1,720,963 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Does Apoptosis Regulate the Function of Retinal Photoreceptors?
No full textApoptosis, or programmed cell death, is an integral component of developmental biology, embryology, and anatomy. All eukaryotic cells possess the molecular machinery necessary to execute apoptosis. However, dysregulated apoptosis in the form of too much or too little cell death results in diseases such as Alzheimer’s disease, autoimmune disorders, and cancer. It is postulated that apoptosis of the photoreceptors in the retina plays a vital role in mediating vision, and evidence is presented here to support this hypothesis. However, the precise mechanisms that regulate this cell death in photoreceptors have yet to be fully elucidated
Lysosomal Enzyme-Induced Cell Death in MCF7 and Mammary Gland Cells
No full textBreast cancer is a major health problem, being the second deadliest form of cancer in women, behind lung cancer, and it is the leading overall cause of deaths in women between 40 and 55 years of age. Great strides have been made in the diagnosis, research, and treatment of breast cancer. However, breast cancer cells that are resistant to radiation, anti-hormonal therapy, and chemotherapy are also resistant to apoptosis. Given these facts, it is likely that innovative new strategies will be required to treat breast cancer. Lack of such strategies is a major problem, because, until they become available, it is likely that there will be little, if any reduction in the number of new breast cancer cases. The idea of activating lysosomes as a way of treating breast cancer is novel and potentially important. Lysosomal enzymes, which can degrade all biological macromolecules, induce apoptosis in a variety of model systems and in breast tumors in mammary carcinomas in animal models. In this report, we demonstrate that lysosomal enzymes can trigger apoptosis in human breast carcinoma cells as well as in rat mammary gland cells
Influence of lysosomal sequestration on multidrug resistance in cancer cells
No full textChemotherapy remains a primary treatment modality for various malignancies. However, resistance to chemotherapeutic drugs is a major obstacle to curative cancer therapy. Lysosomes are acidic organelles that participate in cellular digestion. However, there is rising interest in lysosomes because of their involvement with cancer. For example, extracellular secretion of lysosomal enzymes promote tumorigenesis; cytosolic leakage of lysosomal hydrolases promote apoptosis; and weak chemotherapeutic bases diffuse across the lysosomal membrane and become entrapped in lysosomes in their cationic state. Lysosomal drug sequestration lowers the cytotoxic potential of chemotherapeutics, reduces drug availability to sites of action, and contributes to cancer resistance. This review examines various mechanisms of lysosomal drug sequestration and their consequences on cancer multidrug resistance. Strategies for overcoming drug resistance by exploiting lysosomes as subcellular targets to reverse drug sequestration and drug resistance are also discussed
Mammary Gland Cell Death Also Involves Lysosomal Autophagy
No full textThe mammary gland undergoes apoptosis when estrogen ablation occurs, either naturally or enforced. The gland is known to execute the apoptotic process post weaning. Although the involuting mammary gland displays the characteristic biochemical features of apoptosis, including DNA fragmentation, chromatin condensation, and the formation of apoptotic bodies, it also shows evidence of an autophagic death. In this report, apoptosis of the gland was induced by removing the pups from their nursing mothers. In particular, we show that lysosomes increased in size and number, and moved from basal to apical regions in dying rat mammary gland cells. Lysosomal enzyme activities were significantly greater in degenerating mammary gland (day 4 post weaning) epithelial cells when compared with day 0 gland cells. Moreover, these hydrolases were responsible for degrading cytosolic and nuclear components, and thus the whole cell. Taken together, our results demonstrate that the mammary gland dies by lysosomal autophagy in addition to apoptosis during post-lactational involution. Our studies indicate that the lysosomal compartment may serve as an important target organelle for the creation of specific, effective, and novel therapies for breast cancer
Variations on the Author
No full text“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
No full textWe 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
No full textWe 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
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