1,721,019 research outputs found
Antihypertensive Drugs for Secondary Prevention after Ischemic Stroke or Transient Ischemic Attack: A Systematic Review and Meta-Analysis
No full textBackground and Purpose: Approximately 30% of ischemic strokes occur after a previous stroke or transient ischemic attack. Arterial hypertension is one of the best established risk factors for first and recurrent stroke, both ischemic and hemorrhagic. Guidelines for the secondary prevention of ischemic stroke support the use of blood pressure (BP)-lowering drugs in most patients. However, the evidence for these recommendations comes from meta-analyses that included both ischemic and hemorrhagic stroke patients, whereas these 2 conditions differ quantitatively in several aspects. With this systematic review and meta-analysis, we aimed at summarizing the current evidence on BP-lowering drugs for secondary prevention in patients with ischemic stroke or transient ischemic attack. Methods: We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials up to January 31, 2020. We included randomized controlled trials comparing any specific BP-lowering drug, as monotherapy or combination, with either a control or another BP-lowering drug. Results: Eight studies that enrolled 33 774 patients with ischemic stroke or transient ischemic attack were included in the meta-analysis. Mean follow-up was 25 months (range, 3-48). Moderate-quality evidence indicated that a subsequent stroke occurred in 7.9% (ischemic in 7.4% or hemorrhagic in 0.6%) of patients taking any type of BP-lowering drug compared with 9.7% of patients taking placebo (odds ratio, 0.79 [95% CI, 0.66-0.94]; absolute risk difference, -1.9% [95% CI, -3.1% to -0.5%]). Moderate-quality evidence indicated that mortality occurred similarly in patients taking any type of BP-lowering treatment compared with placebo, with an absolute risk of 7.3% and 7.9%, respectively (odds ratio, 1.01 [95% CI, 0.92-1.10]; absolute risk difference, 0.1% [95% CI, -0.6% to 0.7%]). Conclusions: The use of BP-lowering drugs in patients with ischemic stroke or transient ischemic attack is associated with a 1.9% risk reduction of stroke but does not affect the all-cause mortality risk
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
Effects of elevated egg corticosterone levels on behavior, growth, and immunity of yellow-legged gull (Larus michahellis) chicks
No full textEggs of vertebrates contain steroid hormones of maternal origin that may influence offspring performance. Recently, it has been shown that glucocorticoids, which are the main hormones mediating the stress response in vertebrates, are transmitted from the mother to the egg in birds. In addition, mothers with experimentally elevated corticosterone levels lay eggs with larger concentrations of the hormone, which
produce slow growing offspring with high activity of the hypothalamo–adrenal axis under acute stress. However, the effects and function of transfer of maternal corticosterone to the eggs are largely unknown. In the present study, we injected corticosterone in freshly laid eggs of yellow-legged gulls (Larus michahellis), thus increasing the concentration of the hormone within its natural range of variation, and analyzed the effect of manipulation on behavioral, morphological, and immune traits of the offspring in the wild. Eggs injected with corticosterone had similar hatching success to controls, but hatched later. Mass loss during incubation was greater for corticosterone-treated eggs, except for the
last laid ones. Corticosterone injection reduced rate and loudness of late embryonic vocalizations and the intensity of chick begging display. Tonic immobility response, reflecting innate fearfulness, was unaffected by hormone treatment. Elevated egg corticosterone concentrations depressed T-cell-mediated immunity but had no detectable effects on humoral immune response to a novel antigen, viability at day 10, or
growth. Present results suggest that egg corticosterone can affect the behavior and immunity of offspring in birds and disclose a mechanism mediating early maternal effects whereby stress experienced by females may negatively translate to offspring phenotypic quality
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
Sex differences in begging vocalisations of nestling barn swallows (Hirundo rustica).
