Browsing by Author "Demir, H."

Now showing 1 - 20 of 32

Acetaminophen Intoxication Is Associated With Decreased Serum Paraoxonase and Arylesterase Activities and Increased Lipid Hydroperoxide Levels
(Sage Publications Ltd, 2014) Karadas, S.; Aslan, M.; Gonullu, H.; Kati, C.; Duran, L.; Olmez, S.; Demir, H.
Background: Acetaminophen is at present one of the most commonly used analgesics and antipyretics. Recent evidence has suggested that oxidative stress is involved in the mechanism of acetaminophen intoxication. Paraoxonase-1 (PON1) plays an important role as an endogenous free-radical scavenging molecule. The aim of this study was to evaluate the influence of serum PON1 activity and oxidative stress in patients with acetaminophen intoxication. Methods: A total of 20 patients with acetaminophen intoxication and 25 healthy controls were enrolled. Serum total antioxidant capacity (TAC), lipid hydroperoxide (LOOH) levels, and paraoxonase and arylesterase activities were measured spectrophotometrically. Results: The serum TAC levels and the paraoxonase and arylesterase activities were significantly lower in patients with acetaminophen intoxication compared with controls (all, p < 0.001), while the serum LOOH levels were significantly higher (p < 0.001). Conclusions: Our results suggest that decreased PON1 activity seems to be associated with increased oxidative stress in patients with acetaminophen intoxication. Measuring serum PON1 activity may be useful in assessing the development of toxicity risk in acetaminophen toxicity. It would be useful to recommend vitamins with antioxidant effects such as vitamins C and E along with medical treatments.
The Activities of Serum Paraoxonase and Arylesterase and Lipid Profile in Acute Myeloid Leukemia: Preliminary Results
(verduci Publisher, 2015) Cebi, A.; Akgun, E.; Esen, R.; Demir, H.; Cifci, A.
OBJECTIVE: To investigate the activities of serum paraoxonase-1 (PON1) and arylesterase (ARE), and the lipid profile in newly diagnosed acute myeloid leukemia (AML) patients. PATIENTS AND METHODS: Thirty-two persons (16 of AML and 16 of healthy control) were included to the study. PON1 and ARE activities were measured as spectrophotometrically in serum samples. High density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triglyceride (TG) were analyzed in autoanalyzer. RESULTS: PON1 activities were respectively 16.04 U/L and 18.6 U/L in AML and healthy controls. There was no statistical significance between groups (p > 0.05). The mean ARE activities were respectively 0.21 U/L and 0.36 U/L in AML and healthy controls. Serum ARE activity significantly decreased in AML group (p < 0.001). Serum HDL values were significantly decreased (181.8 +/- 76.2 mg/dl; p = 0.002) in AML. There was no difference in total cholesterol, LDL and triglyceride values (respectively; 181.8 +/- 76.2 mg/dl, 120.6 +/- 64.6 mg/dl, 157.3 +/- 87.2 mg/dl; p > 0.05) between AML and controls. CONCLUSIONS: This is the first documented study about serum PON1 activity in AML patients. Although serum PON1 activities were not changed in both groups, our data suggest that the decreased serum ARE activity and HDL levels may be related the pathogenesis of AML.
Acute Effects of Trichloroacetic Acid on Serum Enzyme Levels and Erythrocyte Carbonic Anhydrase Activity in Rats
(2006) Demir, H.; Çelik, I.
The aim of the present study was to investigate the effects of a sublethal dose of trichloroacetic acid (TCA) on serum enzyme levels and erythrocyte carbonic anhydrase (CA) activity in rats under laboratory conditions. Ten Sprague-Dawley albino rats were divided in 2 groups of 5 rats. A 200 mg/kg dose of TCA was administered intraperitoneally to the 5 rats in the treatment group. An equal amount of saline solution was injected into the control group. Serum enzyme levels and erythrocyte CA activity of the rats were measured 1, 3, and 6 h after treatment. According to the results, while the TCA sublethal dose treatment caused significant increases in lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) after 1 and 3 h, aspartate aminotransferase (AST) significantly increased after 1, 3, and 6 h. No significant differences in the levels of alanine aminotransferase (ALT) and erythrocyte CA were observed in comparison to the controls. It was concluded that TCA may cause toxicity in rats. © TÜBİTAK.
