yasemin aksoy | Hacettepe University (original) (raw)

Papers by yasemin aksoy

Turish journal of Biochemistry, Dec 30, 2012

Chemico-Biological Interactions, 2013

Biochemical Approach to Dental Diseases, 2011

Glucose-6-phosphate dehydrogenase was purified dehydrogenase; purification; K m values; activatio... more Glucose-6-phosphate dehydrogenase was purified dehydrogenase; purification; K m values; activation from human placenta using DEAE-Sepharose fast energy; activation enthalpy; temperature activation flow, 2Ј,5Ј-ADP Sepharose 4B column chromatography, factor (Q 10 ). and chromatofocusing on PBE 94 with PB 74. The enzyme was purified with 62% yield and had a specific activity of 87 units per milligram protein. The pH opti-Glucose-6-phosphate dehydrogenase (G6PD, EC mum was determined to be 7.8, using zero buffer 1.1.1.49, ␤-D-glucose-6-phosphate; NADP + oxidoreducextrapolation method. The purified placental glucosetase) is an enzyme that catalyzes the first step of the 6-phosphate dehydrogenase gave two activity bands pentose phosphate pathway (PPP). PPP has three imon native PAGE: one band, constituting about 3-5% of portant functions: (i) production of reducing equivalents total activity, moved slower than the remaining 95%.

Detection of progression level of periimplantitis may help in the prevention of oral implant fail... more Detection of progression level of periimplantitis may help in the prevention of oral implant failure. C-telopeptide pyridinoline crosslinks of Type I collagen (ICTP) and osteocalcin (OC) are specific markers of bone turnover and bone degradation. Determination of the ICTP and OC levels in the peri-implant sulcus fluid (PISF) may predict the metabolic and ⁄ or inflammatory changes in the peri-implant bone. The aim of this clinical study was to evaluate ICTP and OC levels in the PISF for oral implants with and without peri-implant bone destruction and correlate these levels with the traditional clinical peri-implant parameters (probing depth, plaque index, gingival index and gingival bleeding time index) and radiographic bone level measurements. Fifteen patients with 30 peri-implant sites with bone destruction (radiographic bone loss) and health were included. Clinical parameters were measured and PISF was collected from the sites. Peri-implant sulcus fluid ICTP and OC levels were detected by radioimmunoassay technique from PISF samples. All clinical parameters demonstrated a significant increase in peri-implantitis sites compared with healthy sites. The PISF volume of the peri-implantitis sites was also significantly higher than of the healthy peri-implant sites. Although not statistically significant, a trend of increase was demonstrated in ICTP PISF samples sampled from peri-implantitis sites compared with healthy sites. A significant increase was noticed for OC PISF level in peri-implantitis sites compared with healthy ones. As well as peri-implant clinical measurements, volumetric changes at PISF may be counted as an important clinical parameter to distinguish the bone destruction sites from healthy sites around oral implants.

Chemico-biological ınteractions

OBJECTIVE: Glutathione transferase P1-1 (GST P1-1) is often overexpressed in tumor cells and is r... more OBJECTIVE: Glutathione transferase P1-1 (GST P1-1) is often overexpressed in tumor cells and is regarded as a contributor to their drug resistance. Inhibitors of GST P1-1 are expected to counteract drug resistance and may therefore serve as adjuvants in the chemotherapy of cancer by increasing the efficacy of cytostatic drugs. Finding useful inhibitors among compounds used for other indications would be a shortcut to clinical applications and a search for GST P1-1 inhibitors among approved drugs and other compounds was therefore conducted. METHODS: We tested 1040 FDA-approved compounds as inhibitors of the catalytic activity of purified human GST P1-1 in vitro. RESULTS: We identified chlorophyllide, merbromine, hexachlorophene, and ethacrynic acid as the most effective GST P1-1 inhibitors with IC50 values in the low micromolar range. For comparison, these compounds were even more potent in the inhibition of human GST A3-3, an enzyme implicated in steroid hormone biosynthesis. In distinction from the other inhibitors, which showed conventional inhibition patterns, the competitive inhibitor ethacrynic acid elicited strong kinetic cooperativity in the glutathione saturation of GST P1-1. Apparently, ethacrynic acid serves as an allosteric inhibitor of the enzyme. CONCLUSION AND PRACTICAL IMPLICATIONS: In their own right, the compounds investigated are less potent than desired for adjuvants in cancer chemotherapy, but the structures of the most potent inhibitors could serve as leads for the synthesis of more efficient adjuvants.

