Neutrophils mediate lipid peroxidation in human red cells

Activated neutrophils (ANs) are known to release reactive oxygen species that may cause oxidative damage to surrounding tissues. We determined if ANs could induce lipid peroxidation (LP) in human red cells and investigated the mechanism involved in this interaction. We studied neonatal glucose-6-phosphate dehydrogenase (G6PD) deficient, and sickle red cells, since each of these are known to be susceptible to oxidant injury. Neutrophils were isolated from whole blood and activated by incubation with opsonized zymosan. Mixtures of such neutrophils and red cells at a ratio of 1:100 were incubated for two hours at 37 degrees C, after which the malonyldialdehyde content in red cells was measured as an index of LP. All red cells underwent LP after AN treatment, and the degree of LP was proportional to the amount of AN in the mixture. Superoxide dismutase and catalase partially inhibited LP. When compared to normal red cells, only sickle cells demonstrated a significant increase in AN-mediated LP. Conversion of hemoglobin to carboxy-hemoglobin increased AN-mediated LP, whereas conversion to met- hemoglobin decreased AN-mediated LP. The protective effect of met- hemoglobin on LP was less in sickle cells than in normal cells. We conclude that AN can induce LP in red cells in vitro and that sickle cells are more susceptible to this process than normal cells. Hemoglobin can serve as an electron trap and protect the cell against peroxidative damage, but this mechanism is impaired in sickle cells. We speculate that the pathogenesis of hemolysis associated with infectious disease may include AN-induced red cell LP.     

Effect of aminoguanidine on lipid peroxidation in streptozotocin-induced diabetic rats.

Diabetes mellitus is postulated to be associated with increased lipid peroxidation, which may contribute to vascular complications. One potential mechanism of the increased lipid peroxidation in diabetes is lipid-linked advanced glycosylation and oxidation. Aminoguanidine (AMGN), the prototype inhibitor of advanced glycosylation end product (AGE) formation, has been recently shown to prevent oxidative modification of low-density lipoprotein (LDL) in vitro at a moderate concentration. It is unknown whether AMGN may act as an antioxidant against lipid peroxidation under hyperglycemia in vivo. To investigate the in vivo effect of AMGN on lipid peroxidation in diabetes, we administered AMGN (1 g/L in drinking water) or vitamin E (400 mg/d for 5 d/wk) to streptozotocin (STZ)-induced diabetic rats for 9 weeks and measured plasma lipid hydroperoxides by ferrous oxidation with xylenol orange II (FOX method) and red blood cell (RBC) membrane malondialdehyde (MDA) and related aldehydes as thiobarbituric acid-reactive substances (TBARS). Plasma lipid hydroperoxide was higher in STZ-induced diabetic rats versus control rats (mean +/- SD, 7.53 +/- 2.03 v 5.62 +/- 0.44 micromol/L, P < .05; n = 8 to 14). RBC membrane TBARS were also higher in STZ-induced diabetic rats than in control rats (2.67 +/- 0.46 v 1.81 +/- 0.19 nmol/mL, P < .05). Plasma lipid hydroperoxide was lower in AMGN-treated (6.23 +/- 0.59 micromol/L, P < .05) and vitamin E-treated (5.29 +/- 0.27 micromol/L, P < .05) diabetic rats than in untreated diabetic rats. RBC membrane TBARS were also lower in AMGN-treated (1.93 +/- 0.12 nmol/mL, P < .05) diabetic rats than in untreated diabetic rats. There was no significant difference in plasma glucose, cholesterol, and triglyceride levels among diabetic groups. Although the mechanism(s) of action of AMGN on lipid peroxidation in vivo should be studied further, these results suggest that AMGN may have an additional beneficial effect as an antioxidant against lipid peroxidation in a prevention trial for diabetic vascular complications.     

