1,720,964 research outputs found
Study of the human hypoglossal nucleus: normal development and morpho-functional alterations in sudden unexplained late fetal and infant death
Full text linkThis study evaluated the development and the involvement in sudden perinatal and infant death of the medullary hypoglossal nucleus, a nucleus that, besides to coordinate swallowing, chewing and vocalization, takes part in inspiration. Through histological, morphometrical and immunohistochemical methods in 65 cases of perinatal and infant victims (29 stillbirths, 7 newborns and 29 infants), who died of both unknown and known cause, the authors observed developmental anomalies of the hypoglossal nucleus (HGN) in high percentage of sudden unexplained fetal and infant deaths. In particular, HGN hypoplasia, hyperplasia, positive expression of somatostatin and absence of interneurons were frequently found particularly in infant deaths, with a significant correlation with maternal smoking
Italian national data bank of stillbirth vs. SIDS.
Full text linkSudden perinatal death, which includes antepartum
death (from 22 completed weeks of gestation), intrapartum
death and early neonatal death (occurring
within seven completed days of life), and sudden infant
death syndrome (SIDS), represents one of the major
sociomedical and scientific problems still lacking a
solution in today’s medicine.1 However, little effort is
being made to find a cause of these deaths, as there is
no standard method of performing an autopsy in these
victims, and no database exists from which researchers
can draw autopsy results. Therefore, the need to submit
the young victims to necropsy procedures through a
standardized protocol is unanimously recognized, and
the chance of preventing perinatal unexpected death
and SIDS relies mainly on a better knowledge of the
underlying alterations of organs and etiopathogenetic
mechanisms. Similarly, for diagnostic purposes, an
accurate and careful examination of the circumstantial,
environmental, and familial situation within which the
death occurred is extremely important.
All the information related to victims of sudden
and unexplained fetal death and SIDS will soon be
made available in Italy through a specific data bank
established under the Law 31/2006 “Regulations for
Diagnostic Post Mortem Investigation in Victims of
Sudden Infant Death Syndrome (SIDS) and Unexpected
Fetal Death.”2 This law mandates that infants
who die suddenly within one year of life, and fetuses
that die after 22 weeks of gestation without any
apparent cause, must be rapidly submitted—with the
consent of both parents—to diagnostic postmortem
investigation.3 Information about the pregnancy, fetal
development and delivery, and, in the case of SIDS,
the environmental and familial situation in which the
death occurred—in addition to information related
to risk factors—must be collected by the obstetriciangynecologist,
neonatologist, pediatrician, and pathologist
involved in the case and recorded in the registry of
the data bank. In addition, to facilitate the collection
and analysis of the data, this data bank will allow the
Lino Rossi Research Center in collaboration with the
Epidemiology Center of the Italian National Health
Institute to update the population through public
education
and prevention programs aimed at decreasing
the incidence of stillbirth and SIDS
Severe intra- and periventricular hemorrhage: role of arteriolosclerosis related to maternal smoke
Full text linkThe authors aimed to describe the atherosclerotic lesions of the cerebral arterioles, as a substrate of their rupture and bleeding for ests.
The study was performed on brain of 9 caucasian fetal victims of intra- and periventricular hemorrhage, all grade IV, and 9 control cases.
In the 9 victims of hemorrhage the arteriolar wall structure was altered, focally transformed into a deposit of amorphous eosinophilic material. Such changes often affected the full-thickness of the wall, causing rupture and hemorrhage. In 8 of these cases and in 2 victims of the control group the mothers were heavy cigarette smokers (15-20 cigarettes/day) before and during pregnancy.
The authors conclude that intra- and periventricular haemorrhage can be ascribed to the toxic effects of prenatal absorption of nicotine
Histological and biological developmental characterization of the human cerebellar cortex
No full textThe aim of this study was to investigate the histological and biological features of the human cerebellar cortex development and differentiation. We analyzed 52 brains of fetal and infant death victims, aged from 17 gestational weeks to 12th postnatal month. In particular, in the cerebellar cortex at different ages we evaluated, besides the structural aspects, the expression of several biomarkers implicated in proliferative processes (c-fos, PCNA and apoptosis). We observed morphological patterns progressively evolving every month, from the indefinite structure of the second gestational trimester to the four-layered structure (external granular layer, molecular layer, Purkinje cell layer, internal granular layer) of the late fetal cortex and subsequently to the three-layered postnatal definitive morphology, due to involution of the external granular layer. The evaluation of the biological features of the cerebellar cortex showed high proliferative activity mainly confined to the transient external granular layer in prenatal life, and high apoptotic index after birth. Thus, the histological examination, better with the support of biomarker investigations, allows with accuracy to describe the dynamic sequence of steps that occur in human cerebellar cortex development and to establish in each case the age, namely the pre- or postnatal month of life. Consequently, we can diagnose delayed or altered processes of differentiation during the development of the human cerebellar cortex
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
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
Developmental alterations of the spinal trigeminal nucleus disclosed by substance P immunohistochemistry in fetal and infant sudden unexplained deaths
No full textWe investigated the immunohistochemical expression of substance P (SP) in the brainstems of 56 subjects aged from 17 gestational weeks to 10 postnatal months, who died of unknown (sudden unexplained perinatal deaths and SIDS) and known causes (controls). The goals of this study were: 1) to obtain basic information about the expression of SP during the first phases of human nervous system development; 2) to evaluate whether there are alterations of this neuromodulator in victims of sudden death; 3) to verify any correlation with maternal cigarette smoking.
Immunohistochemistry demonstrated SP-immunoreactivity in the caudal trigeminal nucleus area, with a progressive increase in the density of SP-positive fibers of the corresponding tract during normal development from fetal life to the first postnatal months. Delineation of the structure of the human trigeminal nucleus, little investigated so far, provided essential data on its morphologic and functional development.
Instead, a negative or low SP expression was detectable in the fibers of this tract in a wide subset of SIDS victims and, conversely, a high SP-expression in a wide subset of sudden fetal deaths. We postulate, on the basis of these results, that SP has a functional importance in the early phases of central nervous system development and in the regulation of autonomic functions.
In addition, the observation of a significant correlation between sudden unexplained death, altered SP staining and maternal smoking leads us to suggest a close relation between the absorption of cigarette smoke in utero and a decreased functional activity of the trigeminal nucleus, that can trigger sudden death of the fetus during pregnancy or of the infant in the first months of life
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