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Now showing items 33 - 48 of 138

  • Can Cutting-Needle Biopsy Be an Alternative to Excisional Biopsy in Lymph Node Pathologies?

    Kilicarslan, Aydan   Dogan, Mehmet   Sungu, Nuran   Karakok, Emre   Karabekmez, Leman   Akyol, Mesut   Tatli Dogan, Hayriye  

    Objective: We aimed to compare cutting-needle biopsy (CNB) diagnoses with excisional biopsy diagnoses of enlarging lymph nodes and to determine the diagnostic value of CNB. Material and Method: Out of the 291 cases that underwent CNB from lymph nodes between 2010 and 2016, 60 were included in the study in which pathological lymph nodes were excised after CNB. Demographic information, pathology and imaging reports, the diameters of the lymph nodes and the length of the CNBs of these cases were obtained from the hospital registry system. Diagnoses of the CNBs and excisional biopsies were then compared. Results: According to the excisional biopsy diagnosis, 7 of the 60 cases (11.7%) were benign and 53 of them (88.3%) were malignant. 28 (53%) of the malignant cases were diagnosed as Hodgkin's lymphoma while the others (47%) got a non-Hodgkin's lymphoma diagnosis. In the 8 non-diagnostic CNBs, 3(37%) of them were found to be benign/reactive, while 5 (63%) were diagnosed as malign lymphoma in excisional biopsy. Similarly, 7(64%) of the 11 cases diagnosed as benign/reactive in CNB, were found to be malignant with excisional biopsy. When CNB and excisional biopsy were compared, sensitivity and specificity were 90% and 100%; positive predictive value (PPV) and negative predictive value (NPV) were 100% and 0%, respectively, and the diagnostic accuracy rate (DV) was 86.5%. The mean diameter of the benign lymph nodes was 26.1 mm and the mean diameter of the malignant ones was 35.6 mm. There was no significant difference between malignant and benign lymph node size (p>0.05). There was also no statistically significant difference between CNB length and correct diagnosis (p=3D0.233). Conclusion: CNB is a non-invasive procedure. It is an alternative to excisional biopsy because of its low morbidity and low cost. However, the sensitivity of CNB is lower than its specificity, and we recommend the surgical excision of lymph nodes with a clinically strong neoplasm suspicion because of the presence of false negatives in 7 cases.
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  • Variations of peroxidase activity among Salvia species

    Dogan, Serap   Turan, Pinar   Dogan, Mehmet   Arslan, Oktay   Alkan, Mahir  

    Peroxidase was partially purified from Salvia species such as Salvia tomentosa Miller, Salvia virgata Jacq and Salvia viridis L. using solid (NH4)(2)SO4 precipitation and dialysis methods. We investigated the effect of some kinetic parameters such as buffer concentration, pH, temperature and substrate specificity on peroxidase activity. To clarify the role of peroxidase (POD) in enzymatic browning, oxidation of substrates such as 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS), o-dianisidine, o-phenylenediamine, catechol and guaiacol catalyzed by partially purified peroxidase was followed spectrophotometrically. POD was observed to oxidize some phenolic compounds in the presence of H2O2, leading to enzymatic browning. From the experimental results, we found that (i) POD activities varied with the buffer concentration as depending on the substrate studied, (ii) optimum pH values were 4.5, 2.5, 5.0, 7.0 and 6.0 for S. tomentosa Miller POD; 4.0, 2.5, 6.0, 6.0 and 7.0 for S. virgata Jacq POD; and 3.5, 2.5, 6.0, 7.0 and 7.0 for S. viridis L. POD using ABTS, o-phenylenediamine, o-dianisidine, catechol and guaiacol as substrates, respectively, (iii) optimum temperatures were 40, 30, 50, 50 and 50 degrees C for S. tomentosa Miller; those for S. virgata Jacq 60, 50, 60, 80 and 60 degrees C; and those for S. viridis L. 50, 50, 60, 20 and 50 degrees C using ABTS, o-phenylenediamine, o-dianisidine, catechol and guaiacol as substrates, respectively, and (iv) the substrate specificity of Salvia species was different from specie to specie and the best substrate for Salvia PODs was ABTS. Again, S. tomentosa Miller was the species with the highest POD activity, followed by S. virgata Jacq and S. viridis L. S. tomentosa Miller can be the most suitable Salvia species for dark-tea preparations because of the highest V-max/K-m values. (c) 2006 Elsevier Ltd. All rights reserved.
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  • Adsorption kinetics and thermodynamics of an anionic dye onto sepiolite

