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Öğe Relationship Between Motivational Orientations, Metacognitive Adaptations and Academic Successes of Doctorate Students(Tuba-Turkish Acad Sciences, 2018) Gayef, Albena; Gulpinar, Mehmet Ali; Bakirci, Nadi; Yegen, Berrak C.Motivational orientations and metacognitive adaptations displayed in difficult situations are the two major factors that affect the academic success of students. The aim of this study is to examine relationship between motivational orientations, metacognitive adaptations and academic successes of doctorate students attending to Health Sciences Institute. In this study conducted on 139 students The Modified Archer's Health Professions Motivation Survey, The Positive Metacognitions and Positive Meta-Emotions Questionnaire and performance evaluation forms were used. In the study where metacognitive adaptation levels of doctorate students were found high, their self-confidence levels in extinguishing perseverative thoughts and emotions were found to be significantly different in comparison to their levels of goal orientations towards performance, academic alienation and their use of superficial learning strategies. Their self-confidence levels in interpreting own emotions as cues, restraining from immediate reaction and mind setting for problem solving, establishing flexible and feasible hierarchy of goals were also found to be significantly different in comparison to their levels of academic alienation, use of metacognitive learning strategies, and internal control (p<0.05). It was also observed that academic success of the students at course and thesis stages were found to be significantly different as compared to their level of metacognitive learning strategies, self-confidence levels for setting flexible/feasible hierarchy of goals (p<0.05).Öğe Role of Ovarian Hormones in Psychological Stress-induced Oxidative Organ Damage in Rats(Aves Press Ltd, 2016) Memi, Gulsun; Yegen, Berrak C.Objective: Stress response varies with respect to gender via the hypothalamic-pituitary-gonadal axis. We aimed to investigate the effect of ovarian hormone deficiency on psychological stress response and oxidative damage. Methods: Female Sprague Dawley rats (250-300 g, n=56) were divided as control, sham, and ovariectomy (OVX) groups. Sham operation or surgical OVX were conducted under anesthesia. After 60 days, the rats were placed in a special chamber to induce psychological stress by electric shock and were kept in the same chamber for 30 min on the following 3 days. Glucocorticoid receptor antagonist RU-486 (10 mg/kg), oxytocin receptor antagonist atosiban (1 mg/kg), or saline was intraperitoneally administered 10 min before stress exposure. After the hole-board anxiety test, the rats were decapitated on the 4th day; tissue and blood samples were obtained. Results: Psychological stress increased cortisol levels in the RU-486-administered group, while cortisol levels were decreased in the atosiban-administered group. Serum interleukin (IL)-1 ss levels, but not TNF-alpha levels, were increased by inducing stress. Stress increased oxidative damage in the stomach, colon, and brain of ovariectomized rats (p<0.05-0.001), while atosiban partially reversed and RU-486 exaggerated oxidative damage. GSH levels that were depleted because of stress were partially replenished by administering atosiban; however, RU-486 had no effect on GSH levels. Conclusion: Although the absence of ovarian hormones during psychological stress had no effect on cortisol or anxiety levels, changes in cytokine levels and oxidative tissue damage were observed.Öğe Serum Leptin, Obestatin, and Ghrelin Levels and Gastric Emptying Rates of Liquid and Solid Meals in Non-obese Rats with Roux-en-Y Bypass Surgery or Prosthesis Placement: Implications for the Role of Vagal Afferents(Springer, 2017) Yavuz, Yunus; Kumral, Zarife Nigar Ozdemir; Memi, Gulsun; Cevik, Ozge Dagdeviren; Yegen, Cumhur; Yegen, Berrak C.Background The present study aimed to investigate the effects of Roux-en-Y gastric bypass (RYGB) and prosthesis placement on gastric emptying rate in conjunction with serum ghrelin-obestatin-leptin responses in non-obese rats with intact or denervated afferent innervation. Methods Under anesthesia, male Sprague-Dawley rats underwent either sham operation, RYGB, prosthesis, and/or Gregory cannula placement. Three weeks later, liquid or solid gastric emptying tests were performed and serum ghrelin, leptin and obestatin levels were measured. Results Both prosthesis placement and RYGB surgery delayed non-nutrient liquid emptying; while solid nutrient emptying was delayed only by RYGB. Nutrient-dependent (acid, hyperosmolal and peptone) delay in liquid emptying was abolished in rats with prosthesis. By vagal afferent denervation, delayed liquid emptying was abolished, while solid emptying was further delayed in rats with prosthesis. Ghrelin and obestatin levels were depressed in prosthesis-placed rats, but RYGB surgery had no impact on both levels. Leptin level was elevated in solid-food-given rats with prosthesis, but not changed in RYGB group, while it was reduced following liquid meal. All the changes observed in ghrelin, obestatin, or leptin levels in response to meal ingestion were reversed with vagal afferent denervation. Conclusions Both RYGB and prosthesis placement had delaying effects on gastric emptying rate of non-obese rats. Our results indicate that the short-term changes in gastric motility and hormone responses induced by volume reduction are reversed by afferent denervation, suggesting that sparing the vagal innervation could be essential for reaching optimum motility and hormone changes expected after bariatric surgery.
