1,721,023 research outputs found
Gastrointestinal Surgery and Wernicke Encephalopathy
No full textWernicke encephalopathy (WE) is a cause of rapidly progressive but reversible dementia due to deficit of thiamine (the B1 vitamin). In developed countries, WE is principally described in chronic alcoholism; however, it can also develop in other, probably underestimated and undiagnosed, nonalcoholic conditions. The nonalcoholic conditions causing reduced intake (malnutrition, reduced or absent absorption) or increased consumption of thiamine can be physiologic (aging) or pathologic. Abdominal surgery for cancer is an underestimated cause of atypical WE leading to high morbidity and mortality in which the diagnosis is often missed or delayed. Alongside acute neurological emergence, chronic deficit of thiamine may contribute to the neurodegenerative process leading to senile dementia and Alzheimer's disease. This chapter provides an overview of (1) the main metabolic effects of thiamine in specific brain areas; (2) the natural history of WE in patients who have undergone abdominal surgery for cancer; (3) the mechanisms linking thiamine deficiency to Alzheimer's disease; and (4) alternative causes of rapidly progressive dementias that should be differentiated from atypical WE
Evaluating gaze control on a multi-target sequencing task: The distribution of fixations is evidence of exploration optimisation.
No full textMany high cognitive applications, such as vision processing and representation and understanding of images, often need to analyse in detail how an ongoing visual search was performed in a representative subset of the image, which may be arranged into sequences of loci, called regions of interest (ROIs). We used the Trial Making Test (TMT) in which subjects are asked to fixate a sequence of letters and numbers in a logical alphanumeric order. The main characteristic of TMT is to force the subject to perform a default and well-known path. The comparison of the expected scan-path with the observed scan-path provides a valuable method to investigate how a task force the subject to maintain a top-down internal representation of execution and how bottom-up influences the performance. We developed a mechanism that analyses the scan path using different algorithms, and we compared it with other methods: we found that fixations outside the ROI are direct influence of exploration strategy. The paper discusses the method in healthy subjects
Usefulness of Positron Emission Tomography for genital Chlamydia infection assessment in the murine model.
No full textUsefulness of Positron Emission Tomography for genital Chlamydia infection assessment in the murine model.
Marangoni A.1, Nanni C. 2, Quarta C. 2, Foschi C. 1, Russo I. 1, Nardini P. 1, D’Errico A. 3, Rosini F. 3, Aldini R.4, Cevenini R.1
1Section of Microbiology-DESOS, 3Med. Interna, Dell’invecchiamento e Malattie nefrologiche, 4SMETEC Dpt., University of Bologna.
2Nuclear Medicine, Azienda Ospedaliero-Universitaria di Bologna, Policlinico S.Orsola-Malpighi, Bologna, Italy.
OBJECTIVES
Untreated Chlamydia trachomatis infection can wreak havoc on the reproductive organs profoundly affecting fertility in women. Taken together, the high rate of asymptomatic infections and the severity of the infection related pathology indicate that control of chlamydial infections would require the development of new diagnostic non-invasive techniques for genital infection. The aim of this study was to explore the feasibility of 11C-choline Positron Emission Tomography (PET) in the assessment of the degree of inflammation in a C. muridarum genital infection mouse model.
METHODS
Model of infection. All the experiments were approved by the Ethical Committee of the University of Bologna. Animals used were 43 female Balb/c mice, 6-8 weeks old. All animals received 2.5 mg of medroxyprogesterone acetate i. m. 9 and 2 days prior the infection.
Twenty-one mice were infected by placing 15 μl of sucrose-phosphate-glutamic acid (SPG) buffer containing 106 inclusion forming units (IFUs) of C. muridarum into the vaginal vault. Twelve animals were treated with 15 μl of SPG containing heat-inactivated 106 IFUs of C. muridarum. As controls of inflammation, 7 animals were challenged with 15 μl of SPG. The Experimental design. Twenty-one infected animals were randomly allotted into two groups. Group A: 9 animals underwent a 11C-Choline PET at day 5, 10 and 20 post-infection. Group B: 12 animals were sacrificed at 5, 10, 15, 20 days for culture and histological analysis (3 animals for each time point). The 12 mice treated with inactivated chlamydiae were divided in two groups, as well. Group C: 4 animals underwent a 11C-Choline PET at day 5, 10 and 20 post-inoculation. Group D: 8 animals were sacrificed at 5, 10, 15, 20 days for culture and histological analysis (2 animals for each time point). Five control animals underwent 11C-Choline PET at the same days of the infected animals. Similarly, the remaining two control animals were sacrificed for histological analysis, one at 10 days and the other one at 20 days post-inoculation.
PET. 11C-Choline PET was carried out as follows: each animal was anaesthetized with gas anesthesia (Sevofluorane 3–5% and oxygen 1 l/min) and was injected with approximately 20 MBq of 11C-Choline, in a volume of 0.1 ml. The residual dose was measured to verify the effective dose injected. The animal was subsequently placed on the scanner bed in the prone position, after an uptake time of 10 minutes. Images were acquired with a small animal PET tomograph for a total acquisition time of 15 min. 11C-Choline PET images were reconstructed iteratively (OSEM 2D) and read in three planes (axial, sagittal and coronal).
Semi-quantitative analysis was carried out using the parameter SUV (standardized uptake value) representing mean radioactive counts per gram of tissue, divided by injected dose of radioactivity per gram of animal weight. The target region of interest (ROI) was placed on the pelvis at the level of the cervical-vaginal region.
Histology. The specimens obtained from sacrificed animals were preserved in 10% neutral buffered formalin for about 48 h and put in embedding cassettes, then processed in automatic tissue processor. After dehydration they were infiltrated with molten paraffin wax. Four-μm thick sections were cut with microtome, stained with haematoxylin-eosin and mounted on glass microscope slides.
The uterine horns were scored with respect to inflammation using the following criteria: 0: No inflammation. 1..
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
A cross-recurrence analysis of the pupil size fluctuations in steady scotopic conditions
Full text linkPupil size fluctuations during stationary scotopic conditions may convey information about the cortical state activity at rest. An important link between neuronal network state modulation and pupil fluctuations is the cholinergic and noradrenergic neuromodulatory tone, which is active at cortical level and in the peripheral terminals of the autonomic nervous system (ANS). This work aimed at studying the low- and high-frequency coupled oscillators in the autonomic spectrum (0-0.45 Hz) which, reportedly, drive the spontaneous pupillary fluctuations. To assess the interaction between the oscillators, we focused on the patterns of their trajectories in the phase-space. Firstly, the frequency spectrum of the pupil signal was determined by empirical mode decomposition. Secondly, cross-recurrence quantification analysis was used to unfold the non-linear dynamics. The global and local patterns of recurrence of the trajectories were estimated by two parameters: determinism and entropy. An elliptic region in the entropy-determinism plane (95% prediction area) yielded health-related values of entropy and determinism. We hypothesize that the data points inside the ellipse would likely represent balanced activity in the ANS. Interestingly, the Epworth Sleepiness Scale scores scaled up along with the entropy and determinism parameters. Although other non-linear methods like Short Time Fourier Transform and wavelets are usually applied for analyzing the pupillary oscillations, they rely on strong assumptions like the stationarity of the signal or the a priori knowledge of the shape of the single basis wave. Instead, the cross-recurrence analysis of the non-linear dynamics of the pupil size oscillations is an adaptable diagnostic tool for identifying the different weight of the autonomic nervous system components in the modulation of pupil size changes at rest in non-luminance conditions.
Copyright © 2019 Piu, Serchi, Rosini and Rufa
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
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