Melatonin inhibits lipid peroxidation and stimulates the antioxidant status of diabetic rats

Although melatonin has been established as a free radical scavenger and antioxidant, its effects in diabetes have not been thoroughly investigated. The purpose of this study, therefore, was to investigate the effects of melatonin administration on lipid peroxidation and antioxidant status in streptozotocin (STZ)-induced diabetes in rats. Concentrations of malondialdehyde (MDA) and reduced glutathione (GSH) in erythrocytes and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were compared in 3 groups of 10 rats each [control non-diabetic rats (group I), untreated diabetic rats (group II) and diabetic rats treated with melatonin (group III)]. In the study groups, diabetes developed 3 days after intraperitoneal (i.p.) administration of a single 60-mg/kg dose of STZ. Thereafter, while the rats in group II received no treatment, the rats in group III began to receive a 10-mg/kg i.p. dose of melatonin per day. After 6 wk, the rats in groups II and III had significantly lower body weights and significantly higher blood glucose levels than the rats of group I (P<0.001 and P<0.001, respectively). There were no significant differences in body weight or blood glucose levels between groups II and III. MDA levels in untreated diabetic rats were higher than those in control group rats and in diabetic rats treated with melatonin (P<0.01 and P<0.05, respectively). However, MDA levels in diabetic rats treated with melatonin were not different from those of the control group. The GSH, GSH-Px and SOD levels of untreated diabetic rats were significantly lower than those of the control group (P<0.02, P<0.002 and P<0.05, respectively). In group III, however, melatonin prevented decreases in the thiol antioxidant and the associated enzymes, and so these levels were not significantly different from those in the control group. These results confirm the presence of oxidative stress in STZ-induced experimental diabetes and indicate the beneficial free radical-scavenging and antioxidant properties of melatonin.     

Elevated lipid peroxidation and DNA oxidation in nerve from diabetic rats: effects of aldose reductase inhibition, insulin, and neurotrophic factors

We investigated the effect of treatment with an aldose reductase inhibitor, insulin, or select neurotrophic factors on the generation of oxidative damage in peripheral nerve. Rats were either treated with streptozotocin to induce insulin-deficient diabetes or fed with a diet containing 40% d-galactose to promote hexose metabolism by aldose reductase. Initial time course studies showed that lipid peroxidation and DNA oxidation were significantly elevated in sciatic nerve after 1 week or 2 weeks of streptozotocin-induced diabetes, respectively, and that both remained elevated after 12 weeks of diabetes. The increase in nerve lipid peroxidation was completely prevented or reversed by treatment with the aldose reductase inhibitor, ICI 222155, or by insulin, but not by the neurotrophic factors, prosaptide TX14(A) or neurotrophin-3. The increase in nerve DNA oxidation was significantly prevented by insulin treatment. In contrast, up to 16 weeks of galactose feeding did not alter nerve lipid peroxidation or protein oxidation, despite evidence of ongoing nerve conduction deficits. These observations demonstrate that nerve oxidative damage develops early after the onset of insulin-deficient diabetes and that it is not induced by increased hexose metabolism by aldose reductase per se, but rather is a downstream consequence of flux through this enzyme. Furthermore, the beneficial effect of prosaptide TX14(A) and neurotrophin-3 on nerve function and structure in diabetic rats is not due to amelioration of increased lipid peroxidation.     

Lipid peroxidation and deformability of red blood cells in experimental sepsis in rats: The protective effects of melatonin

Sepsis has been associated with a lipopolysaccharide (LPS) induced bacterial infection and causes biochemical, hemodynamic and physiological alterations in a system. Erythrocyte deformability is very critical for a microcirculatory system to function effectively. Hence, we were interested in examining the effects of a potent antioxidant, melatonin (Mel), on lipid peroxidation and deformability of eythrocytes in LPS-induced experimental sepsis. Male Swiss Albino rats were used in 6 groups, each group comprising of 10 animals. The first group was the control, and the other groups were administered LPS (10 mg/kg, i.p.), Mel (10 mg/kg, i.p.), LPS + L-NAME (5 mM, i.p.), Mel + LPS and Mel + LPS + L-NAME, respectively. Deformability of the RBCs decreased significantly (p < 0.05) in the LPS group in comparison to all other groups. This reduction was prevented with both L-NAME and Mel, but was not as significant as when administering L-NAME or Mel alone. This result was adversely seen in nitric oxide levels, i.e. RBCD was reduced when the NO levels were higher. Therefore in the Mel group the NO levels were reduced while the RBCD enhanced. In addition to these, as an index of lipid peroxidation, the Malondialdehyde levels were elevated in LPS groups whereas the deformability was reduced. This lipid peroxidation was suppressed by Mel and/or L-NAME significantly, where the RBCD was enhanced. These results show that, Melatonin can elevate the RBCD in experimental sepsis due to its nitric oxide scavenging activity and antioxidant effect as revealed by lipid peroxidation.     

