1,721,049 research outputs found
Selective Losses of Brainstem Catecholamine Neurons After Hypoxia-Ischemia in the Immature Rat Pup.
No full textHypoxic-ischemic (HI) injury in the preterm neonate incurs numerous functional deficits, however little is known about the neurochemically-defined brain nuclei that may underpin them. Key candidates are the brainstem catecholamine neurons. Using an immature animal model, the postnatal day (P)-3 (P3) rat pup, we investigated the effects of HI on brainstem catecholamine neurons in the locus coeruleus, nucleus tractus solitarius (NTS), and ventrolateral medulla (VLM). On P21, we found that prior P3 HI significantly reduced numbers of catecholaminergic neurons in the locus coeruleus, NTS, and VLM. Only locus coeruleus A6, NTS A2, and VLM A1 noradrenergic neurons, but not NTS C2 and VLM C1 adrenergic neurons, were lost. There was also an associated reduction in dopamine-beta-hydroxylase-positive immunolabeling in the forebrain. These findings suggest neonatal HI can affect specific neurochemically-defined neuronal populations in the brainstem and that noradrenergic neurons are particularly vulnerable to HI injury
Intrauterine Exposure to Alcohol and Tobacco Use and Childhood IQ: Findings from a Parental-Offspring Comparison within the Avon Longitudinal Study of Parents and Children
No full textThis study aims to test the hypothesis that moderate maternal alcohol and tobacco use in pregnancy is associated with intelligent quotient (IQ) scores in childhood through intrauterine mechanisms. We conducted parental-offspring comparisons between the associations of tobacco and alcohol consumption with child's IQ in the Avon Longitudinal Study of Parents and Children. Analyses were conducted on 4332 participants with complete data on maternal and paternal use of alcohol and tobacco at 18 wk gestation, child's IQ and a range of confounders. IQ was measured at child age 8 with the Weschler Intelligence Scale for Children (WISC-III). We used multivariable linear and logistic regression to estimate mean differences and 95% confidence intervals in IQ scores across the exposure categories and computed f statistics to compare maternal and paternal associations. In fully adjusted models, there was no strong statistical evidence that maternal alcohol and tobacco consumption during pregnancy were associated with childhood IQ with any greater magnitude than paternal alcohol and tobacco consumption (also assessed during their partners' pregnancy). Our findings suggest that the relationship between maternal moderate alcohol and tobacco use in early pregnancy and childhood IQ may not be explained by intrauterine mechanisms
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Exploring the long-term impacts of neonatal hypoglycemia to determine a safe threshold for glucose concentrations
Get PDFHypoglycemia and impaired metabolic transition are frequently observed in neonates during the first 24-48 h after birth [1, 2]. Severe (< 36 mg/dL or 2 mmol/L) and recurrent (3 or more episodes) hypoglycemia can cause neurological injury and developmental delays. The ambiguity regarding a threshold blood glucose concentration remains due to differing values proposed by various professional organizations. This poses a challenge in diagnosing neonatal hypoglycemia in addition to using a single blood glucose value, which in itself is not entirely reflective of various key molecular processes uncovered by in vitro or pre-clinical studies. The symptoms of hypoglycemia can also be present in conditions other than hypoglycemia, e.g., sepsis and polycythemia, and in many cases, hypoglycemia is clinically unrecognized. Therefore, early screening of at-risk and otherwise healthy-appearing neonates is essential. Continuous glucose monitoring and early interventions such as glucose gel, breast and formula feeding, and intravenous glucose administration are utilized to prevent long-term neurological impairments. However, the safe limits of serum glucose that will prevent neuroglycopenia and neural injury are elusive. The impact of early screening and available therapies on neurodevelopmental outcomes remains uncertain due to the absence of a robust clinical design and combining all causes of neonatal hypoglycemia without making further distinctions from other conditions. This review highlights the controversies in definitions and the most recent information on long-term neurodevelopmental outcomes that may impact the early management of NH.Conclusion: Optimizing the definitions and treatment of neonatal dysglycemia is crucial for preventing hypoglycemia-related brain injury. Continuous glucose monitoring technology in neonates offers a promising approach for real-time screening and early intervention. What is Known: • There is ongoing debate regarding the optimal glucose threshold for intervention and prevention of hypoglycemia-induced brain injury. This suggests brain injury may be incurred over a range rather than a single blood glucose concentration. What is New: • Recent studies suggest that glucose concentrations between 36 mg/dL (2 mmol/L) and 47 mg/dL (2.6 mmol/L) are acceptable in asymptomatic neonates. However, neurological injury was observed in early school age with glucose values of <36 mg/dl (<2 mmol/L) and in mid-childhood of <30-36 mg/dL (<1.7 -2 mmol/L). This suggests brain injury may be incurred over a range rather than a single blood glucose concentration. • Continuous glucose monitoring (CGM) highlights real-time glucose measurement and glycemic lability in neonates. Its use may mitigate long-term neurologic injury by improving early recognition and treatment
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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High-fat diet affects pregestational adiposity and glucose tolerance perturbing gestational placental macronutrient transporters culminating in an obese offspring in wild-type and glucose transporter isoform 3 heterozygous null mice
Get PDFWe examined the effect of a high-fat diet (HFD) vs. control diet (CD) upon pregestational and gestational wild-type (wt) and glucose transporter (glut)3 heterozygous (glut3+/-) female mice and observed an increase in pregestational body weights, white adiposity (wt > glut3+/-), circulating cholesterol, and high-density lipoproteins, with glucose intolerance in both genotypes. The HFD-exposed offspring displayed reduced birth weight with catch up to CD-fed in wt vs. an increased birth weight persisting as such at weaning by day 21 in glut3+/- mice. To decipher the mechanism behind this genotype-specific difference in the HFD offspring's phenotype, we first examined placental macronutrient transporters and noted HFD-induced increase in CD36 in wt with no change in other FATPs, sodium-coupled neutral amino acid transporters and system L amino acid transporter in both genotypes. In contrast, while placental Glut1 increased in both the genotypes, only Glut3 increased in the glut3+/- genotype in response to HFD. Hence, we next assessed glut3+/- embryonic (ES) cells under differing stressors of low glucose, hypoxia and inhibition of oxidative phosphorylation. Reduced Glut3-mediated glucose uptake in glut3+/- vs. wt ES cells culminated in deficient growth. We conclude that maternal HFD affects the in utero growth potential of the offspring by altering placental CD36 and Glut1 concentrations. In contrast, a differential effect on placental Glut3 concentrations between glut3+/- and wt genotypes is evident, with an increase occurring in the glut3+/- genotype alone. Deficient Glut3 in ES cells interferes with glucose uptake, cell survival and growth being further exaggerated with low glucose, hypoxia and inhibition of oxidative phosphorylation
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