1,720,966 research outputs found
Cytoarchitectural and functional abnormalities of the inferior colliculus in sudden unexplained perinatal death
No full textThe inferior colliculus is a mesencephalic structure endowed with serotonergic fibers that plays an important role in the processing of acoustic information. The implication of the neuromodulator serotonin also in the aetiology of sudden unexplained fetal and infant death syndromes and the demonstration in these pathologies of developmental alterations of the superior olivary complex (SOC), a group of pontine nuclei likewise involved in hearing, prompted us to investigate whether the inferior colliculus may somehow contribute to the pathogenetic mechanism of unexplained perinatal death. Therefore, we performed in a wide set of fetuses and infants, aged from 33 gestational weeks to 7 postnatal months and died of both known and unknown cause, an in-depth anatomopathological analysis of the brainstem, particularly of the midbrain. Peculiar neuroanatomical and functional abnormalities of the inferior colliculus, such as hypoplasia/structural disarrangement and immunonegativity or poor positivity of serotonin, were exclusively found in sudden death victims, and not in controls. In addition, these alterations were frequently related to dysgenesis of connected structures, precisely the raphe nuclei and the superior olivary complex, and to nicotine absorption in pregnancy. We propose, on the basis of these results, the involvement of the inferior colliculus in more important functions than those related to hearing, as breathing and, more extensively, all the vital activities, and then in pathological conditions underlying a sudden death in vulnerable periods of the autonomic nervous system development, particularly associated to harmful risk factors as cigarette smoking
Impaired orexin receptor expression in the Kölliker–Fuse nucleus in sudden infant Death syndrome: possible involvement of this nucleus in arousal pathophysiology
No full textObjectives: As well known, the sudden infant death syndrome (SIDS) is characterized by the sudden death of a seemingly healthy infant during sleep, frequently resulted from a deficit in arousal phase. Awakening from sleep requires a fully developed and functioning neuronal respiratory network to modulate the ventilation as needed. The pontine Kölliker–Fuse nucleus (KFN) plays a pivotal role in breathing control, thanks to its interconnections with the widespread serotonin and noradrenaline neurons in the brainstem. Numerous studies to date have focused on the implication of orexin, a neuropeptide synthesized by neurons of the lateral hypothalamus, with major projections to the brainstem raphé nuclei and locus coeruleus, in arousal, a neurobiological process closely linked to breathing modifications. The aim of our research has been to demonstrate that also the KFN is a fundamental component of the orexin system, actively involved in arousal. Methods: We have evaluated the expression and distribution of the orexin receptors (orexin-1 and orexin-2 receptors) particularly in the rostral pons, where the KFN is located, of 25 SIDS cases and 18 controls. Results: An intense orexin-1 innervation around the KF neurons has been detected in almost all the controls and only in 20% of SIDS cases. Discussion: On the basis of these results, we believe that: (1) the KFN plays a leading role not only in providing a regular breathing rhythm but also in the coordination of the sleep-to-wake transition; (2) a defective orexin expression in the KFN could prevent arousal, thus assuming a crucial importance in causing SIDS
Unsuspected imported malaria in a case of sudden infant death
No full textHere we describe the case of a 4-mo-old female who
died suddenly without any apparent cause that was
initially mistaken as a case of sudden infant death syn
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drome. Histologic observation of brain sections revealed
blue-black bodies in erythrocytes of the blood vessels,
suggestive of specific stages of the hematic schizogonic
cycle. Further examinations revealed hemozoin and
hemosiderin deposits in the parenchyma of all organs,
leading to the diagnosis of malaria by Plasmodium falci
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parum (P. falciparum). The death occurred in Italy, the
native country of the infant, two weeks after a Christ-
mas holiday spent in Pakistan, the parents’ birthplace,
which has a high malarial endemicity. As this case
demonstrates, the diagnosis of malaria should always
be considered as a differential diagnosis in subjects,
including infants, that die unexpectedly after returning
from P. falciparum endemic area
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
Developmental neuropathology of brainstem respiratory centers in unexplained stillbirth: What's the meaning?
No full textStillbirth is one of the most stressful life events affecting over 3 million pregnancies per year throughout the world. An accurate autopsy of the stillborn fetus, including the placenta and umbilical cord examination, should be performed promptly after delivery. A thorough maternal history also should be taken, including exposures to risk factors. In many cases a death cause, attributable to fetal, maternal, or placental pathology, is clearly identified. However, in 50% or more of cases the cause remains unknown.
The purpose of this study is to highlight possible developmental alterations of the autonomic nervous system in unexplained stillbirths to provide an explanation of the pathogenetic mechanism of their death.
We conducted a careful neuropathological study of the brainstem, where the main vital centers are located, in 85 unexplained stillbirths and 52 age-matched controls died of known cause. Information on the maternal lifestyle, including the smoking habit, was collected in all cases. Hypodevelopment of neuronal centers involved in breathing control, all connected together in a “respiratory network”, precisely hypoplasia of the facial/parafacial complex, Kölliker-Fuse nucleus, pre-Bötzinger nucleus and intermediolateral nucleus, were frequently observed in unexplained deaths, significantly related to maternal cigarette smoking.
We support the hypothesis of a strong action of maternal smoking during pregnancy on the development of brainstem respiratory nuclei and suggest an explanation of the high incidence of the respiratory network alterations in unexplained fetal death, when breathing not represents a vital function
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
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