Browsing by Author "Cakir, Tahir"

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Aminoalkylated Phenolic Chalcones: Investigation of Biological Effects on Acetylcholinesterase and Carbonic Anhydrase I and Ii as Potential Lead Enzyme Inhibitors
(Bentham Science Publ Ltd, 2020) Yamali, Cem; Gul, Halise Inci; Cakir, Tahir; Demir, Yeliz; Gulcin, Ilhami
Background: Phenolic Mannich bases have been reported as acetylcholinesterase (AChE) inhibitors for the medication of Alzheimer's disease. Carbonic Anhydrases (CAs) are molecular targets for anticonvulsant, diuretic and antiglaucoma drugs in the clinic. Phenolic compounds have also been mentioned as CA inhibitors. The importance of Mannich bases in drug design inspired our research group to design novel phenolic Mannic bases as potent enzyme inhibitors. Objective: In this study, novel Mannich bases, 1-(3,5-bis-aminomethyl-4-hydroxyphenyl)-3-(4-substitutedphenyl)-2-propen-1-ones (1-9), were designed to discover new and potent AChE inhibitors for the treatment of Alzheimer's disease and also to report their carbonic anhydrase inhibitory potency against the most studied hCA I and hCA II isoenzymes with the hope to find out promising enzyme inhibitors. Methods: Mannich bases were synthesized by the Mannich reaction. The structures of the compounds were elucidated by H-1 NMR, C-13 NMR, and HRMS. Enzyme inhibitory potency of the compounds was evaluated spectrophotometrically towards AChE, hCA I and hCA II enzymes. Results and Discussion: The compounds showed inhibition potency in nanomolar concentrations against AChE with Ki values ranging from 20.44 +/- 3.17 nM to 43.25 +/- 6.28 nM. They also showed CAs inhibition potency with Ki values in the range of 11.76 +/- 1.29-31.09 +/- 2.7 nM (hCA I) and 6.08 +/- 1.18-23.12 +/- 4.26 nM (hCA II). Compounds 1 (hCA I), 5 (hCA II), and 4 (AChE) showed significant inhibitory potency against the enzymes targeted. Conclusion: Enzyme assays showed that Mannich derivatives might be considered as lead enzyme inhibitors to design more selective and potent compounds targeting enzyme-based diseases.
Catalase, Carbonic Anhydrase and Other Biochemical Parameters in Esophageal Cancers in Turkey
(Asian Pacific Organization Cancer Prevention, 2010) Demir, Halit; Akkus, Zeynel Abidin; Cebi, Aysegul; Cakir, Tahir; Izmirli, Mustafa
Purpose: The main aim of our investigation is to show possible changes in antioxidant balance and selected biochemical parameters in esophageal cancers. Materials and Methods: This study was performed for the determination of levels in 25 patients diagnosed as having cancer in the Yuzuncu Yil University (Medical Oncology) and 15 healthy volunteers at same department with negative cancer signs. Results: The activity levels of catalase of sick and health groups were 33.8 +/- 4.31 (EU/gHg)(-1), 122.4 +/- 31.7 (EU/gHg)(-1), respectively. Th differance between the average levels was significant (p<0.001). CA (carbonic anhydrase) activity was 2.19 +/- 0.12 (EU/gHg)(-1), 2.46 +/- 0.32 (EU/gHg)(-1) in groups at same order with no statistical significance (p>0.05). The levels of albumin, globulin, ferritin, ALT, LDH, glucose, CRP, AST and uric acid were also determined in sick and healthy groups: 4.04 +/- 0.24, 4.04 +/- 0.43 gr/dl (p>0.05); 4.46 +/- 0.82, 3.17 +/- 0.10g/dl (p>0.05); 175.4 +/- 29.1, 260.4 +/- 15.45g/dI (p<0.001); 12.7 +/- 1.13, 19.5 +/- 1.91 ng/ml (p<0.001); 317.6 +/- 13.8, 298.0 +/- 12.1 mg/dl (p>0.05); 106.5 +/- 12.1, 89.7 +/- 2.2 (p>0.05), 5.94 +/- 1.04, 4.41 +/- 0.28 U/L (p>0.05); 19.4 +/- 1.68, 19.5 +/- 1.91 mg/dl (p>0.05); 30.0 +/- 3.24, 10.5 +/- 0.64 mg/dl (p<0.01) respectively. Conclusions: Consequently, in diagnosis of esophageal cancer, CA, CRP, uric acid and antioxidant examinations may be very important factors. Additional studies are needed to further address this important issue.
