The Effect of Supplementation of Grape Seed Proanthocyanidin Extract on Vascular Dysfunction in Experimental Diabetes

Nilsel Okudan,Hu¨lagu Barısxkaner,Hakkı Go¨kbel,Aysxe Saide Sxahin,Muaz Belviranlı,Hatice Baysal 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.11

Increased oxidative stress and impaired endothelium-dependent relaxation could underlie many of the vascular complications associated with diabetes. We aimed to investigate the effect of supplementation with grape seed proanthocyanidin extract (GSPE), a natural antioxidant, on vascular responses and oxidative stress in streptozotocin-induced diabetic rats. Male Sprague–Dawley rats were divided into three groups: control rats, untreated diabetic rats, and GSPE (100 mg/kg, for 6 weeks)-supplemented diabetic rats. Thoracic aorta rings of the rats were mounted in organ baths, and relaxant responses to acetylcholine (ACh), A23187, and sodium nitroprusside (SNP) were assayed in tissues precontracted with 60mM KCl. Plasma samples used for the measurement of malondialdehyde (MDA) level and superoxide dismutase (SOD) activity. The endothelium-dependent relaxations in response to ACh and A23187 were impaired, but endothelium-independent relaxation in response to SNP did not change in diabetic rats. Supplementation with GSPE significantly improved the relaxant responses to ACh and A23187. The MDA level was significantly elevated and the plasma SOD activity was decreased in diabetic rats, but supplementation with GSPE attenuated the elevated MDA levels and increased plasma SOD activity. Thus supplementation of GSPE may attenuate oxidative stress through the inhibition of lipid peroxidation and may restore endothelial function and reduce the risk of vascular disease in diabetes.

An Exploration on the Use of Data Envelopment Analysis for Product Line Selection

Lin, Chun-Yu,Okudan, Gul E. Korean Institute of Industrial Engineers 2009 Industrial Engineeering & Management Systems Vol.8 No.1

We define product line (or mix) selection problem as selecting a subset of potential product variants that can simultaneously minimize product proliferation and maintain market coverage. Selecting the most efficient product mix is a complex problem, which requires analyses of multiple criteria. This paper proposes a method based on Data Envelopment Analysis (DEA) for product line selection. Data Envelopment Analysis (DEA) is a linear programming based technique commonly used for measuring the relative performance of a group of decision making units with multiple inputs and outputs. Although DEA has been proved to be an effective evaluation tool in many fields, it has not been applied to solve the product line selection problem. In this study, we construct a five-step method that systematically adopts DEA to solve a product line selection problem. We then apply the proposed method to an existing line of staplers to provide quantitative evidence for managers to generate desirable decisions to maximize the company profits while also fulfilling market demands.

The Effect of Grape Seed Extracts on Serum Paraoxonase Activities in Streptozotocin-Induced Diabetic Rats

Aysel Kıyıcı,Nilsel Okudan,Hakkı Gokbel,Muaz Belviranlı 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.3

Procyanidins, a group of flavonoids, are oligomeric forms of catechins that are abundant in red wine, grapes, cocoa, and apples. Paraoxonase acts as an antioxidant enzyme and protects low-density lipoprotein-cholesterol against oxidation. In our study we aimed to evaluate the effects of grape seed extract (GSE) on paraoxonase activities in streptozotocin-induced diabetic rats. Our study included four groups of rats: Group I (n=8), control; Group II (n=10), GSE-supplemented; Group III (n=6), streptozotocin-induced diabetic; and Group IV (n=7), GSE-supplemented diabetic rats. Serum paraoxonase activities were determined with a spectrophotometric method. Paraoxonase activities in Group III were significantly lower than in the other three groups (P<.001, P<.001, and P=.005 for Groups I, II, and IV, respectively), and Group IV showed increased paraoxonase activities compared to Group III (P=.005). This is the first study to show an association between paraoxonase status and GSE supplementation and demonstrated that GSE increased paraoxonase activities. This beneficial effect of GSE was more obvious in the diabetic group, which was more prone to atherosclerotic events compared to the healthy population.

Determination of the Most Appropriate Alternative Dispute Resolution Methods for Airport Projects: A Fuzzy VIKOR Approach

Murat Cevikbas,Ozan Okudan,Zeynep Işık 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.8

Being prone to dispute, airport projects involve diverse stakeholders including also national and international aviation authorities, and this complicates the dispute resolution process in these projects. Hence, decision-makers should not entirely rely on standard forms of contracts to settle disputes in airport projects. Instead, these projects necessitate a specific dispute resolution framework that meets their needs. Even though some effort has already been devoted to developing a framework for ADR selection, most of these studies neglect airport projects. Furthermore, existing studies fell short of adopting more advanced techniques such as fuzzy set logic and Fuzzy VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR), posing a variety of drawbacks. Thus, this study aims to guide decision-makers by developing a selection framework of Alternative Dispute Resolution (ADR) methods to resolve disputes in airport projects. Firstly, the literature was reviewed comprehensively to reveal the criteria affecting the selection of ADR methods. Next, Focus Group Discussion (FGD) session was conducted with the participation of 17 experts who have diverse experiences in the dispute resolution process in airport projects to omit or validate the detected criteria obtained from the literature review. This was then followed by the Fuzzy VIKOR method to evaluate the importance of each ADR method. In the final step, sensitivity analysis was performed to confirm the reliability of the results. The results confirmed that a plethora of factors governs the ADR selection process, pinpointing the need for a systematic and holistic framework. Secondly, the “Expert Determination” was determined to be the most convenient ADR method for airport projects. The “Expert Determination” was followed by the “Dispute Adjudication Board (DAB)” and “Arbitration”, respectively. Revealing the very first holistic framework concerning ADR selection for airport projects, this study significantly contributes to the dispute resolution domain. Furthermore, this proposed framework is believed to have promising benefits for the decision-makers while drafting the contract clauses in terms of ADR methods in airport projects.

