A Yeşilkaya

Akdeniz University, Antalya, Antalya, Turkey

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Publications (21)26.83 Total impact

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    ABSTRACT: The pathogenesis of pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH) remains unclear. Interactions between the epithelium and surrounding mesenchyme play an important role in normal lung morphogenesis. Epimorphin, a stromal protein, plays a role in epithelial morphogenesis and lung branching, both of which are involved in pulmonary hypoplasia. In this study, we aimed to examine the relationship between epimorphin and pulmonary hypoplasia associated with CDH in an animal model.
    Pediatric Surgery International 08/2014; · 1.22 Impact Factor
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    ABSTRACT: Aim: In this study, we have evaluated the procedure of transient transfection efficiency of vascular smooth muscle cells (VSMCs) with Lipofectamine (Life Technologies) and FuGENE (ROCHE, FuGENE HD Reagent) transfection reagents using the pCH110 eukaryotic assay vector containing the lacZ reporter gene. We also did try these attainments to transfect VSMCs with RasN17 DNA and affirmed our findings. Material Methods: Plasmid pcH110, which has been purified by cesium chloride gradient centrifugation, was used in all transfections as the assay vector. And c-H-Ras was observed via Western-blot technique. Results: Briefly, the transfection with FuGENE has been given the best results, comparing with Lipofectamin. Under our culture conditions for VSMCs, FuGENE transfection efficiency could be augmented by simply increasing the amount of plasmid DNA 1.5–3 times above the recommended concentration without any visible cytotoxicity. With the FuGENE reagent, optimal transfection efficiency was obtained for primary culture of VSMCs within the recommended concentrations, but at the top of the range. The results indicate that optimization of the transfection process should include plasmid DNA concentrations above the levels suggested by the manufacturers, in order to accomplish the highest transfection efficiency. And, these finding was also supported with our Western-blot results when VSMCs have been transiently transfected with RasN17 DNA. Conclusion: According to the difficulty of transfections of primary cell culture, we used FuGENE reagent with different DNA and plasmid ratio describes by the manufacturer and obtained better transfection efficiency in primary cultured vascular smooth muscle cells. Our findings, precisely implicates to use FuGENE reagent for to get a better transfection efficiency in primary cultured cells, especially in primary cultured VSMCs.
    Turkish Journal of Biochemistry. 01/2012; 37(1):283-289.
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    ABSTRACT: Regular exercise has blood pressure-lowering effects, as shown in different types of experimental hypertension models in rats, including the nitric oxide synthase (NOS) inhibition model. We aimed to investigate possible mechanisms implicated in the exercise effect by evaluating the vasoreactivity of resistance arteries. Exercise effects on agonist-induced vasodilatory responses and flow-mediated dilation were evaluated in vessel segments of the rat chronic NOS inhibition model. Normotensive and hypertensive rats were subjected to swimming exercise (1 h/day, 5 days/wk, 6 wk), while rats in other sedentary and hypertensive groups did not. Hypertension was induced by oral administration of the nonselective NOS inhibitor l-NAME (25 mg/kg day) for 6 wk. Systolic blood pressure, as measured by the tail-cuff method, was significantly decreased by the training protocol in exercising hypertensive rats. The vasoreactivity of resistance arteries was evaluated by both wire and pressure myography studies. An impaired nitric oxide-mediated relaxation pathway in untrained hypertensive rats led to decreased relaxation responses in vessels with intact endothelium. Exercise training significantly improved the responses to acetylcholine and flow-mediated dilation in exercise-trained hypertensive rats in parallel with a decrease in blood pressure. On the other hand contraction (norepinephrine and KCl) and relaxation (sodium nitroprusside) responses of vascular smooth muscle were not different between the groups. Vascular endothelial NOS protein expression was found to be increased in both exercising groups. In conclusion, these results revealed evidence of an increased role of the nitric oxide-dependent relaxation pathway in exercising hypertensive rats.
