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    Adsorption isotherms, kinetics, thermodynamics and desorption studies for uranium and thorium ions from aqueous solution by novel microporous composite P(HEMA-EP)
    (ELSEVIER SCIENCE BV, 2013) Akkaya, Recep; Akkaya, Birnur
    In this research, a novel composite, poly(2-hydroxyethylmethacrylate-expanded perlite) [P(HEMA-EP)], was synthesized and its adsorptive features were investigated. P(HEMA-EP)'s adsorptive features were evaluated for UO22+ and Th4+ ions in terms of the dependency upon the ion concentration, pH, temperature, and time. P(HEMA-EP) was able to bind UO22+ and Th4+ ions with strong chemical affinity. The adsorption results were fitted to the classical Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) sorption models. P(HEMA-EP) was also used to study the removal of UO22+ and Th4+ ions from aqueous solutions in a batch system. The adsorption capacity (X-L) of UO22+ and Th4+ ions was found to be 0.29 and 0.44 mol kg(-1), respectively. The kinetic data corresponds well to the pseudo-second-order equation. Changes in the enthalpy and entropy values demonstrated that the overall adsorption process was spontaneous (Delta G < 0), endothermic (Delta H > 0), and had increased entropy (Delta S > 0), as expected. The reusability of the composites was confirmed for five sequential reuses. (C) 2012 Elsevier B.V. All rights reserved.
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    Adsorptive features of chitosan entrapped in polyacrylamide hydrogel for Pb2+, UO22+, and Th4+
    (ELSEVIER SCIENCE BV, 2008) Akkaya, Recep; Ulusoy, Ulvi
    Chitosan (Ch) was entrapped in polyacrylamide (PAA) by direct polymerization of acrylamide in a suspension of Ch. The adsorptive features of PAA-Ch and Ch were then investigated for pb(2+), UO22+, and Th4+ in view of dependency on ion concentration, temperature, and kinetics. Additional considerations were also given to their ion selectivity and reusability. Isotherms were L and H type of Giles classification and evaluated with reference to Langmuir, Freundlich, and Dubinin-Radushkevich (DR) models. PAA-Ch had higher adsorption capacity than Ch for all studied ions so that the sequences were Th4+ > Pb2+ > UO22+ concordantly with their affective ionic charges. The affinity of Ch in PAA increased for Pb2+ and UO22+ but did not change for Th4+. The values of enthalpy and entropy changed were positive for all studied ions for both Ch and PAA-Ch. The negative free enthalpy change value indicated that the adsorption process is spontaneous in the sequence of Th4+ >= Pb2+ > UO22+. Free energy values derived from DR model implied that the sorption process is the ion exchange. Well compatibility of adsorption kinetics to the pseudosecond-order model predicate that the rate-controlling step is a chemical sorption. The study for ion selectivity showed that both Ch and PAA-Ch had the highest affinity to Pb2+. The reusability tests for Ch and PAA-Ch for Pb2+ for five uses showed that complete recovery of the ion was possible. The studied features of PAA-Ch suggest that the material should be considered as a new adsorbent. It is envisaged that the use of Ch in PAA will enhance practicality and effectiveness of Ch in separation and removal procedures. (C) 2007 Elsevier B.V. All rights reserved.
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    Adsorptive features of polyacrylamide-apatite composite for Pb2+, UO22+ and Th4+
    (ELSEVIER SCIENCE BV, 2009) Ulusoy, Ulvi; Akkaya, Recep
    Micro-composite of polyacrylamide (PAA) and apatite (Apt) was prepared by direct polymerization of acrylamide in a suspension of Apt and characterized by means of FT-IR, XRD, SEM and BET analysis. The adsorptive features of PAA-Apt and Apt were then investigated for Pb2+, UO22+ and Th4+ in view of dependency on ion concentration, temperature, kinetics, ion selectivity and reusability. Experimentally obtained isotherms were evaluated with reference to Langmuir, Freundlich and Dubinin-Radushkevich (DR) models. Apt in PAA-Apt had higher adsorption capacity (0.81,1.27 and 0.69 mol kg(-1)) than bare Apt (0.28.0.41 and 1.33 mol kg(-1)) for Pb2+ and Th4+, but not for UO22+. The affinity to PAA-Apt increased for Pb2+ and UO22+ but not changed for Th4+. The values of enthalpy and entropy changed were positive for all ions for both Apt and PAA-Apt. Free enthalpy change was Delta G<0. Well compatibility of adsorption kinetics to the pseudo-second-order model predicated that the rate-controlling step was a chemical sorption. This was consistent with the free energy values derived from DR model. The reusability tests for Pb2+ for five uses proved that the composite was reusable to provide a mean adsorption of 53.2 +/- 0.7% from 4 x 10(-3) M Pb2+ solution and complete recovery of the adsorbed ion was possible (98 +/- 1%). The results of this investigation suggested that the use of Apt in the micro-composite form with PAA significantly enhanced the adsorptive features of Apt. (C) 2008 Elsevier B.V. All rights reserved.
