1,720,968 research outputs found
Delayed neuronal maturation of the medullary arcuate nucleus in sudden infant death syndrome
No full textRecently, quantitative abnormalities in neuronal populations derived from the rhombic lip (inferior olive nucleus of the brain stem and external granular layer of the cerebellum) have been reported in victims of the sudden infant death syndrome (SIDS). In this study we examined the arcuate nucleus (ARCn) of 35 SIDS victims and 25 controls, to determine neuronal abnormalities involving this nucleus in SIDS. Computer-assisted cell evaluation was made on sections stained with hematoxylin and eosin to study the neuronal dimensions (nuclear and cytoplasmic area, nuclear/cytoplasmic ratio), the form factor and the density of reactive astrocytes. There was a significant reduction of the neuronal area (nuclear and cytoplasmic) in SIDS victims compared with controls. The neuronal populations of SIDS victims had a significantly higher form factor, index of immaturity. The SIDS victims were divided into two groups on the basis of ARCn development: 18 SIDS-A cases with a well-developed ARCn and 17 SIDS-B cases with severe bilateral hypoplasia. The results of our research indicate that the developmental defect is characterized by a reduction in size of the ARC neurons and by neuronal depletion. In SIDS the ARCn has the histomorphological features of neuronal immaturity, and there is a marked reduction of all quantitative cell parameters and lower astrocytes density with respect to controls. On the basis of the morphometric results of the arcuate neuronal populations, we hypothesize that infants whose neurons have failed to reach full maturity are at risk for SIDS because they are unable to develop appropriate cardioventilatory control
Valutazione di prototipi di biostimolanti per aumentare la tolleranza al freddo di piante di fagiolo
No full textI prodotti biostimolanti possono rappresentare uno strumento efficace e sostenibile per incrementare la crescita, la produttività e la qualità delle colture, migliorandone anche la tolleranza a stress di tipo abiotico. La loro efficacia, tuttavia, può essere influenzata da numerosi fattori, tra i quali annoveriamo dose e timing di applicazione. La ricerca in oggetto è stata condotta per verificare l’efficacia di prototipi di prodotti biostimolanti nell’aumentare la tolleranza allo stress da freddo in piante di fagiolo. Sono stati valutati due diversi dosaggi e tre tempi di applicazione. Piante di fagiolo borlotto lingua di fuoco nano (Phaseolus vulgaris L.), sono state coltivate in vaso, su substrato a base di torba, in serra. I trattamenti sono stati: controllo non stressato (H2O), controllo stressato, biostimolante dose 50% e 100% 48h, applicato 48 ore prima dello stress, biostimolante dose 50% e 100% 24 h, applicato 24 h prima dello stress, e infine biostimolante dose 50% e 100% 6 h, applicato 6 ore prima dello stress. Il trattamento è stato eseguito come spray fogliare. Successivamente le piante sono state sottoposte a stress da freddo, per 48 h in cella a 4°C. Trascorso questo periodo si è proceduto con il campionamento e l’analisi delle foglie, sia in vivo, per misurare la fluorescenza della clorofilla a e le clorofille, sia con metodiche di tipo distruttivo, per valutare la perossidazione lipidica, la perdita elettrolitica, antociani e fenoli, zuccheri totali e riducenti e il contenuto di saccarosio. I risultati ottenuti hanno mostrato come il prodotto biostimolante utilizzato abbia avuto una buona efficacia sulle piante, mantenendole in un buono stato di salute generale dopo lo stress da freddo. Prendendo in esame tutte le analisi svolte, il trattamento che è risultato essere più efficace è stato quello applicato con un timing di 24 h prima del verificarsi dello stress da freddo
Cytogenetic aspects of cell proliferation in atherosclerotic plaques
No full textFluorescence in situ hybridization (FISH) using chromosome specific alpha-satellite DNA probes for chromosome 7, was performed on paraffin-embedded sections of 21 cases of human "unstable" atherosclerotic plaques, in order to determine whether trisomy 7, found by some Authors with conventional cytogenetics, is a biological characteristic of the atherosclerotic plaque. In 15 cases (71%) the FISH method showed smooth muscle cells with three or more spots. In particular the trisomy 7 was the most significant and constant result. The presence of an extra chromosome 7 is strictly correlated with an overexpression of the gene for chain A of the platelet-derived growth factor (PDGF), which was mapped at pter-7q22 region. Therefore trisomy 7 seems to correspond to an increase in PDGF synthesis and consequently to an increase in proliferative activity of smooth muscle cells
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
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
. Liquid drainage through the peritoneal diaphragmatic surface
No full textIn 14 spontaneously breathing anesthetized rabbits, we used cyanoacrylate to glue a hollow capsule, at end expiration or at end inspiration, to the peritoneal surface of the tendinous portion of the diaphragm. The capsule was connected to a pressure transducer and a pipette calibrated in microliters. We filled the system with fluid and measured flow into the diaphragmatic surface facing the capsule (Fcap, microliter/cm2), from liquid displacement in the pipette at different hydraulic pressures in the system (Pcap). Pleural liquid pressure was simultaneously measured in the supraphrenic region (Psup). Fcap was positively correlated to transdiaphragmatic pressure gradient (Psup-Pcap) and breathing frequency but was unaffected by protein concentration of capsular fluid. For a breathing frequency of 30 cycles/min and a Psup - Pcap = -2 cmH2O, Fcap was 0.54 microliter.min-1.cm-2 for capsules applied at end expiration and 10-fold greater for capsules applied at end inspiration. Data indicate that the diaphragmatic tendinous portion in rabbits is a draining site for peritoneal fluid and that the conductance of the draining pathways (lymphatic stomata) is related to diaphragmatic tension. In the intact rabbit the average peritoneal fluid drainage through the tendinous portion of the diaphragm (approximately 16 cm2) was estimated at 43 microliters/min
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