    Alkan, Mahir   Demirbas, Ozkan   Dogan, Mehmet  

    The adsorption kinetics of CI reactive blue 221 (RB221), an anionic dye, onto sepiolite was investigated in aqueous solution in a batch system with respect to stirring speed, contact time, initial dye concentration, pH, and temperature. Experimental results have shown that the acidic pH, increasing initial dye concentration and temperature favours the adsorption. Experimental data related to the adsorption of RB221 on sepiolite under different conditions were applied to the pseudo-first-order equation, the pseudo-second-order equation and the intra-particle diffusion equation, and the rate constants of first-order adsorption (k(1)), the rate constants of second-order adsorption (k(2)) and intra-particle diffusion rate constants (k(int),) were calculated, respectively. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intra-particle diffusion model up to 20 min, whereas diffusion is not only the rate controlling step. The activation energy of system (E-a) was calculated as 7.73 kj mol(-1). The thermodynamics parameters of activation such as Gibbs free energy, enthalpy, entropy were also evaluated and found that Delta G(*), Delta H-*, and Delta S-* are 47.9 (49.4,50.0,51.3) kj mol(-1), 5.30 (5.21,5.13,5.05) kj mol(-1), and -145.3 (-148.8,-142.7,-143.1) J K-1 mol(-1) at 20 (30,40,50) degrees C, respectively. The results indicate that sepiolite could be employed as a low-cost material for the removal of textile dyes from effluents. (c) 2006 Elsevier Inc. All rights reserved.
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  • Uptake of trivalent chromium ions from aqueous solutions using kaolinite

    Turan, Pinar   Dogan, Mehmet   Alkan, Mahir  

    The sorption of Cr(III) from aqueous solutions on kaolinite has been studied by a batch technique. We have investigated how solution pH, ionic strength and temperature affect this process. The adsorbed amount of chromium ions on kaolinite has increased with increasing pH and temperature when it has decreased with increasing ionic strength. The sorption of Cr(111) on kaolinite is endothermic process in nature. Sorption data have been interpreted in terms of Freundlich and Langmuir equations. The adsorption isotherm was measured experimentally at different conditions, and the experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir, and the isotherm parameters (q(m) and K) have been calculated as well. The enthalpy change for chromium adsorption has been estimated as 7.0 U mol(-1). The order of enthalpy of adsorption corresponds to a physical reaction. (c) 2007 Elsevier B.V. All rights reserved.
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  • Targeting lysyl oxidase (LOX) overcomes chemotherapy resistance in triple negative breast cancer

    Saatci, Ozge   Kaymak, Aysegul   Raza, Umar   Ersan, Pelin G.   Akbulut, Ozge   Banister, Carolyn E.   Sikirzhytski, Vitali   Tokat, Unal Metin   Aykut, Gamze   Ansari, Suhail A.   Dogan, Hayriye Tatli   Dogan, Mehmet   Jandaghi, Pouria   Isik, Aynur   Gundogdu, Fatma   Kosemehmetoglu, Kemal   Dizdar, Omer   Aksoy, Sercan   Akyol, Aytekin   Uner, Aysegul   Buckhaults, Phillip J.   Riazalhosseini, Yasser   Sahin, Ozgur  

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  • Adsorption kinetics of maxilon yellow 4GL and maxilon red GRL dyes on kaolinite.

