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    Effects of seasonal and physiological variations on the serum major and trace element levels in sheep
    (Humana Press Inc, 2004) Yokus, B; Cakir, DU; Kurt, D
    The aim of this study was to investigate the possible effects of the seasonal and physiological variations on the Cu, Zn, Mg, Fe, Se, Ca, K, Na, Cl, and P concentrations and their relationships with the estradiol and progesterone levels in Sakiz-Ivesi sheep. For this purpose, 34 healthy Sakiz-Ivesi crossbreed sheep were divided into two groups. The first group (n=22) was mated and the second group (n=12) was not mated. They were raised under pasture conditions and without any dietary supplementation. Their serum samples were collected four times a year at each season and under each physiologic condition. The periods are 1 = early pregnancy (October), 2 = late pregnancy (January), 3 = lactation (April), and 4 = dry season (July). The results of this study indicated that (1) Mg concentrations in serum vary with seasonal variations but not physiological variations, (2) Fe and K concentrations in serum vary only with physiological variations, (3) the Cu concentration changes not only pregnancy but also through some other hormonal changes not caused by pregnancy, (4) Ca, P, and Se concentrations could vary with both physiologic and seasonal variations, (5) Zn, Na, and Cl were almost identical for both groups and altered depending on neither season of the year nor the physiologic status, (6) both increased estradiol level and increased progesterone level can raise Cu levels in serum, and (7) increased serum Ca concentrations are related with increased estradiol and decreased P and Mg levels. These observations suggest that seasonal and physiologic variations and sexual cycle have to be taken into consideration for a correct interpretation of elements status. If sheep are maintained at pasture conditions, the nutritional requirements must be supplemented during certain periods. Otherwise, it is apparent that this will cause a decline in the total performance of sheep and, consequently, economic lost.
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    Lipid peroxidation, antioxidant defense, status of trace metals and leptin levels in preeclampsia
    (Elsevier Sci Ireland Ltd, 2005) Atamer, Y; Koçyigit, Y; Yokus, B; Atamer, A; Erden, AC
    Objective: To investigate the changes in enzyme activities of erythrocyte superoxide dismutase (SOD), catalase, and placental glutathione peroxidase (GSH-Px), and analyze the levels of serum malondialdehyde (MDA), copper (Cu), zinc (Zn), selenium (Se), leptin and placental MDA and glutathione (GSH). Study Design: Cross-sectional prospective study consisting of 32 preeclamptic (PE) pregnant, 25 non-pregnant (NP) women, 28 healthy pregnant (HP) women. Levels of lipid peroxides in serum and placenta, and activities of SOD, catalase in erythrocyte and placental GSH level, placental GSH-Px activity were measured by spectrophotometric methods. Serum levels of Cu, Zn, Se measured by atomic absorption spectrophotometry. Serum levels of leptin was measured by enzyme immunoassay by using the Cayman chemical kit. One-way analysis of variance and post hoc Tukey-HSD test and Pearson correlation test were used for the statistical analyses. Results: Serum levels of MDA, Cu, Leptin were markedly higher (P < 0.001); and serum level of Se was markedly lower (P < 0.001) in PE women compared with HP women and NP women. Also, placental MDA level was higher (P < 0.001) and placental GSH-Px activity was lower in PE women compared with HP women. In preeclamptic women erythrocyte catalase activity was markedly increased (P < 0.001), while erythrocyte SOD activity was markedly decreased (P < 0.001) compared to HP women and NP women. Placental GSH level was decreased compared to HP women (P < 0.001). Serum level of Zn was markedly decreased compared to NP women (P < 0.001) but no significant difference was observed in PE pregnant when compared with HP women (P > 0.05). Placental MDA level in PE women had significant negative correlation with serum Se level (r = -0.353, P < 0.05). A negative correlation was found between erythrocyte catalase activity with birth weight (r = -0.528, P < 0.001). Also, there were a significant negative correlation between serum levels of Cu and Se in the preeclamptic women (r = -0.407, P < 0.05). Conclusion: Our data demonstrate that elevation of lipid peroxides together with impaired antioxidant defense mechanisms and status of trace metals and the presence of possible interrelationship and crosstalk between those parameters may be related at least partly to the pathogenesis of preeclampsia. Additionally, lipid peroxides and blood oxidative imbalance could be part of the cytotoxic mechanisms leading to endothelial cell injury. (c) 2004 Elsevier Ireland Ltd. All rights reserved.
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    N-terminal proBNP plasma levels correlate with severity of mitral stenosis
    (I C R Publishers, 2005) Iltumur, K; Karabulut, A; Yokus, B; Yavuzkir, M; Taskesen, T; Toprak, N
    Background and aim of the study: Brain natriuretic peptide (BNP), a neurohormone, is secreted predominantly from the ventricular myocardium. Studies investigating BNP secretion in diseases affecting the right side of the heart are scarce. The relationship between N-terminal proBNP (NT-proBNP) and echocardiographic and clinical findings was studied in cases with isolated moderate to severe rheumatic mitral stenosis (MS), and in patients with previous mitral valve replacement (MVR). Methods: Thirty-two patients with MS (mean age 41.2 +/- 5.7 years), 20 with MVR (mean age 46.0 +/- 4.6 years) and 30 healthy individuals (mean age 40.3 +/- 4.9 years) were included in the study. In addition to NT-proBNP measurements, detailed transthoracic echocardiography was performed in all patients and healthy subjects. Results: Plasma levels of NT-proBNP were significantly higher in patients with MS than in those with MVR or in controls (99.8 +/- 12.7 versus 74.7 +/- 6.9 and 48.5 +/- 10.5 pg/ml, respectively; p < 0.0001 all groups). NT-proBNP levels showed a significantly greater increase in severe MS than in moderate MS (109.8 +/- 5.6 versus 88.3 +/- 7.6 pg/ml, p < 0.0001). NT-proBNP levels also were higher in MVR patients than in controls (74.7 +/- 6.9 versus 48.5 +/- 10.5 pg/ml; p < 0.0001). Although NT-proBNP levels did not correlate with left ventricular ejection fraction (LVEF) in patients with MS (r = -0.33; p > 0.05), there was a positive correlation with pulmonary artery pressure (r = 0.87; p < 0.001) and a negative correlation with mitral valve area (MVA) (r = -0.89; p < 0.0001). However, multivariate analysis identified only MVA as an independent correlate of NT-proBNP (P = -0.47; p = 0.02). Conclusion: In patients with rheumatic MS, NT-proBNP levels correlated positively with MS severity. Moreover, NT-proBNP levels increased significantly in patients with MS, but were significantly lower in those who underwent MVR.