Antioxidant Activity of Psidium Guajava Fruit (Psidium Guajava L.)
(University of Benin, 2024) Açıkgöz, G.; Demir, H.
Purpose: To investigate the antioxidant effect of the methanol extract of Psidium guajava L. fruit. Methods: Freshly harvested fruits of Psidium guajava were washed, and pulverized, and then 10 g of milled fruit puree was homogenized with 100 mL of methanol and centrifuged to obtain the supernatant. Catalase (CAT) activity, glutathione (GSH), and malondialdehyde (MDA) levels were determined by spectrophotometry. The findings were subjected to correlation and regression analysis. Results: Levels of catalase, glutathione, and malondialdehyde were 0.074 ± 0.0021 U/L, 0.0764 ± 0.0021 mmol/g, protein and 1.0931 ± 0.1573 μmol/L, respectively. Positive correlation was detected between MDA levels and GSH, CAT and GSH, and GSH and MDA levels. Predicted values of MDA were obtained from GSH and CAT activity. Conclusion: Psidium guajava L. exerts antioxidant activity which is linked to changes in MDA levels. It may therefore be considered a promising source for the development of active pharmaceutical ingredients with antioxidant properties. © 2024 The authors.
Comparative Analysis of Percentage Depth Dose Calculations by Radiotherapy Treatment Planning System Algorithms in Non-Homogeneous Media
(Yuzuncu Yil Universitesi Tip Fakultesi, 2025) Demir, H.; Çakır, T.
This study aims to investigate the dose distributions produced by three treatment planning systems (TPSs) across various mediums by constructing a phantom that simulates a mediastinal environment. Materials and Methods: We utilized Computerized Tomography (CT) to scan a phantom with bone, PMMA, and lung blocks. It was subsequently moved to Eclipse™ TPS. In Eclipse TPS, we utilized a 6 MV photon beam with a Source Skin Distance of 100 cm and a field size of 20x20 cm2. We obtained the percentage depth doses (PDD) by recording the dose at 3 mm intervals from the center of each block to the desired depths. These processes were repeated for the other two TPSs. We observed that the PDD acquired from bone, PMMA, and lung blocks in Eclipse TPS using the PBC algorithm revealed a significant contrast in the bone block, which increased a s we move away from the build-up area. Subsequently PDD values from the lung medium are compared. Eclipse and Prowess TPS values were found to be similar, while Monaco TPS, utilizing the Monte Carlo Algorithm, demonstrated significant difference. Although Monaco TPS recorded higher PDD values compared to the other two TPSs both before and after the build-up region, it maintained a consistent level in the build-up region and yielded slightly lower doses than the other TPSs. The behaviors of TPSs employed in commercial radiotherapy planning should be calculated in different environments, and compared with the measured values. These differences should be taken into consideration when making treatment decisions. © 2025, Yuzuncu Yil Universitesi Tip Fakultesi. All rights reserved.
Determination of Erythrocyte Catalase and Carbonic Anhydrase Activities in Patients With Coronary Artery Disease
(Gulhane Medical School, University of Health Sciences, 2011) Çebi, A.; Kaya, Y.; Demir, H.