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    Bentonit/zeolit-polihidroksietil metakrilat ve poliakrilamit-ko-maleik asit kompozitlerinin hazırlanması ve metal adsorpsiyon özelliklerinin araştırılması
    (Cumhuriyet Üniversitesi, 2009) Akkaya, Recep; Ulusoy, Ulvi
    Bu araştırmanın temel amacı Bentonit (B) ve Zeolit (Z) minerallerinin hidrojel polimerlerden Polihidroksietil metakrilat (PHEMA) ve Poliakrilamid-ko-maleik asit (PAA-MA) ile oluşturdukları kompozitlerini hazırlamak, karakterize etmek ve bu yapıların adsorban özelliklerini UO2+(Uranil), Tb3+ (Terbiyum) ve Th4+ (Toryum) için araştırmaktır. PHEMA-Z ile ilgili ön çalışmalar, bu yapının adsorban özelliğnin olmadığını gösterdiğinden, PHEMA-Z ilgi dışı bırakılmıştır. PHEMA-B kompozitinde inert bir hidrojel olan PHEMA adsorban özellikteki B için konukçu (host) konumunda iken, PAA-MA-B/Z kompozitlerinde adsorban niteliğe de sahip olan PAA-MA hidrojeli B ve Z'nin konuğu (guest) ilişkisindedir.Polimerlerin hazırlanmasındaki işlemler kullanılan prosedür, kompozitlerin hazırlanmasında da kullanılmış ve kompozitler, B veya Z içeren süspansiyon ortamında çözünmüş halde bulunan ilgili monomerlerin polimerleştirilmesiyle elde edilmiştir. Hazırlanan PHEMA, PAA-MA ve kompozitlerin yapısal karakterizasyonunda FT-IR, TGA, SEM, BET-Porozite ve sıfır yüzey yük noktası (SYN) ile ilgili veri ve analiz sonuçları kullanılmıştır.PAA-MA ve kompozitlerin UO2+, Tb3+ ve Th4+ için adsorban özellikleri; adsorpsiyonun pH, derişim, zaman (kinetik), sıcaklık (termodinamik), iyonik şiddet, seçiciliğe bağlılık açısından incelenmiş ve alınan sonuçlardan yararlanarak ilgili karakteristik parametreler türetilmiştir. İlgilenilen iyonlar için tekrar kullanılabilirlik ve deniz suyundan adsorpsiyon özellikleri araştırılmıştır. UO22+ ve Th4+ ölçümlerinde UV-VIS Spektrofotometrik, Tb3+ ölçülmesinde ise Gama-spektrometrik yöntemler kullanılmıştır. Tb3+ ölçümlerinde TAEK'e bağlı Çekmece Nükleer Araştırma Merkezi'nde nötron aktivasyonu ile elde edilen radyoaktif 160Tb izotopu izleyici olarak kullanılmıştır.FT-IR, XRD, TGA, SEM, BET-porozite ve SYN analiz sonuçları kompozit oluşumu ile ilgili kesin kanıtlar sunmuş, yapıların polimer/mineral hibrit oluşumundan çok biri organik (PHEMA veya PAA-MA) diğeri inorganik özellikteki (B veya Z) iki faz içeren bir karışım olduğu kanısına varılmıştır.Adsorpsiyonun pH ile değişimi araştırması, tüm adsorbanlar için adsorplanan miktarın artan pH ile arttığını göstermiş, bulunan adsorpsiyon miktarları ilgilenilen minerallerin PHEMA ve PAA-MA ile kompozit olarak kullanımının adsorpsiyon kapasitelerini anlamlı bir şekilde artırdığını kanıtlamıştır.Adsorpsiyonun derişimle değişiminin incelenmesi sonucu elde edilen izotermlerin tümünün Giles sınıflandırmasındaki L veya H tipte olduğu görülmüştür. Bu sonuçlar, kullanılan kompozitlerin tüm iyonlara olan yüksek adsorpsiyon ilgisi olarak nitelendirilmiştir. Deneysel izotermlerin Langmuir, Freundlich ve Dubinin-Radushkevich modellerine uyumundan türetilen parametreler bu ilgiyi kanıtlamıştır.Adsorpsiyon kinetiği ile ilgili araştırma sonuçları adsorpsiyonun yalancı ikinci derece modelle açıklanabileceğini göstermiştir. İkinci derece hız denklemine uyum ve Weber-Morris modelinden iki doğrusal bileşen elde edilmesi; adsorpsiyonun derişime bağlı, kimyasal olduğunu ve hız belirleyen basamağın iyon değişimi/kompleks oluşumu olduğunu kanıtlamıştır. İlgilenilen iyonlar için Boyd denkliği ile hesaplanan difüzyon katsayılarının oldukça küçük değerlerde olması ise bunun kanıtı olarak değerlendirilmiştir.Adsorpsiyon entalpi ve entropi değişim değerleri, adsorpsiyonun, araştırması yapılan tüm adsorbanlar ve tüm iyonlar için ısı alan (?H>0, endotermik), entropi artışlı (?S>0) olduğunu, serbest