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    Effect of psychological stress on the L-arginine-nitric oxide pathway and semen quality
    (Assoc Bras Divulg Cientifica, 2006) Eskiocak, S.; Gozen, A. S.; Taskiran, A.; Kilic, A. S.; Eskiocak, M.; Gulen, S.
    It has been reported that mental stress causes abnormality of spermiogram parameters. We investigated the effect of psychological stress on the L-arginine-nitric oxide (NO) pathway. Semen samples were collected from 29 healthy fourth semester medical students just before (stress) and 3 months after (non-stress) the final examinations. Psychological stress was measured by the State Anxiety Inventory questionnaire. After standard semen analysis, arginase activity and NO concentration were measured spectrophotometrically in the seminal plasma. Measurements were made in duplicate. During the stress period, Sperm concentration (41.28 +/- 3.70 vs 77.62 +/- 7.13 x 10(6)/mL), rapid progressive motitity of spermatozoa (8.79 +/- 1.66 vs 20.86 +/- 1.63%) and seminal plasma arginase activity (0.12 +/- 0.01 vs 0.22 +/- 0.01 U/mL) were significantly lower than in the non-stress situation, whereas seminal plasma NO (17.28 +/- 0.56 vs 10.02 +/- 0.49 mu mol/L) was higher compared to the non-stress period (P < 0.001 for all). During stress there was a negative correlation between NO concentration and sperm, concentration, the percentage of rapid progressive motility and arginase activity (r = -0.622, P < 0.01; r = -0.425, P < 0.05 and r = -0.445, P < 0.05, respectively). These results indicate that psychological stress causes an increase of NO level and a decrease of arginase activity in the L-arginine-NO pathway. Furthermore, poor sperm quality may be due to excessive production of NO under psychological stress. In the light of these results, we suggest that the arginine-NO pathway, together with arginase and NO synthase, are involved in semen quality under stress conditions.
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    Total phenolic and flavonoid contents and antioxidant activity of extracts from Vitis vinifera L.
    (Bulgarian Acad Science, 2016) Yesiloglu, Y.; Gulen, S.
    Plants naturally are a rich source of secondary metabolites and novel therapeutic compounds. These compounds are well known for their various beneficial effects on human health. In this study, variation in total phenolic and flavonoid contents and antioxidant activities (DPPH radical-scavenging, reducing power, superoxide radical scavenging, hydrogen peroxide scavenging, total antioxidant activity) of water, acetone and methanol extracts from the Vitis vinifera L. leaves collected from north Turkey was studied. Results indicated that it wassimilar total phenolic and flavonoid contents of methanol extract. Total phenolic content varied from 48.67 +/- 1.15 to 70.87 +/- 1.15 (mg GAE/g dry wt), and total flavonoid content ranged from 45.20 +/- 0.86 to 72.90 +/- 0.40(mg CE/g dry matters). Furthermore, results indicated that the extracts have good antioxidant activities. It was concluded that V. vinifera might be a potential source of antioxidants.