    Journal of Applied Physiology 07/2009; 107(3):896-902. · 3.48 Impact Factor
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    ABSTRACT: Angiotensin II (Ang II) induces a rapid increase in mitogen-activated protein kinase (MAPK) activity through the Ang II type 1 receptor in cultured rat vascular smooth muscle cells (VSMCs). In the present study, we examined the effects of the phospholipase C (PLC) inhibitor U73122, the protein kinase C (PKC) inhibitor GF109203X, and the Ras inhibitor farnesylthiosalicylic acid (FTS) on Ang II-induced activation of p42/p44 MAPKs in cultured VSMCs. Phosphorylation was shown using the Western blot technique with specific phospho-antibodies against MAPK proteins. The PLC inhibitor U73122 abolished the Ang II-induced MAPK activity, while the PKC inhibitor GF109203X only decreased it. There was also an inhibition observed with the Ras inhibitor, FTS on Ang II-induced MAPK activity. These data suggest that Ang II-induced MAPK phosphorylation through the Ang II type 1 receptor could be mediated by Ras and/or PLC-dependent phosphorylations but not by PKC phosphorylation.
    Pharmacology 02/2007; 79(1):27-33. · 1.60 Impact Factor
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    ABSTRACT: We investigated the effects of lipopolysaccharide (LPS) administration on plasma nitrite, nitrotyrosine and 6-keto prostaglandin F1alpha, (PGF1alpha) levels and the related resultant changes in function and histochemistry of aorta in rats. Plasma nitrite and PGF1alpha nitrotyrosine levels were analysed after 5 mg/kg intravenous LPS was administered to rats compared with those in non-treated rats. The distribution of nitrotyrosine in the aorta was studied immunohistochemically. The contractile responses of aortic rings to phenylephrine (PE) from both the LPS-treated and control rats were studied in the organ baths. There were increases in plasma nitrite, PGF1alpha, and nitrotyrosine concentrations of LPS-treated rats compared to non-treated rats. Immunoreactivity of nitrotyrosine residues were detected in the endothelial and smooth muscle cells in LPS-treated but not in control rat aorta. The contractile responses to PE of the LPS-treated rat aortic rings were significantly reduced as compared with those of control rat's. Incubation of the aortic rings from LPS-treated rats with cyclooxygenase inhibitor indomethacine or with a combination of indomethacine and nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) increased the contractile responses to the levels observed in control rats suggesting that both prostanoids and particularly nitric oxide (NO) are involved in the reduced contractile responses in LPS-treated rats. These results supported the view that LPS might cause an increment in both NO and PGI2 levels. This increase in the NO and PGI2 levels may be responsible from the reduction in responses of aorta to contractile agents in LPS-treated rats. Increased peroxynitrite formation in LPS-treated rats may lead to nitration of the tyrosil residues of the proteins in the aorta.
    Journal of physiology and biochemistry 04/2006; 62(1):27-34. · 1.65 Impact Factor
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    ABSTRACT: Intravascular hemolysis is one of the most emphasized mechanisms for destruction of erythrocytes during and after physical activity. Exercise-induced oxidative stress has been proposed among the different factors for explaining exercise-induced hemolysis. The validity of oxidative stress following exhaustive cycling exercise on erythrocyte damage was investigated in sedentary and trained subjects before and after antioxidant vitamin treatment (A, C, and E) for 2 mo. Exercise induced a significant increase in thiobarbituric acid-reactive substance and protein carbonyl content levels in sedentary subjects and resulted in an increase of osmotic fragility and decrease in deformability of erythrocytes, accompanied by signs for intravascular hemolysis (increase in plasma hemoglobin concentration and decrease in haptoglobulin levels). Administration of antioxidant vitamins for 2 mo prevented exercise-induced oxidative stress (thiobarbituric acid-reactive substance, protein carbonyl content) and deleterious effects of exhaustive exercise on erythrocytes in sedentary subjects. Trained subjects' erythrocyte responses to exercise were different from those of sedentary subjects before antioxidant vitamin treatment. Osmotic fragility and deformability of erythrocytes, plasma hemoglobin concentration, and haptoglobulin levels were not changed after exercise, although the increased oxidative stress was observed in trained subjects. After antioxidant vitamin treatment, functional and structural parameters of erythrocytes were not altered in the trained group, but exercise-induced oxidative stress was prevented. Increased percentage of young erythrocyte populations was determined in trained subjects by density separation of erythrocytes. These findings suggest that the exercise-induced oxidative stress may contribute to exercise-induced hemolysis in sedentary humans.
