19 results on '"TAŞDEMIR, E."'
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2. Dynamics of a System of Higher Order Difference Equations with Quadratic Terms
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Taşdemir E
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Quadratic equation ,applied_mathematics ,Rate of convergence ,Order (business) ,Oscillation ,Dynamics (mechanics) ,Applied mathematics ,Mathematics - Abstract
In this paper we investigate the global asymptotic stability of following system ofhigher order difference equations with quadratic terms:xn+1=A+Byn/yn−m^2, yn+1=A+Bxn/xn−m^2, where A and B are positive numbers and the initial values are positive numbers.We also study the boundedness, rate of convergence and oscillation behaviour of thesolutions of related system.
- Published
- 2021
3. GLOBAL DYNAMICAL BEHAVIOURS AND PERIODICITY OF A CERTAIN QUADRATIC-RATIONAL DIFFERENCE EQUATION WITH DELAY.
- Author
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TAŞDEMIR, E., GÖCEN, M., and SOYKAN, Y.
- Subjects
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QUADRATIC equations , *DIFFERENCE equations , *INITIAL value problems , *MATHEMATICAL equivalence , *INTEGRALS - Abstract
Our aim in this paper is to deal with the dynamics of following higher order difference equation xn+1 = A+B xn-m x 2 n where A,B > 0, and initial values are positive, and m = {1,2....}. Furthermore, we discuss the periodicity, boundedness, semi-cycles, global asymptotic stability of solutions of these equations. We also handle the rate of convergence of solutions of these difference equations. [ABSTRACT FROM AUTHOR]
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- 2022
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4. SUM OF THE SQUARES OF TERMS OF GAUSSIAN GENERALIZED TRIBONACCI SEQUENCES: CLOSED FORM FORMULAS OF ∑k=1n GWk².
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SOYKAN, Y., TAŞDEMIR, E., and GÖCEN, M.
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SUM of squares ,GAUSSIAN sums ,LINEAR orderings ,RECURSIVE sequences (Mathematics) ,SQUARE - Abstract
In this paper, closed forms of the sum formulas ∑
k=1 n GWk ², ∑k=1 n GWk+2 GWk and ∑k=1 n GWk+1 GWk for the squares of Gaussian generalized Tribonacci numbers are presented. As special cases, we give sum formulas of Gaussian Tribonacci, Gaussian Tribonacci-Lucas, Gaussian Padovan, Gaussian Perrin, Gaussian Narayana and some other third order linear recurrence sequences. All the summing formulas of well known recurrence sequences are linear except the cases Gaussian Pell-Padovan and Gaussian Padovan-Perrin. [ABSTRACT FROM AUTHOR]- Published
- 2022
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5. Dynamical analysis of a non-linear difference equation
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Taşdemir E., Soykan Y., and Zonguldak Bülent Ecevit Üniversitesi
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Asymptotic periodicity ,Equilibrium point ,Periodicity ,Difference equation ,Unbounded - Abstract
In this article, we investigate the dynamics of the solutions of the following non-linear difference equation xn+1 = xn-2xn-3 - 1; n ? N0 with arbitrary initial conditions x-2; x-1; x0. Besides, we have studied peri- odic behaviours of related difference equation especially asymptotic periodicity and eventually periodicity. Then, we have researched unbounded solutions of difference equation. © 2019 by Eudoxus Press,LLC,all rights reserved.