    Dogan, Mehmet   Karaoglu, M Hamdi   Alkan, Mahir  

    Kaolinite, a low-costly material, is the most abundant phyllosilicate mineral in highly weathered soils. In this work, the adsorption kinetics of maxilon yellow 4GL (MY 4GL) and maxilon red GRL (MR GRL) dyes on kaolinite from aqueous solutions was investigated using the parameters such as contact time, stirring speed, initial dye concentration, initial pH, ionic strength, acid-activation, calcination and solution temperature. The equilibrium time was 150 min for both dyes. The results showed that alkaline pH was favorable for the adsorption of MY 4GL and MR GRL dyes and physisorption seemed to play a major role in the adsorption process. It was found that the rate of adsorption decreases with increasing temperature and the process is exothermic. The adsorption kinetics followed the pseudo-second-order equation for both dyes investigated in this work with the k(2) values lying in the region of 1.79 x 10(4) to 107.87 x 10(4)g/mol min for MY 4GL and 3.44 x 10(4) to 72.09 x 10(4)g/mol min for MR GRL. The diffusion coefficient values calculated for the dyes were in the range of 3.76 x 10(-9) to 62.50 x 10(-9)cm(2)/s for MY 4GL and 1.98 x 10(-9) to 44.00 x 10(-9)cm(2)/s for MR GRL, and are compatible with other studies reported in the literature. The thermodynamic activation parameters such as the enthalpy, entropy and free energy were determined. The obtained results confirmed the applicability of this clay as an efficient adsorbent for cationic dyes.
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  • 4Pi spectral self-interference microscopy.

    Davis, Brynmor J   Dogan, Mehmet   Goldberg, Bennett B   Karl, William C   Unlu, M Selim   Swan, Anna K  

    Spectral self-interference microscopy (SSM) relies on the balanced collection of light traveling two different paths from the sample to the detector, one direct and the other indirect from a reflecting substrate. The resulting spectral interference effects allow nanometer-scale axial localization of isolated emitters. To produce spectral fringes the difference between the two optical paths must be significant. Consequently, to ensure that both contributions are in focus, a low-numerical-aperture objective lens must be used, giving poor lateral resolution. Here this limitation is overcome using a 4Pi apparatus to produce the requisite two paths to the detector. The resulting instrument generalizes both SSM and 4Pi microscopy and allows a quantification of SSM resolution (rather than localization precision). Specifically, SSM is shown to be subject to the same resolution constraints as 4Pi microscopy.
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  • Caseous calcification of the mitral annulus: a rare variant of mitral annular calcification.

    Dogan, Mehmet   Isilak, Zafer   Atalay, Murat   Uz, Omer  

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  • Characterization of biosorption process of As(III) on green algae Ulothrix cylindricum

    Tuzen, Mustafa   Sari, Ahmet   Mendil, Durali   Uluozlu, Ozgur Dogan   Soylak, Mustafa   Dogan, Mehmet  

    Arsenic (As) is generally found as As(III) and As(V) in environmental samples. Toxicity of As(III) is higher than As(V). This paper presents the characteristics of As(III) biosorption from aqueous solution using the green algae (Ulothrix cylindricum) biomass as a function of pH, biomass dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of As(III) by U. cylindricum biomass. The biosorption capacity of U. cylindricum biomass was found as 67.2 mg/g. The metal ions were desorbed from U. cylindricum using 1 M HCl. The high stability of U. cylindricum permitted 10 times of adsorption-elution process along the studies with a slightly decrease about 16% in recovery of As(III) ions. The mean free energy value evaluated from the D-R model indicated that the biosorption of As(III) onto U. cylindricum biomass was taken place by chemical ion-exchange. The calculated thermodynamic parameters, Delta G degrees, Delta H degrees and Delta S degrees showed that the biosorption of As(III) onto U. cylindricum biomass was feasible, spontaneous and exothermic under examined conditions. Experimental data were also tested in terms of biosorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. The results showed that the biosorption processes of As(III) followed well pseudo-second-order kinetics. (C) 2008 Elsevier B.V. All rights reserved.
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  • The treatment of clopidogrel resistance: Triple antiplatelet therapy and future directions

    Acikel, Sadik   Akdemir, Ramazan   Cagirci, Goksel   Yesilay, Asuman Bicer   Dogan, Mehmet   Kilic, Harun  

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  • Adsorption of cationic dyes from aqueous solutions by sepiolite

    Ozdemir, Yasemin   Dogan, Mehmet   Alkan, Mahir  

    Batch sorption experiments were carried out to remove the cationic dyes, methyl violet (MV) and methylene blue (MB), from its aqueous solutions using sepiolite as an adsorbent. Operating variables studied were pH, ionic strength and temperature. Adsorption process was attained to the equilibrium within 3 h. The adsorbed amount of MV and MB dyes on sepiolite increased with increasing pH, ionic strength and temperature. The experimental data were analysed by Langmuir and Freundlich isotherms, and found that the isotherm data were reasonably well correlated by Langmuir isotherm. Furthermore, for the removal of MV and MB dyes, a batch reactor was designed. Adsorption measurements showed that the process was very fast and physical in nature. (c) 2006 Elsevier Inc. All rights reserved.
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  • Calcified ball- like left ventricular thrombus embolized during echocardiography follow-up

    Dogan, Mehmet   Akdemir, Ramazan   Bicer Yesilay, Asuman   Kilic, Harun   Karakurt, Ozlem   Balci, Mustafa Mucahit   Orcan, Salih  

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  • Possible gender identity disorder in an extremely religious Muslim family.