Turkiye Klinikleri Journal of Medical …, Jan 1, 2010

Journal of Maternal …, Jan 1, 2009

Transient hypotension attacks, frequently experienced during pregnancy, have detrimental effects ... more Transient hypotension attacks, frequently experienced during pregnancy, have detrimental effects on maternal and fetal physiology. Despite the strong autoregulatory mechanisms, kidneys are remarkably sensitive to hypoperfusion. Transient hypotension together with high metabolic demand and increased oxygen requirement during pregnancy may disturb the oxidant status and natural course of nitric oxide (NO) metabolism. Therefore, we investigated in this study the effects of systemic hypotension during pregnancy on kidney oxidant status and morphology and plasma NO levels in an experimental hypotension model in rats. Twenty-four rats were allocated into four groups as non-pregnant control (NPC), non-pregnant hypotensive (NPH), pregnant control (PC) and pregnant-hypotensive (PH). Blood pressure was monitored only (NPC, PC) or systemic hypotension by blood withdrawal (NPH, PH) was produced for 30 min following catheterisation on the 15th day of pregnancy or at a corresponding time in the control animals. Animals were sacrificed after 48 h of reperfusion. Malonyldialdehyde (MDA) and reduced glutathione (GSH) levels, superoxide dismutase and catalase activities in the kidneys and plasma NO levels were measured. Tissues were evaluated, histologically. Hypotension and/or pregnancy elevated MDA levels, which was significant in the NPH and PH groups (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). GSH levels were lower in all groups compared with the NPC group (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). Pregnancy itself increased NO only in the control animals (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), not in the hypotensive pregnant rats. Transient hypotension resulted in kidney damage in both hypotension groups, and damage was more prominent in renal cortical regions. The most severe effects were seen in the PH group (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). The findings of this study show that transient hypotension induces a kidney injury in pregnant rats. MDA and GSH in kidneys seem to play a role in the pathophysiology of this injury. However, the roles of antioxidant enzymes and NO and the other underlying mechanisms deserve and necessitate further investigation regarding the long-term health of the mother and fetus.

Turkiye Klinikleri Journal of Medical …, Jan 1, 2002

Yasemin AKSOY ANT OKS DAN MEKAN ZMADA GLUTATYONUN ROLÜ T Klin Tıp Bilimleri 2002, 22 442

Reproductive …, Jan 1, 2010

Endometriotic implants were induced surgically in female Wistar albino rats, which were randomly ... more Endometriotic implants were induced surgically in female Wistar albino rats, which were randomly divided into three groups. The rats in group I (n = 10) and group II (n = 9) were given 2.5 mg/kg/day intraperitoneal and oral atorvastatin, respectively, for 28 days. Group III (n = 9) was given no medication (control). The mean volume and weight of explants in group I were significantly lower (both P < 0.05) compared with group III. Histopathological score of the implants was significantly lower in groups I and II, when compared with group III (P < 0.01 and P < 0.05, respectively). There were significant reductions in explant concentrations of vascular endothelial growth factor and matrix metalloproteinase 9 in group I (P < 0.01 and P < 0.001, respectively) and group II (both P < 0.01) compared with group III while staining due to tissue inhibitor of metalloproteinase 2 was significantly higher in group I (P < 0.01) and group II (P < 0.01) compared with group III. Moreover, explant concentration of superoxide dismutase was significantly increased in groups I and II compared with group III (both P < 0.05). In conclusion, atorvastatin causes significant regression of endometriotic implants in rats. Moreover, intraperitoneal atorvastatin seems to be more effective than oral atorvastatin. RBMOnline

American journal of …, Jan 1, 2010

We sought to test if metformin could regress endometriotic explants in rats.

TURKISH JOURNAL OF …, Jan 1, 2003

For survival, living cells maintain their thiol redox status within acceptable limits by three di... more For survival, living cells maintain their thiol redox status within acceptable limits by three different mechanisms: i. glutathione disulfide export, ii. reduction of glutathione disulfide by pentose phosphate pathway and, iii. reduction of glutathione disulfide by Protein-SH. To assess the relative contribution of each one of the systems, intracellular [glutathione], [glutathione disulfide] and their export, in fresh and aged erythrocytes subjected to oxidative stress, in ±glucose and ±antioxidants, were measured. Glutathione was rapidly oxidized by tert -butylhydroperoxide in ±glucose in both groups. The regeneration of glutathione, in both groups, in ±glucose was about 100 and 50%, respectively. In parallel, intracellular glutathione disulfide concentrations were increased by about 200-350%.

