In vitro oxidation of vitamin E, vitamin C, thiols and cholesterol in rat brain mitochondria incubated with free radicals

Serum total cholesterol level as a potential predictive biomarker for neurological outcomes in cardiac arrest survivors who underwent target temperature management

Cholesterol is an essential substance to maintain cell membranes. Low levels of total cholesterol (TC) are associated with poor prognosis in critically ill patients. Cardiac arrest-induced whole-body ischemia and reperfusion injury cause a sepsis-like syndrome. The Cholesterol level in post-cardiac arrest patients may indicate the degree of endotoxemia or inflammation caused by ischemic and reperfusion injury. We aimed to investigate the association of TC levels with neurologic outcome of out-of-hospital cardiac arrest (OHCA) survivors who underwent target temperature management (TTM). This was a retrospective single-center observational study from May 2018 to April 2021 on a cohort of 106 patients. TC levels were determined in samples obtained immediately and at 24, 48, and 72 hours after the return of spontaneous circulation (ROSC). The primary outcome was poor neurologic outcome at 3 months after ROSC. Poor neurologic outcome was defined by cerebral performance categories 3 to 5. Sixty patients had a poor neurologic outcome. TC levels were significantly lower in the poor neurologic outcome group at each time point. The TC levels for predicting poor neurologic outcome had a sensitivity of 80.8%, with 67.6% specificity at 48 hours (TC48) after ROSC. The areas under the curve value of TC48 was 0.771 (0.670-0.853), with a cutoff value of 114 mg/dL. TC level at 48 hours after ROSC was a helpful marker for the 3-month poor neurologic outcome. This might be an easily accessible predictive marker of neurologic outcome in OHCA survivors treated with TTM.

Predictive Value of Blood Urea Nitrogen to Albumin Ratio in Long-Term Mortality in Intensive Care Unit Patients with Acute Myocardial Infarction: A Propensity Score Matching Analysis

Background

Blood urea nitrogen to albumin ratio (BAR) has been implicated in predicting outcomes of various inflammatory-related diseases. However, the predictive value of BAR in long-term mortality in patients with acute myocardial infarction (AMI) has not yet been evaluated.

Methods

In this retrospective cohort study, the patients were recruited from the Medical Information Mart for Intensive Care III (MIMIC III) database and categorized into two groups by a cutoff value of BAR. Kaplan–Meier (K-M) analysis and Cox proportional hazard model were performed to determine the predictive value of BAR in long-term mortality following AMI. In order to adjust the baseline differences, a 1:1 propensity score matching (PSM) was carried out and the results were further validated.

Results

A total of 1827 eligible patients were enrolled. The optimal cutoff value of BAR for four-year mortality was 7.83 mg/g. Patients in the high BAR group tended to have a longer intensive care unit (ICU) stay and a higher rate of one-, two-, three- and four-year mortality (all p<0.001) compared with those in the low BAR group. K-M curves indicated a significant difference in four-year survival (p<0.001) between low and high BAR groups. The Cox proportional hazards model showed that higher BAR (>7.83) was independently associated with increased four-year mortality in the entire cohort, with a hazard ratio (HR) of 1.478 [95% CI (1.254–1.740), p<0.001]. After PSM, the baseline characteristics of 312 pairs of patients in the high and low BAR groups were well balanced, and similar results were observed in K-M curve (p=0.003).

Conclusion

A higher BAR (>7.83) was associated with four-year mortality in patients with AMI. As an easily available biomarker, BAR can predict the long-term mortality in AMI patients independently.

Metabolic syndrome increases risk of venous thromboembolism recurrence after acute deep vein thrombosis

An improved understanding of which patients are at higher risk of recurrent venous thromboembolism (VTE) is important to designing interventions to reduce degraded quality of life after VTE. Although metabolic syndrome (MetS), the clustering of hypertension, hyperlipidemia, diabetes mellitus, and obesity has been associated with a hypofibrinolytic state, data linking VTE recurrence with MetS remain limited. The purpose of this study was to measure the prevalence of MetS in patients with deep vein thrombosis (DVT) across a large population and determine its effect on VTE recurrence. This was a retrospective analysis of a large statewide database from 2004 to 2017. We measured the frequency with which patients with DVT carried a comorbid International Coding of Diseases diagnosis of MetS components. Association of MetS with VTE recurrence was tested with a multiple logistic regression model and VTE recurrence as the dependent variable. Risk of VTE recurrence conferred by each MetS component was assessed by Kaplan-Meier curves with the log-rank statistic. A total of 151 054 patients with DVT were included in this analysis. Recurrence of VTE occurred in 17% overall and increased stepwise with each criterion for MetS. All 4 components of MetS had significant adjusted odds ratios (OR) for VTE recurrence, with hyperlipidemia having the largest (OR, 1.8), representing the 4 largest ORs of all possible explanatory variables. All 4 MetS variables were significant on Kaplan-Meier analysis for recurrence of VTE. These data imply a role for appropriate therapies to reduce the effects of MetS as a way to reduce risk of VTE recurrence.