    Dogan, Sultan   Dogan, Mehmet  

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  • Adsorption kinetics of maxilon blue GRL onto sepiolite from aqueous solutions

    Dogan, Mehmet   Alkan, Mahir   Demirbas, Ozkan   Ozdemir, Yasemin   Ozmetin, Cengiz  

    Adsorption isotherm of maxilon blue GRL on sepiolite was determined and correlated with common isotherm equations such as Langmuir and Freundlich models. It was found that the Langmuir model appears to fit the isotherm data better than the Freundlich model. Furthermore, adsorption kinetics experiments were carried out to remove the maxilon blue GRL from its aqueous solutions using sepiolite as an adsorbent. The remove rate of maxilon blue GRL by sepiolite was studied by varying parameters such as the contact time, stirring speed, initial dye concentration, ionic strength, pH and temperature. The kinetics experiments indicated that initial dye concentration, ionic strength, pH and temperature could affect the adsorption rate of maxilon blue GRL. Sorption data were fitted to pseudo-first-order, the Elvoich equation, pseudo-second-order, mass transfer and intra-particle diffusion models, and found that adsorption kinetics can be described according to the pseudo-second-order model, from which the rate constant and the adsorption capacity were determined. Rate constants under different conditions were also estimated. In addition, we found that the rate-limiting step was intra-particle diffusion. According to the change of intra-particle diffusion parameter, the adsorption processes could be divided into different stages. Thermodynamic activation parameters such as activation energy E-a, enthalpy Delta H*, entropy Delta S* and free energy Delta G* were determined. These parameters indicate that the adsorption has a low potential barrier corresponding to a physisorption; the adsorption reaction is not a spontaneous one; and the adsorption is physical in nature involving weak forces of attraction and is also endothermic. (c) 2006 Elsevier B.V. All rights reserved.
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  • Closed-form representations of field components of fluorescent emitters in layered media

    Dogan, Mehmet   Aksun, M. Irsadi   Swan, Anna K.   Goldberg, Bennett B.   ünlü, M. Selim  

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  • Some kinetic properties of polyphenol oxidase from Thymbra spicata L. var. spicata

    Dogan, Serap   Turan, Pinar   Dogan, Mehmet  

    Polyphenol oxidase (PPO)of Thymbra (Thymbra spicata L. var. spicata) was isolatedby (NH4)(2)SO4 precipitation and dialysis. A diphenolase from Thymbra plant, active against 4-methylcatechol, catechol and pyrogallol was characterized in detail in terms of pH and temperature optima, stability, kinetic parameters and inhibition behaviour towards some general PPO inhibitors. 4-Methylcatechol was the most suitable substrate, due to the lowest K-m and the biggest V-max/K-m values, followed by catechol and pyrogallol. The Thymbra PPO had maximum activity at pH 5.0, 7.0 and 8.0 with 4-methylcatechol, catechol and pyrogallol substrates, respectively. The optimum temperature of activity for Thymbra PPO was 30, 40 and 50 degrees C for 4-methylcatechol, catechol and pyrogallol substrates, respectively. It was found that optimum temperature and pH were substrate-dependent studied. The enzyme activity decreased due to heat denaturation of the enzyme with increasing temperature and inactivation time. Inhibition of Thymbra PPO was investigated with inhibitors such as L-Cysteine and glutathione using 4-methylcatechol, catechol and pyrogallol as substrates. It was found that L-cysteine was a more effective inhibitor than glutathione owing to lower K-i. The type of inhibition depended on the origin of the PPO studied and also on the substrate used. Furthermore, the IC50 values of inhibitors sudied on PPO were determined by means of activity percentage (I) diagrams. (c) 2006 Elsevier Ltd. All rights reserved.
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