International journal of …, Jan 1, 2011

Objective The aim of this study is to determine serum levels of soluble forms of CD26/dipeptidyl-... more Objective The aim of this study is to determine serum levels of soluble forms of CD26/dipeptidyl-peptidase IV (DPP-IV) and adenosine deaminase (ADA), thought to be markers of T-cell activation, and changes in their levels in response to cyclosporine, etanercept, and psoralen plus ultraviolet A (PUVA) treatments with respect to disease activity. Methods This study is designed as a prospective clinical study with a control group and three months of follow-up. The study included 41 patients with psoriasis and 41 healthy controls that were older than 18 years of age. There were three different treatment groups: PUVA (n = 15), cyclosporine (n = 15), and etanercept (n = 11). To determine disease severity of patients with psoriasis, psoriasis area and severity index (PASI) scores were calculated.

Turk. J. Biol, Jan 1, 2004

Clinical …, Jan 1, 2011

The information concerning aneurysmal progress in Behcet's disease is still insufficient, while r... more The information concerning aneurysmal progress in Behcet's disease is still insufficient, while researches in the role of matrix metalloproteinases (MMPs) in aneurysmal formation are rapidly expanding. The goal of the present study is to investigate the role of metalloproteinase 9 (MMP-9) in vascular complications which is observed in

Journal of Biochemical and Biophysical …, Jan 1, 2000

The first step in the separation of adenine nucleotides from different types of tissues or cells ... more The first step in the separation of adenine nucleotides from different types of tissues or cells is deproteinization. Several sample preparation methods successfully used for a number of tissues or cells failed to work with erythrocytes. Use of strong acids or bases for deproteinization resulted in a low yield due to the hydrolysis of adenine nucleotides. Moreover, the neutralization of these acids or bases increased the ionic strength, resulting in broad and overlapping peaks. In neutral salt precipitation methods, saturated salts caused clogging of the capillaries. A new deproteinization procedure method was developed. The samples were deproteinized by heating of erythrocytes in boiling distilled water at 958C for 5 min. The denatured proteins were removed by centrifugation and membrane filtration. The adenine nucleotides were then separated using a polyacrylamide coated capillary. Depending on the type, diameter, length of the capillary and the voltage applied, an average of 16.50 min was sufficient for the separation of adenine nucleotides. All adenine nucleotides were clearly resolved and gave very sharp peaks. The amount of each adenine nucleotide was calculated from the areas under the peaks and AEC values were calculated using the integrator software. The AEC value of 0.9160.04 (n 5 10) obtained for healthy persons was in good agreement with the literature value of 0.85-0.95. These reported method for sample preparation and capillary electrophoresis is simple, fast and inexpensive compared to the previously reported sample preparation, HPLC and enzymatic methods for the determination of AEC.

TURKISH …, Jan 1, 2004

Aksoy, Sanal Ö, Metin A, Tezcan Ý, Ersoy F, Öðüþ H, Özer N. Antioxidant enzymes in red blood cell... more Aksoy, Sanal Ö, Metin A, Tezcan Ý, Ersoy F, Öðüþ H, Özer N. Antioxidant enzymes in red blood cells and lymphocytes of ataxia-telangiectasia patients. Turk J Pediatr 2004; 46: 204-207.

Journal of …, Jan 1, 2004

We evaluated the oxidative stress in renal tissue during three types of surgery: open donor nephr... more We evaluated the oxidative stress in renal tissue during three types of surgery: open donor nephrectomy (ODN), laparoscopic donor nephrectomy (LDN), and retroperitoneoscopic donor nephrectomy (RDN). The aim was to find out which is the appropriate procedure for harvesting a donor kidney. Twenty-four New Zealand White rabbits were randomized to four groups, each consisting of six rabbits. Group I (control) was subjected to 180 minutes of anesthesia, and transperitoneal nephrectomy was performed without creation of warm ischemia. In group II (ODN), after 180 minutes of anesthesia, warm ischemia was created for 5 minutes, and nephrectomy was performed. Group III (LDN) was subjected to 5 minutes of warm ischemia after 180 minutes of pneumoperitoneum at 12 mm Hg, and the kidney was removed. In group IV (RDN), after pneumoretroperitoneum at 12 mm Hg for 180 minutes, warm ischemia was created for 5 minutes, and nephrectomy was performed. Renal tissues were analyzed to determine malondialdehyde (MDA) and reduced glutathione (GSH) as oxidative-stress markers. Renal tissue GSH levels were decreased, whereas MDA levels were increased in groups II through IV compared with the control group (p&amp;amp;amp;amp;amp;lt;0.05). There was no statistically significant difference between the ODN, LDN, and RDN groups in the renal oxidative-stress markers. No differences were detected in oxidative-stress markers in renal tissue samples between ODN, LDN, and RDN. Therefore, we believe LDN and RDN can be used for live donor kidney harvesting as effectively as ODN without creating greater oxidative stress, which can have deleterious effects on a donor kidney.