period from 2014 to 2018. In addition, it was examined if there were differences in the case history, medical findings, and results of the TTT among patients depending on the referral for the TTT.
Patients and methods:
This work is a retrospective cohort study in which the information from the doctor's letters, outpatient files and electronic hospital information system was collected and evaluated. Included were 205 patients (100 female, 105 male, 15-82 years, mean age 52 years) in whom TTT was carried out between 2014 and 2018 in a cardiologic department. Referrals for the TTT were suspected orthostatic hypotension (OH) (n=53), suspected reflex syncope (n=98), and unexplained syncope (n=54).
Results:
By TTT the diagnosis of OH was established in 32 %, reflex syncope in 27 %, and postural orthostatic tachycardia syndrome (POTS) in 16%. There was an increase in the frequency of positive TTT findings from 2016 to 2018 (54 to 79 %, p=.039). The main finding was a decrease from 2014 to 2018 in the rate of referral for unexplained syncope (33 versus 14%, p=.039). Compared to patients with suspected reflex syncope, patients with an unexplained syncope more often suffered from coronary artery disease (CHD) (19 vs. 5,1 % p=.011) and arrhythmias (24 vs. 10 %, p=.032), were more often taking beta-blockers (26 vs. 7,1 %, p=.002) and more often had ST-segment abnormalities (11 vs. 1 %, p=.008). Also compared to patients with suspected OH, patients with an unexplained syncope more often suffered from palpitations (11 vs. 7,5 %, p=,0024). Compared to patients with suspected reflex syncope, patients with suspected OH had more comorbidities such as CHD (17 vs. 5,1 %, p=.036), hypertension (45 vs. 18 %, p=.01), diabetes mellitus (25 vs. 3,1 %, p=.0) and synucleinopathies (5,7 vs. 0 %, p=.042) and took more medication such as blood-sugar lowering medication (23 vs. 4,1 %, p=.001), antithrombotic agents (42 vs. 12 %, p=.0), diuretics (15 vs. 2 %, p=.004), beta blockers (23 vs. 7,1 %, p=.009), statins (26 vs. 8,2 %, p=.004), anticonvulsants (5,7 vs. 0, p=.042), antiparkinsonian treatments (5,7 vs. 0, p=.042), and antidepressants (26 vs. 11 %, p=.022). Compared to patients with suspected OH, patients with suspected reflex syncope more often suffered from prodromes such as flushing (17 vs. 1,9 %, p=.001) and nausea with vomiting (33 vs. 7,5 %, p=.004).
Conclusions:
Our study confirms the diagnostic value of TTT if patients are referred for the appropriate reasons. The clinical presentation of patients referred because of unexplained syncope may suggest a cardiac origin, what has already been found in studies, which have used implantable loop recorders (ILR) for a recurrent unexplained syncope. In general, we could find many connections between suspected reflex syncope and suspected OH and certain prodromes, comorbidities and taken medication, which have already been cited in several studies
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