Increased levels of plasma cholesteryl ester hydroperoxides in patients with subarachnoid hemorrhage

Cerebrospinal fluid and plasma ascorbate concentrations following subarachnoid haemorrhage

Background

Ascorbate, the biologically active form of vitamin C, is the primary neural anti-oxidant. Ascorbate concentrations have never been quantified following aneurysmal subarachnoid haemorrhage (aSAH).

Objective

To quantify plasma and cerebrospinal fluid (CSF) ascorbate concentrations in patients following SAH.

Design Setting Participants Main Outcome Measures

Cohort study in which plasma and CSF ascorbate concentrations were measured longitudinally in 12 aSAH patients admitted to a quaternary referral intensive care unit and compared to one-off samples obtained from 20 pregnant women prior to delivery in a co-located obstetric hospital. Data are median [interquartile range] or median (95 % confidence intervals).

Results

Forty-eight plasma samples were obtained from the 12 aSAH patients (eight females, age 62 [53-68] years). Eight participants with extra-ventricular drains provided 31 paired CSF-plasma samples. Single plasma and CSF samples were obtained from 20 pregnant women (age 35 [31-37] years). Initial plasma and CSF ascorbate concentrations post aSAH were less than half those in pregnant controls (plasma: aSAH: 31 [25-39] μmol/L vs. comparator: 64 [59-77] μmol/L; P < 0.001 and CSF: 116 [80-142] μmol/L vs. 252 [240-288] μmol/L; P < 0.001). Post aSAH there was a gradual reduction in the CSF:plasma ascorbate ratio from ∼4:1 to ∼1:1. Six (50 %) patients developed vasospasm and CSF ascorbate concentrations were lower in these patients (vasospasm: 61 (25, 97) vs. no vasospasm: 110 (96, 125) μmol/L; P = 0.01).

Conclusion

Post aSAH there is a marked reduction in CSF ascorbate concentration that is most prominent in those who develop vasospasm.

Neuroprotective Properties of Vitamin C: A Scoping Review of Pre-Clinical and Clinical Studies

There is a need for novel neuroprotective therapies. We aimed to review the evidence for exogenous vitamin C as a neuroprotective agent. MEDLINE, Embase, and Cochrane library databases were searched from inception to May 2020. Pre-clinical and clinical reports evaluating vitamin C for acute neurological injury were included. Twenty-two pre-clinical and 11 clinical studies were eligible for inclusion. Pre-clinical studies included models of traumatic and hypoxic brain injury, subarachnoid and intracerebral hemorrhage, and ischemic stroke. The median [IQR] maximum daily dose of vitamin C in animal studies was 120 [50-500] mg/kg. Twenty-one animal studies reported improvements in biomarkers, functional outcome, or both. Clinical studies included single reports in neonatal hypoxic encephalopathy, traumatic brain injury, and subarachnoid hemorrhage and eight studies in ischemic stroke. The median maximum daily dose of vitamin C was 750 [500-1000] mg, or ∼10 mg/kg for an average-size adult male. Apart from one case series of intracisternal vitamin C administration in subarachnoid hemorrhage, clinical studies reported no patient-centered benefit. Although pre-clinical trials suggest that exogenous vitamin C improves biomarkers of neuroprotection, functional outcome, and mortality, these results have not translated to humans. However, clinical trials used approximately one tenth of the vitamin C dose of animal studies.

From Inert Storage to Biological Activity-In Search of Identity for Oxidized Cholesteryl Esters

Esterification of cholesterol is a universal mechanism to store and transport large quantities of cholesterol between organs and tissues and to avoid toxicity of the excess of cellular cholesterol. Intended for transport and storage and thus to be inert, cholesteryl esters (CEs) reside in hydrophobic cores of circulating lipoproteins and intracellular lipid droplets. However, the inert identity of CEs is dramatically changed if cholesterol is esterified to a polyunsaturated fatty acid and subjected to oxidative modification. Post-synthetic, or epilipidomic, oxidative modifications of CEs are mediated by specialized enzymes, chief among them are lipoxygenases, and by free radical oxidation. The complex repertoire of oxidized CE (OxCE) products exhibit various, context-dependent biological activities, surveyed in this review. Oxidized fatty acyl chains in OxCE can be hydrolyzed and re-esterified, thus seeding oxidized moieties into phospholipids (PLs), with OxPLs having different from OxCEs biological activities. Technological advances in mass spectrometry and the development of new anti-OxCE antibodies make it possible to validate the presence and quantify the levels of OxCEs in human atherosclerotic lesions and plasma. The article discusses the prospects of measuring OxCE levels in plasma as a novel biomarker assay to evaluate risk of developing cardiovascular disease and efficacy of treatment.

Beyond and behind the fingerprints of oxidative stress in age-related diseases: Secrets of successful aging

Several years after the first publication of the definition of oxidative stress by Helmut Sies, this topic is still focus of a large body of attention and research in the field of aging, neurodegeneration and disease prevention. The conduction of clinical and epidemiological research without a solid biochemical rationale has led to largely frustrating results without being able to disprove the oxidative stress hypothesis. The present work is dedicated to Helmut Sies and describes the successful scientific approach to bench-to-bedside (-to-behavior) oxidative stress clinical research.