    Journal of Applied Physiology 11/2005; 99(4):1434-41. · 3.48 Impact Factor
  • Journal of the European Academy of Dermatology and Venereology 10/2003; 17(5):614-5. · 2.69 Impact Factor
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    ABSTRACT: Regular training lowers blood pressure in hypertensive humans and other animals. We investigated the response to 4 weeks of treadmill exercise training in hypertensive male Wistar rats receiving the nitric oxide synthase inhibitor N(omega)-nitro- L-arginine methyl ester ( L-NAME). The rats were on either a short- (4 weeks) or long-term (10 weeks) L-NAME treatment protocol and were subjected to running exercise that started concomitantly in the short-term group and in the 6th week in the long-term group. Four weeks of exercise training induced a fall in mean arterial pressure in both the short- [mean (SEM) 137.6 (4.0) mmHg] and long-term hypertensive groups [161.4 (2.3) mmHg] compared to their sedentary hypertensive controls [160.4 (3.3) mmHg and 176.8 (8.9) mmHg, respectively]. Exercise also increased muscle nitric oxide synthase activity in both of the trained hypertensive groups. Muscle nitrite levels were higher in the exercising short-term hypertensive group compared to both the sedentary control and the sedentary hypertensive groups, and were not different between the sedentary and exercising long-term hypertensive groups. Increased wall thickness of the aortic and mesenteric vessels was observed in the hypertensive groups, but was prevented in the exercising long-term hypertensive group. In rat, exercise reduces the elevated blood pressure in L-NAME-induced hypertension via increasing nitric oxide synthase activity. Changes in vessel structure with exercise training may also be involved in the blood-pressure-lowering effects.
    Arbeitsphysiologie 07/2002; 87(2):134-40. · 2.66 Impact Factor
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    ABSTRACT: Oxidant stress is one of the factors proposed to be responsible for damaged erythrocytes observed during and after exercise. The impact of exertional oxidant stress after acute exhaustive treadmill running on erythrocyte damage was investigated in sedentary (Sed) and exercise-trained (ET) rats treated with or without antioxidant vitamins C and E. Exhaustive exercise led to statistically significant increments in the levels of thiobarbituric acid-reactive substance (TBARS) and H2O2-induced TBARS in Sed rats and resulted in functional and structural alterations in erythrocytes (plasma hemoglobin concentrations, methemoglobin levels, and rise in osmotic fragility of erythrocytes with decrease in erythrocyte deformability). Administration of antioxidant vitamin for 1 mo before exhaustive exercises prevented lipid peroxidation (TBARS, H2O2-induced TBARS) in Sed rats without any functional or structural alterations in erythrocytes. Parameters indicating erythrocyte lipid peroxidation and deterioration after exhaustive exercise in rats trained regularly with treadmill running for 1 mo were not different from those in Sed controls. Erythrocyte lipid peroxidation (TBARS) increased in exhausted-ET rats compared with ET controls; however, the plasma hemoglobin, methemoglobin levels, and erythrocyte osmotic fragility and deformability did not differ. Exhaustive exercise-induced lipid peroxidation in ET rats on antioxidant vitamin treatment was prevented, whereas functional and structural parameters of erythrocytes were not different from those of the ET controls. We conclude that exertional oxidant stress contributed to erythrocyte deterioration due to exercise in Sed but not in ET rats.