- Published
- 2019
6. Gastrointestinal stromal tümörlerde NF-?B, CD9 VE VEGF'in prognostik önemi
- Author
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Taşdemir, E. Arzu, Soyuer, Işın, and Patoloji Anabilim Dalı
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Pathology ,Patoloji - Abstract
Amaç: Gastrointestinal stromal tümörler (G?ST) gastrointestinal sistemin en sıkgörülen mezenkimal tümörleridir. Bu çalısmanın amacı G?ST tanısı alan olgularıntekrar gözden geçirilmesi, prognostik faktörlerin incelenmesi ve NF-?B, CD9 veVEGF'in prognostik bir öneminin olup olmadığının saptanmasıdır.Materyal ve metod: 2001?2007 yılları arasında Erciyes Üniversitesi Tıp Fakültesi(EÜTF) Patoloji Anabilim Dalı'nda tanı alan 35 G?ST olgusu çalısmaya alındı.Olgular, tümörün biyolojik davranısını belirlemek amacı ile tümör çapı ve mitozsayısına dayanan 2002 National Institutes of Health (NIH) konsensus riskkategorizasyonu temel alınarak çok düsük, düsük, intermediyer ve yüksek risk olarak4 gruba ayrıldı. ?mmunohistokimyasal olarak CD117, CD34, desmin, SMA,vimentin, S-100, Ki?67 yönünden incelendi. CD117 ve CD34 pozitif olan G?STolgularına CD9, VEGF ve NF?B uygulandı. Kullanılan antikor sonuçlarının tümörkarakteristikleri ve birbirleri ile olan iliskilerinin değerlendirilmesi için ki-kare,Fischer'in exact testi ve multivariyete analiz testleri kullanıldı. ?statiksel anlamlılık p< 0.05 olarak kabul edildi.Bulgular: NF?B (p:0.329), CD9 (p:0.269) ve VEGF (p:0.372) ile risk gruplarıarasında istatistiksel olarak anlamlı fark bulunmamakla birlikte; NF?B pozitifboyanan olguların %79,22'si, CD9 ile pozitif boyanan olguların %81'i, VEGF ilepozitif boyanan olguların, %80'i yüksek risk grubunda idi.Tartısma: Baska birçok malign lezyonda davranısın öngörülmesinde önem tasıdığıbulunan NF?B, CD9 ve VEGF'in yüksek risk grubundaki G?ST'lerde, yüksekoranlarda eksprese olduğu görülmüstür. Prognozu belirlemede tümör çapı, 50BBS'ndaki mitoz oranı, Ki?67 proliferasyon indeksi ve diğer parametrelerle birliktekullanılabilir.Anahtar kelimeler: NF?B, CD9, VEGF, gastrointestinal stromal tumör. Purpose: Gastrointestinal stromal tumors (GISTs) are most frequent mesenchymaltumors of gastrointestinal system. Our current study aimed to review cases withGIST, to examine prognostic factors and to determine whether NF-KB, CD9 andVEGF have prognostic value or not.Materials and Methods: 35 cases with GIST which was diagnosed in PathologyDepartment of Erciyes University between 2001 and 2007 were included in thestudy. Cases were classified according to tumor diameter and number of mitosis in 4group as very low risk, low risk, intermediate risk and high risk based on to 2002NIH consensus which has worldwide acceptance. Cases were examinedimmunohistologically for CD117, CD34, Desmin, SMA, Vimentin, S-100 and Ki-67.CD9, VEGF and NF-KB immunohistochemistry were applied to GIST cases withpositive CD117 and CD34. Chi-square test, Fischer Exact test and multi-variantanalyses were used to asses tumor characteristics of antibody results and theirrelationships.Results: While there are no statistically significant difference between NF-KB(p=0.329), CD9 (p=0.269) and VEGF (p=0.372) and risk groups; 79.22% of caseswhich were stained positive with NF-KB, and 81% of cases which were stainedpositive with CD9 and 80% of cases which stained positive with VEGF are in highrisk group.Conclusion: It was seen that NF-KB, CD9 and VEGF which are important inpredicting behaviors of other malign tumors have been expressed at high rates inhigh risk group GISTs. This can be use to determine prognosis with tumor diameter,mitosis rate under 50 BBS, Ki-67 proliferation index and other parameters.Key Words: NF?B, CD9, VEGF, gastrointestinal stromal tumor. 83
- Published
- 2008
7. PSY38 - Prevalence-Based Measurement of the Economic Burden of Rare Diseases: Case Review To Determine the Annual Cost of Acromegaly In Italy
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Tasdemir, E., Magestro, M., Griner, B.P., Cummins, G., Van, Engen A., Kreeftmeijer, J., Niemira, J., and Tao, C.
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- 2014
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8. PSY36 - Prevalence-Based Measurement of the Economic Burden of Rare Diseases: Case Review To Determine the Annual Cost of Acromegaly In France
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Tasdemir, E., Magestro, M., Griner, B.P., Cummins, G., Van, Engen A., Kreeftmeijer, J., Niemira, J., and Tao, C.