entalpi (?G) değerleri ise adsorpsiyon sürecinin beklenildiği gibi kendiliğinden yürüdüğünü göstermiştir. DR modelinden türetilen serbest enerji (EDR) değerlerinin 8 kJ mol-1 değerinden büyük bulunması adsorpsiyonunun serbest enerji açısından da tüm adsorbanlar için kimyasal olduğunu kanıtlamıştır.Kompozitlerin yeniden kullanılabilirlikleri ile ilgili sonuçlar; PHEMA-B, PAA-MA-B ve PAA-MA-Z'nin tekrar kullanılabilir olduğunu, PAA-MA kopolimerinin ise kimyasal kararsızlık nedenli olarak etkin kullanılamayacağını göstermiştir.Adsorbanlara UO2+, Tb3+ ve Th4+ adsorpsiyonunun CaCl2 derişimine bağlı iyonik şiddetle değişimi incelemesi, ortam iyon şiddetinin PHEMA-B'ye UO22+ ve Tb3+ adsorpsiyonunun anlamlı bir şekilde azalttığını, ancak Th4+ adsorpsiyonunu etkilemediğini göstermiştir. İyonların PAA-MA, PAA-MA-B ve PAA-MA-Z'ye olan ilgisi iyonik şiddet artışından etkilenmemiştir.Adsorbanların ilgili iyonlar için seçicilik araştırması; tüm adsorbanlar için iyon seçiciliğin, artan iyon yükü ile azalan bir şekilde UO22+>Tb3+>Th4+ sıralamasında olduğunu göstermiştir.Kompozitlerin, ilgilenilen iyonları içeren deniz suyu ve saf sudan adsorpladıkları miktarlarının kıyaslanması sonucunda, tüm kompozitlerin adsorpsiyon etkinliğinin Tb3+ ve Th4+ için değişmediği, ancak deniz suyundan gerçekleşen adsorpsiyonun UO22+ için azaldığı görülmüştür.
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    Bentonite-acrylamide-histidine-Cu(II) Microcomposite for Cytochrome c Adsorption
    (ISMITHERS, 2012) Akkaya, Birnur; Akkaya, Recep
    Bentonite-acrylamide-histidine with an average particle diameter of 200-1000 mu m was produced by bulk polymerization of bentonite, acrylamide, bisacrylamide, AIBN and histidine. Bentonite-acrylamide-histidine-Cu(II) microcomposite was prepared by loading copper ions. The microcomposite was characterized by scanning electron microscopy (SEM), specific surface area and elemental analysis. Cytochrome c adsorption studies were performed, for the first time, by using the new metal chelated affinity support (bentonite-acrylamide-histidine-Cu(II)) microcomposite in batchwise experiments.
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    Cross-Linked Bentonite-Acrylamide-histidine-Based Metal-Chelate Affinity Microcomposites for Lysozyme Separation From Egg White
    (TAYLOR & FRANCIS INC, 2012) Akkaya, Birnur; Akkaya, Recep
    Among different adsorbents, a new support for immobilized metal affinity chromatography was used for lysozyme separation from egg white. For this purpose, acrylamide, bisacrylamide, bentonite, and L-histidine in the presence of an initiator (azobisisobutyronitrile, AIBN) were mixed and bentonite-acrylamide-histidine microcomposites were prepared by bulk polymerization. Characterization studies were performed by SEM, FT-IR, XRD, and BET. Specific surface area of the bentonite and BABH microcomposite was found to be 33.4 and 1.42 m2/g, respectively. Cu2+ ions (20 mu mol/g) were chelated on these bentonite-acrylamide-histidine (50 mu mol/g L-histidine incorporation) microcomposites. The lysozyme adsorption capacity of the Cu2+ ions chelated microcomposites increased the lysozyme adsorption up to 100 mg/g while the lysozyme adsorption capacity of the bentonite-acrylamide-histidine was 24 mg/g. More than 89% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl. Bentonite-acrylamide-histidine-Cu(II) was used for the purification of lysozyme from chicken egg white. The purity of lysozyme was estimated by SDS-PAGE. Specific activity of the purified lysozyme was found as 50,000 U/mg using Micrococcus lysodeikticus as substrate. The new metal-chelate affinity microcomposites were suitable for repeated use for five cycles without a noticeable loss of capacity.
