186,206 research outputs found
[Doppler echocardiographic evaluation of the new mechanical bileaflet Sorin Bicarbon valve prosthesis compared with St. Jude Medical].
No full textBACKGROUND: Despite the Bicarbon valve has been marketed for more than two years, no systematic Doppler evaluation of its normal functioning has yet been published. Therefore, the aims of this study were to establish the normal flow characteristics for the Bicarbon bileaflet prosthetic heart valve and to compare them with those obtained from the St. Jude Medical valve prosthesis. METHODS: Doppler echocardiographic characteristics of normally functioning Bicarbon prostheses were prospectively assessed in 76 consecutive patients (44 males and 32 females, mean age 60 +/- 10 years) with 79 valves in mitral (n = 29) and aortic (n = 50) position whose function was considered normal by clinical and echocardiographic evaluation. In addition, Doppler characteristics of the Bicarbon valves in aortic position were compared to those of 27 normal functioning St. Jude Medical implanted during the same period. RESULTS: For the mitral valve prostheses, we found non significant difference among prosthesis sizes in terms of transprosthetic gradients or pressure half time. Peak and mean gradients were similar in the 27-mm and 31-mm size valves (from 11 +/- 4 to 11 +/- 2 mm Hg and from 5 +/- 2 to 5 +/- 1 mm Hg, respectively; p = NS for both). Similarly, the pressure half time was similar in the 27-mm and in the 31-mm size valve (85 +/- 16 and 76 +/- 13 msec; p = NS). Conversely, for the aortic valve prostheses, there was a significant decrease in transprosthetic gradients and an increase in effective orifice areas as prosthesis size increased. Mean gradient was 13 +/- 1 mm Hg in 19-mm size valves, and it decreased to 6 +/- 2 mm Hg in the 29-mm size. Effective prosthetic valve area calculated using the continuity equation, ranged between 1.0 +/- 0.3 cm2 for 19-mm size valves to 3.5 +/- 0.7 cm2 for 29-mm size. With analysis of variance, effective prosthetic aortic valve area differentiated various valve sizes (F = 23.3; p < 0.0001) better than peak (F = 3.2; p = 0.017) or mean (F = 4.19; p = 0.0035) gradients alone did. Furthermore, effective prosthetic aortic valve area correlated better than peak and mean gradients with prosthetic size (r = 0.87, r = -0.58 and r = -0.57; respectively). In addition, peak and mean transprosthetic gradients and effective prosthetic aortic valve areas did not show any statistically significant difference between the Bicarbon and the St. Jude Medical valves in aortic position, either in 19 and 21 mm (25 +/- 8 mm Hg, 13 +/- 4 mm Hg, 1.3 +/- 0.3 cm2 and 32 +/- 11 mm Hg, 17 +/- 6 mm Hg, 1.2 +/- 0.4 cm2, respectively; p = NS), or in 23 and 25 mm (21 +/- 8 mm Hg, 11 +/- 4 mm Hg, 2.1 +/- 0.5 cm2 and 24 +/- 11 mm Hg, 12 +/- 5 mm Hg, 1.8 +/- 0.4 cm2, respectively; p = NS) or in 27 and 29 mm (12 +/- 2 mm Hg, 7 +/- 1 mm Hg, 2.8 +/- 0.9 cm2 and 16 +/- 5 mm Hg, 7 +/- 2 mm Hg, 2.6 +/- 0.4 cm2, respectively; p = NS). CONCLUSIONS: This study suggest that the Bicarbon valve prosthesis offers relatively little resistance to forward flow except at a small anulus diameter. Furthermore, these is no statistically significant difference between the Bicarbon and the St. Jude Medical in aortic position with regard to early hemodynamic performances
Effect of chemical pollutants on F-actin cytoskeleton in earthworm coelomocytes
No full textEarthworms are very important organisms for soil formation and organic matter breakdown in most terrestrial environments. Because of their strong interaction with soil, they are profoundly affected by soil pollution. The coelomic fluid is one of the first targets of toxicants in earthworms because it can receive and vehicle pollutants to the all animal tissues. The aim of the present work was to investigate possible pollutant-induced alterations in earthworms coelomocytes cytoskeleton in view of future application as sensitive biomarker for soil monitoring and assessment applications. The study was carried out on the earthworm Eisenia foetida. The animals were exposed in controlled laboratory conditions either to the heavy metal based fungicide copper sulphate or to the PAH fluorantene. Coelomocytes were labelled with rhodamine-phalloidine for F-actin visualization by confocal laser scanning microscopy. The attention was focussed on granulocytes which are the cell type major involved in humoral immune response.