The Comparison of Brain and Lens Doses in Whole Brain Radiotherapy With Different Treatment Plannings
(Akad Doktorlar Yayinevi, 2009) Ugurluer, Gamze; Izmirli, Mustafa; Palamik, Zehra A.; Cakir, Tahir
The aim of study was to evaluate the effects ontarget volume (brain) and lens doses with different treatment plannings in patients who received whole brain radiotherapy because of brain metastases. The system tomography scans of 14 patients at 0.5 cm intervals, were transferred to three-dimensional treatment planning computer and the normal tissues and target volumes were outlined. Seven different treatment plannings were done for each patient. Plan I: Angled blocked plan; Plan II: Non-angled blocked plan; Plan III: Helmet plan; Plan IV: Blocked plan with the inferior border at the inferior orbital ridge; Plan V: Angled unblocked plan; Plan VI: Non-angled unblocked plan; Plan VII: Conventially planned non-angled unblocked plan. Brain and lens minimum, maximum and mean doses and brain V95 and D95 doses were recorded for each plan using dose-volume histograms. When the plans were compared according to the brain minimum, mean, V95 and D95 doses, it was observed that the doses in Plan VII were lower than the others (mean 1171.57 cGy, mean 3294.64 cGy, 97.48% and mean 2990.57 cGy respectively, p < 0.05). When the plans were compared according to the lens doses, the minimum, maximum and mean doses were higher in the unblocked plans (p < 0.05). It was seen that with the angling of beams five degrees to the posterior the lens doses decreased (p < 0.05). This study shows that using 3 dimensional treatment planning, brain minimum doses increases and the dose inhomogenity decreases, and lens doses decreases using customized blocks and angling of beams five degrees posteriorly.
Determining the Photon Interaction Parameters of Iodine Compounds as Contrast Agents for Use in Radiology
(Elsevier, 2020) Cakir, Tahir
Purpose: x-ray contrast agents that contain iodine are commonly used for interventional and diagnostic procedures. To progress selective x-ray imaging, and discriminate the attenuating media, it is important to determine the absorption edge values and absorption features of the compounds used as contrast agents. For this purpose, mu rho (mass attenuation coefficients), Zeff (effective atomic number) and Nel (electron density), which characterize the possibility of interaction with x-ray of iodine containing contrast agents (ICCAs: Iodixanol, Iohexol, Iopamidol, Iopromide, and Ioxagalete) were calculated using WinXCom code and Penelope Monte Carlo simulation programs. Materials and methods: Calculations were obtained in an energy range from 1keV to 1GeV. The values of Zeff and Nel were calculated using the mu rho values of compounds. Variation in mu rho, Zeff, and Nel values of the ICCAs were determined depend on x-ray energies. Results and discussion: It was determined that in the low energy region, where the probability of photoelectric absorption was high. In the intermediate energy region, where the compton scattering process occurs. Additionally, an increase was observed in the potential for pair production effect in the presence of high energy values. Moreover, since Z4-5 depended on the photoelectric effect, the cross-section significantly contributed to the Zeff values of the ICCAs; the highest values for Zeff and Nel were observed in low energy ranges. Furthermore, the results obtained from the two different code programs were similar to one another. Conclusion: The results of this study may be useful for determining the accuracy of the Zeff and Nel values of ICCAs using dual energy CT. As such, this research can contribute to developing a method for enhancing CT image quality.