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- 2014
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9. Synthesis, characterization and crystal structure of caffeine complex of mn(Ii) p-hydroxybenzoate
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Öztürkkan Özbek, F. E., MUSTAFA SERTÇELİK, Taşdemir, E., Hökelek, T., Çatak Çelik, R., and Necefoğlu, H.
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lcsh:Chemistry ,p-hydroxybenzoic acid ,mn(ii) ,lcsh:QD1-999 ,lcsh:TP155-156 ,supramolecular crystal structure ,lcsh:Chemical engineering ,caffeine - Abstract
A new manganese(II) complex containing p-hydroxybenzoate and caffeine ligands, namely [Mn(OH-C6H4COO)2(H2O)4].2(C8H10N4O2).8H2O has been prepared. The synthesized complex has been characterized by elemental analyses, FT-IR spectroscopy, X-ray crystallography, and molar conductance measurements. The thermal properties of the complex were analyzed by TGA/DTA. The complex crystallizes in the monoclinic space group P21/c having cell dimensions a=11.1311(2), b=14.3579(3), c=13.5383(3) Å, β=101.879(2)º, V=2117.34(8) Å3, Z=2. In the mononuclear complex, Mn atom is coordinated by two p-hydroxybenzoate anions and four water molecules. Moreover, the asymmetric unit of the complex also contains four uncoordinated water molecules and one caffeine ligand. Crystal structure of the complex has 3D supramolecular networks formed via O-HOH···Ocaf, O-Hw···Ow, O-Hw···Ncaf, O-Hw···Ocaf, and O-Hw···Ocar hydrogen bonds.
10. Natural history of patients with infantile nephrolithiasis: what are the predictors of surgical intervention?
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Saygılı SK, Kırlı EA, Taşdemir E, Canpolat N, Çalışkan S, Sever L, Talat Z, and Önal B
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- Humans, Infant, Kidney, Retrospective Studies, Ultrasonography, Kidney Calculi therapy, Lithotripsy, Nephrolithiasis epidemiology, Nephrolithiasis surgery
- Abstract
Background: We evaluated the risk factors for the requirement of surgical intervention in infants with nephrolithiasis., Methods: The medical records of 122 (156 kidney units (KU)) infants were reviewed. The clinical features, stone characteristics, changes in stone status, and treatment protocols were noted. The stone status of the KU was categorized into 3 groups according to the change in size between the first and last ultrasound: resolution, unchanged, and growth., Results: The median age was 8 months (r: 2-12). The median length of follow-up was 16 months (r: 10-36). Resolution was detected in 94 KUs (60%). Stone growth was detected in 39 KUs (25%), and stone size was unchanged in 23 KUs (15%). Surgical intervention was required in 26 patients (17%). A history of intensive care unit (ICU) follow-up and a stone size > 5 mm at time of diagnosis were defined as independent risk factors for stone growth (p = 0.005, < 0.001, respectively). The surgical intervention rate was higher in stones > 5 mm and stones with pelvic localization (p = 0.018, 0.021, respectively). Stone resolution was higher in patients with stone size ≤ 5 mm (p = 0.018)., Conclusion: A stone size > 5 mm at the time of diagnosis and a history of ICU follow-up are independent risk factors for stone growth. Pelvic localization of stones and stones > 5 mm are associated with an increased risk of surgical intervention.
- Published
- 2021
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11. Clinical and immunophenotypic characteristics of patients with chromosome 22q11.2 deletion syndrome: a single institution's experience.