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    A Crosslinked Carboxylic Acid Containing Cation Exchange Monolithic Cryogel for Human Serum Albumin Separation
    (TAYLOR & FRANCIS INC, 2012) Akkaya, Birnur; Akkaya, Recep
    For this work, we synthesized poly(N-isopropylacrylamide-acrylamide)-acrylic acid (poly(NIPAM-Am)-AAc) monolithic cryogel for a human serum albumin separation (HSA) from a protein mixture (human serum immunoglobulin, human serum albumin and lysozyme) and performed HSA adsorption studies using the cryogel to do continuous system experiments in a syringe column connected by a peristaltic pump. Poly(NIPAM-Am)-AAc with a pore size of 10-100 mu m was produced by free radical polymerization that proceeded in an aqueous solution of monomers frozen inside a syringe column. The monolithic poly(NIPAM-Am)-AAc cryogel was characterized by performing swelling studies, FTIR and SEM that showed a swelling ratio of 6.2 g H2O/g dry cryogel. The maximum HSA adsorption by the cryogel was 42.5 mg/g polymer at pH 4.0 in a 50 mM acetate buffer. We also studied the effect of two different temperatures (25 and 40 degrees C). The higher temperature increased the adsorption capacity of the cryogel. HSA molecules could be reversibly adsorbed and desorbed five times with the same poly(NIPAM-Am)-AAc cryogel without a noticeable loss of their HSA adsorption capacity. The synthesized cryogel was used to separate albumin from the protein mixture. Adsorbed albumin was eluted by changing the pH of the buffer (pH 7.0 and 25 degrees C). Poly(NIPAM-Am)-AAc monolithic cryogel behaved as a cation exchange column because of its functional carboxylic group.
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    Dizi ve Filmlerde Hemşire İmajının Kültür Endüstrisi ve Popüler Kültür Bağlamında İncelenmesi: Türkiye'den İki Vakanın Analizi
    (SET Teknoloji, 2019) Akkaya, Recep; Darıcı, Sefer
    Film, dizi ve medya içeriklerinin insanların bilişsel olarak algılamalarını etkilediği ve davranışlarına yön verdiği bilinen bir gerçektir. Medya aynı zamanda popüler kültürün yaygınlaşmasında ve yaratılan imajların sunulmasında en etkili araçlardan biridir. Bireysel ve toplumsal algıyı şekillendiren bazı medya içerikleri bir yandan cinsel obje olarak hemşire imajını şekillendirmeye çalışmakta bir yandan da farklı mecralarda bunu tekrar ederek zihinlere kazımaktadır. Türkiye’de sağlık çalışanları tarafından tepkiyle karşılanan iki vakanın analizinin yapıldığı bu çalışma eleştirel bir bakış açısıyla soruna yaklaşmakta ve etik öneriler sunmaktadır.
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    Effects of pH, concentration and temperature on radionuclides sorption onto polyhydroxyethyl methacrylate-expanded perlite composite
    (SPRINGER, 2013) Akkaya, Recep
    Poly (hydroxyethylmethacrylate-expanded perlite) [P(HEMA-EP)], was synthesized and its adsorptive features were investigated for natural radionuclides (TI+, Ra2+, Bi3+, Ac3+ and Pb2+) in aqueous media at differing initial pH, initial radionuclides concentration and adsorption thermodynamics. The amounts of natural radionuclides at equilibrium were determined by gamma spectrometry. The Langmuir adsorption capacities (X-L) were found to be in the order of Pb-212 (0.4 MBq kg(-1)) > Ac-228 and Tl-208 (0.3 MBq kg(-1)) > Ra-226 and Bi-212 (0.2 MBq kg(-1)). These findings indicated that P(HEMA-EP) adsorbed natural radionuclides with high affinity. It was also demonstrated that the adsorption mechanism was spontaneous (Delta G < 0), the process was exothermic (Delta H < 0) thus increasing entropy (Delta S > 0). The composite was reused for four more times after regeneration without any detectable changes either in its structure or adsorptive capability.
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    Investigation of the effect of REM sleep deprivation on epileptic seizures caused by pentylenetetrazole in mice
    (2020) Akkaya, Recep; Karabulut, Sebahattin; Taşkıran, Ahmet Şevki
    Aim: To investigate whether different periods of rapid eye movement sleep deprivation (REM SD)contribute to seizure susceptibility, hippocampal oxidative status and balance of inhibition-excitationin the acute epilepsy model.Methods: REM SD was performed using the modified multiple platforms method on adult maleBALB/c mice. Pentylentetrazol (PTZ) was injected to induce seizures and hippocampal totalantioxidant status (TAS), total oxidant status (TOS), gamma aminobutyric acid (GABA), andglutamate levels were measured using the ELISA method.Results: PTZ-induced seizures following 8 h and 72 h REM SD significantly reduced thehippocampal TAS levels, but did not affect the TOS levels. In REM SD groups, especially after 8hours of REM sleep loss, there was a significant increase in glutamate in PTZ induction. Thehippocampal GABA levels were increased by PTZ-induced seizures after 72 h REM SD. PTZinduction after 8 hours of RAM SD leads to a significant increase in the seizure duration.Conclusion: It can be speculated that the REM SD can contribute to seizure susceptibility bychanging the oxidant-antioxidant balance and excitatory and inhibitory tone in the hippocampus.
