A chemiluminescence method is described for the determination of lipid hydroperoxides in chloroform-methanol extracts of foods or biological materials. The method is based on registration of the luminol-dependent light emission induced by hemoglobin-catalyzed decomposition of hydroperoxides. The applicability of the assay and the optimal conditions for assessment of lipid hydroperoxides in different systems were determined. The main advantages of the chemiluminescence method are its high specificity and sensitivity. By this method 0.01nmol of lipid hydroperoxides could be determined.
The effect of vitamin E on prostacyclin (PGI2) production by cultured bovine aortic endothelial cells was evaluated in vitro. We found that human plasma-derived serum (PDS) conveys a stimulatory effect on PGI2 production by cultured vascular endothelial cells. In the present study, therefore, PDS was used as a physiological stimulant for PGI2 production. There was no effect of vitamin E alone on PGI2 production without stimulation by PDS. However, simultaneous addition of vitamin E and PDS to the cultures enhanced PGI2 production in a dose-dependent manner. Furthermore, preincubation with vitamin E prior to stimulation with PDS also enhanced PGI2 production. The enhancing effect of preincubation with vitamin E was demonstrated to occur in a time- and dose-dependent manner. These results clearly indicate that vitamin E at physiological doses can enhance PGI2 production by cultured bovine aortic endothelial cells stimulated with an agent such as PDS. It seems likely that vitamin E may contribute to increase PGI2 synthesis by the vascular wall in vivo, thereby reducing platelet aggregation and thrombus formation.
To study ultra weak chemiluminescence (CL) from polycyclic aromatic hydrocarbons, we examined the CL emission of benzo(a)pyrene (BP) and 3-methylcholanthrene (MC) in postmitochondrial supernatant supplemented with NADPH. The integrated CL emission resulting from the metabolism of the BP and MC displayed saturation kinetics. In each case, the rate of CL emission correlated with the rate of metabolism; and by addition of trichloropropane oxide the CL intensity from BP and MC was decreased. This result suggests that epoxide hydrase is necessary for the CL emission. The CL from both compounds was similar in terms of emission spectrum, indicating that these compounds are metabolized by microsomal enzymes to form exciplex species such as diol-dioxetane and diol-epoxide. Such species could cause both mutagenicity and CL emission.
Blood glucose levels of streptozocin (STZ)-induced diabetic rats dropped from hyperglycemic levels to hypoglycemic levels within 24-48h after treatment with vanadyl sulfate (VS) by intraperitoneal injection. Results of the glucose tolerance test indicated that the diabetes was completely improved by VS administration, but the plasma insulin levels were still low. Determination of both vanadyl and total vanadium in VS-treated STZ-rats suggested that the vanadyl is possibly in a pharmacologically active form. Several vanadyl complexes such as vanadyl-cysteine methyl ester (VCys), -oxalate (VOX), -malonate (VMA), -salicylaldehyde (VSA), and -(+)-tartarate (VTA) were tested by oral administration. The order of normoglycemic effect in STZ-rats was VA>VCys>VTA>VSA>VOX. The action of VCys was dose-dependent in the range of 1-10mgV/kg body weight, and this complex was shown to be a potent agent in restoring the normoglycemic level in STZ-induced diabetic rats.
Guinea pigs given an adequate amount (2.0mg/100g/day) of ascorbic acid and treated with a potent chemical carcinogen, N-nitrosodiethylamine, showed significantly increased hepatic cytochrome P-450 levels without a change in arylhydrocarbon hydroxylase activity. In animals fed an excessive amount (50mg/100g/day) of ascorbic acid, N-nitrosodiethylamine administration significantly decreased hepatic and pulmonary arylhydrocarbon hydroxylase and cytochrome P-450 levels. However, the cytochrome c-reductase activity remained unaffected. Hepatic and pulmonary glutathione S-transferase and reduced glutathione levels responded differentially to N-nitrosodiethylamine challenge in the two groups of animals.
The effect of ellagic acid, a component of Eucalyptus maculata, on lipid peroxidation was examined in rats treated with either carbon tetrachloride or 60Co-irradiation. The increase in the lipid peroxide level of the liver induced by carbon tetrachloride administration was suppressed when ellagic acid was given. This suppressing effect was also found when the liver was examined morphologically. The increase in the lipid peroxide levels of the serum, liver, and spleen after 60Co-irradiation was also abrogated by treatment with ellagic acid. These suppressing effects of ellagic acid exceeded those of α-tocopherol.