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Nepesov S, Aygün FD, Küçüksezer U, Taşdemir E, Çokuğraş H, and Camcıoğlu Y
- Abstract
Aim: The aim of this study was to identify the clinical and immunologic features of patients with 22q11.2 deletion syndrome who were followed up in our clinic. Thus, it is aimed to identify the syndrome early, choose the right treatment options according to humoral and cellular immunologic analysis, and enlighten how to follow up these kinds of patients with immunodeficiencies., Material and Methods: We retrospectively collected data by reviewing the files of 11 patients with 22q11.2 deletion syndrome who were followed up in our clinic between January 2003 and January 2015. The diagnoses were based on the patients' clinical, genetic, and immunologic features. Demographic features, family history, initial symptoms on admission, physical findings, and results of immunologic studies of the patients. Age of diagnosis, treatment options, and clinical follow-up were evaluated., Results: The patients' diagnosis age ranged from 1-11 months and the most common symptoms of admission were cardiac murmur and atypical facial appearance, which were detected during a routine physical examination. All patients had cardiac anomalies, and four patients had a history of cardiovascular surgery. Eight patients (72.7%) had a history of severe infection; recurrent lower respiratory tract infections were reported in six patients (54.5%), pulmonary tuberculosis in one patient (9.1%), and moniliasis resistant to treatment was detected in one patient. None of the patients required intravenous immunoglobulin replacement therapy, and antibiotic prophylaxis was administered to two patients with lymphopenia., Conclusion: 22q11.2 deletion syndrome is a multi-systemic disorder that should be evaluated by a multidisciplinary team. It should be kept in mind for patients with neonatal hypocalcemic tetany or recurrent infections or atypical facial appearance with cardiac anomalies. Early diagnosis should lead to immunologic analysis and enable the choice of treatment. Preventive measures against infection is recommended for the patients with incomplete immunodeficiency, and thymus transplantation is recommended for patients with complete immunodeficiency., Competing Interests: Conflict of Interest: The authors have no conflicts of interest to declare.
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- 2019
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12. A Novel Mutation of KIF11 in a Child with 22q11.2 Deletion Syndrome Associated with MCLMR.
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Güneş N, Taşdemir E, Jeffery H, Yetik H, Ostergaard P, and Tüysüz B
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Microcephaly with or without chorioretinopathy, lymphedema, or mental retardation (MCLMR; OMIM 152950) is a rare autosomal dominantly inherited syndrome. Mutations in the kinesin family member 11 ( KIF11 ) gene have been associated with this condition. Here, we report a de novo novel heterozygous missense mutation in exon 12 of the KIF11 gene [c.1402T>G; p.(Leu468Val)] in a boy with 22q11.2 microdeletion syndrome. His major features were microcephaly, ventricular septal defect, congenital lymphedema of the feet, and distinct facial appearance including upslanting palpebral fissures, a broad nose with rounded tip, anteverted nares, long philtrum with a thin upper lip, pointed chin, and prominent ears. His right eye was enucleated due to subretinal hemorrhage and retinal detachment at age 3 months. Lacunae of chorioretinal atrophy and the pale optic disc were present in the left eye. He also had a de novo 1.6-Mb microdeletion in the Di George/VCFS region of chromosome 22q11.2 in SNP array, which was confirmed by FISH analysis. In this study, for the first time, we describe the co-occurrence of a KIF11 mutation and 22q11.2 deletion syndrome in a patient with MCLMR.
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- 2019
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13. Influence of Time and Direction Information on Video Head Impulse Gains.
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Yılmaz O, Öz E, Kurt S, Aşkın ÖE, Taşdemir E, Mutlu BÖ, Keleş A, and Cevizci R
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- Adult, Analysis of Variance, Female, Head Impulse Test, Humans, Male, Task Performance and Analysis, Time, Vestibule, Labyrinth, Young Adult, Eye Movements physiology, Head Movements physiology, Reflex, Vestibulo-Ocular physiology
- Abstract
Objective: The objective of this study was to establish which factor leads to a higher vestibulo-ocular reflex (VOR) gain: the timing of the movement or the direction of the movement. For this purpose, healthy volunteers were examined under three conditions: (1) when they were informed about the timing of the head movement; (2) when they were informed about the direction of the head movement; and (3) when they knew both the timing and the direction of the head movement., Materials and Methods: This study included data from 19 participants between the ages of 20 and 23 years with no neurological or vestibular ailments. The gains of the video head impulse test (vHIT) were measured under four different conditions and the final control tests. Five subgroups were defined, and the differences in the subgroups were assessed with using several statistical procedures., Results: We found that there were significant differences between all subgroups gains on the right and left head rotations. Nevertheless, nonsignificant differences were found by performing independent samples t-tests and Mann-Whitney U tests between left and right head rotations for the pairwise comparisons of subgroups. Also, analysis of variance (ANOVA) results indicated that vHIT gains for the right and left , respectively). Thus, knowing the timing or direction or both does not affect vHIT gains., Conclusion: The results of these experiments revealed that there is no association whatsoever between VOR gain and awareness of the timing or direction of the movement or both.