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    Kitosan ve poliakrilamit-kitosan kompozitine U, Th, PB, Tl, Ra, Bi ve Ac adsorpsiyonunun incelenmesi
    (Cumhuriyet Üniversitesi, 2005) Akkaya, Recep; Ulusoy, Ulvi
    ÖZET YÜKSEK LİSANS TEZİ KİTOSAN VE POLİAIOÛLAMİT-KİTOSAN KOMPOZİTİNE U, Th, Pb, Tl, Ra, Bi ve Ac ADSORPSİYONUNTJN İNCELENMESİ Recep AKKAYA Cumhuriyet Üniversitesi Fen Bilimleri Enstitüsü Kimya Anabilim Dalı Danışman: Yrd. Doç. Dr. Ulvi ULUSOY Bu incelemenin temel amacı, bu çalışmada adsorban olarak kullanılan ve bir bidrojel olan polyakrilamit (PAA) ile kitosandan (Ch) oluşan kompozitin (PAA-Ch) hazırlanması ve bu yapının adsorban özelliklerinin araştırılmasıdır. PAA yüksek su tutma özellikleri ve metal adsorpsiyonuna asal (inert) davranışı nedeniyle kompozitin polimer bileşeni olarak kuUanılmıştır. Kompozitin diğer bileşeni olan kitosan selülozdan sonra doğada en yaygın bulunan bir biyopolimer olan kitinden elde edilen bir aminopolisakkarittir. Ch ve PAA-Ch'nin yapısal karekterizasyonu FT-IR spektrumları alınarak yapılmıştır. Bunların adsorplama özellikleri ise Pb2+, Th4+, UC«22+ ve toryum içerikli florit mineralinden özütlenen bir çözeltiden doğal radyoaktif metal iyonlarının adsorpsiyon çalışmaları ile karşılaştırılarak araştırılmıştır. Adsorpsiyon incelemerinde; Pb2+, Th4+ ve UC<22+ spektrofotometrik (UV-VIS), florit özüt çözeltisinden doğal radyoaktif element iyonları (Tf, Pb2+, Ra2+, Bi3+ ve Ac3+) ise gama spektrometrik [NaI(Tl) dedektör ile kombine çok kanallı analizör ıuve ilgili bilgisayar programı içeren sayım sistemi kullanılarak] yöntemle saptanmıştır. Adsorpsiyon parametreleri deneysel olarak bulunan adsorpsiyon izotenrderinin Langmuir ve Freundlich denkliklerine uyumundan türetilmiş ve adsorpsiyon kinetiği araştırılmıştır. Ch ve PAA-Ch'nin İR spektrumlarının karşılaştırılmasından PAA-Ch'nin PAA ve Ch arasında bir kimyasal bağlanma olmadığını ve yapının iki polimerik yapının kompoziti (karışım) olduğu bulunmuştur. Hem Ch hem de PAA-Ch için bulunan Pb2+, Th4+, UC22+ adsorpsiyon izotermlerinin Langmuir ve Freundlich modellerine uyduğu ve izotermlerin Giles sınıflandırmasında L ve H-tip izotermlere uyduğu saptanmıştır. Bu sonuç Ch ve PAA-Ch'nin Pb2+, Th4+ ve UÜ22+ iyonlarına yüksek ilgisinin olduğunu göstermiştir. Tl4", Pb2+, Ra2+, Bi3+ ve Ac3+ iyonlarına ait izotermlerin ise her iki yapı için C-tip olduğu görülmüştür. Adsorpsiyon istemliliğinin bir ölçüsü olan Langmuir denge sabiti (Kl; L ve H- tipler için) ve dağılım katsayısı (K<ı; C-tip için) değerlerinin PAA'nın yapıya girmesi ile anlamlı bir şekilde arttığı bulunmuştur. Yine aynı iyonlarla ilgili yapılan kinetik inceleme sonucun da genel olarak beklenildiği gibi adsorpsiyonların I. derece tepkime kinetiğine uydığu görülmüştür. PAA-Ch, Ch'nin bir polimer ile kompoziti olarak ilk kez bu incelemede kullanılmıştır. Adsorpsiyon sonuçları Ch ve PAA-Ch'nin adsorpsiyon kapasiteleri temelinde kıyaslandığında Ch'nin kompozit yapısında daha işlevsel bir adsorban olduğu görülmektedir. Saf olarak Pb2+, Th4+, UO22"1" ve özüt çözeltiden bazı iyonlar için yapılan bu incelemenin sonuçlan bu kompozitin diğer metal iyonları içinde kullanılabileceğini göstermektedir. PAA-Ch'nin çevre kirliliğine neden olan boya ve pestisit gibi organik kökenli diğer atıklar için de etkin bir adsorban olabileceği öngörülmektedir. Anahtar sözcükler: Adsorpsiyon, kompozit, kitosan, uranyum, toryum, kurşun, radyoaktif metaller, kinetik iv
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    Meloxicam, a selective COX-2 inhibitor, displays anticonvulsive effects in pentylenetetrazoleinducedacute seizures in mice through GABA and glutamate mediated mechanism
    (2022) Sahın, Bilal; Akkaya, Recep; Karabulut, Sebahattin