Effects of Coenzyme Q10 Supplementation on Plasma Adiponectin, Interleukin-6, and Tumor Necrosis Factor-α Levels in Men

Hakkı Gökbel,Serdar Gergerliog˘lu,Nilsel Okudan,Ibrahim Gu,Sadık Bu¨yu¨kbas,Muaz Belviranlı 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.1

The aim of the study was to determine the effects of coenzyme Q10 supplementation on plasma adiponectin, interleukin (IL)-6, and tumor necrosis factor (TNF)-α levels in sedentary men. Fourteen healthy, nonsmoking, sedentary men participated in the study. The protocol was approved by the Ethical Committee of our institution. This study was a randomized, double-blind, crossover trial. Blood samples were collected from all participants before coenzyme Q10 or placebo supplementation. The participants were randomly allocated to two groups. Seven participants received oral coenzyme Q10 (100mg/day) supplementation, and seven participants received placebo (glucose) for 8 weeks. At the end of the 8 weeks, a second blood sampling was performed. After a 4-week washout period, placebo was given to the participants who used coenzyme Q10 the first time, and vice versa, and blood sampling was repeated. Plasma was stored at −80°C until the time of analysis for adiponectin, IL-6, and TNF-α. Both CoQ10 and placebo supplementation did not affect plasma adiponectin and TNF-α levels. IL-6 level increased with coenzyme Q10 supplementation, but this increase did not differ from that seen with placebo supplementation. Coenzyme Q10 supplementation did not affect plasma adiponectin, IL-6, and TNF-α levels in sedentary men.

An Exploration on the Use of Data Envelopment Analysis for Product Line Selection

Chun-Yu Lin,Gul E. Okudan 대한산업공학회 2009 Industrial Engineeering & Management Systems Vol.8 No.1

We define product line (or mix) selection problem as selecting a subset of potential product variants that can simultaneously minimize product proliferation and maintain market coverage. Selecting the most efficient product mix is a complex problem, which requires analyses of multiple criteria. This paper proposes a method based on Data Envelopment Analysis (DEA) for product line selection. Data Envelopment Analysis (DEA) is a linear programming based technique commonly used for measuring the relative performance of a group of decision making units with multiple inputs and outputs. Although DEA has been proved to be an effective evaluation tool in many fields, it has not been applied to solve the product line selection problem. In this study, we construct a five-step method that systematically adopts DEA to solve a product line selection problem. We then apply the proposed method to an existing line of staplers to provide quantitative evidence for managers to generate desirable decisions to maximize the company profits while also fulfilling market demands.

A Design Framework for Additive Manufacturing: Integration of Additive Manufacturing Capabilities in the Early Design Process

Sarath C. Renjith,Kijung Park,Gül E. Okudan Kremer 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.2

Additive manufacturing has emerged as an integral part of modern manufacturing because of its unique capabilities in various application domains. As efforts to effectively apply additive manufacturing, design for additive manufacturing (DfAM) has risen to provide a set of guidelines based on a practical design framework or a methodology during the product design process of additive manufacturing. However, most existing DfAM methods do not effectively consider the capabilities of extant additive manufacturing technologies in the early design stages, and therefore it is hard to map functional requirements from customer needs onto a product design for additive manufacturing. Moreover, available DfAM methods tend to rely on the direct application of a specific decision method rather than a systematic approach with appropriate deployment and transformation of available design decision methods considering the additive manufacturing environment. Consequently, existing DfAM methods lack suitability for use by additive manufacturing novices. To tackle these issues, this study develops a design framework for additive manufacturing through the integration of axiomatic design and theory of inventive problem-solving (TRIZ). This integrated approach is effective because the axiomatic design approach can be used to systematically define and analyze a design problem, while the TRIZ problem-solving approach combined with an additive manufacturing database can be used as an idea generation tool to generate innovative solutions for the design problem. A case study for a housing cover redesign is presented to apply and validate the proposed design framework.

An Investigation on Process Capability Analysis for Fused Filament Fabrication

Elif Elçin Günay,Anusha Velineni,Kijung Park,Gül E. Okudan Kremer 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.4

Additive manufacturing (AM) has become a popular manufacturing technology today. Many companies have been investingin AM technologies and skill development to carefully integrate them into their capabilities. Despite its benefi ts, AM hasseveral disadvantages that require in-depth analysis and process engineering. This research focuses on the reproducibilityissue of fused fi lament fabrication (FFF) for polylactic acid printing to reveal whether the AM technology can produce partscomparable to those by traditional or subtractive manufacturing. For this purpose, identifi cation of optimal process parametersand process capability analysis are integrated to achieve repeatable minimum deviation from target dimensions. First,a design of experiments is planned and performed to determine the optimal combination of signifi cant factors to ensuredimensional accuracy. Then, process capability analysis under optimal factor settings is performed to examine whether theprinted part dimensions satisfy the target performance levels. Findings from this study show the FFF process can match thereproducibility of manufacturing parts produced by traditional manufacturing technologies.