    Journal of Applied Physiology 12/2001; 91(5):1999-2004. · 3.48 Impact Factor
  • D K Korgun, S Bilmen, A Yesilkaya
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    ABSTRACT: In the present study, we measured the concentrations of reduced glutathione (GSH) and malonyldialdehyde (MDA) and the activities of glutathione peroxidase (GSH-Px), glutathione S-transferase (GSH-S-T), superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G-6-PD) in erythrocytes obtained freshly from adult male donors which was preserved with CPDA-1 anticoagulant (citrate,phosphate, dextrose, adenine) on different days of storage. At the end of the study, storage-associated alterations in antioxidant activities were noted and discussed. GSH, GSH-Px, GSH-S-T, SOD, CAT and G-6-PD activities decreased, but erythrocyte MDA levels, as anindex of lipid peroxidation, increased during the storage period. According to our results, glutathione-dependent antioxidant systems in erythrocytes might be depleted during long storage in blood bags.
    Research communications in molecular pathology and pharmacology 02/2001; 109(5-6):357-63.
  • A Yesilkaya, R Altinayak, D K Korgun
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    ABSTRACT: To examine the antioxidant effect of bilirubin (BR) on leukocyte, we treated leukocytes obtained from healthy subjects with an oxidant and various concentrations of BR. High concentrations of BR decreased thiobarbituric acid reactive substances (TBARS) and catalase activities, increased superoxide dismutase (SOD) activity, but had no effect on glutathione (GSH) concentration. Our results showed that under physiological conditions, BR has an antioxidant effect only in high concentrations.
    General Pharmacology 08/2000; 35(1):17-20.
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    ABSTRACT: Nitric oxide (NO) plays a major role in vascular regulation. Modulation of NO synthesis is known to influence blood pressure. Inhibition of NO synthesis by NG-nitro-L-arginine methyl ester (L-NAME; 72 mg/kg/day, p.o., 21 days) resulted in 60% increase in blood pressure in rats. Red blood cell (RBC) transit time measured by the cell transit analyzer increased significantly in the L-NAME treated group, in comparison to normotensive rats. RBC aggregation measured in autologous plasma, by a photometric rheoscope also increased significantly in the hypertensive rats. RBC cytosolic free calcium concentration was also significantly higher in the hypertensive animals. Incubation of RBC from hypertensive and control animals with NO donor, sodium nitroprusside (SNP; 10-1000 microM) for 60 minutes resulted in a dose-dependent decrease in RBC aggregation, however aggregation index was significantly higher in hypertensive group at each SNP concentration. Incubation with SNP had no effect on RBC deformability in the control group, while a slight decrease in RBC transit time was observed only at 10 microM SNP in the hypertensive group. These results imply that NO may play a role in the regulation of rheological properties of RBC and the alterations in these properties may at least in part be involved in the development of L-NAME induced hypertension.
    Clinical hemorheology and microcirculation 02/2000; 22(4):267-75. · 3.40 Impact Factor
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    ABSTRACT: Fetal distress (FD) adversely affects fetal gastric physiology and histology, increasing gastric acid secretion and disturbing gastric protective mechanism. Considering these findings, an experimental study was planned to test whether ranitidine prevents FD-related gastric physiological and histological changes during late gestational period. In this study, a rabbit model of FD was created by way of intermittent maternal aortic occlusion. In group 1 (SC), saline treated animals underwent control operation. In group 2 (SD), FD was created in saline treated animals. In group 3 (RC), ranitidine treated animals underwent control operation. In group 4 (RD), FD was created in ranitidine treated animals. Blood lactic acid levels of the fetuses were 2.3 +/- 1.0 mg/L in SC group and 4.7 +/- 1.8 mg/L in group SD (p < 0.01); 2.5 +/- 0.9 mg/L in group RC and 6.7 +/- 2.5 mg/L in group RD (p < 0.01). Fetal gastric acid secretion was 5.94 +/- 2.13 microEq/h in group SC and 8.26 +/- 2.24 microEq/h in group SD (p < 0.05); 6.63 +/- 2.3 microEq/h in group RC and 6.04 +/- 2.43 microEq/h in group RD (p < 0.05). Fetal gastric PGE2 level was 16.4 +/- 2.65 microg/g-wet weight in group SC and 7.62 +/- 1.86 microg/g-wet weight in group SD (p < 0.01); 15.6 +/- 2.61 microg/g-wet weight in group RC and 8.44 +/- 1.44 microg/g-wet weight in group RD (p < 0.01). In addition, histopathological examination showed normal gastric structure in groups SC and RC, but there were mild erosive and hemorrhagic changes in groups SD and RD. Because prophylactic ranitidine significantly decreased gastric acid secretion, but did not prevent harmful histopathologic effects in FD, it is suggested that gastric damage cannot be avoided by decreasing gastric acid secretion alone. However PGE2 analogs with or without H2 receptor blockers may have a potential role to prevent FD-related gastric damage.