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- 2017
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14. Influence of coumarin and some coumarin derivatives on serum lipid profiles in carbontetrachloride-exposed rats.
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Taşdemir E, Atmaca M, Yıldırım Y, Bilgin HM, Demirtaş B, Obay BD, Kelle M, and Oflazoğlu HD
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- Animals, Male, Rats, Rats, Sprague-Dawley, Carbon Tetrachloride toxicity, Coumarins pharmacology, Lipids blood
- Abstract
In the present study, coumarin and some coumarin derivatives (esculetin, scoparone, and 4-methylumbelliferone) were investigated for their lipid-lowering effect in rats. Male Sprague-Dawley rats (150-200 g) were divided into six groups and each group comprised of five rats. Hepatic injury-dependent hyperlipidemia was induced by carbon tetrachloride (CCl
4 , 1.25 ml/kg). Coumarin and coumarin derivatives esculetin (35 mg/kg), scoparone (35 mg/kg), 4-methylumbelliferone (35 mg/kg), or coumarin (30 mg/kg) were administered to experimental groups at 12-h intervals. Animals received the derivatives esculetin, scoparone or 4-methylumbelliferone prior to the administration of a single toxic dose of CCl4. Serum total cholesterol (TC), triglyceride (TG), very low-density lipoprotein cholesterol (VLDL-C), and low-density lipoprotein cholesterol (LDL-C) levels significantly increased in CCl4 -treated group ( p < 0.05, p < 0.01, p < 0.01, and p < 0.05, respectively), while levels of serum high-density lipoprotein cholesterol (HDL-C) decreased ( p < 0.01). 4-Methylumbelliferone had no recovery effects on serum TC levels, however, significantly prevented CCl4 -induced hyperlipidemia by reducing TG and VLDL-C levels ( p < 0.05 and p < 0.05, respectively). In addition, coumarin had no recovery effect on any of the serum lipid parameters against CCl4 -induced hyperlipidemia. Among the coumarin derivatives only esculetin and scoparone significantly prevented serum HDL-C in CCl4 -induced dyslipidemia. The results from this study indicate that the chemical structure of coumarins plays an important role on the regulation of serum lipid profiles.- Published
- 2017
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15. Comparison of the anti-diabetic effects of resveratrol, gliclazide and losartan in streptozotocin-induced experimental diabetes.
- Author
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Yazgan ÜC, Taşdemir E, Bilgin HM, Deniz Obay B, Şermet A, and Elbey B
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- Animals, Blood Glucose metabolism, Diabetes Mellitus, Experimental blood, Diabetes Mellitus, Experimental enzymology, Gliclazide pharmacology, Gliclazide therapeutic use, Glycated Hemoglobin metabolism, Hypoglycemic Agents therapeutic use, Losartan pharmacology, Losartan therapeutic use, Male, Rats, Rats, Wistar, Resveratrol, Stilbenes pharmacology, Stilbenes therapeutic use, Diabetes Mellitus, Experimental drug therapy, Hypoglycemic Agents pharmacology
- Abstract
Aim: The aim of this study was to compare the effect of the resveratrol with gliclazide and losartan in streptozotocin induced diabetic rats., Materials and Methods: Adult male Wistar albino rats were divided into five groups of seven rats each. Diabetes was induced with a single intraperitoneal (i.p.) injection of streptozotocin (55 mg/kg). Rats with blood glucose levels above 250 mg/dl after 48 h of streptozotocin injection were included in the diabetic group. Gliclazide and resveratrol were administered for 3 weeks at 5 mg/kg per day and losartan was administered for 3 weeks at 30 mg/kg per day in an oral aqueous suspension. At the end of the third week all rats were euthanized and fasting blood glucose, HbA1c and the metabolic activity of the hepatic enzymes hexokinase and glucose-6 phosphate dehydrogenase were measured in tail blood and liver specimens. All parameters were quantified using an ELISA plate reader., Results: Resveratrol and gliclazide significantly reduced both blood glucose levels and HbA1c levels in diabetic rats (p < 0.001). However, losartan did not exhibit the same effects (p < 0.05). The enzymatic activity of the liver enzymes hexokinase, glucose-6 phosphate dehydrogenase, fructose 1,6-biphosphatase, pyruvate kinase and glucose-6 phosphatase were enhanced by resveratrol and gliclazide, while losartan treatment was not associated with significant changes in liver carbohydrate metabolism., Conclusion: Resveratrol was not effective in improving liver carbohydrate metabolism relative to gliclazide, a drug widely used to treat diabetes. Dose-response profile of resveratrol remains indeterminate and additional studies may be necessary to determine effective dosing in diabetes.