Telmisartan ameliorates oxidative stress and subarachnoid haemorrhage-induced cerebral vasospasm

OBJECTIVES

Growing evidence suggests that oxidative stress is one of the factors contributing to subarachnoid haemorrhage (SAH)-induced cerebral vasospasm. SAH-induced cerebral vasospam alters thioredoxin (Trx) cycle enzymes and thioredoxin-interacting protein (TXNIP) as an important endogenous antioxidant system. In this study, we have explored the effects of telmisartan on the vascular morphological changes, endothelial apoptosis, tissue oxidative stress status and the level of Trx cycle enzymes/ TXNIP in a rabbit SAH model.

METHODS

Forty male New Zealand rabbits were randomly divided into five groups of eight rabbits each: control group, sham group, SAH group, SAH + vehicle group and SAH + telmisartan group. SAH was created by a single cisterna magna blood injection. SAH + telmisartan group received telmisartan treatment (5 mg/kg intraperitoneal, once daily) for 72 h. The brainstem tissue Trx1, Trx2, Trx reductase (TrxR), TrxR1and TXNIP levels were investigated. Total oxidant status (TOS), total antioxidant status (TAS), malondialdehyde (MDA) levels and tumour necrosis factor alpha (TNF alpha) levels were investigated. Basilar artery segments were investigated for cross-sectional area, wall thickness measurements and endothelial apoptosis.

RESULTS

Telmisartan treatment restored the lowered level of Trx1, TrxR, TAS and the expression of TrxR1 seen in SAH. Telmisartan treatment also decreased TXNIP expression, TOS, MDA and TNF alpha levels. Morphological changes of cerebral vasospasm were attenuated after treatment. Endothelial apoptosis significantly reduced.

DISCUSSION

Treatment with telmisartan ameliorates oxidative stress and SAH-induced cerebral vasospasm in rabbits. These effects of telmisartan may be associated with downregulation of TXNIP and upregulation of Trx/TrxR.

Role of oxidized LDL and lectin-like oxidized LDL receptor-1 in cerebral vasospasm after subarachnoid hemorrhage

OBJECT

Cerebral vasospasm after subarachnoid hemorrhage (SAH) is a serious complication. Free radicals derived from subarachnoid clotting are recognized to play an important role. Oxidized low-density lipoprotein (ox-LDL) and lectin-like oxidized LDL receptor-1 (LOX-1) have been shown to be related to the pathogenesis of atherosclerosis and may increase in cerebral arteries after SAH, due to the action of free radicals derived from a subarachnoid clot. These molecules may also affect the pathogenesis of vasospasm, generating intracellular reactive oxygen species and downregulating the expression of endothelial NO synthase (eNOS). If so, apple polyphenol might be effective in the prevention of vasospasm due to an abundant content of procyanidins, which exhibit strong radical scavenging effects, and the ability to suppress ox-LDL and LOX-1. The purposes of this study were to investigate changes in levels of ox-LDL and LOX-1 after SAH and whether administering apple polyphenol can modify cerebral vasospasm.

METHODS

Forty Japanese white rabbits were assigned randomly to 4 groups: an SAH group (n = 10); a shamoperation group (n = 10), which underwent intracisternal saline injection; a low-dose polyphenol group (n = 10) with SAH and oral administration of apple polyphenol at 10 mg/kg per day from Day 0 to Day 3; and a high-dose polyphenol group (n = 10) with SAH and oral administration of apple polyphenol at 50 mg/kg per day. At Day 4, the basilar artery and brain was excised from each rabbit. The degree of cerebral vasospasm was evaluated by measuring the cross-sectional area of each basilar artery, and the expression of ox-LDL, LOX-1, and eNOS was examined for each basilar artery by immunohistochemical staining and reverse transcriptase polymerase chain reaction. In addition, neuronal apoptosis in the cerebral cortex was evaluated by TUNEL.

RESULTS

Compared with the sham group, the expression of ox-LDL and LOX-1 in the basilar arterial wall was significantly increased in the SAH group, the expression of eNOS was significantly decreased, and the cross-sectional area of basilar artery was significantly decreased. Compared with the SAH group, the cross-sectional area of basilar artery was increased in the polyphenol groups, together with the decreased expression of ox-LDL and LOX-1 and the increased expression of eNOS. In the high-dose polyphenol group, those changes were statistically significant compared with the SAH group. In the low-dose polyphenol group, those changes were smaller than in the high-dose polyphenol group. No apoptosis and no changes were seen in the cerebral cortex in all groups.

CONCLUSIONS

This is the first study suggesting that ox-LDL and LOX-1 increase due to SAH and that they may play a role in the pathogenesis of vasospasm. It is assumed that procyanidins in apple polyphenol may inhibit a vicious cycle of ox-LDL, LOX-1, and ROS in a dose-dependent manner. Apple polyphenol is a candidate for preventive treatment of cerebral vasospasm.

The importance of early brain injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a medical emergency that accounts for 5% of all stroke cases. Individuals affected are typically in the prime of their lives (mean age 50 years). Approximately 12% of patients die before receiving medical attention, 33% within 48 h and 50% within 30 days of aSAH. Of the survivors 50% suffer from permanent disability with an estimated lifetime cost more than double that of an ischemic stroke. Traditionally, spasm that develops in large cerebral arteries 3-7 days after aneurysm rupture is considered the most important determinant of brain injury and outcome after aSAH. However, recent studies show that prevention of delayed vasospasm does not improve outcome in aSAH patients. This finding has finally brought in focus the influence of early brain injury on outcome of aSAH. A substantial amount of evidence indicates that brain injury begins at the aneurysm rupture, evolves with time and plays an important role in patients' outcome. In this manuscript we review early brain injury after aSAH. Due to the early nature, most of the information on this injury comes from animals and few only from autopsy of patients who died within days after aSAH. Consequently, we began with a review of animal models of early brain injury, next we review the mechanisms of brain injury according to the sequence of their temporal appearance and finally we discuss the failure of clinical translation of therapies successful in animal models of aSAH.