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    Oxidative DNA damage in rats exposed to extremely low frequency electromagnetic fields
    (Informa Healthcare, 2005) Yokus, B; Cakir, DU; Akdag, MZ; Sert, C; Mete, N
    Extremely low frequency (ELF) electromagnetic field (EMF) is thought to prolong the life of free radicals and can act as a promoter or co-promoter of cancer. 8-hydroxy-2-deoxyguanosine (8OHdG) is one of the predominant forms of radical-induced lesions to DNA and is a potential tool to asses the cancer risk. We examined the effects of extremely low frequency electro magnetic field (ELF-EMF) (50 Hz, 0.97 mT) on 8OHdG levels in DNA and thiobarbituric acid reactive substances (TBARS) in plasma. To examine the possible time-dependent changes resulting from magnetic field, 8OHdG and TBARS were quantitated at 5 0 and 100 days. Our results showed that the exposure to ELF-EMF induced oxidative DNA damage and lipid peroxidation (LPO). The 8OHdG levels of exposed group (4.39 +/- 0.88 and 5.29 +/- 1.16 8OHdG/dG. 105, respectively) were significantly higher than sham group at 50 and 100 days (3.02 +/- 0.63 and 3.46 +/- 0.38 8OHdG/dG.10(5)) (p < 0.001, p < 0.001). The higher TBARS levels were also detected in the exposure group both on 50 and 100 days (p < 0.001, p < 0.001). In addition, the extent of DNA damage and LPO would depend on the exposure time (p < 0.05 and p < 0.05). Our data may have important implications for the long-term exposure to ELF-EMF which may cause oxidative DNA damage.
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    The role of enzymatic antioxidant defense system and lipid peroxidation on gentamicin nephrotoxicity in rat renal tissues
    (Mbr Press Inc, 1998) Isik, FB; Erdinc, L; Mete, N; Erdinc, M; Ketani, MA; Yokus, B
    The activities of antioxidant enzymes, superoxide dismutase (SOD), Glutathione peroxidase (GSH-Px) and catalase (CAT), and the levels of malondialdehyde (MDA), an end product of lipid peroxidation, in kidney tissues were measured in rats treated with gentamicin alone (100 mg/kg/day subcutaneously (s.c.)) for 10 days or gentamicin together with vitamin E (300 mg/kg/day intraperitoneally (i.p)) for 10 days. Gentamicin caused depression in activities of the antioxidant enzymes (SOD, GSH-Px, CAT)) and elevation in MDA levels. These effects were highly significant when compared to the effects of placebo in control group (P < 0.001). Vitamin E was found to be ineffective for preventing gentamicin induced nephrotoxicity as determined both functionally and histopathologically. Although there was a borderline decrease of MDA levels (p < 0.05) in rats taking vitamin E, there was no difference in the activities of antioxidant enzymes between the rats taking gentamicin with or without vitamin E. Our finding suggests that gentamicin nephrotoxicity causes a decrease in the activities of antioxidant enzymes and an increase in the level of lipid peroxidation, and vitamin E do not has any preventive effect against gentamicin nephrotoxicity.
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    Seasonal and physiological variations in serum chemistry and mineral concentrations in cattle
    (Humana Press Inc, 2006) Yokus, B; Cakir, UD
    The present study reports the seasonal and physiological variations of copper, zinc, magnesium, iron, sodium chlorine, potassium, calcium, phosphor-us, urea, alkaline phosphatase (ALP), creatinine (CR), aspartate aminotransferase (AST), alanine aminotrinsferase (ALT), cholesterol, albumin, globulin, lactate dehydrogenase (LDH), and total protein concentrations in cattle. Two groups of mated (n = 14) and nonmated (n = 10) healthy cows were selected for the study. Serum samples were collected at each of four periods: (1) early pregnancy (May), (2) midpregnancy (August), (3) late pregnancy (October), and (4) lactation (February). Physiological variations result in changes of cholesterol, calcium, LDH, and total protein concentrations. Phosphorus varies only with seasonal but not physiological changes, whereas ALP, copper, magnesium, and potassium concentrations change with physiological and seasonal conditions. The copper concentration is increased through the pregnancy. Neither the seasonal nor the physiologic variations affect zinc, iron, sodium, chlorine, calcium, urea, creatinine, albumin, and globulin values in both groups in all periods. Thus, these values can be used as reference for both mated and nonmated bovines. The measured total protein might not reflect its true value because of dehydration during the hot season. These observations suggest that seasonal and physiologic variations have to be taken into consideration for the correct interpretation of serum chemistry and elements status in cattle. Nutritional supplements are required for cattle during certain periods to avoid a decline of their performance, which would then represent consequent economic loses.