1,720,974 research outputs found
Developmental competence of gametes reconstructed by germinal vesicle transplantation from fresh and cryopreserved bovine oocytes
No full textOBJECTIVE:
To evaluate the use of fresh or frozen bovine oocytes as an animal model for reconstructing artificial gametes by germinal vesicle transplantation (GVT), to study nucleocytoplasmic interaction and define clinical procedures for ooplasm donation in humans.
DESIGN:
Prospective experimental study.
SETTING:
University-based experimental laboratory.
ANIMAL(S):
Bovine oocytes from slaughterhouse ovaries.
INTERVENTION(S):
A total of 446 gametes were reconstructed from fresh immature oocytes; nuclear and cytoplasmic competencies were analyzed through the assessment of meiotic progression and cytoskeleton reorganization; embryonic developmental capability was evaluated after parthenogenetic activation of metaphase II (MII) reconstructed oocytes. Furthermore, the distribution of mitochondria in karyoplast and cytoplast in grafted oocytes was studied. Finally, meiotic and developmental competencies were determined in 199 gametes reconstructed from vitrified immature oocytes.
MAIN OUTCOME MEASURE(S):
Maturational and developmental rate of reconstructed oocytes, cytoskeleton organization, and mitochondrial distribution.
RESULT(S):
Gametes reconstructed from either fresh or cryopreserved immature oocytes showed similar meiotic competence (41.6% vs. 37.7%, respectively). All reconstituted oocytes that reached MII displayed a normal distribution of cytoskeletal elements. Embryonic developmental capability was higher in oocytes derived from fresh than from cryopreserved gametes (30.8% vs. 8.1%, respectively). Finally, oocyte centrifugation was effective in obtaining karyoplasts with <5% of mitochondria.
CONCLUSION(S):
Cows can provide a suitable organism model to develop GVT technique in both research and clinical settings as well as in fertility preservation programs
In vitro reproductive toxicity of polychlorinated biphenyls : effects on oocyte maturation and developmental competence in cattle
No full textPolychlorinated biphenyls (PCBs) are one of the most persistent and widespread group of endocrine disrupting compounds in the ecosystem. High concentrations of these substances are known to be present in sewage sludge from industrial, agricultural, and domestic origin that is spread in increasing amounts on arable land and pasture as fertilizer and is found in water, representing an increasing risk for the reproductive health of farm animals. Objective of this study was to determine the impact of PCBs on maturation and developmental competence of cattle oocytes. Since PCBs are a family of 209 molecules present in the environment as a mixture, Aroclor-1254, a pool of more than 60 congeners, was used in these experiments as its composition is considered to be environmentally relevant. Cumulus-oocytes complexes were exposed during IVM to serial concentrations of Aroclor-1254 (between 1 microg/ml and 0.0001 microg/ml) and compared with control groups. Aroclor decreased the percentage of oocytes that reached metaphase II stage after 24 hr, at doses as low as 0.01 microg/ml. Groups treated with 0.001 microg/ml or above, showed an impaired fertilization rate and a dramatic increase of polyspermy. Moreover, exposure during maturation resulted in a reduced proportion of oocytes that cleaved and developed until blastocyst stage although no differences in embryo cell numbers were observed. The present study indicates that very low PCBs concentrations are sufficient to disrupt bovine oocyte maturation, its fertilization, and developmental competence. These results also provide a set of reference data for the assessment of the risk posed by these substances to animal reproductive health, though further work will be necessary to equate in vitro doses to in vivo exposures
SIGNIFICANCE OF ALBUMINURIA IN THE FOLLOW-UP OF ACUTE POSTSTREPTOCOCCAL GLOMERULONEPHRITIS
No full textThe present study was aimed at assessing the diagnostic value of urinary albumin (uA) excretion rate in the long-term follow-up of patients suffering from acute post-streptococcal glomerulonephritis (APSGN). 26 patients, who had presented primarily with nephritic syndrome and showing increased uA without a concomitant rise in total proteinuria (uTP) were followed-up for 131 months on average (range 36-288). At the last check, 14 patients did not show urinary abnormalities, 9 had a persistent increase in uA, 1 increased uTP and 2 renal insufficiency. Urinary and clinical signs of the disease were not seen during observation periods prolonged for 79 months on average (range 20-156) after normalization of uA. No pathological findings were remarked in biopsy specimens obtained in 3 patients when uA was normalized; in contrast, when both uTP and uA (12 cases) or when isolated uA (14 cases) were increased a pattern of diffuse mesangial proliferative glomerulonephritis was constantly observed. These results indicate that the abnormal uA excretion rate during long-term follow-up of APSGN allows to identify a subset of patients with persistent renal disease; conversely, the occurrence of normal uA seems to point to a good diagnostic and prognostic significance
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
Effects of antihypertensive drugs on glomerular function in normotensive and hypertensive subjects: hormonal aspects.
No full textAppropriate 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
Nuclear-cytoplasmic cooperation in bovine oocytes can be investigated by germinal vesicle transplantation
No full textSarcoglycans are a sub-complex of transmembrane proteins which are part of the dystrophin-glycoprotein complex (DGC). They are expressed above all in the skeletal, cardiac and smooth muscle. Although numerous studies have been conducted on the sarcoglycan sub-complex in skeletal and cardiac muscle, the manner of distribution and localization of these proteins along the non-junctional sarcolemma is still not clear. Furthermore, there are unclear data about the actual role of sarcoglycans in human skeletal muscle affected by sarcoglycanopathies. In our studies on human skeletal muscle, normal and pathological, we determined the localization, distribution and interaction of these glycoproteins. Our results, on normal human skeletal muscle, showed that the sarcoglycans can be localized both in the region of the sarcolemma over the I band and over the A band, hypothesizing a correlation between regions of the sarcolemma occupied by costameres and the metabolic type of the fibers (slow and fast). Our data on skeletal muscle affected by sarcoglycanopathy confirmed the hypothesis of a bidirectional signaling between sarcoglycans and integrins and the interaction of filamin2 with both sarcoglycans and integrins. In addition, we have recently demonstrated, in smooth muscle, the presence of •-SG, in contrast with data of other Authors. Finally, we analyzed the association between contractile activity and quantitative correlation between •- and •-SG, in order to better define the arrangement of sarcoglycan subcomplex
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