1,720,981 research outputs found
Exploring the Influence of Vitamin C Concentrations on the Dynamics of RT-PCR Assay Reactions
No full textSharafi, Parisa/0000-0002-7400-4851The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that caused the COVID-19 pandemic to break out touched off a global health catastrophe characterized by various degrees of disease severity among those who were afflicted. Many strategies, such as vitamin C administration, have been investigated to reduce COVID-19 symptoms. Although the exact processes by which vitamin C affects COVID-19 remain unclear, noticeable changes in PCR test results were noted in our laboratory settings. This study uses PCR analysis to investigate the effects of varying vitamin C dosages and durations on COVID-19 test results. PCR cycle threshold (Ct) values were used to categorize nasopharyngeal tissues from 98 patients (Ct 30, Ct >= 30, negative). Vitamin C was applied at different concentrations (0, 1, 10, 50, and 100 mg/ml), and PCR analyses were carried out at 1, 10, 24, and 48 h marks after the vitamin was applied. Particularly in samples with lower Ct values, the data showed significant changes in the reaction graphs and metrics with increasing vitamin C concentration. Higher concentrations of vitamin C were correlated with diminished metrics, occasionally leading to negative results for samples with Ct >= 30 values. Notably, samples that showed no discernible viral loads had different pictorial representations. These results raise questions regarding the reliability of PCR results in the presence of vitamin C intake and have implications for COVID-19 diagnosis. In light of the current pandemic, more studies are necessary to confirm and expand these findings and provide a critical understanding of clinical procedures and the interpretation of test results.The study was supported financially by TOBB Economy and Technology University Hospital.TOBB Economy and Technology University Hospita
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
Adipojenik farklılaşma üzerine mekanik kuvvetlerin etkisi.
No full textNumerous intra and extra cellular factors take role in differentiation of cell towards a given lineage. These factors have crucial role in cell-cell and cell-environment interactions. In this study, the aim is to investigate the effect of mechanical forces on the adipogenic differentiation of preadipocytes and mesenchymal stem cells in an in vitro model. Human preadipocytes and mesenchymal stem cells were embedded in 2 % agarose discs. According to the stress-relaxation test results it was observed that initial mechanical properties of agarose-mesenchymal stem cell (MSC) discs did not change compared to acellular agarose whereas those of preadipocytes decreased significantly. The discs with cells were exposed to compression under different weights (1.4 ± 0.2 g, 7.5 ± 0.2 g, and 14.6 ± 0.3 g.) continuously in differentiation medium for 21 days. The control discs were treated with differentiation medium without any compressive weight on top of them. After 21 days, total ribonucleic acids (RNA) have been isolated. Adipogenic differentiation was investigated via reverse transcription coupled quantitative polymerase chain reaction (PCR). The expression of peroxisome proliferators-activated receptors (PPAR-gamma), CCAAT-enhancer binding protein (C/EBP-Beta), leptin, adiponectin, adipophilin and human stearoyl-CoA desaturase (hSCD) have been assessed as adipogenic markers. Differentiation to adipocytes has been further investigated by histochemical Sudan IV staining and immunochemistry and compared to control group. Decrease in the expression of adipogenic factors, size and number of lipid droplets were observed for both MSCs and preadipocytes subjected to compression in agarose discs. The decreases were correlated with the level of mechanical stress. The highest depletion of gene expression was observed in leptin and C/EBP. From our results, it was shown for the first time that mechanical stress impaired the adipogenic differentiation of MSCs and preadipocytes in agarose discs. However, the differentiation pathways should be further investigated.M.S. - Master of Scienc