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- 2015
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16. Protective effects of coumarin and coumarin derivatives against carbon tetrachloride-induced acute hepatotoxicity in rats.
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Murat Bilgin H, Atmaca M, Deniz Obay B, Ozekinci S, Taşdemir E, and Ketani A
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- Animals, Carbon Tetrachloride Poisoning metabolism, Carbon Tetrachloride Poisoning pathology, Carbon Tetrachloride Poisoning prevention & control, Chemical and Drug Induced Liver Injury metabolism, Chemical and Drug Induced Liver Injury pathology, Coumarins chemistry, Hymecromone analogs & derivatives, Hymecromone pharmacology, Male, Rats, Rats, Sprague-Dawley, Umbelliferones pharmacology, Antioxidants pharmacology, Chemical and Drug Induced Liver Injury prevention & control, Coumarins pharmacology
- Abstract
The comparison of the antioxidant activity of some coumarins with their molecular structure is well determined. However, the protective function of coumarins with various chemical structures against liver toxicity has not yet been well established. Therefore, the aim of this study was to evaluate the possible cytoprotective properties of coumarin and some coumarin derivatives against CCl(4) (carbon tetrachloride)-induced hepatotoxicity. Coumarin (1,2-benzopyrone) and coumarin derivatives esculetin (6,7-dihydroxycoumarin), scoparone (6,7-dimethoxycoumarin) and 4-methylumbelliferone (7-hyroxy-4-methyl) were examined for their protective effect against CCl(4)-induced hepatotoxicity in Male Sprague-Dawley rats. A single toxic dose of CCl(4) (1.25 ml kg(-1), orally) produced liver damage in rats, seen histologically as centrilobular necrosis. Administration of CCl(4) increased serum enzyme levels of aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP). Pre-treatment of rats with esculetin (31.15 mg kg(-1), orally) and scoparone (35 mg kg(-1), orally) significantly prevented CCl(4)-induced increase in serum enzymes, whereas 4-methylumbelliferone (35 mg kg(-1)) and coumarin (30 mg kg(-1)) had no effect against CCl(4)-induced rise in serum enzymes. Morphological findings were consistent with the plasma transaminase observations. Among the coumarin analogs, esculetin, which possesses orthodihydroxy coumarins, showed the strongest protective effect against CCl(4)-induced liver damage, followed by scoparone, 4-methylumbelliferone and coumarin, respectively. The results of this study indicate that the chemical structures of coumarins play an important role in the prevention of liver toxicity., (Copyright © 2010 Elsevier GmbH. All rights reserved.)
- Published
- 2011
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17. Dose dependent effects of ghrelin on pentylenetetrazole-induced oxidative stress in a rat seizure model.
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Obay BD, Taşdemir E, Tümer C, Bilgin H, and Atmaca M
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- Animals, Brain drug effects, Brain metabolism, Disease Models, Animal, Liver drug effects, Liver metabolism, Rats, Ghrelin pharmacology, Oxidative Stress drug effects, Pentylenetetrazole pharmacology, Seizures metabolism
- Abstract
It has been suggested that free oxygen radicals play a role in the genesis of epilepsy and in post-seizure neuronal death. The aim of this study was to investigate the dose dependent effect of ghrelin on pentylenetetrazole (PTZ)-induced oxidative stress in a rat seizure model. For this purpose, the ghrelin groups were treated with intraperitoneal injections of ghrelin at doses of 20, 40, 60 and 80 microg/kg before the PTZ injection. Superoxide dismutase (SOD) and catalase (CAT) activities, and reduced glutathione (GSH) and thiobarbituric acid-reactive substance (TBARS) levels were measured in erythrocytes, liver and brain tissue. TBARS, the indicator of lipid peroxidation, was significantly increased in erythrocytes, liver and brain tissue, while antioxidant enzyme activities and glutathione levels were significantly decreased in PTZ injected rats. Ghrelin pretreatment prevented lipid peroxidation and the reduction in antioxidant enzyme activities and GSH levels against PTZ-induced oxidative stress in a dose dependent manner. The present data indicates that PTZ at a convulsive dose induces an oxidative stress response by depleting the antioxidant defense systems and increasing lipid peroxidation in the erythrocytes, liver and brain of rats. Ghrelin pretreatment diminished oxidative stress and prevented the decrease in antioxidant enzyme activities, and thus may reduce neuronal death in the brain during seizures. However, further studies are needed in order to confirm our hypothesis.