Free oxygen radicals or reactive oxygen species are accepted to have an active role in the patogenesis of coronary artery disease. Thirty five patients with coronary artery disease including 10 women and 25 men were enrolled in this study performed in order to determine the activities of catalase (CAT) and carbonic anhydrase (CA) in patients with coronary artery disease. Control group included 33 individuals, seven women and 26 men, with normal angiograms. CAT and CA enzyme activities in red blood cell samples of patients and control subjects were measured with spectrophotometry (with Aebi method) and carbon dioxide hydration method, respectively, and compared statistically. CAT values were 13.09±4.74 EU/gHb and 21.30±17.99 EU/gHb-1 and CA enzyme activities were 0.75±0.28 EU/gHb and 2.06±0.24 EU/gHb in patients with coronary artery disease and control subjects, respectively. The erythrocyte CAT and CA enzyme activities in the patient group were statistically significantly lower than those of the control group (p=0.015, p<0.001). It may be concluded that acid-base balance in the erythrocytes is disordered with the decreasing CA enzyme activities of patients with coronary artery disease. The lower levels of CAT enzyme activity which is a protective enzyme against free radical damage may be due to the oxidative stress from which the patients suffered, and manipulations toward erasing this stress may be effective in the prevention and treatment of the disease. © Gülhane Askeri Tip Akademisi 2011.
Do the Trace Elements Play a Role in the Etiopathogenesis of Developmental Dysplasia of Hip
(verduci Publisher, 2018) Guner, S.; Guner, S. I.; Gokalp, M. A.; Ceylan, M. F.; Unsal, S. S.; Demir, H.
OBJECTIVE: Alterations in the connective tissue of the hip joint capsule and ligaments might account for the increased laxity seen in patients with developmental dysplasia of the hip. The tensile features of the connective tissue depend on collagen. A number of prior studies have noted the association between the trace elements and collagen biosynthesis. The aim of this research is to determine whether there exists an association between the trace elements and developmental dysplasia of the hip. PATIENTS AND METHODS: This investigation included 27 patients with developmental dysplasia of the hip (18 females and nine males; mean age 24.3 +/- 6.3 months, range 18-36 months) and 26 healthy controls (15 females and 11 males; mean age 23.8 +/- 5.4 months, range 18-36 months). The levels of the serum trace elements in the groups were statistically compared. RESULTS: The Cu levels of the patients with developmental dysplasia of hip were statistically higher than those of the control group (p<0.05). The Zn, Fe, Mg, and Mn levels of the patients with developmental dysplasia of hip were statistically lower than those of the control group (p<0.05). CONCLUSIONS: We found an association between developmental dysplasia of the hip and the serum trace element levels. We, therefore, believe that the trace element levels may shed light on the etiopathogenesis of developmental dysplasia of the hip. This work should be supported by future studies concerning the causes of the alterations in the serum trace element levels seen in patients with developmental dysplasia of the hip.
Dosimetric Comparison of 3d-Conformal and Imrt Techniques Used in Radiotherapy of Gastric Cancer: a Retrospective Study
(Prof.Dr. İskender AKKURT, 2024) Gul, O.V.; Demir, H.; Kanyilmaz, G.; Cakir, T.
This study aimed to compare three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) planning techniques commonly used in gastric cancer radiotherapy with dose volume histograms. Computed tomography (CT) images of 20 gastric cancer patients were retrospectively analyzed. 3D-CRT, 5F-IMRT and 7F-IMRT treatment plans were created for each patient. The 3 plans were compared on dose volume histogram (DVH). 3D-CRT, 5F-IMRT and 7F-IMRT plans achieved a prescribed dose of 45 Gy for 95% of PTV volume. D95 values were 45.06±0.47 Gy for 3D-CRT, 46.39±0.38 Gy for 5F-IMRT and 45.20±0.11 Gy for 7F-IMRT. In 3D-CRT, 5F-IMRT and 7F-IMRT techniques, the 13 Gy receiving volumes of the right kidney were found to be 35.08+9.59, 36.25+7.97 and 37.03+9.03 respectively. Moreover, the volume of the right kidney receiving a 20 Gy and 30 Gy dose received less dose with 5F-IMRT than with 7F-IMRT. Since each patient's critical organs are at different distances from the target and each technique has its own advantages in terms of critical organs, we suggest that the useful technique should be decided by clinical consensus. © IJCESEN.