An Immunohistochemical Study on the Presence of Nitric Oxide Synthase Isoforms (Nnos, Inos, Enos) in the Spinal Cord and Nodose Ganglion of Rats Receiving Ionising Gamma Radiation To Their Liver
(Walter de Gruyter Gmbh, 2020) Yilmaz, Osman; Soyguder, Zafer; Keles, Omer Faruk; Yaman, Turan; Yener, Zabit; Uyar, Ahmet; Cakir, Tahir
Introduction: This study determined the presence of nitric oxide synthesis isoforms (nNOS, iNOS, and eNOS) in thoracic spinal cord segments and nodose ganglia of rats with gamma-irradiated livers. Material and Methods: Male rats (n = 32) were divided into equal groups A, B, C, and D. In group A, the controls, no radiation was applied, while groups B, C, and D received 10 Gy of ionising gamma radiation. The rats of group B were euthanized at the end of the first day (d1), those of group C on the second day (d2), and those of group D on the third day (d3). The liver, spinal cord segments, and nodose ganglion tissues were dissected and fixed, and the liver sections were examined histopathologically. The other tissues were observed through a light microscope. Results: Regeneration occurred at the end of d3 in hepatocytes which were radiation-damaged at the end of d1 and d2. On d1, some nNOS-positive staining was found in the neuronal cells of laminae I-III of the spinal cord and in neurons of the nodose ganglion, and on d3, some staining was observed in lamina X of the spinal cord, while none of note was in the nodose ganglion. Dense iNOS-positive staining was seen on d1 in the ependymal cells of the spinal cord and in the glial cells of the nodose ganglion, and on d3, there was still considerable iNOS staining in both tissues. There was clear eNOS-positive staining in the capillary endothelial cells of the spinal cord and light diffuse cytoplasmic staining in the neurons of the nodose ganglion on d1, and on d3, intense eNOS-positive staining was visible in several endothelial cells of the spinal cord, while light nuclear staining was recognised in the neurons of the nodose ganglion. Conclusion: The nNOS, iNOS, and eNOS isoforms are activated in the spinal cord and nodose ganglion of rats after ionising radiation insult to the liver.
Modification of the Radial Beam Port of Itu Triga Mark Ii Research Reactor for Bnct Applications
(Pergamon-elsevier Science Ltd, 2015) Akan, Zafer; Turkmen, Mehmet; Cakir, Tahir; Reyhancan, Iskender A.; Colak, Uner; Okka, Muhittin; Kiziltas, Sahip
This paper aims to describe the modification of the radial beam port of ITU (Istanbul Technical University) TRIGA Mark II research reactor for BNCT applications. Radial beam port is modified with Polyethylene and Cerrobend collimators. Neutron flux values are measured by neutron activation analysis (Au-Cd foils). Experimental results are verified with Monte Carlo results. The results of neutron/photon spectrum, thertnal/epithermal neutron flux, fast group photon fluence and change of the neutron fluxes with the beam port length are presented. (C) 2015 Elsevier Ltd. All rights reserved.
Photon Attenuation Properties of Concretes Containing Magnetite and Limonite Ores
(oficyna Wydawnicza Politechniki Wroclawskiej, 2017) Gur, Aycan; Artig, Birol; Cakir, Tahir
In this study, gamma shielding properties of concretes containing magnetite and limonite ores at different ratios (5%, 10%, 15%, 20%, and 30%) were investigated by using a Co-60 (1.25 MeV) radioactive source which was built in Thratron 1000E (TM) device used for radiotherapy purposes. Then, the photon transmission values (I/I-0) were measured by 0.6 cm(3), farmer type, PTW (TM) ion chamber. The dose readings (I-0 and I), made by PTW (TM) Unidose Electrometer, were used to calculate the linear attenuation coefficient (mu, cm(-1)), the mean free path (lambda, cm), and the mass attenuation coefficient (mu(rho), cm(2)/g) by the Lambert equations, and the results were compared with the calculations obtained using the WinXCom computer program. The findings from this study revealed that the concretes containing magnetite and limonite ores were more effective than the ordinary concrete in the attenuation of gamma rays. It was determined that the values of the mean free path decreased with the increasing concentrations of magnetite and limonite ores while the linear attenuation coefficients for 10 concrete blocks increased with the increasing magnetite and limonite ore concentrations. A comparison of the theoretical values obtained from the WinXCom computer program and the experimental results revealed a good level of conformity.