No full textParents of sexually reproducing species should adjust their investment in production of sons and daughters in relation to the relative costs and reproductive value of offspring of either sex. Sex allocation mediated by differential allocation of care such as food provisioning, however, requires that parents can identify offspring sex. We analysed sex differences in offspring begging calls that may serve as a cue for parents to discriminate between sons and daughters. A combination of three sonagraphic variables of begging calls of nestling barn swallows allowed us to classify them according to sex at day 16, but not at day 12 after hatching, suggesting that sex differences in begging calls arise during the nestling period as the time of fledging approaches. Hence, parents may be able to discriminate between sons and daughters by auditory cues, which would enable differential allocation of food between offspring during the late nestling and early fledging stages
Stem cell transplantation for ischemic stroke
Full text linkBackground Stroke is a leading cause of morbidity and mortality worldwide, with very large healthcare and social costs, and a strong demand for alternative therapeutic approaches. Preclinical studies have shown that stem cells transplanted into the brain can lead to functional improvement. However, to date, evidence for the benefits of stem cell transplantation in people with ischemic stroke is lacking. This is the first update of the Cochrane review published in 2010. Objectives To assess the efficacy and safety of stem cell transplantation compared with control in people with ischemic stroke. Search methods We searched the Cochrane Stroke Group Trials Register (last searched August 2018), CENTRAL (last searched August 2018), MED-LINE (1966 to August 2018), Embase (1980 to August 2018), and BIOSIS (1926 to August 2018). We handsearched potentially relevant conference proceedings, screened reference lists, and searched ongoing trials and research registers (last searched August 2018). We also contacted individuals active in the field and stem cell manufacturers (last contacted August 2018). Selection criteria We included randomized controlled trials (RCTs) that recruited people with ischemic stroke, in any phase of the disease (acute, subacute or chronic), and an ischemic lesion confirmed by computerized tomography or magnetic resonance imaging scan. We included all types of stem cell transplantation, regardless of cell source (autograft, allograft, or xenograft; embryonic, fetal, or adult; from brain or other tissues), route of cell administration (systemic or local), and dosage. The primary outcome was efficacy (assessed as neurologic impairment or functional outcome) at longer term follow-up (minimum six months). Secondary outcomes included post-procedure safety outcomes (death, worsening of neurological deficit, infections, and neoplastic transformation). Data collection and analysis Two review authors independently applied the inclusion criteria, assessed trial quality and risk of bias, and extracted data. If needed, we contacted study authors for additional information. We performed random effects meta-analyses when two or more RCTs were available for any outcome. We assessed the certainty of the evidence by using the GRADE approach. Main results In this updated review, we included seven completed RCTs with 401 participants. All tested adult human non-neural stem cells; cells were transplanted during the acute, subacute, or chronic phase of ischemic stroke; administered intravenously, intra-arterially, intracerebrally, or into the lumbar subarachnoid space. Follow-up ranged from six months to seven years. Efficacy outcomes were measured with the National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS), or Barthel Index (BI). Safety outcomes included case fatality, and were measured at the end of the trial. Overall, stem cell transplantation was associated with a better clinical outcome when measured with the NIHSS (mean difference [MD]-1.49, 95% confidence interval [CI]-2.65 to-0.33; five studies, 319 participants; low-certainty evidence), but not with the mRS (MD-0.42, 95% CI-0.86 to 0.02; six studies, 371 participants; very low-certainty evidence), or the BI (MD 14.09, 95% CI-1.94 to 30.13; three studies, 170 participants; very low-certainty evidence). The studies in favor of stem cell transplantation had, on average, a higher risk of bias, and a sample size of 32 or fewer participants. No significant safety concerns associated with stem cell transplantation were raised with respect to death (risk ratio [RR] 0.66, 95% CI 0.39 to 1.14; six studies, participants; low-certainty evidence). We were not able to perform the sensitivity analysis according to the quality of studies, because all of them were at high risk of bias. Authors’ conclusions Overall, in participants with ischemic stroke, stem cell transplantation was associated with a reduced neurological impairment, but not with a better functional outcome. No obvious safety concerns were raised. However, these conclusions came mostly from small RCTs with high risk of bias, and the certainty of the evidence ranged from low to very low. More well-designed trials are needed
Antiplatelet drugs for secondary prevention in patients with ischemic stroke or transient ischemic attack: a systematic review and network meta-analysis
Full text linkBackground: Antiplatelet drugs may prevent recurrent ischemic events after ischemic stroke but their relative effectiveness and harms still need to be clarified. Within this network meta-analysis we aimed to summarize the current evidence for using antiplatelet drugs for secondary stroke prevention. Methods: We searched MEDLINE, EMBASE and CENTRAL up to September 2020. Randomized controlled trials (RCTs) assessing antiplatelet drugs for secondary stroke prevention were included. We did pairwise meta-analyses and network meta-analyses using random-effects models. Primary outcomes were all strokes (ischemic or hemorrhagic) and all-cause mortality. Results: The review included 57 RCTs, 50 (n = 165,533 participants) provided data for the meta-analyses. Compared to placebo/no treatment, moderate to high-confidence evidence indicated that cilostazol, clopidogrel, dipyridamole + aspirin, ticagrelor, ticlopidine, and aspirin ≤ 150 mg/day significantly reduced the risk of all strokes (odds ratios, ORs and absolute risk difference, ARD): cilostazol 0.51 (95 % confidence interval, CI, 0.37 to 0.71; 3.6 % fewer), clopidogrel 0.63 (95 % CI, 0.49 to 0.79; 2.7 % fewer), dipyridamole + aspirin 0.65 (95 % CI, 0.55 to 0.78; 2.5 % fewer), ticagrelor 0.68 (95 % CI, 0.50 to 0.93; 2.3 % fewer), ticlopidine 0.74 (95 % CI 0.59 to 0.93; 1.9 % fewer), aspirin ≤ 150 mg/day 0.79 (95 % CI, 0.66 to 0.95; 1.5 % fewer). Aspirin > 150 mg/day and the combinations clopidogrel/aspirin, ticagrelor/aspirin, also decrease all strokes but increase the risk of hemorrhagic events. Only aspirin > 150 mg/day significantly reduced all-cause mortality (OR 0.86, 95 % CI 0.76 to 0.97; ARD 0.9 %, 95 %CI 1.5–0.2 % fewer, moderate confidence). Compared to aspirin ≤ 150 mg/day, clopidogrel significantly reduced the risk of all strokes, cardiovascular events, and intracranial hemorrhage outcomes. Cilostazol also appeared to provide advantages but data are limited to the Asian population. Conclusions: Considering the benefits and harms ratio, cilostazol, clopidogrel, dipyridamole + aspirin, ticagrelor, ticlopidine, and aspirin ≤ 150 mg/day appear to be the best choices as antiplatelet drugs for secondary prevention of patients with ischemic stroke or TIA. Systematic review registration: PROSPERO CRD42020159896
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