    Aim: To investigate the possible anticonvulsive effect of the selective COX-2 inhibitor meloxicam in\rpentylenetetrazole (PTZ)-induced epileptic seizures in mice and to examine its possible role on inhibition and\rexcitation balance in the brain.\rMethod: 30 BALB-c albino mice (16-18 weeks old) weighing 30-33 gr were used. Animals were randomly\rdivided into five groups (n = 6 for each group). Group 1: control, group 2: received saline (10 ml/kg, i.p.) 30\rminutes before PTZ (60 mg/kg i.p.) administration, group 3: received saline (10 ml/kg, i.p.) 30 minutes after\rPTZ (60 mg/kg i.p.) injection, group 4: received 60 mg/kg meloxicam i.p., 30 minutes before PTZ (60 mg/kg\ri.p.) administration. Group 5: received meloxicam (60 mg/kg i.p.) 30 minutes after PTZ injection (60 mg/kg,\ri.p.). The animals were observed for 30 minutes and the seizure stages and first myoclonic jerk times (FMJ)\rwere recorded. After 24 hours, brain tissues were removed and the cortex and hippocampus were separated for\rbiochemical assessments. ELISA method was used to measure GABA and glutamate levels.\rResults: Administration of meloxicam before PTZ induced seizure, reduced seizure stages and prolonged FMJ\rduration (p<0.05). Pre-treatment with meloxicam increased GABA levels in the cortex and decreased\rglutamate levels in the hippocampus (p<0.05). Post-treatment of meloxicam after PTZ-induced seizure\rincreased GABA levels in the hippocampus (p<0.05).\rConclusion: The results of our experimental study suggest that meloxicam has anti-convulsive effects and\rthese effects may be mediated by GABA and glutamate, which are the main indicators of inhibition and\rexcitation balance in the brain.
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    Metforminin Tek Başına veya Valproik asit ile Beraber Farelerde Pentilentetrazol ile İndüklenen Nöbetler Üzerine Koruyucu Etkisi
    (Kahramanmaraş Sütçü İmam Üniversitesi, 2022) Gümüş, Erkan; Ergül, Mustafa; Gülmez, Kader; Ulu, Mustafa; Akkaya, Recep; Özdemir, Ercan; Taşkıran, Ahmet Şevki
    Özet Amaç: Bu çalışmanın amacı, metforminin pentilentetrazol (PTZ) ile indüklenen nöbet davranışı üzerindeki etkilerini ve nöronal hasar üzerindeki nöroprotektif etkisini araştırmaktır. Gereç ve Yöntemler: 35-38 gram ağırlığındaki otuz beş (35) erkek BALB-c Albino fare rastgele beş gruba ayrıldı: Kontrol grubu (1), Salin+PTZ grubu (2), Valproik Asit (VPA 200 mg/kg i.p.)+PTZ grubu (3), Metformin (200 mg/kg i.p.)+PTZ grubu (4) ve VPA+Metformin+PTZ grubu (5). PTZ (60 mg/kg, intraperitoneal- i.p.), nöbetleri indüklemek için ilaç enjeksiyonundan 30 dakika sonra enjekte edildi ve nöbet aşamaları ve davranışsal skorlama değerlendirildi. İşlem tamamlandıktan sonra beyin dokuları çıkarıldı ve biyokimyasal ve histopatolojik prosedürlerle analiz edildi. Hipokampal Cornu Ammonis (CA)1, CA2, CA3 ve DG (dentat girus) bölgeleri histopatolojik olarak değerlendirildi ve oksidatif stres belirteçleri (toplam antioksidan durum (TAS), toplam oksidan durum (TOS)) ölçüldü. Bulgular: Salin+PTZ grubuyla karşılaştırıldığında, Metformin tek başına ilk miyoklonik jerk (FMJ) başlangıç süresini etkilemedi, ancak VPA ve metformin kombinasyonun FMJ başlangıç süresini anlamlı derecede artırdığı izlendi (p<0.05). Ek olarak, VPA ile beraber ve/veya VPA olmadan metformin tedavisi beyin oksidatif stresini önemli ölçüde azalttı (p<0.05). Ayrıca, histopatolojik değerlendirme ile metformin uygulamasının ve VPA+metformin kombinasyonunun hipokampal CA1, CA2, CA3 ve DG alanlarındaki dark nöron oluşumunu azalttığı saptandı (p<0.05). Sonuç: Metforminin, epileptik nöbetleri ve beyin oksidatif stresini azalttığı ve PTZ ile indüklenen nöbet sonrası nöral hasarı önlediği tespit edilmiştir.
