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Neonatal pulmonary hypoplasia frequently associated with brainstem hypodevelopment
No full textOur recent studies in stillbirths have reported the frequent detection of hypoplasia of both the arcuate nucleus and the lungs. The objective of this study was to correlate neonatal lung and brainstem development. A total of 58 sudden perinatal unexplained deaths were investigated. A complete autopsy was performed, including an in-depth examination of the brainstem as well as of the cardiac conduction system on serial sections, according to our guidelines. The stage of lung development was evaluated by a macroscopic criterion, i.e. the correlation between lung weight and body weight (LW/BW), and by a microscopic criterion, namely the radial alveolar count (RAC). In 65% of cases pulmonary hypoplasia was diagnosed, on both the gross and microscopic criteria. In over 50% of cases histological examination of the brainstem showed concomitant hypodevelopment of the brainstem, particularly bilateral hypoplasia, monolateral hypoplasia, partial hypoplasia, delayed neuronal maturation, as well as decreased neuronal density of the arcuate nucleus, an important chemoreceptor center that controls the breathing activity. Hypodevelopment of the pre-Bötzinger and parabrachial Kölliker-Fuse complex cardiorespiratory nuclei was also detected. The possibility of analyzing the development of fetal specific structures in utero by magnetic resonance techniques and so making a prenatal diagnosis of lung hypoplasia associated with arcuate nucleus hypoplasia could have clinical applications in prenatal counseling, allowing early therapeutic planning
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
Association between pulmonary hypoplasia and hypoplasia of arcuate nucleus in stillbirth
No full textOBJECTIVE: To investigate lung development and to correlate pulmonary hypoplasia with hypoplasia of the arcuate nucleus in stillbirths. STUDY DESIGN: We examined 26 stillbirths which occurred after 25 complete gestational weeks. The brainstem and the lung were the particular focus of this study. The brainstem was examined according to the protocol routinely followed in our Institute. As regards the lung examination, the development stage was evaluated on the basis of the correlation between lung and body weight (LW/BW), and according to microscopic parameters, that is, the presence of cartilaginous bronchi up to the distal level and the radial alveolar count (RAC). The normal reference values for the last 3 months of gestation correspond to >0.022 for LW/BW and from 2.2 to 4.4 for RAC. RESULTS: In 17 cases (65%) pulmonary hypoplasia was observed, characterized by a LW/BW value below 0.022 and RAC below 2.2. In nine cases (35%), microscopic examination of brainstem serial sections showed varying degrees of hypoplasia of the arcuate nucleus (ARCn). In eight cases (31%) the pulmonary hypoplasia was associated with hypoplasia/agenesis of the ARCn. CONCLUSIONS: This study demonstrated that in about a third of stillbirths there is a congenital hypodevelopment of both lung and arcuate nucleus. In these cases the ARCn hypoplasia would exert a negative effect on respiratory movements in utero and therefore on lung development. When the pulmonary hypoplasia is not accompanied by hypodevelopment of this nucleus the explanation could be a failure to block the inhibitory action of the Kölliker-Fuse nucleus
Association between the hypoplasia of the medullary arcuate nucleus and hypoplasia of the lung in unexpected late fetal death stillborn infants
No full textStillbirth is defined as late fetal death before the complete expulsion or retraction of the fetus from the mother. It represents about half of the cases of perinatal mortality, with a prevalence of 5 to 12 per 1000 births
The pathologic investigations that have been carried in this field are unfortunately sporadic and incomplete. In particular, the studies on the pathology of the autonomic nervous system in fetuses are sadly lacking, despite the fact that abnormalities of these structures are often the main pathologic substrate for unexpected fetal death, as the hypoplasia of the arcuate nucleus, an important cardio-respiratory center of the ventral medullary surface, in SIDS.
This study attempts to assess the pathologic findings in 26 stillborn infants with a gestational age of 25 to 40 weeks. The brainstem and the lung were the particular focus of this study.
The brainstem was examined according to the protocol routinely followed in our Institute, available at the web-site http://users.unimi.it/-pathol/sids.html.
The pertinent nuclei in histological serial sections were outlined, namely the parabrachial/Kölliker-Fuse complex, the nucleus hypoglossus, the dorsal vagus motor nucleus, the tractus solitarii nucleus, the nucleus ambiguus, the trigeminal tractus and nucleus, the arcuate nucleus and the ventrolateral reticular formation.
As regards the lung examination, in each case the stage of development was evaluated on the basis of a macroscopic criterion used at autopsy, namely the correlation between lung weight and body weight (LW/BW), and according to microscopic criteria, that is, the presence of cartilaginous bronchi up to the distal peripheral level and the radial alveolar count (RAC). The normal reference values for the last three months of gestation correspond to > 0.022 for LW/BW and for RAC they range from 2.2 to 4.4.
In 17 cases (65%) pulmonary hypoplasia was observed, characterized by a decrease in volume and/or weight of the lungs, without lobulation anomalies or alteration of the indices of pulmonary development, with LW/BW value below 0.022, a RAC below 2.2 and the presence of cartiloginous bronchi up to the distal peripheral level.
In 9 cases (35%), microscopic examination of serial sections of the brainstem showed varying degrees of hypoplasia of the arcuate nucleus. Precisely, in 8 cases a marked bilateral hypoplasia was evident and in one, the nucleus was completely absent (agenesis). In 8 of these cases there was also hypoplasia of the reticular formation.
A significant correlation (p<0.05) was observed between pulmonary hypoplasia and arcuate nucleus agenesis/hypoplasia. In fact, 8 cases (31%) were characterized by congenital hypodevelopment of both arcuate nucleus and lung. In all these cases chronic hypoxic signs were found.
These results suggest that in about a thirth of stillbirths the hypoplasia of the arcuate nucleus would exert a negative effect on respiratory movements in utero and therefore on lung development. In the cases where pulmonary hypoplasia is not accompanied by hypodevelopment of this nucleus the explanation could be a wrong physiological mechanism, more precisely a failure to block the ihibitory action of the pontine Kölliker-Fuse nucleus.
In conclusion, all the findings of our study confirm the hypothesis that functional or structural alterations of components of the vegetative nervous system which modulate fetal breathing, as the arcuate nucleus hypoplasia, may lead to disturbances in the development of the respiratory apparatus, in particular to pulmonary hypoplasia in stillbirth
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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