Lipid peroxidation in human red cells

In this review we have discussed the chemistry and biochemistry of lipid peroxidation as well as lipid repair mechanisms in human RBCs. We have presented findings relating to the effect of lipid peroxidation on the RBC membrane and on several properties that are determinants of RBC survival in vivo. Since we have not discussed how oxidative damage to membrane proteins or hemoglobin may affect RBC survival, the role of lipid oxidation must be considered in a broader perspective. Considerable evidence has recently been reported to indicate that oxidative hemoglobin denaturation plays an extremely important role in RBC survival. Since all cellular components are susceptible to peroxidative damage, it is likely that multiple reactions will be important with regard to RBC oxidant injury, just as they have been implicated in many degenerative processes, and that certain "compartments" of the membrane may be more susceptible than others due to congenital or acquired defects in membrane structure.     

Cytosolic free calcium levels in sickle red blood cells

In this study, we used a recently developed nuclear magnetic resonance (NMR) technique to measure ionized calcium in sickle erythrocytes. The NMR technique, which involves 19F NMR studies of a fluorinated calcium chelator quinMF, [2-(2-amino-4-methyl-5-fluorophenoxy)methyl-8- aminoquinoline-N,N,N',N'- tetraacetic acid] provides a novel approach to the study of ionized calcium in erythrocytes since the presence of hemoglobin precludes the use of fluorescent calcium indicators. The mean value for ionized calcium in oxygenated sickle erythrocytes was 18 +/- 2 nmol/L (SE). Experiments with normal RBCs gave a mean value of 21 +/- 2 nmol/L (SE). After 1 hour of deoxygenation, mean values for ionized calcium in sickle erythrocytes did not increase as compared with values obtained under oxygen. To investigate whether deoxygenation stimulated endocytosis, sickle erythrocytes were deoxygenated for 1 hour in the presence of impermeant FBAPTA (1,2 bis-(2-amino-5- fluorophenoxy) ethane N,N,N',N'-tetraacetic acid). Cells were then separated from the extracellular medium and assayed for the presence of FBAPTA; they had incorporated significant quantities of the extracellular FBAPTA. This incorporation was not observed with normal erythrocytes. These data are consistent with at least a portion of the elevation in total cell calcium in sickle erythrocytes arising as a consequence of an endocytotic process in which extracellular calcium ions are incorporated into vesicles. Additional experiments show that these intracellular vesicles accumulate Ca2+ on further deoxygenation, consistent with a transient increase in ionized cell calcium. These studies represent the first use of NMR spectroscopy to evaluate endocytotic processes.     

Estrogen levels and lipid peroxidation following exercise

Recent large-scale clinical trials have confirmed that estrogens are powerful antioxidants that effectively prevent lipid peroxidation. In particular, estrogen decreases oxidative modification of low-density lipoprotein both in vitro and in vivo. Estrogen levels fluctuate during the menstrual cycle and during perimenopause, and they are permanently depressed at menopause. Thus, it is of interest to evaluate the lipid peroxidation response under conditions of low estrogen status. It is of additional interest to evaluate lipid peroxidation under such conditions in response to situations that augment free radical production, such as exercise. Aerobic exercise, and more recently anaerobic exercise regimens, are reported to variably affect free radical production and lipid peroxidation. In addition to the exercising woman's estrogen status and menstrual history, other factors to consider when evaluating an exercising woman's risk for increased lipid peroxidation include the intensity of exercise and/or the woman's fitness level as well as her current dietary antioxidant status.     