    American Journal of Perinatology 02/1999; 16(5):209-15. · 1.57 Impact Factor
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    ABSTRACT: 1. The effects of halothane and isoflurane anesthesia on red blood cell (RBC) deformability, lipid peroxidation and antioxidant enzymes were tested in rabbits. 2. RBC transit time was significantly increased to 2.12 +/- 0.07 msec after 1-hr halothane anesthesia preceded by 6 mg/kg pentobarbital injections from 1.98 +/- 0.07 msec preanesthesia value (p < 0.05). Thiobarbituric acid-reactive substances also were increased significantly, being 23.35 +/- 2.75 nmol/gHb and 33.11 +/- 5.34 nmol/gHb before and after anesthesia, respectively (p < 0.05). 3. Under halothane anesthesia without prior pentobarbital injection or under isoflurane anesthesia with or without pentobarbital injection, no significant alterations were observed in these parameters. 4. RBC superoxide dismutase activity was decreased in the group anesthetized with the pentobarbital-halothane combination. The impaired RBC deformability and increased oxidant damage might be related to the free radical formation during the metabolism of halothane. Pentobarbital can potentiate this effect either by inducing cytochrome P-450 or by altering antioxidant defense. 5. Alterations in RBC mechanical properties may contribute to the tissue perfusion problems that develop after surgery under general anesthesia.
    General Pharmacology 07/1998; 31(1):33-6.
  • A Yeşilkaya, A Yeğin
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    ABSTRACT: 1. The in vitro effects of cumene hydroperoxide and t-butyl hydroperoxide on intact human erythrocyte membrane (Na(+)-K+)ATPase activities have been studied. 2. (Na(+)-K+)ATPase activities on erythrocyte membranes decreased in agreement with the results of chemiluminescence experiments. 3. Our results demonstrated that the organic hydroperoxides inhibit the activity of (Na(+)-K+) ATPase enzyme and that the antioxidants used prevent this inhibition.
    General Pharmacology 04/1998; 30(4):495-8.
  • A Yeşilkaya, A Yeğin, S Ozdem, T A Aksu
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    ABSTRACT: Recently, it has been suggested that bilirubin may act as a potent biological chain-breaking antioxidant. To observe the effects of free bilirubin on antioxidant reactions in cumene hydroperoxide-treated erythrocytes (15 g hemoglobin/dl), we added bilirubin at four different concentrations (0.5, 1, 5, and 10 mg/dl). We measured the thiobarbituric acid-reactive substance and reduced glutathione levels, and some antioxidant enzyme activities, namely superoxide dismutase, catalase, and glucose-6-phosphate dehydrogenase. Thiobarbituric acid-reactive substance and chemiluminescent signals decreased during the incubation. Superoxide dismutase activities also decreased but not as much as in the control group. Glucose-6-phosphate dehydrogenase activities and reduced glutathione levels increased, but catalase activities remained the same as the control group. Our results suggest that bilirubin--in the concentrations we have used--partially prevented the oxidant effects of cumene hydroperoxide.
    International Journal of Clinical & Laboratory Research 02/1998; 28(4):230-4.