Effect of Alloxan on Urea, Creatine and Bilirubin Levels in Serum of Rats
(Blackwell Publishing, 2007) Cebi, A.; Yasar, S.; Oto, G.; Demir, H.
Effect of Radiotherapy on Erythrocyte Catalase, and Carbonic Anhydrase Activities, Serum Levels of Some Trace Elements and Heavy Metals (Zn, Cu, Pb, Cd, Mn, Fe, Mg and Co) in Cancer Patients
(Ijrr-iranian Journal Radiation Res, 2022) Tuncer, G. Seven; Demir, H.; Izmirli, M.; Cakir, T.; Yilmazer, G.; Demir, C.
Background: We tried to reveal the relationship between the levels of some important minerals, rare elements and heavy metals by measuring serum cobalt (Co), lead (Pb), zinc (Zn), iron (Fe), copper (Cu), cadmium (Cd), magnesium (Mg), manganese (Mn), catalase (CAT) and carbonic anhydrase (CA) levels in head and neck, CNS, esophagus, stomach and breast cancers receiving radiotherapy. Materials and Methods: Serum Cu, Fe, Pb, Zn, Co, Mg, Mn and Cd levels were measured using atomic absorption spectrophotometry. Carbonic anhydrase activity (CA), CO2 hydration measurements were made using bromothymol blue method as indicator. Results: Catalase activity, carbonic anhydrase activity and serum copper, lead, zinc, iron, cobalt, cadmium, manganese, magnesium measurements for baseline and post-radiotherapy values differ greatly in cancer patients compared to healthy subjects (p<0.05). Conclusion: As a result, these findings have a significant impact on the pathophysiology of cancer. It can be argued that this paper shows a preliminary study for examining the effect of radiotherapy treatment on the activity of erythrocyte catalase, carbonic anhydrase and serum levels of cobalt, lead (Pb), zinc, iron, copper, cadmium, magnesium and manganese in the head and neck, CNS, stomach, esophagus and breast cancers receiving radiotherapy treatment.
Effects of 900 Mhz Electromagnetic Field Emitted by Cellular Phones on Electrocardiograms of Guinea Pigs
(Sage Publications Ltd, 2014) Meral, I.; Tekintangac, Y.; Demir, H.
This study was carried out to determine the effects of electromagnetic field (EMF) emitted by cellular phones (CPs) on electrocardiograms (ECGs) of guinea pigs. A total of 30 healthy guinea pigs weighing 500-800g were used. After 1 week of adaptation period, animals were randomly divided into two groups: control group (n=10) and EMF-exposed group (n=20). Control guinea pigs were housed in a separate room without exposing them to EMFs of CPs. Animals in second group were exposed to 890-915MHz EMF (217Hz of pulse rate, 2W of maximum peak power and 0.95wtkg(-1) of specific absorption rate) for 12hday(-1) (11h 45min stand-by and 15min speaking mode) for 30 days. ECGs of guinea pigs in both the groups were recorded by a direct writing electrocardiograph at the beginning and 10th, 20th and 30th days of the experiment. All ECGs were standardized at 1mV=10mm and with a chart speed of 50 mmsec(-1). Leads I, II, III, lead augmented vector right (aVR), lead augmented vector left (aVL) and lead augmented vector foot (aVF) were recorded. The durations and amplitudes of waves on the trace were measured in lead II. The data were expressed as mean with SEM. It was found that 12hday(-1) EMF exposure for 30 days did not have any significant effects on ECG findings of guinea pigs. However, this issue needed to be further investigated in a variety of perspectives, such as longer duration of exposure to be able to elucidate the effects of mobile phone-induced EMFs on cardiovascular functions.
Effects of Applied Electrical Field on Biochemical Parameters and Erythrocytes of Rats
(Mrs Pushpa Agarwal, 2006) Demir, H.; Cakir, T.; Karakaya, C.; Ilhan, A. Cebi; Onursal, N.; Gur, A.