SVCT2-Dependent plasma and mitochondrial membrane transport of ascorbic acid in differentiating myoblasts

The Na⁺-dependent Vitamin C transporter 2 (SVCT2) is expressed in the plasma and mitochondrial membranes of various cell types. This notion was also established in proliferating C2C12 myoblasts (Mb), in which the transporter was characterised by a high and low affinity in the plasma and mitochondrial membranes, respectively. In addition, the mitochondrial expression of SVCT2 appeared particularly elevated and, consistently, a brief pre-exposure to low concentrations of Ascorbic Acid (AA) abolished mitochondrial superoxide formation selectively induced by the cocktail arsenite/ATP. Early myotubes (Mt) derived from these cells after 4 days of differentiation presented evidence of slightly increased SVCT2 expression, and were characterised by kinetic parameters for plasma membrane transport of AA in line with those detected in Mb. Confocal microscopy studies indicated that the mitochondrial expression of SVCT2 is well preserved in Mt with one or two nuclei, but progressively reduced in Mt with three or more nuclei. Cellular and mitochondrial expression of SVCT2 was found reduced in day 7 Mt. While the uptake studies were compromised by the poor purity of the mitochondrial preparations obtained from day 4 Mt, we nevertheless obtained evidence of poor transport of the vitamin using the same functional studies successfully employed with Mb. Indeed, even greater concentrations of/longer pre-exposure to AA failed to induce scavenging of mitochondrial superoxide in Mt. These results are therefore indicative of a severely reduced mitochondrial uptake of the vitamin in early Mt, attributable to decreased expression as well as impaired activity of mitochondrial SVCT2.

The association between lipid profiles and the neurologic outcome in patients with out-of-hospital cardiac arrest

BACKGROUND

Lipid profiles are known to be a risk factor for development of cardiovascular disease. However, the relationship between lipid profiles and outcome in out-of-hospital cardiac arrest (OHCA) survivors remains unclear. We aimed to examine the association between lipid profiles and neurologic outcome in OHCA survivors.

METHODS

This retrospective observational study included adult (≥18 years) OHCA survivors between January 2016 and December 2018. We measured patients' lipid profiles after return of spontaneous circulation (ROSC) including total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglyceride. The primary outcome was neurologic outcome at hospital discharge. Good neurologic outcome was defined cerebral performance categories 1 and 2.

RESULTS

A total of 182 patients were included. Of them, 57 (31.3%) were discharged with good neurologic outcomes. Median serum levels of total cholesterol (178.0 vs. 123.0 mg/dL), HDL (44.0 vs. 31.0 mg/dL), and LDL (104.0 vs. 75.0 mg/dL) were significantly higher in patients with good neurologic outcome. The area under the curves of total cholesterol, HDL, LDL, and triglyceride were 0.742 (95% confidence interval [CI], 0.672-0.803), 0.729 (95% CI, 0.658-0.792), 0.683 (95% CI, 0.610-0.750), and 0.572 (95% CI, 0.497-0.645), respectively. Total cholesterol (odds ratio [OR], 1.013; 95% CI, 1.000-1.025; p = 0.043) and HDL (OR, 1.071; 95% CI, 1.021-1.123; p = 0.005) levels were associated with good neurologic outcomes.

CONCLUSIONS

The levels of total cholesterol and HDL after ROSC were associated with good neurologic outcomes in patients with OHCA, without considering the effect of other lipid profiles simultaneously.

Mitochondrial Uptake and Accumulation of Vitamin C: What Can We Learn from Cell Culture Studies?

SIGNIFICANCE

The mitochondrial fraction of l-ascorbic acid (AA) is of critical importance for the regulation of the redox status of these organelles and for cell survival. Recent Advances: Most cell types take up AA by the high-affinity sodium-dependent vitamin C transporter 2 (SVCT2) sensitive to inhibition by dehydroascorbic acid (DHA). DHA can also be taken up by glucose transporters (GLUTs) and then reduced back to AA. DHA concentrations, normally very low in biological fluids, may only become significant next to superoxide-releasing cells. Very little is known about the mechanisms mediating the mitochondrial transport of the vitamin.