Protective Effects of Urtica Dioica L. Seed Extract on Liver Tissue Injury and Antioxidant Capacity in Irradiated Rats
(Univ Sao Paulo, Conjunto Quimicas, 2020) Yildizhan, Kenan; Demirtas, Omer Can; Uyar, Ahmet; Huyut, Zubeyir; Cakir, Tahir; Keles, Omer Faruk; Yener, Zabit
Radiotherapy is often used for the treatment of cancer. However, it causes some side effects in patients. This study aimed to determine the hepatoprotective effects of Urtica dioica L. seed-extract (UDSE) in radiation-induced liver injury. Thirty-two male rats were randomly divided into 4 groups (n=8): control(C) group: no action was taken; radiation (R) group: irradiation was administrated at 5Gy single-fraction, radiation with UDSE(R+UDSE) group: irradiation was administrated at 5 Gy single-fraction and animals were fed pellets with 30 mL UDSE/kg; UDSE group: animals were fed pellets with 30 mL UDSE/kg. All of the experiments were performed in all of the groups over 10 days. Malondialdehyde (MDA) and reduced-glutathione (GSH) levels and superoxide-dismutase (SOD), catalase (CAT), glutathione-peroxidase (GSH-Px), aspartate-transaminase (AST), and alanine-aminotransferase (ALT) activities were detennined. Histopathological findings were also evaluated in liver tissues. SOD, CAT and GSH-Px activities and GSH levels in the serum and liver were significantly increased, while MDA levels decreased in the R+UDSE group compared with the R group (P<0.05). Moreover, AST and ALT serum activities in the R+UDSE group were lower than those in the R group (P<0.05). In addition, radiation induced degenerative/necrotic changes in the R group were significantly compensated in the R+UDSE group. The results showed that radiation increased oxidative stress and decreased antioxidant capacity, as well as degeneration in the liver. However, UDSE attenuated these degenerative changes.
Radioprotective Profile of Urtica Dioica L. Seed Extract on Oxidative Dna-Damage in Liver Tissue and Whole Blood of Radiation-Administered Rats
(Univ Sao Paulo, Conjunto Quimicas, 2020) Cakir, Tahir; Yildizhan, Kenan; Huyut, Zubeyir; Uyar, Ahmet; Arihan, Okan
It was aimed to investigate the radioprotective activity of Urtica dioica L. seed extract (UDSE) in the vvho le blood and liver of radiation-administered rats, both biochemically and immunohistochemically. 32 rats were divided into 4 groups (n:8). Control group (C): no administration for 10 days. Radiation group (IR): fed pellets for 10 days after exposure to radiation. Radiation + UDSE (IR+UDSE) group: exposed to radiation and fed UDSE for 10 days. UDSE group (UDSE): fed UDSE for 10 days. Radiation (5Gy ) was given as a single fraction. 8-hydroxy-2-deoxyguanosine (8-OHdG) and deoxyguanosine (dG) levels were analyzed by biochemical method and glutathione peroxidase 1 (GPx-1) analyses were performed by immunohistochemical method in the liver and blood tissues of the rats. The increased 8-OHdG rates and decreased GPx-1 immunorcactivity was observed in the IR group. Those parameters were ameliorated in the IR+UDSE group when compared to the IR group. UDSE is likely to be a valuable radioprotector against the harmful effects of radiation.