The purpose of this study was to determine whether there was any effect of some biochemical parameters and erythrocyte carbonic anhydrase on electrical field stimulation in female rat. The experiments were performed under the animals' scientific procedures and conform to National Institute of Health guidelines for the use of experimental animals. This study was carried out on female Sprague-Dawley rats (250-270 g). Comparasons were made using student-t tests. A p value less than 0.001 was considered statistically significant. It was demonstrated that alanine aminotransferase, aspartate aminotransferase, amylase and lactate dehydrogenase in serum were significantly affected by this electric field stimulation (p < 0.001). In addition, particularly carbonic anhydrase activity was affected by applied electrical field.
Erratum: Effects of Some Drugs on Enzyme Activity of Catalase From Bovine Liver (Asian Journal of Chemistry (2006) 18, 1 (601-607))
(Chemical Publishing Co., 2006) Alkan, S.; Savran, A.; Demir, H.; Ceylan, H.
Hallermann Streiff Syndrome
(Wiley-blackwell, 2008) Tuncer, O.; Kirimi, E.; Demir, H.; Caksen, H.; Gulmemet, F.
Immobilization of Catalase Via Adsorption Onto Natural and Modified Montmorillanit Analsim-Clay
(Polish Chemical Soc, 2009) Alkan, S.; Gur, T.; Gur, A.; Uruc, H.; Demir, H.
Immobilization of the enzyme catalase on natural and modified montmorillanit analsim-clays was investigated using a batch system. Such an immobilization does not result in enzyme inactivation and constitutes a valuable method for immobilizing catalase at high ionic strength. In the immobilization process, the effect of pH, ionic strength and reaction temperature were chosen as parameters. Furthermore the optimization of immobilization conditions were studied using data obtained from experimental results. For the free catalase and three different immobilized catalase enzymes, the optimum pH values 8, 7, 7 and 8; reaction temperature 30 degrees C; ionic strength 0.25 M were found. It was determined that enzyme activity for enzyme supported by natural clay was 73.3%, when it was retained during the storage at 4 degrees C for a period of 60 days. It was observed that storage and operational stabilities of the enzyme increased with immobilization. The results obtained show that montmorillanit analsim-clay is valuable and favourable support the simple adsorption of enzymes.
Immobilization of Polyphenol Oxidase Purified From Igdir Apricot on Bardakci-Clay
(2008) Demir, H.; Gur, A.; Yilidz, A.; Gur, T.
It is known that immobilized enzymes more useful and advantageous than free enzymes. In this work, polyphenol oxidase purifed by affinity chromatography from lgdir apricot was immobilized onto natural bardakci-clay by physical adsorption method. The properties of the immobilized enzyme were compared to the tree enzyme. The PPO activity of immobilized clay was determined, and then the effects of reaction optimum temperature, thermostability, optimum pH, ionic effect and kinetic parameters were investigated. Catechol was used as substrate, the activities of immobilized and free polyphenol oxidase were determined in the reaction mixture containing substrate catechol. The results obtained from experiments indicated that physical adsorption is favourable for attachment of enzyme onto bardakci-clay.
Increased Oxidative Stress in Living Kidney Donors: Correlation of Renal Functions With Antioxidant Capacity
(Elsevier Science inc, 2017) Yildirim, M.; Karahan, M.; Kucuk, H. F.; Demir, T.; Demir, H.; Turan, H.; Ari, E.