CRITICAL ISSUES

Information on AA transport is largely derived from studies using cultured cells and is therefore conditioned by possible cell culture effects as overexpression of SVCT2 in the plasma membrane and mitochondria. Mitochondrial SVCT2 is susceptible to inhibition by DHA and transports AA with a low affinity as a consequence of the restrictive ionic conditions. In some cells, however, high-affinity mitochondrial transport of AA is observed. Mitochondrial uptake of DHA may take place through GLUTs, an event followed by its prompt reduction to AA in the matrix. Intracellular levels of DHA are, however, normally very low.

FUTURE DIRECTIONS

We need to establish, or rule out, the role and significance of mitochondrial SVCT2 in vivo. The key question for mitochondrial DHA transport is instead related to its very low intracellular concentrations.

Pro- and Antioxidant Functions of the Peroxisome-Mitochondria Connection and Its Impact on Aging and Disease

Peroxisomes and mitochondria are the main intracellular sources for reactive oxygen species. At the same time, both organelles are critical for the maintenance of a healthy redox balance in the cell. Consequently, failure in the function of both organelles is causally linked to oxidative stress and accelerated aging. However, it has become clear that peroxisomes and mitochondria are much more intimately connected both physiologically and structurally. Both organelles share common fission components to dynamically respond to environmental cues, and the autophagic turnover of both peroxisomes and mitochondria is decisive for cellular homeostasis. Moreover, peroxisomes can physically associate with mitochondria via specific protein complexes. Therefore, the structural and functional connection of both organelles is a critical and dynamic feature in the regulation of oxidative metabolism, whose dynamic nature will be revealed in the future. In this review, we will focus on fundamental aspects of the peroxisome-mitochondria interplay derived from simple models such as yeast and move onto discussing the impact of an impaired peroxisomal and mitochondrial homeostasis on ROS production, aging, and disease in humans.

[Correction of the oxidant-antioxidant balance in lungs during hyperoxia by liposomal alpha-tocopherol and retinoids in the experiment]

The influence of inhaled liposomes, containing dipalmitoyl phosphatidylcholine and a-tocopherol, and liposomes containing dipalmitoyl phosphatidylcholine, retinol and retinoic acid, on parameters of the oxidantantioxidant system in lungs of newborn guinea pigs exposed to hyperoxia during 3 and 14 days has been studied. Administration of both types of liposomes under conditions of prolonged hyperoxia (14 days) results in normalization of glutathione peroxidase activity and prevents elevation of the levels of lipid and protein peroxidation products in bronchoalveolar lavage fluid. Unlike liposomes with a-tocopherol, administration of liposomes containing retinoids did not cause the normalizing effect on the content of nonprotein SH-compounds in the bronchoalveolar fluid and contributed to significant reduction of the a-tocopherol level in lung tissues.

Cholesterol Levels Are Associated with 30-day Mortality from Ischemic Stroke in Dialysis Patients

BACKGROUND

We investigated the impact of serum cholesterol levels on 30-day mortality after ischemic stroke in dialysis patients.

METHODS

From the Taiwan Stroke Registry data, we identified 46,770 ischemic stroke cases, including 1101 dialysis patients and 45,669 nondialysis patients from 2006 to 2013.

RESULTS

Overall, the 30-day mortality was 1.46-fold greater in the dialysis group than in the nondialysis group (1.75 versus 1.20 per 1000 person-days). The mortality rates were 1.64, .62, 2.82, and 2.23 per 1000 person-days in dialysis patients with serum total cholesterol levels of <120 mg/dL, 120-159 mg/dL, 160-199 mg/dL, and ≥200 mg/dL, respectively. Compared to dialysis patients with serum total cholesterol levels of 120-159 mg/dL, the corresponding adjusted hazard ratios of mortality were 4.20 (95% confidence interval [CI] = 1.01-17.4), 8.06 (95% CI = 2.02-32.2), and 6.89 (95% CI = 1.59-29.8) for those with cholesterol levels of <120 mg/dL, 160-199 mg/dL, and ≥200 mg/dL, respectively.

CONCLUSIONS

Dialysis patients with serum total cholesterol levels of ≥160 mg/dL or <120 mg/dL on admission are at an elevated hazard of 30-day mortality after ischemic stroke.

Serum Cholesterol Levels within the High Normal Range Are Associated with Better Cognitive Performance among Chinese Elderly

OBJECTIVES

The association between cognitive function and cholesterol levels is poorly understood and inconsistent results exist among the elderly. The purpose of this study is to investigate the association of cholesterol level with cognitive performance among Chinese elderly.