Cerebrospinal fluid catecholamine levels as predictors of outcome in subarachnoid hemorrhage

OBJECTIVE

Subarachnoid hemorrhage (SAH) is associated with marked sympathetic activation at the time of ictus. The purpose of this study is to determine whether early central catecholamine levels measured from cerebrospinal fluid (CSF) relate to outcome in patients with SAH.

METHODS

Observational study of consecutive SAH grade 3-5 patients who underwent ventriculostomy placement, but did not undergo open craniotomy for aneurysm obliteration. CSF samples were obtained during the first 48 h following symptom onset and assayed for catecholamine levels. Statistical analyses were performed to determine whether the levels predicted mortality by day 15 or mortality/disability by day 30.

RESULTS

For the 102 patients included, mean age was 58, and 73% were female - 21% experienced day-15 mortality, and 32% experienced mortality/disability by day 30. Early mortality was related to Hunt-Hess (H/H) grade (p < 0.001), neurogenic cardiomyopathy (NC) (p = 0.003), cerebral infarction (p = 0.001), elevated intracranial pressure (ICP) (p = 0.029), epinephrine (EPI) level (p = 0.002) and norepinephrine/3,4-dihydroxyphenylglycol (NE/DHPG) ratio (p = 0.003). Mortality/disability was related to H/H grade (p < 0.001), NC (p = 0.018), infarction (p < 0.001), elevated ICP (p = 0.002), EPI (p = 0.004) and NE/DHPG (p = 0.014). Logistic regression identified age [OR 1.09 (95% CI 1.01-1.17)], H/H grade [9.52 (1.19-77)], infarction [10.87 (1.22-100)], ICP elevation [32.26 (2-500)], EPI [1.06 (1.01-1.10)], and (inversely) DHPG [0.99 (0.99-1.00)] as independent predictors of early mortality. For mortality/disability, H/H grade [OR 21.74 (95% CI 5.62-83)], ICP elevation [18.52 (1.93-166)], and EPI [1.05 (1.02-1.09)] emerged as independent predictors. Proportional-hazards analysis revealed age [HR 1.041 (95% CI 1.003-1.08)], H/H grade [6.9 (1.54-31.25)], NC [4.31 (1.5-12.35)], and EPI [1.032 (1.009-1.054)] independently predicted early mortality.

CONCLUSIONS

CSF catecholamine levels are elevated in SAH patients who experience early mortality or disability. EPI may potentially serve as useful index of outcome in this population of patients with SAH.

Biomarkers and vasospasm after aneurysmal subarachnoid hemorrhage

Subarachnoid hemorrhage from the rupture of a saccular aneurysm is a devastating neurological disease that has a high morbidity and mortality not only from the initial hemorrhage, but also from the delayed complications, such as cerebral vasospasm. Cerebral vasospasm can lead to delayed ischemic injury 1 to 2 weeks after the initial hemorrhage. Although the pathophysiology of vasospasm has been described for decades, the molecular basis remains poorly understood. With the many advances in the past decade in the development of sensitive molecular biological techniques, imaging, biochemical purification, and protein identification, new insights are beginning to reveal the etiology of vasospasm. These findings will not only help to identify markers of vasospasm and prognostic outcome, but will also yield potential therapeutic targets for the treatment of this disease. This review focuses on the methods available for the identification of biological markers of vasospasm and their limitations, the current understanding as to the utility and prognostic significance of identified biomarkers, the utility of these biomarkers in predicting vasospasm and outcome, and future directions of research in this field.

Oxidative stress and its role in the pathogenesis of ischaemic stroke

Stroke is one of the leading causes of mortality and morbidity, with astronomical financial repercussions on health systems worldwide. Ischaemic stroke accounts for approximately 80-85% of all cases and is characterised by the disruption of cerebral blood flow and lack of oxygen to the affected area. Oxidative stress culminates due to an imbalance between pro-oxidants and antioxidants and consequent excessive production of reactive oxygen species. Reactive oxygen species are biphasic, playing a role in normal physiological processes and are also implicated in a number of disease processes, whereby they mediate damage to cell structures, including lipids, membranes, proteins, and DNA. The cerebral vasculature is a major target of oxidative stress playing a critical role in the pathogenesis of ischaemic brain injury following a cerebrovascular attack. Superoxide, the primary reactive oxygen species, and its derivatives have been shown to cause vasodilatation via the opening of potassium channels and altered vascular reactivity, breakdown of the blood-brain barrier and focal destructive lesions in animal models of ischaemic stroke. However, reactive oxygen species are involved in normal physiological processes including cell signalling, induction of mitogenesis, and immune defence. Primarily, this review will focus on the cellular and vascular aspects of reactive oxygen and nitrogen species generation and their role in the pathogenesis of ischaemia-reperfusion phenomena. Secondly, the proposed mechanisms of oxidative stress-related neuronal death will be reflected upon and in summation specific targeted neuroprotective therapies targetting oxidative stress and their role in the pathogenesis of stroke will be discussed.