Activities of human neutrophils and eosinophils to generate O2- were investigated by use of 2-methyl-6-[p-methoxyphenyl]-3, 7-dihydroimidazo [1, 2-α] pyrazin-3-one (MCLA) as a chemiluminescence probe and N-formylmethionyl-leucyl-phenylalanine (fMLP) and cytochalasin B. In some cases, rat mast cells were used instead of human neutrophils and eosinophils. The luminescence intensity was dependent upon the number of neutrophils, and the maximal luminescence intensity was given at 1×10-6M fMLP with a fixed number of the cells. Luminescence intensity caused by the addition of 0.5μM MCLA and 1×10-6M fMLP to a suspension of eosinophils reached maximum at 30s and decreased rapidly thereafter. Biphasic luminescence intensity was observed with 1×10-6M fMLP-stimulated neutrophils and eosinophils in the presence of 5μg/ml cytochalasin B. These MCLA-dependent luminescences by fMLP-stimulated eosinophils were completely abolished by 0.5μM SOD. On the other hand, addition of MCLA and fMLP to a suspension of rat mast cells showed no significant luminescence irrespective of the presence of cytochalasin B.
The formation of gastric mucosal lesions and the increase in thiobarbituric acid (TBA)-reactive substances induced by water-immersion restraint stress or burn stress in rats were significantly inhibited by the treatment with superoxide dismutase (SOD) and/or catalase. Allopurinol inhibited the formation of gastric mucosal injury induced by burn stress, but not the increase in TBA reactants. A drop in the polymorphonuclear leukocyte (PMN) count induced by an injection of anti-rat PMN antibody did not inhibit the aggravation of gastric mucosal lesions or the increase in TBA reactants in either of the stress models. These results suggest that active oxygen species and lipid peroxidation may play a role in the formation of gastric mucosal damage induced by stress. Reduced microcirculation of the gastric mucosa induced by water-immersion restraint or burn stress did not change following treatment with SOD and/or catalase, suggesting that the effectiveness of SOD and catalase on the gastric mucosal lesions induced by stress may occur via the scavenging of oxygen radicals, and not through an effect on gastric mucosal microcirculation.
This study assessed the biochemical status of serumα-tocopherol (Toc), retinol (Ret), and lipids in elementary school children (ages 9-12 years, 38 males and 37 females) and searched for relationships among them. No significant difference was observed between the sexes for total cholesterol (T-C) (165 and 163mg/100ml for males and females, respectively), high-density lipoprotein-cholesterol (HDL-C) (64 and 62mg/100ml), low-density lipoprotein-cholesterol (LDL-C) (101mg/100ml for both groups), or for triglycerides (TG) (79 and 77mg/100ml). Therefore, the percentage of HDL-C to T-C (39 and 38%) and the LDL-C/HDL-C ratio (1.67 and 1.68) were about the same for both sexes. Toc and Ret levels of males and females were 5.48 and 5.57μg/ml and 478 and 449ng/ml, respectively. The ratios of Toc/TG (7.50 and 7.93μg/mg) and Ret/TG (666 and 613ng/mg) also showed no significant differences. A correlation was found between the T-C level and LDL-C (r=0.85, p<0.001) and also between it and the ratio of LDL-C/HDL-C (r=0.42, p<0.001). The atherogenic index, LDL-C/HDL-C ratio, showed a negative correlation with the HDL-C level (r=-0.73, p<0.001). The Toc level was positively correlated with the ratio of Toc/TG (r=0.45, p<0.001), and the ratio of Toc/TG was inversely correlated with the TG level (r=-0.80, p<0.001). Serum Ret levels showed a positive correlation with the ratios of Ret/TG (r=0.63, p<0.001), and the Ret/TG ratio showed an inverse correlation with the TG level (r=-0.56, p<0.001). The ratios of Toc/TG were positively correlated with the ratios of Ret/TG (r=0.56, p<0.001), and these ratios showed a positive correlation With the HDL-C (r=0.42, p<0.001; and r=0.36, p<0.01, respectively). These results reveal that relationships among the risk factors for coronary heart disease are the same in children as in adults and that the TG levels affect the relative nutritional status of vitamins E and A in serum. Thus, the ratios of Toc/TG and Ret/TG may be useful for assessment of hyperlipidemia in children.
Serum lipid peroxide levels of normal premenopausal women were lower than those of normal postmenopausal women. When premenopausal women received bilateral ovariectomy, their serum lipid peroxide levels were significantly increased when examined 15 days after the operation as compared with their levels before the operation, and these levels remained high even when measured at 60 days after the operation. On the contrary, no change was found in another group of premenopausal women who had received hysterectomy with unilateral ovariectomy. These results support the view that female hormones have a preventive effect on an increase in serum lipid peroxide levels in women.