DESIGN

A cross-sectional study was implemented in 2012 and data were analyzed using generalized additive models, linear regression models and logistic regression models.

SETTING

Community-based setting in eight longevity areas in China.

SUBJECTS

A total of 2000 elderly aged 65 years and over (mean 85.8±12.0 years) participated in this study.

MEASUREMENTS

Total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) concentration were determined and cognitive impairment was defined as Mini-Mental State Examination (MMSE) score ≤23.

RESULTS

There was a significant positive linear association between TC, TG, LDL-C, HDL-C and MMSE score in linear regression models. Each 1 mmol/L increase in TC, TG, LDL-C and HDL-C corresponded to a decreased risk of cognitive impairment in logistic regression models. Compared with the lowest tertile, the highest tertile of TC, LDL-C and HDL-C had a lower risk of cognitive impairment. The adjusted odds ratios and 95% CI were 0.73(0.62-0.84) for TC, 0.81(0.70-0.94) for LDL-C and 0.81(0.70-0.94) for HDL-C. There was no gender difference in the protective effects of high TC and LDL-C levels on cognitive impairment. However, for high HDL-C levels the effect was only observed in women. High TC, LDL-C and HDL-C levels were associated with lower risk of cognitive impairment in the oldest old (aged 80 and older), but not in the younger elderly (aged 65 to 79 years).

CONCLUSIONS

These findings suggest that cholesterol levels within the high normal range are associated with better cognitive performance in Chinese elderly, specifically in the oldest old. With further validation, low cholesterol may serve a clinical indicator of risk for cognitive impairment in the elderly.

Mitochondria-Targeted Photodynamic Therapy with a Galactodendritic Chlorin to Enhance Cell Death in Resistant Bladder Cancer Cells

Here, we report the rational design of a new third-generation photosensitizer (PS), a chlorin conjugated with galactodendritic units, ChlGal₈, to improve the effectiveness of bladder cancer treatment. ChlGal₈ shows better photochemical and photophysical properties than a recently reported homologous porphyrin, PorGal₈. In addition to inheriting excellent photostability, the ability to generate singlet oxygen, and the ability to interact with the proteins galectin-1 and human serum albumin (HSA), ChlGal₈ exhibits high absorption in the red region of the electromagnetic spectrum. In vitro studies of anticancer activity of ChlGal₈ revealed that once this PS is taken up by UM-UC-3 bladder cancer cells, it induces high cytotoxicity after a single dose of light irradiation. In HT-1376 bladder cancer cells resistant to therapy, a second light irradiation treatment enhanced in vitro and in vivo photodynamic efficacy. The enhanced phototoxicity in HT-1376 cancer cells seems to be due to the ability of ChlGal₈ to accumulate in the mitochondria, via facilitative glucose transporter 1 (GLUT1), in the period between single and repeated irradiation. A photodynamic therapy (PDT) regimen using an extra dose of light irradiation and ChlGal₈ as PS represents a promising strategy in treating resistant cancers in a clinical setting.

Hyperlipidemia is associated with lower risk of poststroke mortality independent of statin use: A population-based study

Background Although statin therapy is associated with reduced stroke and mortality risk, some studies report that higher lipid levels are associated with improved outcomes following ischemic stroke. Aims We examined the association of hyperlipidemia (HLD) combined with statin therapy on all-cause mortality in stroke patients. Methods All stroke patients in the Greater Cincinnati Northern Kentucky region of ∼1.3 million were identified using ICD-9 discharge codes in 2005 and 2010. Stroke patients with and without HLD were categorized based on their reported statin use at baseline or discharge into three groups: no-HLD/no-statins, HLD/no-statins, and HLD/on-statins. Cox proportional hazards model was used to estimate the risk of mortality at 30 days, 1 year, and 3 years poststroke. Results Overall, 77% (2953) of the 3813 ischemic stroke patients were diagnosed with HLD and 72% ( n = 2123) of those patients were on statin medications. The mean age was 70.0 ± 14.6 years, 56% were women, and 21% were black. In adjusted analyses, the HLD/no-statins group showed 35% (adjusted hazard ratio (aHR) = 0.65, 95% CI: 0.46-0.92), 27% (aHR = 0.73, 95% CI: 0.59-0.90), and 17% (aHR = 0.83, 95% CI: 0.70-0.97) reduced risk of mortality at 30 days, 1 year, and 3 years, respectively, poststroke, compared with no-HLD/no-statins group. The HLD/on-statins group showed an additional 17% significant survival benefit at 3 years poststroke compared with HLD/no-statins group. Conclusions A diagnosis of HLD in ischemic stroke patients is associated with reduced short- and long-term mortality, irrespective of statin use. Statin therapy is associated with significant, additional long-term survival benefit.