Role of gap junctions in early brain injury following subarachnoid hemorrhage

Gap junction inhibition has been demonstrated to reverse the vascular contraction that follows experimental subarachnoid hemorrhage. This study hypothesizes that the use of established gap junction inhibitors: octonal and carbenoxolone, to interrupt cell to cell communication will provide neuroprotection against early brain injury after SAH. The filament perforation model of SAH was performed in male Sprague-Dawley rats weighing between 300 and 380 g. Octanol (260.46 mg or 781.38 mg/kg), carbenoxolone (100 mg/kg), or vehicles were given via intraperitoneal injection 1 h after SAH. Neurologic deficits and cerebral apoptosis were assessed 24 and 72 h after SAH. In addition, Western blot analysis was performed to confirm the in vivo inhibition of CNS gap junctions. The administration of octanol and carbenoxolone both failed to attenuate the neurological deficits induced by SAH, and they did not reduce neuronal apoptosis. Additionally, carbenoloxone increased post SAH mortality and exacerbated SAH-induced apoptosis. Despite previous studies that show gap junction inhibitors reverse vasospasm following experimental SAH, they failed to improve clinical outcomes or provide neuroprotection in this study.

Correlation of F4-neuroprostanes levels in cerebrospinal fluid with outcome of aneurysmal subarachnoid hemorrhage in humans

Aneurysmal subarachnoid hemorrhage (aSAH) is one type of hemorrhagic stroke in humans. F(2)-isoprostanes (F(2)-IsoPs) and F(4)-neuroprostanes (F(4)-NPs), derived from arachidonic acid and docosahexaenoic acid (DHA), respectively, are specific markers of lipid peroxidation. We previously demonstrated that F(2)-IsoPs levels in cerebrospinal fluid (CSF) of aSAH patients positively correlated with poor clinical conditions. In this work, we refined F(4)-NPs analysis and investigated the role of potential oxidative damage to neurons in aSAH patients by detecting F(4)-NPs in CSF. [(2)H(4)]-15-F(2t)-IsoP, rather than [(18)O(2)]-17-F(4c)-NP or [(2)H(4)]-PGF(2 alpha), was used as the internal standard for F(4)-NPs analysis. One problem of the use of [(18)O(2)]-17-F(4c)-NP was the potential interference resulting from F(2)-dihomo-IsoPs in CSF. CSF specimens of 15 aSAH patients for up to 10 days and those of 12 non-aSAH controls were analyzed. First day, mean, and peak levels of F(4)-NPs were all significantly higher in aSAH patients than in controls and correlated with the Fisher Scale and 3-month Glasgow Outcome Scale, but only mean levels of F(4)-NPs correlated with Hunt and Hess Grade. The results first demonstrate oxidative damage to DHA in brain tissue following aSAH and suggest that F(4)-NPs in CSF could be a better predictor for outcome of aSAH than F(2)-IsoPs at early time points.

Pathogenesis of cerebral vasospasm following aneurysmal subarachnoid hemorrhage: putative mechanisms and novel approaches

Cerebral vasospasm is a potentially incapacitating or lethal complication in patients with aneurysmal subarachnoid hemorrhage (SAH). The development of effective preventative and therapeutic interventions has been largely hindered by the fact that the underlying pathogenic mechanisms of cerebral vasospasm remain poorly understood. However, intensive research during the last 3 decades has identified certain mechanisms that possibly play a role in its development. Experimental data suggest that calcium-dependent and -independent vasoconstriction is taking place during vasospasm. It appears that the breakdown products of blood in the subarachnoid space are involved, through direct and/or indirect pathways, in the development of vasospasm after SAH. Free radicals reactions, an imbalance between vasoconstrictor and vasodilator substances (endothelium derived substances, e.g., nitric oxide, endothelin; arachidonic acid metabolites, e.g., prostaglandins, prostacyclin), inflammatory processes, an upheaval of neuronal mechanisms that regulate vascular tone, endothelial proliferation, and apoptosis have all been put forward as causative and/or pathogenic factors. Translational research in the field of vasospasm has traditionally aimed to identify agents/interventions in order to block the cascades initiated after SAH. The combination of novel approaches such as cerebral microdialysis, magnetic resonance spectroscopy, proteomics, and lipidomics could serve a dual purpose: elucidating the complex pathobiochemistry of vasospasm and providing clinicians with tools for early detection of this feared complication. The purpose of this Mini-Review is to provide an overview of the pathogenesis of cerebral vasospasm and of novel approaches used in basic and translational research.

Calcium channel blocker, azelnidipine, reduces lipid hydroperoxides in patients with type 2 diabetes independent of blood pressure

Anti-hypertensive agents with antioxidative effects are potentially useful for diabetic patients with hypertension to prevent the onset and progression of their complication. While dihydropyridine-type calcium antagonists are among the frequently used anti-hypertensive drugs, azelnidipine, a novel calcium antagonist, has been reported to have a unique anti-oxidative effect in vitro and in animals. In this study, we measured lipid hydroperoxides in human sample using diphenyl-1-pyrenylphosphine for the first time, and used the value of lipid hydroperoxides as an index of oxidative stress. Then, we compared the antioxidative properties of azelnidipine and amlodipine, a frequently used calcium antagonist in hypertensive diabetic patients. Administration of vitamin C and E for 8 weeks significantly reduced lipid hydroperoxides in erythrocyte membrane in normal subjects. In hypertensive diabetic patients, azelnidipine treatment for 12 weeks induced a more significant fall in erythrocyte lipid hydroperoxide level than amlodipine, though blood pressure during each treatment was comparable. Our data confirm the usefulness of lipid hydroperoxides in erythrocyte membrane as a marker of oxidative stress in vivo, and indicate that azelnidipine has a unique antioxidative property in human.