Background. Substantial attention has recently been paid to the possibility of an increased risk of chronic kidney disease (CKD) in living kidney donors. It has been demonstrated that CKD patients suffer from increased oxidative stress, which have been reported to show a strong association with several clinical problems such as accelerated atherosclerosis. The purpose of the current cross-sectional, single-center study was to evaluate the relationship between renal functions of living kidney donors and systemic oxidative stress. Methods. A total of 55 living kidney donors operated at least 1 year ago and 40 age and sex-matched healthy individuals were enrolled in this study. Plasma malondialdehyde (MDA) levels were determined as oxidative stress marker. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as antioxidants. Renal function parameters and proteinuria were also assessed. Results. Mean serum creatinine levels were higher (P = .022) and 24-hour creatinine clearance was lower (P = .016) in living kidney donors compared with healthy controls. Serum MDA levels were higher (P = .034), and SOD and GPx activities were lower (P = .023 and P < .001, respectively). There was a significant positive correlation between serum GPx activity and 24-hour creatinine clearance levels (r = 0.524, P < .01). A linear regression analysis showed that serum GPx activity was still significantly and positively correlated with creatinine clearance (regression coefficient = 0.416, P < .001). Conclusion. Our data demonstrated that living kidney donors exhibit slightly reduced kidney function, increased oxidative stress, and decreased antioxidant activity. We propose that 24-hour creatinine clearance is positively correlated with antioxidant enzyme GPx. To our knowledge, this is the first study to demonstrate the association between renal functions and antioxidant activity in kidney donors.
Investigations of the Inhibition Kinetics of Some Drugs and Chemicals on Enzyme of Polyphenol Oxidase Purified From Apricot's (Salak)
(2007) Cimen, C.; Demir, H.; Gur, A.; Kubilay, S.
Polyphenol oxidase (PPO) was purified from Igdir apricot, with a 367 fold purification of PPO by affinity chromatography being achieved. Amount of the protein was determined according to Bradford method. Vmax and Km values were found by means of Lineweaver- Burk graphs. Asetly salisilic acid, paracetamol, ascorbic acid (vitamin C), sodium sulphate, copper sulphate, glucose, sodium nitrite, sodium chlorure, glisine, sodium azide, 2-merkaptoethanol, tyrosine, citric acid, etilendiamin tetra acetic acid (EDTA) ve p-amino benzoic acid were used as inhibitor. Inhibition constants Ki of each inhibitor were found from Lineweaver-Burk graphs. It was found that the p-aminobenzoik acid function showed the highest inhibitory effect.
Levels of Serum Α-Tocopherol, Retinol and Colecalciferol in Coronary Heart Disease Patients
(Blackwell Publishing, 2007) Cebi, A.; Kaya, Y.; Yoruk, I. H.; Demir, H.; Tuncer, M.
Measuring Out-Of Dose To the Whole Brain in Radiotherapy
(Yuzuncu Yil Universitesi Tip Fakultesi, 2024) Demir, H.; Gül, O.V.; Tuğrul, T.
The aim of this study is to measure out-of-field lens and thyroid doses in whole brain radiotherapy with thermoluminescence dosimeters (TLD) and compare them with treatment planning system (TPS) calculation values. Before Computed Tomography (CT), TLDs were placed on the lens and thyroid surfaces of the rando phantom and then the phantom was scanned with CT. Data was transferred from CT to RayStation™ TPSs and then target volume and critical organs were determined. The treatment plan was created. TLDs were placed on the lens es and thyroid for out-of-field dose measurement. For the right lens, the mean value of TLD measurements were 188.3±2.2 cGy and the mean values of TPS measurement were 192.0±0.2 cGy. The average TLD measurement for the left lens was 190.2±0.5 cGy, and the average TPS dose reading was 192.0±0.1 cGy. For doses in the thyroid region, which is further from the target, the TLD measurement and TPS reading averages were 44.9±5.2 cGy and 40.9±6.3 cGy, respectively. Accordingly, right lens point doses calculated from TPS were 1.93% higher than TLD measurements. For the left lens, this difference in the same direction was determined as 0.93%. Within the thyroid region, TLD measurements were observed to be higher than TPS readings. We measured out-of-field doses via TLDs and found that TPS calculations for thyroid were 8.90% lower than the measured dose. The results we obtained from our study are guiding in estimating out-of-field lens and thyroid doses in 3DCRT whole brain irradiation. © 2024, Yuzuncu Yil Universitesi Tip Fakultesi. All rights reserved.