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    ABSTRACT: Although effects of stress on the stomach have been extensively investigated in children and adults, our knowledge about effects of fetal distress (FD) on the fetal stomach is quite limited. Therefore, an experimental study was planned to evaluate the effects of FD on fetal gastric physiology and histology. In this study, a model of FD was created by way of intermittent maternal aortic occlusion in pregnant rabbits. In total, 21 fetuses of 6 pregnant rabbits were available for surgical and laboratory procedures. Laboratory examinations showed that (1) fetal gastric acid secretion was 4.24 +/- 2.68 muEq/h in the control group and 18.08 +/- 6.34 muEq/h in the distress group (p < 0.01) and (2) fetal gastric PGE2 level was 16.59 +/- 6.15 mg/g wet weight in the control group and 9.86 +/- 3.46 mg/g wet weight in the distress group (p < 0.05). Histopathologically, there were mild hemorrhagic and errosive changes in the distressed fetuses, but not in control fetuses. These findings support that FD adversely affects fetal gastric physiology through two mechanisms consisting of increased gastric acid secretion and decreased fetal gastric protection in rabbits. Consequently, gastric injury should be noted as a potential problem among hypoxia-associated abnormalities encountered in the distressed fetus.
    American Journal of Perinatology 09/1997; 14(8):503-7. · 1.57 Impact Factor
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    ABSTRACT: Erythrocytes and hemolysates from 10 normal and 10 glucose-6-phosphate dehydrogenase-deficient individuals were incubated with cumene hydroperoxide, and free radical-induced lipid peroxidation was monitored by chemiluminescence. Chemiluminescence intensities in erythrocytes of normal and deficient subjects were similar in the presence or absence of glucose-6-phosphate dehydrogenase substrates. Hemolysates of normal and deficient subjects also showed similar chemiluminescence in the absence of substrates. However, with the addition of substrates to the incubation medium, deficient hemolysates reached maximum chemiluminescence intensity within a shorter period, and maximum values were higher than in normal hemolysates. We believe this offers a new means of detection of glucose-6-phosphate dehydrogenase-deficient patients.
    International Journal of Clinical & Laboratory Research 02/1997; 27(1):55-9.
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    ABSTRACT: An experimental system which assesses the antioxidant potential of ascorbic acid, glutathione, uric acid, and taurine was developed. The system comprised hemoglobin, luminol, t-butyl hydroperoxide, and different concentrations of antioxidants in TRIS-HCl buffer (pH 7.4). Control assays were performed by excluding antioxidants. Chemiluminescence was detected using a liquid scintillation counter in single photon mode. All antioxidants, when applied in the appropriate concentrations, decreased the maximum chemiluminescence values. The minimum concentrations which decreased the chemiluminescence values were defined for each of the antioxidants.
    International Journal of Clinical & Laboratory Research 02/1996; 26(2):119-23.
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    ABSTRACT: We studied the effect of cumene hydroperoxide, t-butyl hydroperoxide, and hydrogen peroxide on intact healthy human erythrocytes (15 g hemoglobin/dl) using chemiluminescence to monitor peroxidation. We measured the chemiluminescence spectrum, the process of hemolysis, the pH shift, and absorbance spectrum during the incubation with chemicals producing oxidative stress. Maximum chemiluminescence was reached with cumene hydroperoxide at about 50 min, but with t-butyl hydroperoxide at 100 min. The effect of organic hydroperoxide was concentration dependent, whereas the effect of hydrogen peroxide was independent of concentration. Peroxides induced hemolysis after 30 min. The pH shift to alkaline was observed in the first 20-min period. Incubation with organic hydroperoxides induced a decrease in absorption at 580, 545, and 345 nm. Hydrogen peroxide induced a decrease in the same period of time but this returned to the normal range by 120 min. There was no change in absorption at 420 nm with any of the peroxidative agents. Our results suggest that low-level chemiluminescence is a useful model for studying hydroperoxide-induced peroxidation in human erythrocytes.
    International Journal of Clinical & Laboratory Research 02/1996; 26(1):60-8.