The joint effect of oxidative stress and antioxidants on the risk of an aneurysmal rupture subarachnoid hemorrhage: a case-control study in Japan

PURPOSE

A case-control study was conducted in Japan to examine the joint effects of oxidative stress and antioxidants on the risk of subarachnoid hemorrhage (SAH).

METHODS

The study included 201 consecutive patients with first spontaneous SAH aged 30 to 79 years who had aneurysm(s) confirmed by angiography and/or computed tomographic scan and were admitted to two medical hospitals in Nagoya, Japan, from April 1992 to March 1997. Community control subjects were identified and matched to each case by gender and age (+/-2 years). Conditional logistic regression modeling was used to compute odds ratios (ORs) adjusted for body mass index, physical activity, family history of SAH, a history of hypertension, drinking habit, and frequency of green-yellow vegetables and fruits, and tea consumption.

RESULTS

The greatest risk for SAH was posed by combination of current smoking and a less frequent intake of soy products (adjusted OR = 5.3; 95% confidence interval [CI], 2.0 to 14.3). Less frequent intake of soy products significantly elevated SAH risk, independent of smoking habits.

CONCLUSION

These data suggested that enhancement of the antioxidant defense system such as much intake of soy products may be important in preventing SAH rather than the reduction of such oxidants as smoking. Our findings should prove useful for targeting individuals/populations in programs for primary prevention of SAH.

Elimination of lipid peroxide during hemodialysis

BACKGROUND/AIMS

This study is aimed to show the antioxidative effect of hemodialysis (HD) by demonstrating the elimination of toxic lipid peroxides.

METHODS

Blood samples were obtained from patients on regular maintenance HD before and 15, 30, 60, 120 and 240 min after the start of each HD session. Plasma cholesteryl ester hydroperoxide (CE-OOH), phosphatidylcholine hydroperoxide (PC-OOH), and eliminators of lipid peroxides (LOOH) such as apolipoprotein A-I (apoA-I) and lecithin:cholesterol acyltransferase (LCAT) were investigated. The hydroxyl radical scavenging activity was measured for the evaluation of the pro-oxidative side.

RESULTS

CE-OOH and PC-OOH were elevated in patients with chronic kidney disease both on and not on HD, while these values were much higher in HD patients. CE-OOH quickly dropped during the first 30 min of HD, then gradually decreased until 240 min. CE-OOH concentrations were related to those of apoA-I. In contrast, PC-OOH showed an increase 30 min after the start of HD, a change which resembled that of LCAT and was the reverse of the hydroxyl radical scavenging activity.

CONCLUSION

These results demonstrate the antioxidative action through CE-OOH elimination involving apoA-I. The pro- and antioxidative effects of HD on LOOH are not uniform but PC-OOH is mainly influenced prooxidatively.

Increased levels of F2-isoprostanes following aneurysmal subarachnoid hemorrhage in humans

Subarachnoid hemorrhage (SAH) resulting from aneurysmal rupture is the major cause of nontraumatic SAH. We hypothesized that oxidative stress could be increased following aneurysmal SAH due to hemoglobin release and ischemia-reperfusion injury and that may further contribute to poor outcome. We collected plasma and cerebrospinal fluid (CSF) samples from 11 non-SAH controls and 15 aneurysmal SAH patients for up to 10 days after surgery and investigated status of oxidative stress in patients. Results showed that mean or peak levels of F(2)-isoprostanes (F(2)-IsoPs), a specific marker of lipid peroxidation, and total nitrate/nitrite, metabolites of nitric oxide and peroxynitrite, in CSF and plasma were significantly higher in SAH patients than in controls. First-day levels were also higher in CSF, but not in plasma, in SAH patients. Moreover, mean and peak levels of CSF F(2)-IsoPs were positively correlated with poor outcome or severity of clinical conditions in patients. Furthermore, levels of retinol, delta-tocopherol, beta+gamma-tocopherol, lutein, beta-carotene, and coenzyme Q(10) in plasma were significantly lower in SAH patients than in controls. Our results indicate that oxidative damage may play important roles in the severity and complications of aneurysmal SAH and suggest that means to suppress lipid peroxidation may be beneficial in improving the outcome of aneurysmal SAH.