A panoramic overview of mitochondria and mitochondrial redox biology

Mitochondria dysfunction was first described in the 1960s. However, the extent and mechanisms of mitochondria dysfunction’s role in cellular physiology and pathology has only recently begun to be appreciated. To adequately evaluate mitochondria-mediated toxicity, it is not only necessary to understand mitochondria biology, but discerning mitochondrial redox biology is also essential. The latter is intricately tied to mitochondrial bioenergetics. Mitochondrial free radicals, antioxidants, and antioxidant enzymes are players in mitochondrial redox biology. This review will provide an across-the-board, albeit not in-depth, overview of mitochondria biology and mitochondrial redox biology. With accumulating knowledge on mitochondria biology and mitochondrial redox biology, we may devise experimental methods with adequate sensitivity and specificity to evaluate mitochondrial toxicity, especially in vivo in living organisms, in the near future.

Changes in the mitochondrial antioxidant systems in neurodegenerative diseases and acute brain disorders

Oxidative and nitrosative stress (ONS) contributes to the pathogenesis of most brain maladies, and the magnitude of ONS is related to the ability of cellular antioxidants to neutralize the accumulating reactive oxygen and nitrogen species (ROS/RNS). While the major ROS/RNS scavengers and regenerators of bio-oxidized molecules, superoxide dysmutases (SODs), glutathione (GSH), thioredoxin (Trx) and peroxiredoxin (Prx), are distributed in all cellular compartments. This review specifically focuses on the role of the systems operating in mitochondria. There is a growing consensus that the mitochondrial SOD isoform - SOD2 and GSH are critical for the cellular antioxidant defense. Variable changes of the expression or activities of one or more of the mitochondrial antioxidant systems have been documented in the brains derived from human patients and/or in animal models of neurodegenerative diseases (Alzheimer's disease, Parkinson's disease), cerebral ischemia, toxic brain cell damage associated with overexposure to mercury or excitotoxins, or hepatic encephalopathy. In many cases, ambiguity of the responses of the different antioxidant systems in one and the same disease needs to be more conclusively evaluated before the balance of the changes is viewed as beneficial or detrimental. Modulation of the mitochondrial antioxidant systems may in the future become a target of antioxidant therapy.

Prognostic factors for long-term poor outcomes after acute ischemic stroke in very old age (>80 years) patients: Total cholesterol level might differently influence long-term outcomes after acute ischemic stroke at ages above 80 years

AIM

We investigated the differences in determinant factors for functional outcomes between patients aged >80 years and those aged <80 years after acute ischemic stroke (AIS). In particular, we would like to know the differential impacts of initial total cholesterol (TC) levels between the two groups.

METHODS

We defined a poor outcome as 3-6 modified Rankin Scale 90 days after AIS.

RESULTS

In the present study, 2772 participants were enrolled. Among them, 374 patients (13.5%) were aged >80 years, and 1061 patients had a poor outcome 90 days after AIS. The proportion was significantly higher in patients aged >80 years than in those aged <80 years after AIS. Regarding factors relating to poor outcomes, previous history of stroke, stroke severity and stroke subtypes of ischemic stroke were independent factors in patients aged <80 years, and the stroke severity and initial TC level independently influenced the outcome for patients aged >80 years. In particular, risk of poor outcome adjusted for age, stroke severity and subtypes of ischemic stroke for patients (OR [95% CI]) in the first quartile range (≤157 mg%) were 2.21 (1.06-4.62), in the third quartile range (184-210 mg%) 2.76 (1.27-6.01) and in the fourth quartile range (≥211 mg%) 2.75 (1.21-6.24) compared with those in the second quartile range (158-183 mg%) in patients aged >80 years.

CONCLUSIONS

There were also some differences in related factors regarding occurrences of poor outcome between the two groups. In particular, the initial TC level might play a crucial role for the outcome after AIS in the very old population.