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    Modification by natural sources to reduce immuno-reactivity of milk proteins
    (2020) Akkaya, Recep; Akkaya, Birnur; Çetinkaya, Serap
    The main aim of the current study was to reduce the IgE-binding capacity of cow’s milkthrough its chemical modification by natural source treatment. The presence of childrenallergic responses to cow's milk has become a growing concern in the world. A possibleapproach to reduce protein allergen is to block IgE-binding epitopes of protein allergen byvarious methods. One of them is protein glycation. We wanted to examine effect of someadditives especially lemon juices on milk protein modification by using electrophoresis and2D gel electrophoresis. As a result of this study lemon juice (ascorbic acid) enhanced glycationof milk proteins.
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    Neuroprotective effect of astaxanthin (ATX) against cognitive impairment on PTZ-induced epileptic seizures in rats and against PTZ-induced neurotoxicity in SH-SY5Y human neuroblastoma cell culture
    (Sivas Cumhuriyet University, 2019) Karademir, Mustafa; Gümüş, Erkan; Taştemur, Yaşar; Ergül, Merve; Ergül, Mustafa; Karabulut, Sebahattin; Akkaya, Recep
    Objective: Epilepsy is a common brain disorder that seizures could cause neuronal loss in the hippocampus. Oxidative stress has an important role in the pathology of this way. The aim of this study was to investigate the neuroprotective effect of astaxanthin (ATX), on pentylenetetrazole (PTZ) induced epileptic seizures in rats and in SH-SY5Y human neuroblastoma cell culture.Method: In our study, we used 42 male 230-250 g Wistar Albino rats. Animals were divided into seven groups as control, saline (PTZ; 1 ml/kg serum physiologic), positive control (2,5 mg/kg diazepam), 10 mg/kg, 20 mg/kg, 40 mg/kg and 80 mg/kg ATX for seven days. Thirty min after the administration of the last drug at the indicated doses, PTZ was administered 45 mg/kg to induce an epileptic seizure. The animals were observed for 30 min. Seizure stages according to the Racine Scale (RC) and first myoclonic jerk times (FMJ). Twenty four hours after PTZ injection, passive avoidance test was performed, and then brain tissues were removed for biochemical and histopathological evaluation. The hippocampal Cornu Ammonis 1 (CA1), CA3 and dentate gyrus (DG) regions were evaluated histopathologically regarding neuronal damage. Besides, oxidative stress markers total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI)) were measured in brain tissues. Furthermore, ATX was performed in vitro SH-SY5Y human neuroblastoma cell culture to evaluate PTZ-induced neurotoxicity.Results: When epileptic behaviors were evaluated, ATX did not affect RC and FMJ (p>0, 05). However, ATX reduced both cognitive impairment in passive avoidance test and neuronal damage in the hippocampus (p<0, 05). Moreover, ATX reduced both TOS levels and OSI in the brain (p<0, 05). Besides of these in vitro studies, ATX increased neuronal viability in vitro. Conclusions: Although ATX does not have antiepileptic properties directly, it has a protective effect on not only in vivo but also in vitro. These effects may occur by possible oxidative pathways.
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    New Composite, Poly(Hydroxyethylmethacrylate-Expanded Perlite), for Single step Separation of Egg White Lysozyme
    (2018) Akkaya, Birnur; Akkaya, Recep
    In this study, we investigated adsorption behaviour of lysozyme on poly(hydroxyethylmethacrylateexpanded perlite) [P(Hema-Ep)]. For this purpose, we synthesized P(Hema-Ep) composite by bulk polymerization and it was characterized by SEM, FTIR and swelling ratio. The fresh chicken egg white lysozyme was used as a model protein, had an isoelectric point (pI) 10.7 and molecular weight (MW) 14 kDa. Adsorption capacity was found 51 mg g-1 at room temperature and in 0.1 M pH=8.0 phosphate buffer. Experiments on desorption and reusability were also performed. It appears that P(Hema-Ep) composites can be used ten times without lost of efficiency. Lysozyme purification, without causing any denaturation, can be performed from chicken egg white by using this new synthesized composite in a single step.
