1,720,966 research outputs found
Evaluation of scar penetrating neovascularisation in a rat epigastric flap model
No full textAim: The aim of this study is to investigate neovascularisation patterns in the presence of scar tissue and to compare the venous vs arterial components of the scar penetrating neovascularisation. Methods: Forty male Spraque-Dawley Rats, which were divided into four groups, were used for this study. At the beginning of the study a vertical midline abdominal incision was made to all animals. Six weeks after the incisions were made, epigastric flaps based on inferior epigastric vessels were raised. In the first group both left and right epigastric artery and veins were protected. In the second group only the right epigastric artery and vein was protected. In the third group, besides the right epigastric artery and vein, only the left epigastric artery was kept intact. In the fourth group, besides the right epigastric artery and vein, only the left epigastric vein was kept intact. Results: The percentages of necrotic areas on the flaps were statistically evaluated. The percentages of the necrotic areas on the left side of the flaps were significantly higher in the second group (p = 0.0305). Total flap area necrosis was also significantly higher in the second group (p = 0.026). In each group, vessel formations were identified which were extending through the midline scar tissue in the angiographic evaluations. Conclusions: These results suggest that scar penetrating neovascularisation on an epigastric flap with one sided pedicle, which is supported by a vein or an artery on the contralateral side, can be enough to facilitate the flap circulation
Venous component in scar penetrating neovascularisation
No full textBackground: The impact of old scar tissue on the venous anatomy of a flap's pedicle is an important question in reconstructive surgery. This study tried to investigate the venous component in scar penetrating neovascularisation. Methods: Fifty Sprague-Dawley rats were used in this experimental study. Two experimental groups were designed. In the first group, incisions were performed over the epigastric flap pedicles. In the second group, 1 cm wide segments were excised over the pedicles. Ten weeks after the initial operations, angiographies and histological examinations were performed. A control group was used to demonstrate the normal arterial and venous anatomy of the pedicle. Results: Arterial angiographies revealed that axial pattern arteries were visible in the incision group as opposed to the excision group. Although venous angiographies showed that there were more venous capillary formations in the incision group, none of the experimental groups had regenerated a vein with an axial pattern. Histological examinations revealed that venous vessel formations were significantly less in the distal samples of the experimental groups when compared to the control group (p < 0.05). Conclusions: In this study, it has been observed that arterial pedicles do regenerate over old incision scars as opposed to veins. In the excision scars neither arterial or venous restoration of the axial pedicle was possible. In these cases, only a random type of limited circulation was restored
Sıçan karın flebi modelinde insizyon skarını penetre eden neovaskularizasyonun incelenmesi
No full textunknow
Calculation of contraction patterns in rat skin flap model
No full textIntroduction: In this study rat abdominal skin flaps were observed daily to explain their contraction behavior and a mathematical formula has been developed. Methods: 24 male rats were used for the study. Abdominal skin flaps based on the inferior epigastric neurovascular bundles were raised. In the first group all flaps were sutured to their donor area without any extra physical or chemical interference. In the second groups steroid was applied under the flaps to change the contraction rate. Results: Contraction rate was significantly higher in necrotic tissues in both groups. A formula was used to correct for the contraction. The corrected results for the seventh day necrotic area percentage measurements were significantly higher than actual measurements. (p = 0.0001). Conclusions: By using the mathematical formula developed in this study, pre-contraction value of the experimental skin flaps can be achieved and the results can be interpreted more accurately
Comparison of contraction rates of epigastric and extended dorsal island skin flaps in rats
No full textFlap surgery is a wide field in plastic and reconstructive surgery practice and experimental research is needed to improve surgical success. These research is often performed on rats. Rat is a loose-skinned animal and contraction of skin flaps on rats is an underestimated condition. Besides this variable contraction of survived and necrotic tissues may mislead calculations and results. In this study, contraction patterns of epigastric and dorsal island skin flaps were investigated to identify this phenomenon. Forty-two male Sprague-Dawley rats were divided into four groups. Eleven epigastric flaps with unilateral pedicles, 11 epigastric flaps with bilateral pedicles, 10 extended dorsal island skin flaps with unilateral pedicles, and 10 extended dorsal island skin flaps with bilateral pedicles were prepared. Total, necrotic and viable flap areas were calculated from standardized photographs which were taken daily. The animals were placed on marked papers and image processing software was used the calculate flap areas from the photographs. Respect to these daily flap areas, the contraction rates in epigastric flaps were highly significant. The area loss in necrotic tissues were faster than the viable areas. Compared to the epigastric flaps, the contraction was not significant in extended dorsal island skin flaps flap groups. In conclusion, the rat extended dorsal island skin flap is a more reliable model for experimental flap research, which is resistant to contraction, when compared to the epigastric skin flap model
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