Bilirubin production and oxidation in CSF of patients with cerebral vasospasm after subarachnoid hemorrhage

Delayed cerebral vasospasm after subarachnoid hemorrhage (SAH) remains a significant cause of mortality and morbidity; however, the etiology is, as yet, unknown, despite intensive research efforts. Research in this laboratory indicates that bilirubin and oxidative stress may be responsible by leading to formation of bilirubin oxidation products (BOXes), so we investigated changes in bilirubin concentration and oxidative stress in vitro, and in cerebral spinal fluid (CSF) from SAH patients. Non-SAH CSF, a source of heme oxygenase I (HO-1), and blood were incubated, and in vitro bilirubin production measured. Cerebrospinal fluid from SAH patients was collected, categorized using stimulation of vascular smooth muscle metabolism in vitro, and information obtained regarding occurrence of vasospasm in the patients. Cerebral spinal fluid was analyzed for hemoglobin, total protein and bilirubin, BOXes, malonyldialdehyde and peroxidized lipids (indicators of an oxidizing environment), and HO-1 concentration. The formation of bilirubin in vitro requires that CSF is present, as well as whole, non-anti-coagulated blood. Bilirubin, BOXes, HO-1, and peroxidized lipid content were significantly higher in CSF from SAH patients with vasospasm, compared with nonvasospasm SAH CSF, and correlated with occurrence of vasospasm. We conclude that vasospasm may be more likely in patients with elevated BOXes. The conditions necessary for the formation of BOXes are indeed present in CSF from SAH patients with vasospasm, but not CSF from SAH patients without vasospasm.

Prediction of Cerebral Vasospasm in Patients Presenting with Aneurysmal Subarachnoid Hemorrhage: A Review

OBJECTIVE:

Cerebral vasospasm is a devastating medical complication of aneurysmal subarachnoid hemorrhage (SAH). It is associated with high morbidity and mortality rates, even after the aneurysm has been treated. A substantial amount of experimental and clinical research has been conducted in an effort to predict and prevent its occurrence. This research has contributed to significant advances in the understanding of the mechanisms leading to cerebral vasospasm. The ability to accurately and consistently predict the onset of cerebral vasospasm, however, has been challenging. This topic review describes the various methodologies and approaches that have been studied in an effort to predict the occurrence of cerebral vasospasm in patients presenting with SAH.

METHODS:

The English-language literature on the prediction of cerebral vasospasm after aneurysmal SAH was reviewed using the MEDLINE PubMed (1966–present) database.

RESULTS:

The risk factors, diagnostic imaging, bedside monitoring approaches, and pathological markers that have been evaluated to predict the occurrence of cerebral vasospasm after SAH are presented.

CONCLUSION:

To date, a large blood burden is the only consistently demonstrated risk factor for the prediction of cerebral vasospasm after SAH. Because vasospasm is such a multifactorial problem, attempts to predict its occurrence will probably require several different approaches and methodologies, as is done at present. Future improvements in the prevention of cerebral vasospasm from aneurysmal SAH will most likely require advances in our understanding of its pathophysiology and our ability to predict its onset.

Time course of production of hydroxyl free radical after subarachnoid hemorrhage in dogs

Vasospasm after subarachnoid hemorrhage (SAH) is associated with lipid peroxidation. However, lipid peroxides increase in a delayed fashion after SAH and may be a byproduct of but not a cause of vasospasm. This study correlated vasospasm with hydroxyl free radical and lipid peroxide levels. 24 dogs had baseline cerebral angiography and induction of SAH by 2 injections of blood into the cisterna magna at baseline and 2 days later. Angiography was repeated 4, 7, 10, 14 or 21 days after the first injection (n = 4 per group) and a microdialysis catheter was inserted into the premedullary cistern. Control dogs (n = 4) underwent angiography and microdialysis but not SAH. Salicylic acid, 100 mg/kg, was administered intravenously, and microdialysis fluid was collected and analyzed by high pressure liquid chromatography for 2,3- and 2,5-dihydroxybenzoic acids (DHBA). Malondialdehyde was measured in subarachnoid clot removed from the prepontine cistern and in the basilar artery itself at the time of euthanasia. Significant vasospasm developed 4 to 14 days after SAH. Malondialdehyde levels were significantly elevated in the basilar artery and subarachnoid clot 4 days after SAH (p < 0.0001, ANOVA) but not at other times. 2,5-DHBA levels were significantly greater than control at 4 to 14 days and they peaked at 4 days (p < 0.05, ANOVA). 2,3-DHBA was significantly increased at 4 days after SAH (p < 0.05, ANOVA). There were significant correlations between basilar artery malondialdehyde levels and vasospasm and cerebrospinal fluid 2,5-DHBA levels and vasospasm. These results suggest the presence of hydroxyl free radical after SAH and demonstrate a correlation between such production, as measured by trapping with salicylate, and the early phase of vasospasm. The correlation with vasospasm implicates free radicals and lipid peroxidation in this phase of vasospasm.

Cholesteryl ester oxidation products in atherosclerosis

Lipid oxidation products are formed at sites of increased oxidant stress and have been shown to accumulate in atherosclerotic lesions. Although recent studies have focused on the formation and metabolism of oxidized lipids, very little is known about their biological activities and possible (patho)physiological functions. Oxidation of cholesteryl esters containing unsaturated fatty acids leads to the formation of hydroperoxides that are either reduced to alcohols or degrade into biologically active "core-aldehydes". In this review, the mechanisms of formation and metabolic fate of oxidized cholesteryl esters, their occurrence, as well as possible biological activities are discussed. Based on the current knowledge, cholesteryl ester oxidation leads to the formation of biologically active substances, which could actively contribute to the progression of atherosclerotic lesions and their resulting complications.

Increased levels of lipid peroxides as predictive of symptomatic vasospasm and poor outcome after aneurysmal subarachnoid hemorrhage

OBJECT

Cerebral vasospasm remains a devastating medical complication of aneurysmal subarachnoid hemorrhage (SAH). Reactive oxygen species and subsequent lipid peroxidation are reported to participate in the causes of cerebral vasospasm. This clinical study was performed to investigate the relationships between levels of lipid peroxides in cerebrospinal fluid (CSF) and both delayed cerebral vasospasm and clinical outcome after SAH.