Glycated hemoglobin and lipid peroxidation in erythrocytes of diabetic patients

In diabetes, glycation and subsequent browning (or glycoxidation) reactions are enhanced by elevated glucose concentrations. It is unclear whether the diabetic state per se also induces an increase in the generation of oxygen-derived free radicals (OFRs). However, there is some evidence that glycation itself may induce the formation of OFRs. OFRs cause oxidative damage to endogenous molecules, including cholesterol. 7-Oxocholesterol is known to be one of the major products of cholesterol oxidation. The level of cholesterol peroxidation products was assessed in erythrocyte membrane lipid by monitoring the peak height ratio of 7-oxocholesterol, one of the products of cholesterol peroxidation, to cholesterol with gas chromatography/mass spectrometry (GC/MS). The peak height ratio of 7-oxocholesterol to cholesterol was used as a biomarker of lipid peroxidation. The hemoglobin A1c (HbA1c) value, an index of glycemic stress, was measured by high-performance liquid chromatography. We examined the relationship between the levels of cholesterol peroxidation products and HbA1c in erythrocytes of diabetic and healthy subjects. There was a significantly increased ratio of 7-oxocholesterol to cholesterol in diabetic erythrocytes compared with control erythrocytes. The ratio of 7-oxocholesterol to cholesterol was significantly correlated with the level of HbA1c. This suggests that glycation of hemoglobin via chronic hyperglycemia is linked to cholesterol peroxidation in erythrocytes of both diabetic and healthy subjects.     

The effect of cadmium on visual evoked potentials in alloxane-induced diabetic rats: relation to lipid peroxidation

Fifty-two healthy male Swiss albino rats, aged three months, were used in this study. They were divided into four groups: control (c), diabetic (D), cadmium (Cd), and diabetic + Cd (D+Cd). A diabetic condition was induced in D and D + Cd groups by administration of alloxane (5 mg/100 g). After this treatment, Cd and D + Cd groups were injected intraperitoneally with CdCl₂ (2 mg/kg week). At the end of the 2-month experimental period, flash visual evoked potentials (FVEPs) of the four groups were recorded with disk electrodes attached with electrode paste 0.5 cm in front of and behind the bregma. The mean latencies off the P₁, N₁, P₂, N₂ and P₃ components were significantly prolonged in the diabetic group compared with the control group. The mean latencies of P₃ in the D + Cd group and of P₁ and P₃ in the Cd group were longer than those of the control group. P₂N₂ amplitude of Cd and D + Cd groups were significantly increased compared with the control group. On the other hand, thiobarbituric acid-reactive substances (TBARS) were determined as an indicator of lipid peroxidation. Our data showed that Cd treatment and diabetic condition caused a significant increase of lipid peroxidation in kidney, brain, retina and lens. Received: 11 January 1999 / Accepted in revised form: 20 December 1999     

Antioxidant enzyme levels in red blood cells from cataract patients.

BACKGROUND: It seems very likely that oxidative mechanisms play a major role in aetiology and pathogenesis of senile cataract. In particular, lens proteins are subject to extensive oxidative modifications. OBJECTIVE: The purpose of this work was to analyze the activities of the protective enzymes superoxide dismutase (SOD) and catalase (CAT) in patients of both sexes affected by cataract. METHODS: The SOD activity was measured in red blood cells using the Minami and Yoshikawa method, and the CAT activity was measured in haemolysates by the method of Aebi. The results were compared with those obtained in a group of healthy subjects of both sexes and matched ages. RESULTS: The SOD activity shows a significant increase when compared with controls, whereas the CAT activity was not modified. CONCLUSIONS: The balance of the anti-oxidants in red blood cells from cataract patients is altered.     

