1,721,142 research outputs found
Floating drug delivery system of itraconazole: Formulation, in vitro and in vivo studies
No full textOzdemir, Ayse Nurten/0000-0003-3228-6579; Vural, Imran/0000-0002-1627-3834A multiple unit oral floating drug delivery system of itraconazole was developed to prolong gastric residence time, target stomach mucosa and increase drug bioavailability. To prepare non-effervescent floating microspheres/beads, ionotropic gelation method was used. Since the solubility of itraconazole is low at pH 1.2, it was attempted to increase the solubility by preparing inclusion complexes using randomly methylated beta-cyclodextrin and with polyvinylpyrrolidone cross linked and starch. in this study, the effects of formulation parameters like, concentration and types of polymer, crosslinking agent and the excipients, the floating ability, surface characteristics and drug release profiles were investigated. Optimum formulation (NG17) was used for Caco-2 cell culture studies. in permeability studies, at pH 5, 6 and 7.4, the formulation NG17 at pH 5, which is the pH of the proximal region of small intestine (absorption window of itraconazole), showed the highest permeability value which is 5.88x10(-6) cm/s. NG17 was also used for in vivo imaging studies. It was conducted in rabbits by using gamma scintigraphy and obtained that NG17 floated for 6.5 h in the stomach. As a result, it was found that, with non-effervescent floating bead formulations, the bioavailability of itraconazole can be improved
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
Hedeflendirilmiş Antikanser İlaç Yüklü Polimerik Nanotaşıyıcıların Formülasyonları ve Karakterizasyonları
No full textThe distribution of the drugs used in cancer chemotherapy without distinction between the diseased area and the healthy area causes damage to healthy tissue. By using targeted drug delivery systems it is intended to selectively accumulate cancer chemotherapy drugs at the diseased site, thus preventing healthy tissue damaging. Doxorubicin is an anticancer drug with serious side effects such as cardiotoxicity. In this study it was aimed to formulate and characterize a passive and active targeted drug delivery system by encapsulating doxorubicin to pH-sensitive polymeric micelles and by conjugating these micelles to peptide-18 which targets breast cancer cells. Due to its “stealth effect” and biocompatibility properties, poly(2-ethyl-2-oxazoline) was used as an alternative to poly(ethylene glycol) in the formulation of polymeric micelles. pH-sensitive poly(2-ethyl-2-oxazoline) and cationic poly(ethylenimine) containing block copolymers poly(2-ethyl-2-oxazoline)–b-poly(ε-caprolactone) and poly(2-ethyl-2-oxazoline)-co-poly(ethyleneimine)-b-poly(ε-caprolactone) were used for the preparation of doxorubicin loaded micelles. In vitro characterization studies such as micelle size, zeta potential, encapsulation efficiency, in vitro pH sensitive release studies and colloidal stability studies were performed for these formulations. Prepared formulations were evaluated in terms of biocompatibility with L929 fibroblast cells in cell culture and evaluated for their anticancer activity with MCF-7 and SKBR-3 breast cancer cells. Polymeric micelles prepared in this study are passive and active targeted formulations. They are able to encapsulate a large amount of doxorubicin, and are stable in neutral conditions (pH 7.4, blood circulation), while providing higher doxorubicin release in acidic conditions (tumor tissue and cells) and their anticancer effect is shown on MCF-7 and SKBR-3 breast cancer cells. The results showed that a new drug delivery system was developed which has the potential to be used for a more effective cancer treatment.Bu çalışma TÜBİTAK 1003 (Proje numarası:213M728) kapsamında desteklenmiştir.Kanser kemoterapisinde kullanılan ilaçların hastalıklı bölge ile sağlıklı bölge arasında bir ayrım gözetmeden dağılımı, sağlıklı dokunun da zarar görmesine neden