1,721,013 research outputs found
Investigation of injury mechanisms on pregnant mice in the acute and chronic term after cerebral ischemia
No full textHamilelik ve doğum sonrası dönemde, hormonal değişimleri içeren birçok fizyolojik olayın meydana geldiği bilinmektedir. Meydana gelen hormonal değişimler hamileliğin korunmasına ve plasentanın gelişimine katkı sağlamaktadır. Yapılan literatür çalışmaları ile lohusalık döneminde hemorarjik ve normal iskemi meydana gelme riskinin arttığı görülmektedir. Bunun sebebi olarak hamilelik ve lohusalık döneminde, hormonal değişimlere bağlı olarak beyin dinamiğinde meydana gelen değişimler gösterilmektedir. Ek olarak, hamilelik ve doğum sonrasının, iskeminin patofizyolojik süreçleri üzerinde iyileştirici etkilerinin olduğuna inanılmaktadır. Yapılan çalışmalar ile çiftleşme deneyimi olan farelerin, çiftleşme deneyimi olmayan farelere kıyasla iskemi sonrası beyindeki enfarkt hacimlerinin daha küçük olduğu, astrosit ve mikroglia sayısında azalma meydana geldiği, pro-enflamatuar sitokinlerin sayısının azaldığı, büyüme faktörlerinin ise sayılarının arttığı gösterilmektedir. Aynı zamanda iskemi sonrası, daha önce çiftleşmiş farelerde, çiftleşmemiş farelere kıyasla eksitotoksisitenin daha fazla iyileştirme gösterdiği ve anjiyogenezisin arttığı bilinmektedir. Altta yatan tüm bu mekanizmalar net olarak anlaşılamamış olsa da hamilelik ve doğumun iskemi üzerinde koruyucu etkilerinin olduğu düşünülmektedir. Bu tezde hamileliğin iskemik hasar üzerindeki etkilerinin anlaşılması amacıyla, hamile ve hamile olmayan farelerde orta serebral arter tıkanması metodu kullanılmıştır. Farelerde serebral iskemi sırasında hamilelik, beyin kan akımında ve apoptotik hücre sayısında bir değişim meydana getirmemiştir. Ancak nöronal sağ kalımı, nörogenezi ve aksonal projeksiyonu artırdığı ve gliogenezi, glial yara alanını ve striatumda meydana gelen atrofiyi azalttığı gözlemlenmiştir.It is well-known that many physiological events involving hormonal changes occur during pregnancy and pospartum period. The hormonal changes that take place contribute to the protection of pregnancy and development of the placenta. In the literature it has been reported that the risk of hemorrhagic and ischemic stroke during the period of postpartum increased. This observation has been attributed to the changes in the brain dynamics due to hormonal variations during pregnancy and postpartum period. In addition, pregnancy and postpartum are believed to have healing effects on the pathophysiological processes following ischemia. Studies have shown that ischemic multiparous mice have smaller infarct volumes in the brain after ischemia, decreased number of astrocytes, microglia and amount of pro-inflammatory cytokines, but increased number of growth factors when compared to ischemic virgin mice. It is also known that excitotoxicity is alleviated and angiogenesis is induced after ischemia in multiparous mice when compared with virgin mice. Although all of these underlying mechanisms are not clearly understood, it has been suggested that pregnancy and delivery may have protective effects on ischemia. In this thesis, in order to understand the effects of pregnancy on ischemic damage middle cerebral artery occlusion method has been performed in pregnant and non-pregnant mice. Cerebral blood flow and apoptotic cell counts were not altered in pregnant mice which were exposed to ischemia/reperfusion injury. However, we observed increased neuronal survival, neurogenesis and axonal projection, and reduced atrophy, glial scar area and gliogenesis in the striatum
Investigation of the effect of fetal microchimeric cell following brain injury
No full text[Abstract Not Available]Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TUBITAK
Effects of neurotrophic factors cdnf and manf on brain plasticity and repair after brain ischemia