Changes in ascorbate, glutathione and α-tocopherol concentrations in the brain regions during normal development and moderate hypoglycemia in rats

Ascorbate, glutathione and α-tocopherol are the major low molecular weight antioxidants in the brain. The simultaneous changes in these compounds during normal development, and under a pro-oxidant condition are poorly understood. Ascorbate, glutathione and α-tocopherol concentrations in the olfactory bulb, cerebral cortex, hippocampus, striatum, hypothalamus, midbrain, cerebellum, pons and medulla oblongata were determined in postnatal day (P) 7, P14 and P60 male rats. A separate group of P14 and P60 rats were subjected to acute hypoglycemia, a pro-oxidant condition, prior to tissue collection. The concentrations of all three antioxidants were 100-600% higher in the brain regions at P7 and P14, relative to P60. The neuron-rich anterior brain regions (cerebral cortex and hippocampus) had higher concentrations of all three antioxidants than the myelin-rich posterior regions (pons and medulla oblongata) at P14 and P60. Hypoglycemia had a differential effect on the antioxidants. Glutathione was decreased at both P14 and P60. However, the decrease was localized at P14 and global at P60. Hypoglycemia had no effect on ascorbate and α-tocopherol at either age. Higher antioxidant concentrations in the developing brain may reflect the risk of oxidant stress during the early postnatal period and explain the relative resistance to oxidant-mediated injury at this age.

Neuroprotective effect of pseudoginsenoside-f11 on a rat model of Parkinson's disease induced by 6-hydroxydopamine

Pseudoginsenoside-F11 (PF11), a component of Panax quinquefolism (American ginseng), plays a lot of beneficial effects on disorders of central nervous system. In this paper, the neuroprotective effect of PF11 on Parkinson's disease (PD) and the possible mechanism were investigated in a rat PD model. PF11 was orally administered at 3, 6, and 12 mg/kg once daily for a period of 2 weeks before and 1 week after the unilateral lesion of left medial forebrain bundle (MFB) induced by 6-hydroxydopamine (6-OHDA). The results showed that PF11 markedly improved the locomotor, motor balance, coordination, and apomorphine-induced rotations in 6-OHDA-lesioned rats. The expression of tyrosine hydroxylase (TH) in substantia nigra (SN) and the content of extracellular dopamine (DA) in striatum were also significantly increased after PF11 treatment. Moreover, significant reduction in the levels of striatal extracellular hydroxyl radical (^∙OH), detected as 2,3- and 2,5-dihydroxy benzoic acid (2,3- and 2,5-DHBA), and increase in the level of striatal extracellular ascorbic acid (AA) were observed in the PF11-treated groups compared with 6-OHDA-lesioned rats. Taken together, we propose that PF11 has potent anti-Parkinson property possibly through inhibiting free radical formation and stimulating endogenous antioxidant release.

Role of glutamate and nitric oxide in onset of motor neuron degeneration in neurolathyrism

Neurolathyrism is associated with a complex pattern of alterations in the glutamatergic system of the cortical motor region of brain. It is a neurological disorder consorted with excessive consumption of Lathyrus sativus (Grass pea), comprising large amounts of the neurotoxin, β-N-oxalyl-L-α,β-diaminopropionic acid (ODAP). ODAP being a potent agonist of ionotropic glutamate receptors enhances their activity and also blocks the astrocytic glutamate/cystine transporters, abutting the neurons. This leads to the sustained increase in the concentration of Glutamate in the synapse which triggers excitotoxicity. L. sativus also contains high levels of arginine and homoarginine which are natural substrates of nitric oxide production, when NO levels increases, it forms peroxynitrite radicals which cause irreparable damage to mitochondria and cellular macromolecules leading to motor neuron degeneration. This review brings together all the molecular events reported so far, emphasizing on the possible role of glutamate and nitric oxide mediated cell death.

Inhibition of lipid peroxidation and protein oxidation by endogenous and exogenous antioxidants in rat brain microsomes in vitro

Reactive oxygen and reactive nitrogen species oxidize and nitrate DNA, lipid and proteins thus leading to neuronal death. Both endogenous and dietary antioxidants were shown to afford neuroprotection either by scavenging free radicals or inducing antioxidant enzymes. That said, the differential contribution of endogenous versus nutritional antioxidants to prevent neurodegeneration is still debated. In this study the free radical scavenging activity of two endogenous antioxidants, such as bilirubin and its precursor biliverdin, was compared with that of the dietary antioxidant alpha-tocopherol in rat brain microsomes exposed to peroxyl radical or peroxynitrite in vitro. Bilirubin and biliverdin (1-200 μM) inhibited both peroxyl radical- and peroxynitrite-dependent lipid peroxidation with a greater potency and efficacy than alpha-tocopherol. However, both BV and BR displayed greater potency and efficacy in preventing peroxynitrite- than peroxyl radical-induced lipid peroxidation. The greater antioxidant effect of both bilirubin and biliverdin than alpha-tocopherol was also confirmed against peroxyl radical- and peroxynitrite-induced protein oxidation. In conclusion, both bilirubin and biliverdin exhibited a greater antioxidant activity than alpha-tocopherol in preventing oxidative stress damage in rat brain.