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    New Composite, Poly(Hydroxyethylmethacrylate-Expanded Perlite), for Single step Separation of Egg White Lysozyme
    (Sivas Cumhuriyet University, 2018) Akkaya, Birnur; Akkaya, Recep
    In this study, we investigated adsorption behaviour of lysozyme on poly(hydroxyethylmethacrylate-expanded perlite) . For this purpose, we synthesized P(Hema-Ep) composite by bulk polymerization and it was characterized by SEM, FTIR and swelling ratio. The fresh chicken egg white lysozyme was used as a model protein, had an isoelectric point (pI) 10.7 and molecular weight (MW) 14 kDa. Adsorption capacity was found 51 mg g-1 at room temperature and in 0.1 M pH=8.0 phosphate buffer. Experiments on desorption and reusability were also performed. It appears that P(Hema-Ep) composites can be used ten times without lost of efficiency.  Lysozyme purification, without causing any denaturation, can be performed from chicken egg white by using this new synthesized composite in a single step.
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    New low-cost composite adsorbent synthesis and characterization
    (TAYLOR & FRANCIS INC, 2013) Akkaya, Recep; Akkaya, Birnur
    In this research, a novel composite, poly(acrylamide-expanded perlite) [P(AAm-EP)], was synthesized and characterized. The chemical synthesis was achieved by using free-radical polymerization and a number of structural characterization methods, including Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET)-porosity, and swelling tests. Free-radical polymerization of acrylamide (AAm) over expended perlite (EP) was successfully performed. The effect of reaction variables, such as dosage of the initiator, total concentration of the reactants, reactant ratio, mixing time, temperature, and reaction time, were investigated in detail. Expended perlite was cross-linked with acrylamide to enhance its chemical resistance. P(AAm-EP) composite has a specific surface area of 31.7m(2) g(-1).
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    Positive effects of angiotensin-converting enzyme (ACE) inhibitor, captopril, on pentylenetetrazole-induced epileptic seizures in mice
    (Pharmacotherapy Group, 2020) Tastemur, Yasar; Gumus, Erkan; Ergul, Merve; Ulu, Mustafa; Akkaya, Recep; Ozturk, Aysegul; Taskiran, Ahmet Sevki
    Purpose: To evaluate the effects of an angiotensin-converting enzyme (ACE) inhibitor, captopril, on pentylenetetrazole (PTZ)-induced seizures and post-seizure hippocampal injury. Materials: Thirty-five male Balb-c mice weighing 30 - 33 g were divided into control, saline PTZ, s(erum ;physiologic 1 ml/kg as solvent), positive control (valproic acid 200 mg/kg), captopril (25 mg/kg/day for 7 days), and captopril (50 mg/kg/ day for 7 days) groups. PTZ (60 mg/kg) was administered thirty minutes after medication administration to induce epileptic seizures. The animals were observed for 30 min to record Racine stages, the time of the first myoclonic jerk (FMJ), and the occurrence of the first generalized tonic-clonic seizure (GTCS). Cornu Ammonis (CA)1, CA2, CA3, and the dentate gyrus (DG) of the hippocampus underwent histopathological examinations. The levels of total oxidant status (TOS), oxidative stress markers (total antioxidant status, TAS), and oxidative stress index (OSI) were measured in the brain tissue. Results: Compared to PTZ group, 25 mg/kg captopril decreased seizure scores and delayed FMJ and GTCS (p < 0.05). Histopathological assessment demonstrated that both 25 and 50 mg/kg captopril alleviated neuronal injury in CA1, CA2, CA3, and DG compared to PTZ (p < 0.05). Also, TOS and OSI levels in the brain tissue were reduced by both 25 and 50 mg/kg doses of captopril (p < 0.05). Conclusion: Captopril favorably improves epileptic seizure parameters and acts against post-seizure neuronal injury in the hippocampus. Captopril may be a drug of choice in epileptic individuals with hypertension.
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    Production and immobilization of a novel thermoalkalophilic extracellular amylase from bacilli isolate
    (ELSEVIER SCIENCE BV, 2012) Akkaya, Birnur; Yenidunya, Ali Fazil; Akkaya, Recep
    A Thermoalkalophilic amylase was produced from an environmental bacterial isolate. The enzyme was then immobilized through its amino groups onto the epoxy rings of magnetic poly glycidyl methacrylate [m-poly (GMA)] beads. The free enzyme was active within a large pH range, between 7 and 12 and displayed the optimum activity at 95 degrees C and pH 10. The immobilization appeared to increase the stability of the enzyme as its bound form showed optimum activity at 105 degrees C and pH 11.0. Kinetic studies demonstrated that immobilized enzyme had higher K-m and lower V-max values. The activity of the free and bound enzyme was determined, at 37 degrees C and pH 10.0 and pH 11.0, respectively, in the presence of various organic solvents and detergents (5%, v/v). Results obtained indicated that detergents, sodium dodecyl sulfate (SDS) and TritonX-100, caused six fold increase and that various organic solvents also increased the activity of the amylase. (C) 2012 Elsevier B.V. All rights reserved.