No full textKüçük protein yapıları ile nörotrofik faktörler, nöronların gelişimi sırasındaki rollerinin yanı sıra beyinde nöronların hayatta kalımı, nörogenez ve sinaptik bağlantıların korunmasında da mutlak rol oynamaktadırlar. Nörotrofik faktörlerin ifadelerindeki azalma veya bu faktörlerin yokluğu birçok nörodejeneratif hastalığın patobiyolojisinde rol oynamaktadırlar. Yapısal olarak birbirlerine benzerlikleri ile bilinen iki nörotrofik faktör olan Serebral Dopamin Nörotrofik Faktör (CDNF) ve Mezensefalik Astrosit-Kökenli Nörotrofik Faktör (MANF) literatürde daha önceden tanımlanmış olan nörotrofik faktörlerden farklı, benzersiz bir protein yapısına sahiptirler. Bu farklılığın, MANF ve CDNF'nin diğer nörotrofik faktörlerden farklı sinyal yolakları kullanmalarına ve bu nedenle daha önceden bilinen nörotrofik faktörlerden farklı etkilere sahip olmalarına yol açabileceği düşünülmektedir. Bu nedenle, yeni mekanizmaların bulunması, başta beyin felci olmak üzere nörodejeneratif hastalıkların tedavisinde yeni yaklaşımlar sunabilecek potansiyele sahiptir. Bu tezde MANF ve CDNF nörotrofik faktörlerinin hasar sonrası in vivo şartlarda nöronal hayatta kalım, aracılık eden sinyal iletim yolakları, doku modellemesi, nörogenez, gliogenez ve piramidal trakt plastisitesi üzerine olan restoratif etkilerinin araştırılması ve aynı zamanda fonksiyonel iyileşme üzerine olan etkileri ile karşılaştırılması amaçlanmıştır. Bu mekanizmaların çalışılması amacıyla, insanlarda inme vakalarının yaklaşık % 80'inden sorumlu olan iskemik beyin felci modeli olarak farede orta serebral arter tıkanması tekniği kullanılmıştır. İskemi sonrası hem CDNF hem de MANF tedavisinin apoptotik hücre sayısını azalttığı, yeni nöron oluşumunu arttırdığı, glial yara alanını düşürdüğü, motor koordinasyon ve el çekme/kavrama gücünü arttırarak fonksiyonel geri kazanımı sağladığı ve özellikle kontralateral striatumda gen ve protein seviyesinde yaptığı değişiklikler sayesinde aksonal uzamayı arttırarak plastisiteyi sağladığı görülmüştür. Elde edilen bulguların beyin felci gibi nörodejeneratif hastalıkların tedavisine yönelik yeni hedef moleküllerin bulunmasına katkı sağlaması beklenmektedir.Neurotrophic factors are small proteins that play essential roles in development of neurons and the maintenance of neuronal synaptic function. Decrease of absence of neurotrophic factor levels play important roles in pathobiology of several neurodegenerative disorder. Recently identified CDNF (Cerebral Dopamine Neurotrophic Factor) and MANF (Mesencephalic Astrocyte-Derived Neurotrophic Factor) have unique protein structures which are different than the other known neurotrophic factor families. This difference is considered to be the reason for MANF and CDNF to use distinct signaling pathways than other neurotrophic factors. To this end, elucidating the new mechanisms has the potential to offer new approaches in the treatment of neurodegenerative disorders including brain ischemia. In this project, restorative effects of MANF and CDNF on in vivo neuronal survival following an insult, mediating signaling pathways, tissue modelling, neurogenesis, gliogenesis and pyramidal tract plasticity were investigated and also compared with their effects on functional recovery. In order to study these mechanisms, Middle Cerebral Artery Occlusion, which is responsible for approximately 80 % of all stroke cases in humans was used. Both CDNF and MANF treatment decreased the number of apoptotic cells and glial scar, increased neurogenesis, motor coordination and grip strength, ameliorates functional recovery and regulates several protein and gen expression in the contralateral hemisphere finally axonal growth and plasticity after cerebral ischemia. With the use of this method and due to its similarity of this method with clinical stroke cases, it is expected this thesis to contribute to the identification of novel target molecules in several neurodegenerative disorders including stroke
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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