METHODS

Levels of phosphatidylcholine hydroperoxide (PCOOH) and cholesteryl ester hydroperoxide (CEOOH) in the CSF were measured in 20 patients with aneurysmal SAH. The patients' CSF was collected within 48 hours of hemorrhage onset and on Day 6 or 7 post-SAH. On Day 7, angiography was performed to verify the degree and extent of the vasospasm. The relationship between the patients' clinical profiles and the levels of lipid peroxides in the CSF were investigated. Both PCOOH and CEOOH were detectable in CSF, and their levels decreased within 7 days after onset of SAH. The levels of CEOOH within 48 hours after onset of hemorrhage were significantly higher in patients in whom symptomatic vasospasm later developed than in patients in whom symptomatic vasospasm did not develop (p = 0.002). Levels of PCOOH measured within 48 hours after onset of hemorrhage were significantly higher in patients with poor outcomes than in patients with good outcomes (p = 0.043).

CONCLUSIONS

Increased levels of lipid peroxides measured in the CSF during the acute stage of SAH were predictive of both symptomatic vasospasm and poor outcome. Measurements of lipid peroxides in the CSF may be useful prognostically for patient outcomes as well as for predicting symptomatic vasospasm.

Clinical trials in head injury

Traumatic brain injury (TBI) remains a major public health problem globally. In the United States the incidence of closed head injuries admitted to hospitals is conservatively estimated to be 200 per 100,000 population, and the incidence of penetrating head injury is estimated to be 12 per 100,000, the highest of any developed country in the world. This yields an approximate number of 500,000 new cases each year, a sizeable proportion of which demonstrate significant long-term disabilities. Unfortunately, there is a paucity of proven therapies for this disease. For a variety of reasons, clinical trials for this condition have been difficult to design and perform. Despite promising pre-clinical data, most of the trials that have been performed in recent years have failed to demonstrate any significant improvement in outcomes. The reasons for these failures have not always been apparent and any insights gained were not always shared. It was therefore feared that we were running the risk of repeating our mistakes. Recognizing the importance of TBI, the National Institute of Neurological Disorders and Stroke (NINDS) sponsored a workshop that brought together experts from clinical, research, and pharmaceutical backgrounds. This workshop proved to be very informative and yielded many insights into previous and future TBI trials. This paper is an attempt to summarize the key points made at the workshop. It is hoped that these lessons will enhance the planning and design of future efforts in this important field of research.

Cholesterol 7-hydroperoxides in rat skin as a marker for lipid peroxidation

Concentrations of cholesterol 7alpha- and 7beta-hydroperoxides (Ch 7-OOHs) in the skin of rats were determined by HPLC with a chemiluminescence detector. We demonstrated that (a) the concentrations of Ch 7-OOHs in rat skin were highly correlated with rat age (r = 0.929; N = 51, 1 to 55 weeks old), (b) the concentrations of Ch 7-OOHs in the skin of rats in an ambient light room were not significantly different from those found in rats kept in a dark room for 12 weeks, and (c) lipid peroxidation in vitro induced by ADP-Fe2+ caused an increase in the concentrations of Ch 7-OOHs in homogenates of rat skin. These results indicated that levels of Ch 7-OOHs in skin might be a good marker for aging of rats and might be independent of housing illumination, thus a good marker for endogenous lipid peroxidation. Furthermore, we observed that ultraviolet light B (UVB) irradiation markedly enhanced the concentrations of Ch 7-OOHs in the skin of rats in vivo depending on the duration of the irradiation, and the increases in Ch 7-OOHs were inhibited by radical scavengers, i.e. tocopherols. Therefore, it was suggested that the levels of Ch 7-OOHs in the skin could also be a good marker for UVB-dependent lipid peroxidation.

Quantitative determination of cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides in rat skin

An assay method for determination of cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides (ChOOHs) in rat skin using high-performance liquid chromatography (HPLC) with a chemiluminescence detector has been developed. In the assay method, free form and free plus ester forms of ChOOHs could be separately determined by HPLC in combination with the treatment of a tissue extract by cholesterol esterase. Lower limits of quantitation for cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides were 0.2, 0.1, and 0.5 nmol/g skin, respectively. This assay method showed that (i) good absolute recoveries of ChOOHs from rat skin (80-90% of radiolabeled ChOOHs added to rat skin); (ii) negligible autoxidation of cholesterol caused by the assay procedure (<9.4x10(-5)% of radiolabeled cholesterol added to rat skin); and (iii) good correlation between ChOOHs added to rat skin and ChOOHs determined, indicating this assay method is applicable to quantify ChOOHs in rat skin. By using this assay method, we observed that (i) cholesterol 5alpha-hydroperoxide was detected in skin of rats pretreated with oral doses of pheophorbide a and subsequent visible irradiation; (ii) concentrations of cholesterol 7-hydroperoxides in skin of rats in an ambient light room were not significantly different from those in a dark room for 12 weeks; and (iii) ultraviolet light B irradiation markedly enhanced the concentrations of cholesterol 7-hydroperoxides in the skin of rats.