New establishment of hypertensive diabetic animal models: neonatally streptozotocin-treated spontaneously hypertensive rats

Hypertensive diabetic animal models have been developed by injecting streptozotocin (STZ) in neonatal stroke-resistant spontaneously hypertensive rats (SHRSR) and stroke-prone SHR (SHRSP) at the age of two days. After the treatment, the animals showed mild insulin deficiency and mild hyperglycemia at the age of three to four months. Diabetic nephropathy was produced particularly in STZ-treated SHRSR at the age of six months. The effect of neonatal STZ injection on hyperglycemia varied among normotensive Wistar-Kyoto rats (WKY), SHRSR, and SHRSP; SHRSR showed the highest glucose levels, SHRSP showed intermediate levels, and WKY was the lowest. All STZ-treated SHRSR showed glycosuria, while glycosuria was not observed in the treated SHRSP and WKY. Histologic study indicated that these strain differences were partly ascribed to differences in islet B-cell sensitivity to toxic effects of STZ. The development of hypertension was not accelerated in these SHRSR and SHRSP compared with respective nontreated controls. Since STZ-treated SHRSR develop mild diabetic symptom with hypertension and develop mild diabetic glomerulosclerosis, they are good models for studying vascular complications or other problems relating to the synergism between hypertension and diabetes mellitus.     

Comparison of in situ hybridization and immunocytochemistry for the detection of residual beta cells in the pancreas of streptozotocin-treated diabetic rats

The relative efficacy of immunocytochemistry versus in situ hybridization in identifying residual beta cells was studied in rats with streptozotocin-induced diabetes. Consecutive sections of pancreas of streptozotocin-treated diabetic rats and control animals were alternately subjected to in situ hybridization (synthetic oligonucleotides complementary to rat preproinsulin mRNA) and immunocytochemistry (monoclonal antibodies to insulin). The results obtained with both methods were quantitated with the use of computer-assisted image analysis, and the ratio of cells positive by immunocytochemistry to those positive by in situ hybridization was determined. Under normoglycaemic conditions the values obtained by immunocytochemistry correlated well with those obtained by in situ hybridization (immuno/in situ > 95%). In the streptozotocin diabetic animals, however, immunocytochemistry resulted in a distinct underestimation of the number of residual beta cells (immuno/in situ < 80%). This difference was even more striking in small islet cell clusters (<100 m) immuno/in situ 20%). These results suggest that in situ hybridization for prohormone mRNA is the method of choice for the identification of residual or regenerating beta cells with very low insulin content. Caution should be used when interpreting quantitative data in diabetic conditions that are based exclusively on immunocytochemical detection methods.     

Role of xanthine oxidase in ethanol-induced lipid peroxidation in rats

To investigate a possible role of free radical production by xanthine oxidase in the pathogenesis of ethanol-induced hepatic lipid peroxidation, chow-fed rats were given ethanol (5 g/kg) and placed at 32 degrees C for 6 h, which resulted in increased hepatic malondialdehyde levels. Pretreatment with allopurinol in amounts that effectively inhibited xanthine metabolism also significantly decreased ethanol-induced lipid peroxidation, suggesting participation of free radicals produced by xanthine oxidase in the peroxidative process. Both acetaldehyde and purine can serve as substrates for xanthine oxidase. Pretreatment with cyanamide increased hepatic acetaldehyde levels 5-fold, yet this was associated with a decrease in lipid peroxidation, indicating that acetaldehyde is not the xanthine oxidase substrate involved. By contrast, ethanol increased hepatic contents of hypoxanthine and xanthine and enhanced urinary output of allantoin (a final product of xanthine metabolism), incriminating increased metabolism of purines. Ethanol administration also enhanced hepatic nicotinamide adenine dinucleotide (reduced form). A corresponding rise of nicotinamide adenine dinucleotide (reduced form) in vitro inhibited xanthine dehydrogenase activity by 60%-76%. Increased purine degradation, possibly associated with a shift from the dehydrogenase to the xanthine oxidase pathway (secondary to nicotinamide adenine dinucleotide [reduced form]-mediated inhibition of xanthine dehydrogenase activity) is proposed as a possible mechanism for ethanol-stimulated free radical production. Because allopurinol attenuates the associated lipid peroxidation, this agent might be considered for possible therapeutic use in alcohol-induced liver damage.     