Olgun Yağ Hücrelerinin Rekombinant Protein Ifade Kapasitelerinin İncelenmesi
No full textThis study postulates that the
extracellular transport of the secretory proteins of the adipocytes (adipokines) can be
utilized to achieve recombinant protein expression. Adipokines are exported outside
of the adipocytes by the help of leader sequences which deduce the extracellular
export traffic. It is aimed to achieve the expression of a recombinant protein
extracellularly by using the leader sequences of the 7 selected adipokines. This
approach will aid in production and extracellular secretion of the protein of interest
by mature adipocytes. The efficiency and intracellular- extracellular follow-up of
these export signals will be done by fusing these export signals to N- terminal of
Green Fluorescence Protein (GFP). The S/MAR sequences increase the episomal
persistence of the transgenic vector where it is located to and prolong its expression
in mammalian cells. In this study, it is aimed to use this property of S/MAR
sequences by adding it to the vector construct to increase the episomal expression of
the transgenes in mature adipocytes (non-dividing cells). It is proposed to compare
the efficacy of two different S/MARs in this study, the S/MAR sequences of
Apolipoprotein B (APO-B) and Interferon B (IFN-B) genes. The efficiency of this
designed recombinant gene expression construct will be shown by expressing the
dominant-negative form of myostatin (MSTNdn), as a model of gene of interest, in
adipocytes and observing its effect on myoblast cells. As a result of this study, export
signal of Retinol Binding Protein (RBP4) has been selected as the most efficient
export signal. No differences have been observed between the selected S/MAR
sequences. At the end of this study, the in vitro efficiency of the designed vector
construct containing selected export signal (RBP4), S/MAR sequences, and MSTNdn
was shown by implementing the secretion of this model recombinant protein from
the transfected mature adipocytes.Olgun yağ hücreleri, çok sayıda
adipokin ve sitokin salgılayan, protein yapımı yönünden zengin hücrelerdir. Tez
kapsamında, yağ hücrelerinin protein salgı mekanizmasının rekombinant protein
ifadesi ve salgısı amacıyla kullanım imkanlarının araştırılması amaçlanmıştır. İlk
olarak, yağ hücrelerine özgü hücre içi salgısal proteinlere ait 7 farklı adipokinin
sinyal dizilerinin salgı etkinliği bakımından karşılaştırılması yapılmıştır. Bu
karşılaştırma, yeşil floresan protein (GFP) bildirici geninin bu öncü sinyal dizilerinin
“N” terminaline füzyon ile ekleyip hücre içi ve dışında takibi gerçekleşmiştir.
Farklılaşmış, olgun yağ hücreleri G1 evresinde olup bölünmemektedir. Bu nedenle
aktarılan vektörlerin gen ifade sürecinin bölünen hücrelere göre daha kalıcı olması
beklenmektedir. Ancak, gen ifadesinin koruması ve ifade süresinin daha da
uzatabilmesi amacıyla hazırlanan vektörlere scaffold/matrix bağlanma bölgesi
(S/MAR) dizilerinin eklenmesi hedeflenmiştir. Bu amaçla, İnterferon beta (IFNβ) ve
Apolipoprotein B (APOB) genlerinin S/MAR dizileri, hazırlanan vektöre
yerleştirilerek bildirici gen ifadesi sürecinin takibi yapılmış olunup en uzun süre gen
ifadesi sağlayan S/MAR dizisi karşılaştırmalı olarak ortaya konmuştur. Olgun yağ
hücrelerinde rekombinant gen ekspresyonu ve salgısını sağlayan yaklaşımın
etkinliğinin dominant-negatif etkili miyostatin (MSTNdn) aracılığı ile hücre
kültüründe gösterilmesi amaçlanmıştır. Bu çalışma sonucunda en etkin öncü dizisi
olarak Retinol bağlama proteini (RBP4) genine ait öncü dizisi seçilmiştir. S/MAR
dizileri arasında bir fark görünmemiştir. Çalışmanın son basamağında yukarıda
sıralanan deneysel yaklaşımlarla belirlenen en uygun salgı sinyali (RBP4), S/MAR
dizisi ve MSTNdn içeren vektör omurgasının etkinliğinin gösterilebilmesi amacıyla
olgun yağ hücrelerince salgısı sağlanarak etkinliği in vitro deneylerle gösterilmiştir
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
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