- Published
- 2008
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18. Effect of ghrelin on gastric myoelectric activity and gastric emptying in rats.
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Tümer C, Oflazoğlu HD, Obay BD, Kelle M, and Taşdemir E
- Subjects
- Animals, Electrodes, Implanted, Ghrelin metabolism, Male, Parasympatholytics pharmacology, Rats, Rats, Sprague-Dawley, Gastric Emptying drug effects, Gastric Mucosa metabolism, Ghrelin pharmacology, Myoelectric Complex, Migrating drug effects
- Abstract
Ghrelin is a recently discovered peptide in the endocrine cells of the stomach, which may stimulate gastric motility via the vagal nerve pathway. However, the mechanism of ghrelin-induced changes in gastrointestinal motility has not been clearly defined. The purpose of this study was to investigate the pharmacological effects of ghrelin on gastric myoelectrical activity and gastric emptying in rats, and to investigate whether cholinergic activity is involved in the effects of ghrelin. The study was performed on Sprague-Dawley rats implanted with serosal electrodes for electrogastrographic recording. Gastric slow waves were recorded from fasting rats at baseline and after injection of saline, ghrelin, atropine, or atropine+ghrelin. Gastric emptying of non-caloric liquid was measured by the spectrophotometric method in conscious rats. Intravenous administration of rat ghrelin (20 microg/kg) increased not only dominant frequency, dominant power and regularity of the gastric slow wave but also the gastric emptying rate when compared with the control rats (P<0.01, P<0.05, P<0.05, P<0.001 respectively). These stimulatory actions of ghrelin on both gastric myoelectrical activity and gastric emptying were not fully eliminated by pretreatment with atropine sulphate. These results taken together suggest that ghrelin may play a physiological role in the enteric neurotransmission controlling gastric contractions in rats.
- Published
- 2008
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19. Effect of ghrelin administration on phagocytic activity in acute cold-restraint stress exposed rats.
- Author
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Tümer C, Bilgin HM, Obay BD, Diken H, Taşdemir E, and Sermet A
- Subjects
- Animals, Ghrelin, Injections, Intraperitoneal, Macrophages, Peritoneal drug effects, Macrophages, Peritoneal physiology, Male, Nitrites blood, Peptide Hormones administration & dosage, Peptide Hormones blood, Rats, Rats, Wistar, Restraint, Physical, Cold Temperature, Peptide Hormones pharmacology, Phagocytosis drug effects
- Abstract
Ghrelin, an endogenous ligand for growth hormone secretagogue receptor, was identified in the rat stomach. This peptide acts through nitric oxide (NO) by expressing endothelial nitric oxide synthase (eNOS) and down regulating inducible nitric oxide synthase (iNOS) at its gastroproprotective effect against restraint stress induced damage. Recently the ghrelin receptor has also been detected in peripheral systems including immune tissue. We have investigated the possible effect of ghrelin on phagocytic activity of peritoneal macrophages in acute cold-restraint stress (ACRS) exposed rats. The rats were divided into control, stress and ghrelin groups. In ghrelin groups, single dose and three days consecutive dose of ghrelin (20 microg/kg. i.p.) were applied to rats that were exposed to ACRS for 4 h. 1 ml of saline was injected i.p. after ACRS for 3 consecutive days to the rats of the stress groups. Ghrelin administration reduced the increased phagocytic activity induced by ACRS. We conclude that ghrelin exerts an important role at macrophage phagocytic activity in ACRS exposed rats.
- Published
- 2007
- Full Text
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