1,721,194 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
Author Correction: Hydrogel mechanical properties in altered gravity (npj Microgravity, (2024), 10, 1, (83), 10.1038/s41526-024-00388-2)
No full textIn this article the affiliation, “Department of Aerospace Engineering, Khalifa University of Science and Technology, Abu Dhabi 127788, UAE” for the author “Yarjan Abdul Samad” was inadvertently omitted. The original article has been corrected
Chitosan may decrease serum valproate and increase the risk of seizure reappearance.
No full textWe report two cases of probable interaction between the commonly used anticonvulsant valproate and chitosan, a substance available worldwide to help weight loss.
A 35 year old woman with idiopathic generalised epilepsy, who had not had seizures for three years while taking valproate (500 mg twice/day; 52 μg/ml) and phenobarbital (75 mg/day), had the sudden reappearance of myoclonic jerks, absences, and a tonic-clonic seizure a few days after a dietary supplementation with chitosan (500 mg twice/day) for weight loss. She denied changing her diet and consuming other drugs or natural substances. Seizures remitted after chitosan was stopped. Three months later she restarted chitosan and within five days she had daily absences, myoclonus, and generalised abnormalities on electroencephalogram. Serum concentrations of valproate were undetectable despite regular intake of the drug, whereas phenobarbital remained at therapeutic concentration (20 μg/ml). Chitosan was discontinued. Seizures remitted and valproate concentration returned to baseline levels (50 μg/ml) within four days.
A 29 year old woman with idiopathic generalised epilepsy, who was treated with valproate (1250 mg/day; 65 μg/ml) and remained seizure free for two years, had two tonic-clonic seizures and daily absences after one week of chitosan supplementation (500 mg/day). No changes of the regular intake of antiepileptic treatment or consumption of any other drugs were reported. Valproate serum levels were undetectable and seizures promptly disappeared after chitosan was stopped.
The Naranjo probability scale1 confirms that chitosan treatment was the most likely cause of drastic lowering of valproate serum levels and the reappearance of seizures in these patients. In both women, the event remitted and valproate levels returned to the target range after chitosan was stopped.
Chitosan has been proposed as a safe and effective dietary supplement to aid weight loss by reducing the amount of absorbed dietary fat and thereby improving caloric balancing.2 Structurally, it is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). The amino group has a pKa value of about 6.5 and chitosan acts a positively charged polymer that binds to the negatively charged lipids in the gastrointestinal tract, preventing their absorption.2 3
We think that the anionic carboxyl group of the lipophilic valproate may attach to the positive charged tertiary amino group of chitosan so that it is extracted rather than absorbed, resulting in a lowering of its serum concentration. Alternatively, limited absorption of valproate may be caused by the suppressed enterohepatic recirculation of the drug because of the negative effect of chitosan on enteric bacteria.4
This interaction has not been reported by the Italian Agency for Pharmaceuticals or by the manufacturers of chitosan. It is known, however, that chitosan can affect the absorption of fat soluble vitamins, and that the anticoagulation effect of warfarin may be increased through this mechanism.5 As chitosan products are freely available, healthcare professionals should be aware of their potential interaction with all lipophilic substances
Apoptotic myonuclei in human Duchenne Muscular Dystrophy
No full textThe current view that apoptosis precedes necrosis in death of dystrophin-deficient muscle fibers of the mdx mouse has been well substantiated. Moreover, apoptotic myonuclei have been reported to increase in dystrophin-deficient mice 2 days after spontaneous exercise. To investigate the role of apoptosis in human muscular dystrophy, muscles from 11 patients of different ages with Duchenne muscular dystrophy were analyzed for apoptosis. The amount of apoptosis was assessed by terminal deoxynucleotidyl transferase assay, and the expression of bcl-2 and bax was examined by immunohistochemistry. Although very rare in normal muscles (less than 0.1%), apoptotic nuclei were detected in dystrophic muscles, particularly at the interstitial level. Nevertheless, few dystrophin- deficient myofibers with centrally located nuclei showed a positive reaction for DNA fragmentation. A mosaic pattern of bcl-2/bax-positive myofibers characterized dystrophic muscles, thus the relative proportion of pro- and..
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
Caveolinopathies: mutations in caveolin-3 cause four distinct autosomal dominant muscle diseases
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