Pretreatment with statins improves early outcome in patients with first-ever ischaemic stroke: a pleiotropic effect of statins or a beneficial effect of hypercholesterolemia?

Background

Data from different studies suggest a favourable association between pretreatment with statins or hypercholesterolemia and outcome after ischaemic stroke. We examined whether there were differences in in-hospital mortality according to the presence or absence of statin therapy in a large population of first-ever ischaemic stroke patients and assessed the influence of statins upon early death and spontaneous neurological recovery.

Methods

In 2,082 consecutive patients with first-ever ischaemic stroke collected from a prospective hospital-based stroke registry during a period of 19 years (1986-2004), statin use or hypercholesterolemia before stroke was documented in 381 patients. On the other hand, favourable outcome defined as grades 0-2 in the modified Rankin scale was recorded in 382 patients.

Results

Early outcome was better in the presence of statin therapy or hypercholesterolemia (cholesterol levels were not measured) with significant differences between the groups with and without pretreatment with statins in in-hospital mortality (6% vs 13.3%, P = 0.001) and symptom-free (22% vs 17.5%, P = 0.025) and severe functional limitation (6.6% vs 11.5%, P = 0.002) at hospital discharge, as well as lower rates of infectious respiratory complications during hospitalization. In the logistic regression model, statin therapy was the only variable inversely associated with in-hospital death (odds ratio 0.57) and directly associated with favourable outcome (odds ratio 1.32).

Conclusions

Use of statins or hypercholesterolemia before first-ever ischaemic stroke was associated with better early outcome with a reduced mortality during hospitalization and neurological disability at hospital discharge. However, statin therapy may increase the risk of intracerebral haemorrhage, particularly in the setting of thrombolysis.

Serum lipid levels and 3-month prognosis in Chinese patients with acute stroke

INTRODUCTION

The possible correlation between serum lipid levels and outcome after stroke is still controversial. Therefore we examined whether serum lipid levels at admission had any prognostic value in the 3-month outcome after stroke.

METHODS

We performed a prospective, observational study of 649 patients with acute ischaemic stroke and intracerebral haemorrhagic stroke (ICH). Information on age, sex, history of arterial hypertension, diabetes mellitus, drinking, current smoking status, stroke type, Glasgow Coma Scale and Scandinavian Stroke Scale score, time from stroke onset, and presence of atrial fibrillation was obtained. Serum lipid levels were measured in blood samples taken from fasting patients 12 to 48 hours following ictus. Death and poor neurological outcome (Modified Rankin Scale score of > or =3 points) were defined as outcome events. A logistic regression model was performed to estimate the effect of the above variables on outcome after stroke.

RESULTS

We found that the median levels of serum total cholesterol (TC), triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) in good outcome patients with acute stroke were significantly higher (P<0.005) than those of poor outcome patients. The low levels of serum TC, TG and HDL-C (P<0.05) were independently related to increased 3-month poor outcome after acute ischaemic stroke and ICH. However, there was no significant relationship between LDL-C levels and 3-month outcome.

CONCLUSION

The data from this study show that low levels of serum TC, TG and HDL-C are strong independent predictors of 3-month poor outcome in patients with acute ischaemic stroke and ICH.

Genetic findings in Parkinson's disease and translation into treatment: a leading role for mitochondria?

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder and in most patients its aetiology remains unknown. Molecular genetic studies in familial forms of the disease identified key proteins involved in PD pathogenesis, and support a major role for mitochondrial dysfunction, which is also of significant importance to the common sporadic forms of PD. While current treatments temporarily alleviate symptoms, they do not halt disease progression. Drugs that target the underlying pathways to PD pathogenesis, including mitochondrial dysfunction, therefore hold great promise for neuroprotection in PD. Here we summarize how the proteins identified through genetic research (alpha-synuclein, parkin, PINK1, DJ-1, LRRK2 and HTRA2) fit into and add to our current understanding of the role of mitochondrial dysfunction in PD. We highlight how these genetic findings provided us with suitable animal models and critically review how the gained insights will contribute to better therapies for PD.

