1,720,973 research outputs found
Lipid peroxidation in human spermatozoa from men with genitourinary infections
No full textA fluorescent assay was used to reveal the presence of lipid peroxidation (LPO) in spermatozoa from individuals with genitourinary infections (GI). The incidence of LPO was compared with sperm pathologies (apoptosis, immaturity, necrosis) evaluated by transmission electron microscopy (TEM) and motility. A C11-BODIPY581/591 probe was used to detect and localize LPO in sperm from 34 individuals. The sperm morphological characteristics were studied by TEM and the results were mathematically assessed. Using the LPO percentage we divided the patients into four groups. Group 1 included ten patients with GI with almost normal progressive motility, a very low percentage of LPO and sperm pathology values that were not far from the standard ranges. Group 2 had eleven infected patients showing reduced motility, LPO of 10 to 20% and sperm pathologies that were just out of normal range. Group 3 included 6 infected patients with progressive motility ≤22%, low levels of LPO with a higher percentage of apoptosis and necrosis. Group 4 had 7 patients showing normal semen parameters, without GI, LPO ranged from 0% to 1% and a normal incidence of sperm pathologies. In all groups, LPO was inversely correlated with sperm motility and directly correlated with low semen quality. However, the LPO percentage was low in Group 3, in which sperm necrosis, concomitant with GI, was the predominant pathology. C11-BODIPY581/591 is a useful labeling method for quantifying and localizing LPO in spermatozoa from patients with GI. The detection of LPO could be questionable in cases of sperm necrosis because in this pathology the plasma membrane is often disrupted and the lipidic probe is unable to intercalate within the phospholipidic bilayer. Copyright © Informa Healthcare USA, Inc
Sperm ultrastructure and 18, X, Y aneuploidies in a man with a 46 XY, 47 XY + 18 mosaic karyotype: case report
No full textPURPOSE:
To describe sperm morphology and meiotic segregation in the case of a man with a 46 XY/ 47 XY + 18 mosaic karyotype.
MATERIALS AND METHODS:
A 25-year-old man came to our Centre for semen analysis. Morphological sperm evaluation was performed by light and electron microscopy; meiotic segregation was examined by fluorescence in situ hybridisation (FISH) technique using probes for chromosomes 18, X and Y. PCR was carried out on DNA from peripheral blood lymphocytes to analyze Y microdeletions.
RESULTS:
Mathematically elaborated transmission electron microscopy data highlighted a low number of sperm devoid of ultrastructural defects, and the presence of characteristics of apoptosis and immaturity. FISH showed the presence of aneuploidies of chromosome 18 and sex chromosomes.
CONCLUSIONS:
In this case of mosaicism morphological and meiotic spermatogenetic impairment is shown, as well as structural chromosomal alterations
Distribution of alpha-, gamma (+beta)- and delta-tocopherol in the seminal plasma, spermatozoa and seminal vesicles of rabbit
No full textDietary vitamin E supplementation plays a key role in animal reproduction by protecting germ cells from oxidative damage. Recently, alpha-tocopherol homologues (namely, beta-, gamma- and delta-tocopherol) have been the object of increasing research because of their peculiar nonantioxidant properties. We found that these tocol-derived compounds are not homogeneously distributed among semen components. Alpha-T was the major vitamin E homologue found in all semen fractions. Half of the total gamma (+beta)-T was found in germ cells, while more than 50% of total delta-T was preferentially accumulated in seminal plasma. The concentration of various tocol-derived compounds depended on their relative amounts in diet and the competition for saturable enzymes implicated in their metabolism. A higher concentration of delta-T in seminal plasma may be related to its more polar nature. However, the biological function of this compound in semen remains to be cleared. To our knowledge, this is the first study aimed at identifying alpha-tocopherol homologues in rabbit semen fractions. © 2008 The Authors
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
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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