1,720,957 research outputs found
1-Chloro-2-hydroxypropane epoxidase in rat liver and other organs
No full text1,2-Dichloropropane, a widely used solvent for paint and varnish, is metabolized by the rat liver microsomal system to give a hydroxyl metabolite which is then epoxidized. The present study reports on a method for determining 1-chloro-2-hydroxypropane epoxidase and its distribution in several organs in rats. 10000xg supernatants from 20% w/v homogenates (0.1 ml) were incubated with 0.3 ml of a cofactor mixture (0.08 μmol NADP, 1.5 μmol glucose-6-phosphate, 7.8 μmol niacinamide and 3.9 μmol MgCl2 in phosphate buffer 0.1 M, pH 7.4) and 0.1 ml of substrate (0.01 M). After incubation for 30 min at 37°C, formation of propylene glycol was measured according to Harger & Forney. Enzyme activities (nmol-1 mg protein-1, mean±SD) were as follows: liver 2.84±0.61; kidney cortex 8.50±1.22; testis 8.41±2.19; lung 4.61±1.15. These results support our previous report that the solvent has a greater toxic effect on the kidney. This may be due to the higher epoxide formation during the metabolism of the solvent
Biochemical pattern of rat liver during and after treatment with 1,2-dichloropropane
No full text1,2-Dichloropropane (1,2 D) induces liver acute toxicity. In chronic experimental treatment of rats, biochemical and histological pattern shows a hyperplastic damage of the liver cell. The present work studies the behaviour of the liver metabolic pattern during and after treatment with 1,2 D. Male, albino, Wistar rats, starting weight 200±10 grams, were treated i.p. for 4 weeks (5 days/week, 2 days without treatment) with 0 and 250 mg/kg b.w. of 1,2 D dissolved in corn oil. The rats were sacrificed after 5, 10, 15 and 20 treatments, and two months after suspension of the treatment. After the sacrifice, the liver was drawed and prepared for determination of Cytochrome P-450 activity (Cyt P-450), reduced glutathione content (GSH), and glutathione S-transferases activity (GST). GSH content shows a statistically significant increase after ten treatments, GST activity significantly increases after 15 treatments, and Cyt P-450 significantly decreases after 20 treatments. Phase II components of liver metabolism are then firstly involved by 1,2 D. The biochemical pattern is indicative of a hyperplastic evolution of the liver cell as it is confirmed by histology. Suspension of the treatment shows a return to normal values of Phase I and Phase II components. These results shows after the suspension of the treatment a tendency to repair of the lesions induced by 1,2 D
gamma-Glutamyltransferase in urine as an early index of kidney involvement in cadmium exposure.
No full textno abstract availabl
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
Exploring the Limits of a Redundant Actuation System through Co-Design
No full textThis paper assesses the energy efficiency of a redundant actuation architecture combining Quasi-Direct Drive (QDD) motors and Series Elastic Actuators (SEAs) by comparing its energy consumption to Geared Motors (GMs) and SEAs alone. We consider this comparison for two robotic systems performing different tasks. Our results show that using the redundant actuation we can save up to 99% of energy with respect to SEA for sinusoidal movements. This efficiency is achieved by exploiting the coupled dynamics of the two actuators, resulting in a latching-like control strategy. We also show that these large energy savings are not straightforwardly extendable to nonsinusoidal movements, but smaller savings (e.g., 7%) are nonetheless possible. The presented results were obtained thanks to the framework of concurrent design (co-design), namely the simultaneous optimization of hardware parameters and control trajectories. This shows that the combination of complex hardware morphologies and advanced numerical co-design can lead to peak hardware performance that would be unattainable by human intuition alone
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
Biological monitoring of cadmium exposure: reliability of spot urine samples
Full text linkConcentration-dilution of spot urine samples is a shortcoming of the biological monitoring of industrial xenobiotics. To ascertain whether the adjustment of urinary cadmium measured in spot samples is appropriate, urine samples were taken three times, once a week for 3 successive weeks, from 25 welders employed in the manufacture of jewelry (total 75 samples). Cadmium, creatinine, specific gravity, total urinary solutes, urinary volume and urinary flow rate were measured in 12-h collections and in spot samples taken immediately afterwards. Creatinine and total urinary solutes showed high inverse correlation with urinary flow rate (r = -0.858 and r = -0.768 respectively). Urinary cadmium displayed a similar trend but the correlation was not significant (r = -0.145). Creatinine adjustment of urinary cadmium values in spot samples increased the correlation with the same index in timed samples adjusted for urinary volume (r = -0.808) or urinary flow rate (r = 0.821) compared with non-adjustment (r = 0.732 and r = 0.738, respectively). Creatinine adjustment of spot sample values is also suitable for a wide range of urinary concentrations; discarding excessively diluted or concentrated urines, correlation of urine samples improved for non-adjusted or specific gravity-adjusted values, whereas no changes were observed for creatinine-adjusted values
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
- …