Results showed a significant (P<0.01) increase in the F-actin content in granulocytes from treated animals with respect to control groups either in copper or fluorantene exposed animals. While in copper exposed animals the increase was markedly limited to the cortical region of the cells, in fluorantene exposed animals a general increase of F-actin polimeryzation was observed in the whole cell.
In conclusion the present study demonstrated that F-actin cytoskeleton of earthworm coelomocytes represents an important cellular target of the effect of organic or inorganic chemical pollutants in these bioindicator organisms and give useful information for a potential use of this response as exposure/effect biomarker in soil risk assessment
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Potential toxicity and genotoxicity of soils around a high impacted site
No full textThe importance of earthworms in testing the adverse effects of chemicals on soil biota has been recognised by various environmental organisations and resulted in a set of standard toxicity tests. Recently, there is growing interest in the use of biomarkers as a new complementary approach providing more information about the stress response of the organisms to pollutants.
The aim of the present work was to apply an integrated approach of toxicity tests (mortality and reproduction rates) and genotoxic biomarkers (micronuclei and comet assay) on the bioindicator organism Eisenia foetida in the assessment of arsenic contamination risk around a national high impacted site (Termo-Electric Central, Cerano, Brindisi, Italy). The animals were exposed to soil samples obtained from 20 sites in the area around the Central. The exposure was carried out for two weeks (acute toxicity test) and for four weeks for the reproduction test. The adults were then removed from the soil and the newborns were counted after further 4 weeks. On the adults exposed for 4 weeks micronuclei and comet assay were performed on coelomatic cells.
Obtained results excluded the presence of acute toxicity in all the sampled sites but revealed the presence of relevant chronic toxicity in some sites. Micronuclei and comet assay data showed a high significant (P<0.01) correlation with chronic toxicity test and with arsenic concentration in the soil.
The study suggests the applicability of the proposed integrated approach of genotoxicity biomarkers and chronic toxicity test in the assessment of arsenic risk contamination in the soil
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Palladium oxide nanoparticles: Preparation, characterization and catalytic activity evaluation
No full textStable palladium oxide nanoparticles were prepared in aqueous suspension with a very simple procedure, by dissolving palladium nitrate in water at a concentration around 10-4 M. UV-visible absorption spectroscopy was adopted to follow the formation of these nanoparticles, which were characterized by TEM microscopy, along with XRD, XPS and Raman measurements. DFT calculations allowed to interpret the Raman data and to clarify the species present at the surface of the nanoparticles. The catalytic activity of the latter was evaluated by monitoring the reduction of p-nitrophenol to p-aminophenol. This investigation paves the way to the use of these colloidal nanoparticles in processes of heterogeneous catalysis, in particular those concerning the catalytic degradation of aromatic derivatives that represent a serious danger for the environment as pollutants, as in the case of p-nitrophenol
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Dr. Edward P. Wimberly, ITC, July 2011
No full textThis video is a conversation with Dr. Edward P. Wimberly. Dr. Wimberly talks about his book, "No Shame in Wesley's Gospel: A Twenty-First Century Pastoral Gospel". Brad Ost, AUC Woodruff Library, is the interviewer
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