Etiology of cerebral vasospasm

Cerebral vasospasm is a gradual onset and prolonged constriction of the cerebral arteries in the subarachnoid space after subarachnoid hemorrhage. The principal cause is the surrounding blood clot. The significance of vasospasm is that flow through the constricted arteries may be reduced sufficiently to cause cerebral infarction. Subarachnoid blood clot is sufficient to cause vasospasm; it does not require additional arterial injury, intracranial hypertension or brain infarction, although these elements are often coexistent. The blood released at the time of aneurysmal rupture into the alien subarachnoid environment is an extraordinarily complex mix of cellular and extracellular elements that evolves as clotting occurs; cells disintegrate; local inflammation, phagocytosis and repair take place; severe constriction alters the metabolism and structure of the arterial wall as well as the balance of vasoconstrictor and dilator substances produced by its endothelium, neurogenic network and perhaps smooth muscle cells.

High-performance liquid chromatography analysis of cholesterol linoleate hydroperoxide in oxidized low density lipoproteins: calibration by conjugated diene internal standard

The cholesterol linoleate hydroperoxides formed in LDL after oxidant stress are measured by HPLC, with UV detection at 234 nm. Calibration is performed with a conjugated diene internal standard. This internal standard is synthesized by the transesterification of the methyl ester of conjugated diene linoleic acid with a long-chain alcohol, such as arachidyl alcohol (C20). Different long-chain alcohols can be used during the transesterification, to achieve internal standards with variable HPLC retention times. The method allows measurement of cholesterol linoleate hydroperoxide in LDL very early during attack with Cu2+ or other initiator, so that the kinetics of antioxidant loss and hydroperoxide formation can be concurrently monitored.

Oxidative injury in the nervous system

A free radical is a highly reactive chemical species that can react with organic macromolecules leading to cell and tissue damage and consequent functional disruption. Free radical or oxidative injury is increasingly recognized as an important factor in the pathophysiology of many human diseases, including those that affect the nervous system. This review summarizes important evidence implicating oxidative injury in the pathogenesis and progression of many important neurological disorders, including cerebrovascular disease, epilepsy, amyotrophic lateral sclerosis, and Huntington's disease. Results of controlled clinical trials of various antioxidant therapies in neurological disease performed to date are also highlighted.

Increased plasma levels of lipid hydroperoxides in patients with ischemic stroke

A large body of experimental research indicates that the generation of free radicals leading to oxidative stress plays a role in the pathogenesis of ischemic brain injury, but evidence in humans is limited. We examined plasma levels of lipid hydroperoxides (measured as cholesteryl ester hydroperoxides, CEOOH) and ascorbic acid in 32 patients with cortical stroke, as compared with 13 patients with lacunar infarct. Patients with cortical stroke had significantly increased levels of CEOOH, which peaked on Day 5 after the ictus. Small decreases in ascorbic acid concentrations were not significant. There was a significant positive correlation of CEOOH with the NIH stroke scale, and a significant negative correlation with the Glasgow coma scale. Concentrations of CEOOH were significantly higher in patients with total anterior cerebral syndrome as compared with patients with partial anterior cerebral syndrome or posterior cerebral syndrome. Stroke volumes computed from CT or MRI scans were significantly correlated with plasma CEOOH levels. These findings implicate oxidative stress in ischemic brain injury in humans and suggest that measurements of CEOOH in plasma may be useful both prognostically as well as in monitoring therapeutic interventions.

U74389G prevents vasospasm after subarachnoid hemorrhage in dogs

OBJECTIVE

Oxygen-derived free radicals may contribute to vasospasm after the rupture of an intracranial aneurysm through direct vasoconstricting effects occurring within the arterial wall or, secondarily, by causing lipid peroxidation in the subarachnoid erythrocytes with secondary induction of vasoconstriction. U74389G is a potent inhibitor of lipid peroxidation and a scavenger of oxygen-derived free radicals. This study determined the relative contributions of oxygen-derived free radicals and lipid peroxidation to vasospasm in the double-hemorrhage dog model.

METHODS

Sixteen dogs underwent baseline (Day 0) cerebral angiography and induction of subarachnoid hemorrhage by two injections of blood into the cisterna magna 2 days apart. They were randomized to receive drug vehicle (n=8) or U74389G (n=8, 3 mg/kg of body weight/d) intravenously. Drug administration and end point analysis were blinded. The end points were angiographic vasospasm, as assessed by comparison of angiograms obtained before and 7 days after subarachnoid hemorrhage, and the levels of malondialdehyde and salicylate hydroxylation products (dihydroxybenzoic acids) in cerebrospinal fluid and of malondialdehyde in subarachnoid blood clots and basilar arteries 7 days after hemorrhage.

RESULTS

Comparisons within groups of Day 0 and Day 7 angiograms and between groups of angiograms obtained at Day 7, showed significant vasospasm in animals in the vehicle group (mean+/-standard error, 51%+/-4) but not in the U74389G group (25%+/-11, P < 0.05, unpaired t test). High-pressure liquid chromatographic assays of malondialdehyde and dihydroxybenzoic acids in cerebrospinal fluid, subarachnoid blood clots, and basilar arteries showed no significant differences between groups.

CONCLUSION

The significant prevention of vasospasm by U74389G without change in levels of indicators of free radical reactions suggests that the effect of the drug is related to other processes occurring in the arterial wall and that cerebrospinal fluid levels of oxygen radicals and lipid peroxides are not useful markers of vasospasm.