olmaktadır. Hedeflendirilmiş ilaç taşıyıcı sistemler ile kanser tedavisinde kullanılan ilaçların seçici bir şekilde hastalıklı bölgede biriktirilmesi ve bu şekilde sağlıklı dokuların zarar görmemesi amaçlanmaktadır. Doksorubisin kardiyotoksisite gibi ciddi yan etkileri olan antikanser bir ilaçtır. Bu çalışmada meme kanseri hücrelerini hedefleyen peptit-18 ligandı konjuge edilmiş pH duyarlı polimerik misellere doksorubisinin enkapsüle edilmesi ile pasif ve aktif hedeflendirilmiş yeni bir ilaç taşıyıcı sistemin formülasyonu ve karakterizasyonunun yapılması amaçlanmıştır. “Görünmezlik etkisi” ve biyouyumluluk özellikleri nedeniyle, polimerik misellerin formülasyonunda poli (2-etil-2-oksazolin), poli (etilen glikol) 'e alternatif olarak kullanılmıştır. pH duyarlı gruplar olan poli(2-etil-2-oksazolin) ve katyonik poli(etilenimin) polimerlerini yapısında barındıran poli(2-etil-2-oksazolin)-b-poli(ε-kaprolakton) ile poli(2-etil-2-oksazolin)-ko-poli(etilenimin)-b-poli(ε-kaprolakton) polimerleri kullanılarak hazırlanan doksorubisin enkapsüle edilmiş miseller, kritik misel konsantrasyonu, misel büyüklüğü, zeta potansiyel, enkapsülasyon etkinliği, in vitro salım, kolloidal stabilite çalışmaları ile karakterize edilmişlerdir. Hazırlanan formülasyonlar hücre kültüründe L929 fibroblast hücreleri ile biyouyumluluk açısından değerlendirilmiş, MCF-7 ve SKBR-3 meme kanseri hücreleri ile antikanser etkinlikleri açısından değerlendirilmişlerdir. Bu çalışmada hazırlanan polimerik miseller yüksek miktarda doksorubisini enkapsüle edebilen, nötral koşullarda (pH 7,4, kan dolaşımı) kararlı iken, asidik koşullarda (tümör dokusu ve hücreleri) daha yüksek doksorubisin salımı sağlayan, MCF-7 ve SKBR-3 meme kanseri hücreleri üzerinde antikanser etkisi gösterilmiş, pasif ve aktif hedeflendirilmiş formülasyonlardır. Elde edilen sonuçlar, daha etkin bir kanser tedavisinde kullanılma potansiyeli olan, yeni bir ilaç taşıyıcı sistemin geliştirildiğini ortaya koymuştur
Dry powders for the inhalation of ciprofloxacin or levofloxacin combined with a mucolytic agent for cystic fibrosis patients
No full textObjective: This study aimed to design and characterize an inhalable dry powder of ciprofloxacin or levo- floxacin combined with the mucolytics acetylcysteine and dornase alfa for the management of pulmonary infections in patients with cystic fibrosis.
Methods: Ball milling, homogenization in isopropyl alcohol and spray drying processes were used to pre- pare dry powders for inhalation. Physico-chemical characteristics of the dry powders were assessed via thermogravimetric analysis, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry and scanning electron microscopy. The particle size distribution, dissolution rate and permeability across Calu-3 cell monolayers were analyzed. The aerodynamic parameters of dry powders were determined using the Andersen cascade impactor (ACI).
Results: After the micronization process, the particle sizes of the raw materials significantly decreased. X-ray and DSC results indicated that although ciprofloxacin showed no changes in its crystal structure, the structure of levofloxacin became amorphous after the micronization process. FT-IR spectra exhibited the characteristic peaks for ciprofloxacin and levofloxacin in all formulations. The dissolution rates of micro- homogenized and spray-dried ciprofloxacin were higher than that of untreated ciprofloxacin. ACI results showed that all formulations had a mass median aerodynamic diameter less than 5lm; however, levo- floxacin microparticles showed higher respirability than ciprofloxacin powders did. The permeability of levofloxacin was higher than those of the ciprofloxacin formulations.
Conclusion: Together, our study showed that these methods could suitably characterize antibiotic and mucolytic-containing dry powder inhalers
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
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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