冠状动脉慢血流现象与血清脂质过氧化水平的关系

目的: 观察冠状动脉慢血流现象（CSF）患者血清脂质过氧化水平的变化,并探讨CSF的影响因素。方法: 采用TIMI帧计数（TFC）法作为测定CSF的指标,将入选病例分为两组:CSF组35例,正常对照组35例,均排除既往冠心病、心肌病及其他类型心脏病。采用生化法测定血清中超氧化物歧化酶（SOD）,谷胱甘肽过氧化物酶（GSH-PX）,丙二醛（MDA）,过氧化脂质（LPO）的含量。结果: CSF组的血清MDA、LPO明显高于对照组［MDA:（18.9±2.0）μmol/L vs.（10.5±1.3）μmol/L,P<0.01］,［LPO:（2.8±0.4）μmol/L vs.（1.9±0.2）μmol/L,P<0.01］;CSF组血清GSH-PX明显高于对照组［GSH-PX:（0.22±0.04）μmol/L vs.（0.20±0.03）μmol/L,P<0.05］。CSF组血清SOD明显低于对照组［SOD:（72±11）kU/L vs.（79±10）kU/L,P<0.01］。在校正体质量指数、总胆固醇、尿素氮等后CSH-PX、MDA、LPO是CSF的危险因素（分别OR=3.987、4.782、3.381;分别为P<0.05、P<0.01、P<0.01）。SOD则是其保护因素（OR=0.892,P<0.05）。结论: CSF患者血清SOD下降,MDA、LPO、GSH-PX上升,体内氧化应激增强。     

姜黄素对酒精诱导的大鼠脂质过氧化反应的影响

目的:观察姜黄素对酒精性肝病大鼠肝脏氧化应激指标SOD,MDA和NO及血清ALT,AST和ALP水平的影响,探讨姜黄素对酒精诱导的大鼠脂质过氧化反应的影响.方法:将40只SD大鼠随机分为对照组、模型组、姜黄素治疗Ⅰ组(40 mg/kg)、姜黄素治疗Ⅱ组(80 mg/kg)和姜黄素治疗Ⅲ组(160mg/kg),每组8只.除对照组用等量生理盐水灌胃外,其他组均采用56度白酒6.72 g/(kg·d)灌胃的方法制作酒精性肝病大鼠模型,6 wk后姜黄素治疗Ⅰ、Ⅱ、Ⅲ组分别加用姜黄素ig,至12 wk末,处死大鼠,抽取血标本测定血清ALT、AST及ALP水平;留取肝组织标本测定SOD活性、MDA及NO含量,常规HE染色观察肝脏病理变化.结果:与对照组相比,模型组大鼠血清ALT、AST及ALP水平显著升高(86.4±7.5 vs 33.5±10.3;201.0±16.8 vs 116.5±12.0;205.1±20.0 vs 104.6±9.4:均P<0.01);肝组织SOD活性明显下降(80.21±4.55 vs 180.24±27.53,P<0.01),MDA及NO含量显著升高(3.29±0.34vs 1.35±0.12;4.37±0.21 vs 2.72±0.13:均P<0.01).与模型组相比,各姜黄素治疗组血清ALT、AST及ALP水平(Ⅰ组:66.5±9.6,171.4±10.8,176.4±13.7:Ⅱ组:52.4±12.0,145.8±11.9,146.9±13.8:Ⅲ组:40.9±7.9,135.0±11.8,127.1±12.6)明显降低(P<0.05或P<0.01),肝组织MDA及NO含量(Ⅰ组:2.84±0.27,4.01±0.17;Ⅱ组:1.95±0.23,3.60±0.16;Ⅲ组:1.65±0.08,3.22±0.13)均显著降低(P<0.05或P<0.01),而SOD活性(92.36±6.47,117.69±21.96,146.70±27.361明显提高(P<0.05或P<0.01),其中以Ⅱ、Ⅲ治疗组较为显著.模型组大鼠肝细胞出现不同程度的脂肪变性,伴有点、灶状坏死,炎性细胞浸润,各姜黄素治疗组肝脏病理变化不同程度的轻于模型组.结论:姜黄素能抑制脂质过氧化,减轻或防治酒精诱导的肝损伤.