Novel free radical monitoring in patients with neurological emergency diseases

Detection of Reactive Oxygen and Nitrogen Species by Electron Paramagnetic Resonance (EPR) Technique

During the last decade there has been growing interest in physical-chemical oxidation processes and the behavior of free radicals in living systems. Radicals are known as intermediate species in a variety of biochemical reactions. Numerous techniques, assays and biomarkers have been used to measure reactive oxygen and nitrogen species (ROS and RNS), and to examine oxidative stress. However, many of these assays are not entirely satisfactory or are used inappropriately. The purpose of this chapter is to review current EPR (Electron Paramagnetic Resonance) spectroscopy methods for measuring ROS, RNS, and their secondary products, and to discuss the strengths and limitations of specific methodological approaches.

Vitamin C Induces the Reduction of Oxidative Stress and Paradoxically Stimulates the Apoptotic Gene Expression in Extravillous Trophoblasts Derived From First-Trimester Tissue

AIM

To investigate the effects of vitamin C on the expression of the genes related to apoptosis in extravillous trophoblasts (EVTs) in the first trimester.

METHODS

Extravillous trophoblasts were cultured under 2% O2 followed by 2% O2 or 8% O2 with or without vitamin C. The level of reactive oxygen species (ROS) in the cultured medium was estimated using electron spin resonance spectroscopy. The expression levels of the genes TP53, BCL2, and BAX were quantified using real-time quantitative polymerase chain reaction.

RESULTS

Reactive oxygen species were found to be decreased after adding vitamin C under increasing oxygen concentrations. In addition, the ratio of BAX/BCL2 also increased after adding vitamin C under conditions of 2% O2, while the gene expression level of BCL2 increased after adding vitamin C under increasing oxygen concentrations. In contrast, the gene expression level of TP53 and the ratio of BAX/BCL2 both decreased.

CONCLUSION

We have revealed that vitamin C reduces ROS and may promote the apoptosis of EVTs under conditions of 2% O2 while paradoxically preventing apoptosis under increasing oxygen concentrations.

Evaluation of oxidative stress levels in the conjunctival epithelium of patients with or without dry eye, and dry eye patients treated with preservative-free hyaluronic acid 0.15 % and vitamin B12 eye drops

PURPOSE

Increased levels of oxidative stress have been seen in animal models of dry eye and in the conjunctival epithelial cells of patients with Sjögren's syndrome. The aims of this study were to compare the levels of oxidative stress in patients with dry eye and patients without dry eye and to evaluate the effects of treatment with preservative-free eye drops containing hyaluronic acid 0.15 % and vitamin B12 on oxidative stress and dry eye symptoms.

METHODS

Three cohorts of patients who were to undergo planned cataract surgery were enrolled: patients with dry eye randomized to either no treatment (n = 29) or treatment (n = 32) with hyaluronic acid/vitamin B12 eye drops, and patients without dry eye (n = 42). Patients were assessed by Schirmer's type I test, fluorescein clearance test (FCT), Break Up Time (BUT), and Ocular Surface Disease Index (OSDI). Lipid peroxidation, a marker of oxidative stress, was assessed by LP-CHOLOX test.

RESULTS

Compared with patients without dry eye, patients with dry eye had significantly increased levels of oxidative stress, higher OSDI and FCT scores, and significantly lower Schirmer's test and BUT scores. Treatment with eye drops containing hyaluronic acid 0.15 % and vitamin B12 was associated with significantly reduced levels of oxidative stress and OSDI and FCT scores and significantly increased Schirmer's test and BUT scores.

CONCLUSIONS

These findings indicate that oxidative stress is associated with dry eye and that hyaluronic acid/vitamin B12 eye drops may attenuate oxidative stress and inflammation, improving dry eye symptoms. Further study in controlled clinical trials is warranted.

Status of systemic oxidative stress during therapeutic hypothermia in patients with post-cardiac arrest syndrome

Therapeutic hypothermia (TH) is thought to be due to the downregulation of free radical production, although the details of this process remain unclear. Here, we investigate changes in oxidative stress and endogenous biological antioxidant potential during TH in patients with post-cardiac arrest syndrome (PCAS). Nineteen PCAS patients were enrolled in the study. Brain temperature was decreased to the target temperature of 33°C, and it was maintained for 24 h. Patients were rewarmed slowly (0.1°C/h, <1°C/day). The generation of reactive oxygen metabolites (ROMs) was evaluated in plasma samples by d-ROM test. Plasma antioxidant capacity was measured by the biological antioxidant potential (BAP) test. Levels of d-ROMs and BAP levels during the hypothermic stage (33°C) were suppressed significantly compared with pre-TH induction levels (P < 0.05), while both d-ROM and BAP levels increased with rewarming (33-36°C) and were correlated with brain temperature. Clinical monitoring of oxidative stress and antioxidant potential is useful for evaluating the redox state of patients undergoing TH after PCAS. Additional therapy to support the antioxidant potential in the rewarming stage following TH may reduce some of the observed side effects associated with the use of TH.

Possible involvement of oxidative stress as a causative factor in blood-brain barrier dysfunction in stroke-prone spontaneously hypertensive rats

To elucidate the pathogenic roles of oxidative stress on blood-brain-barrier (BBB) dysfunction, we compared the chronological changes of oxidative stress in blood and cerebral tissue between stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY). Plasma and tissue oxidative stress was assayed by the diacron-reactive oxygen metabolite (d-ROM) test using 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a reference oxidative stress marker. The plasma and cerebral cortex d-ROM levels increased in SHRSP after 16weeks of age, but not in WKY. There were no significant differences in 8-OHdG or lipid peroxidation markers between SHRSP and WKY. Antioxidant capacity, as estimated by the biological antioxidant potential test, was similar between SHRSP and WKY at all ages examined. The changes in plasma and tissue d-ROM levels coincided with changes in glucose transporter-1 and aquaporin-4 expression, as functional constituents of the BBB. These results indicate that plasma oxidative stress increases before the onset of tissue damage, and plays an important role in BBB dysfunction rather than decreases in antioxidant capacity. The plasma d-ROM test appears to be useful for predicting vasogenic cerebral edema in severe hypertension.

Therapeutic time window for edaravone treatment of traumatic brain injury in mice

Traumatic brain injury (TBI) is a major cause of death and disability in young people. No effective therapy is available to ameliorate its damaging effects. Our aim was to investigate the optimal therapeutic time window of edaravone, a free radical scavenger which is currently used in Japan. We also determined the temporal profile of reactive oxygen species (ROS) production, oxidative stress, and neuronal death. Male C57Bl/6 mice were subjected to a controlled cortical impact (CCI). Edaravone (3.0 mg/kg), or vehicle, was administered intravenously at 0, 3, or 6 hours following CCI. The production of superoxide radicals (O₂^∙−) as a marker of ROS, of nitrotyrosine (NT) as an indicator of oxidative stress, and neuronal death were measured for 24 hours following CCI. Superoxide radical production was clearly evident 3 hours after CCI, with oxidative stress and neuronal cell death becoming apparent after 6 hours. Edaravone administration after CCI resulted in a significant reduction in the injury volume and oxidative stress, particularly at the 3-hour time point. Moreover, the greatest decrease in O₂^∙− levels was observed when edaravone was administered 3 hours following CCI. These findings suggest that edaravone could prove clinically useful to ameliorate the devastating effects of TBI.