1,720,959 research outputs found
Cell fusion and creatine kinase activity in cultures of chick embryo myoblasts
No full textIn primary cultures of myoblasts from embryonic chick skeletal muscle, cells undergo a period of proliferation lasting 2 days, and then fuse into multinucleated myotubes. It is a generally accepted idea that cell fusion represents a critical event followed by the synthesis of specific proteins. It was reported that no specific enzymes are synthesized by mononucleated myoblasts (COLEMANan d CoLEhiAN, 1968; SHAINBEReGt ul., 1971; LOOMIS el al., 1973). We investigated the relationship between cell fusion and the activity of specific enzymes, in order to verify whether the expression of these phenomena is linked to a common regulative signal. The activity of creatine kinase (CPK; E.C. 2. 7. 3 2.) has been investigated in culture conditions which prevent cell fusion without affecting cell growth. These culture conditions consisted of the use of a nutritional medium at low serum concentration (MOLINAROet al., 1974). The inhibition of cell fusion obtained by low serum concentration depends primarily on the reduced Ca++ concentration, since the addition of Ca++ restores cell fusion
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
AUTORADIOGRAPHIC STUDY OF DNA SYNTHESIS AND THE CELL CYCLE IN SPERMATOGONIA AND SPERMATOCYTES OF MOUSE TESTIS USING TRITIATED THYMIDINE
No full text« Azione Colchicino-Simile di un Derivato Acridinico e Azione Combinata di Tale Composto e di Colchicina Sopra le Cellule Emopoietiche Dell'Embrione di Pollo »
No full text The antimitotic action of an acridine derivative (Italchina Farmitalia = Atebrin = 6-chloro-2-methoxy-9-α-diethylamino-δ-pentilaminoacridine) administered alone and in association with Colchicine has been studied on basophil megaloblasts of chick embryos. In comparison to the controls, the following results have been obtained in the embryos treated with Italchina: 1) A marked decrease of mitotic index. 2) A high percentage increase of metaphases and significant percentage diminution of pro-, ana- and telophases. 3) Degenerative cytolytic lesions of interphasic nuclei and mitotic lesions: sticking of chromosomes, anaphase bridges, chromosomes breaking, irregular and often picnotic metaphases. On the basis of the obtained results it is stated that Italchina exerts a double mitostatic action: a pre-prophasic action (radiomimetic) and a statmokinetic one (colchicine-like). The combined treatment Italchina + Colchicine shows that Italchina enhances the action of Colchicine. The conclusions obtained by Rondoni and Necco on the in vitro fibroblasts of chick embryos are confirmed. </jats:p
L'epoca di comparsa delle cellule argentofile e delle cellule argentaffini nell'intestino di embrione di pollo
No full textVariations 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
« Influenza Degli Ormoni Sessuali Sulla Crescita Dell'Adenocarcinoma Mammario Spontaneo Del Topo in Vitro »
No full text Explants from spontaneous mammary adenocarcinoma of C 3 H and IV B mice were treated « in vitro » with oestrone, progesterone and testosterone. The « roller-tubes » technique was used for the observation of the migration area, the « roller-slides » technique for histological preparations and mitotic index calculations, the Carrel flasks for phase contrast microscopical observations. Growth determination was carried out in 15 days old cultures by planimetric measurements of the migration area and calculations of the mitotic index. 1) Cultured tumor cells show a tendency to convert from round into fusiform shape, increasing considerably in size and assuming a more differentiated aspect (Caspersson's « B » cells). The tendency to cytological differentiation is accompanied with a gradual reduction of the proliferation. 2) Oestrone administration enhances considerably the growth (increase of the migration area to more than the 400 per cent) and the tendency to the cyto-histological differentiation of the tumor. The stimulating effect of oestone is exerted only on epithelial elements. 3) Progesterone administration brings about a lower increase of the growth (augment of the migration area of the 308 per cent at a dilution of gr. 1.100-5/cc. and of the 39 per cent at a dilution of gr. 5.10-5/cc.) and of the tendency to cyto-histological differentiation of the tumour. In contrast with what observed for oestrone, the stimulating effect would be manifest also on the stroma. 4) Testosterone administration inhibits strongly the tumour growth of the 66 per cent at a dilution of gr. 1.10-5/cc and of the 29 per cent at a dilution of gr. 5.10-5/cc.) without influencing its differentiation. The stroma seems to be scarcely influenced by hormonal treatment. The inhibiting action of testosterone is accompanied by regressive phenomena of the tumour elements. Results show that the spontaneous adenocarcinoma of mouse maintains « in vitro » the hormono-dependency properties which are characteristic of the normal mammary cell. </jats:p
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