Clinical laboratory findings associated with in-hospital mortality

The diagnostic approach and the clinical management of critically ill patients is challenging. The recognition of biomarkers related to in-hospital mortality is of importance for identification of patients at increased risk of death. Many prediction models assessing the severity of illness and likelihood of hospital survival were developed using logistic regression analyses. These models include several laboratory parameters, such as white blood cell counts, serum bilirubin, serum albumin, blood glucose, serum electrolytes and markers which reflect acid-base disturbances. Recently, several other biomarkers, including troponin, B-type natriuretic peptide (BNP), N-terminal proBNP, C-reactive protein, procalcitonin, cholesterol and coagulation related markers have emerged as clinically useful tools for risk stratification and mortality prediction of heterogeneous and more specific subgroups of critically ill patients. More investigations are required to verify whether risk stratification based on mortality-related biomarkers may translate into targeted treatment strategies to improve clinical outcome of the critical illness. Biomarkers which are related to in-hospital mortality are highlighted in the current review.

Lipid metabolism in cognitive decline and dementia

This review will focus on the current knowledge on circulating serum and plasma risk factors of cognitive decline of degenerative (Alzheimer's disease, AD) or vascular origin (vascular dementia, VaD) linked to cholesterol homeostasis and lipoprotein disturbances, i.e. total cholesterol (TC), 24S-hydroxy-cholesterol, lipoprotein(a) (Lp(a)), or apolipoprotein E (APOE). These measures linked to lipoprotein metabolism appear to be altered in AD, VaD, or predementia syndrome relative to controls, but with contrasting results. At present, several studies have demonstrated the dependence of APOE serum levels upon the APOE genotype, nonetheless serum APOE levels seems not to be a credible risk factor or a biochemical marker for AD instead of APOE genotyping. In fact, there was no consistent association of serum or plasma apoE protein levels with the disease when controlled for APOE genotype. In addition, there are some evidence that higher Lp(a) levels could be linked with AD, although there are studies suggesting an increased presence of low molecular weight apo(a) in AD, VaD, and frontotemporal dementia, that are associated with elevated Lp(a) levels. In fact, the apo(a) gene is highly polymorphic in length due to variation in the numbers of a sequence encoding the apo(a) kringle 4 domain, and plasma levels of Lp(a) are inversely correlated with apo(a) size. Furthermore, although serum/plasma levels of TC and 24S-hydroxycholesterol are not credible diagnostic markers for AD and cognitive decline, the current evidence suggests that they may be modifiable risk/protective factors. The prevailing wisdom is that high TC is a risk factor for dementia. However, the relationship between TC and dementia may vary considerably depending on when cholesterol is measured over the life course or, alternatively, in relation to the underlying course of the disease. Several observational studies have suggested that statins, which are effective in lowering cholesterol, may reduce the risk of dementia, but the results of these reports are inconclusive. Thus, more studies with long-term follow-up and serial assessments of TC are needed to further clarify the causal relationship between cholesterol and dementia.

Vitamin C enters mitochondria via facilitative glucose transporter 1 (Gluti) and confers mitochondrial protection against oxidative injury

Reactive oxygen species (ROS)-induced mitochondrial abnormalities may have important consequences in the pathogenesis of degenerative diseases and cancer. Vitamin C is an important antioxidant known to quench ROS, but its mitochondrial transport and functions are poorly understood. We found that the oxidized form of vitamin C, dehydroascorbic acid (DHA), enters mitochondria via facilitative glucose transporter 1 (Glut1) and accumulates mitochondrially as ascorbic acid (mtAA). The stereo-selective mitochondrial uptake of D-glucose, with its ability to inhibit mitochondrial DHA uptake, indicated the presence of mitochondrial Glut. Computational analysis of N-termini of human Glut isoforms indicated that Glut1 had the highest probability of mitochondrial localization, which was experimentally verified via mitochondrial expression of Glut1-EGFP. In vitro mitochondrial import of Glut1, immunoblot analysis of mitochondrial proteins, and cellular immunolocalization studies indicated that Glut1 localizes to mitochondria. Loading mitochondria with AA quenched mitochondrial ROS and inhibited oxidative mitochondrial DNA damage. mtAA inhibited oxidative stress resulting from rotenone-induced disruption of the mitochondrial respiratory chain and prevented mitochondrial membrane depolarization in response to a protonophore, CCCP. Our results show that analogous to the cellular uptake, vitamin C enters mitochondria in its oxidized form via Glut1 and protects mitochondria from oxidative injury. Since mitochondria contribute significantly to intracellular ROS, protection of the mitochondrial genome and membrane may have pharmacological implications against a variety of ROS-mediated disorders.

Lower Serum Triglyceride Level Is Associated With Increased Stroke Severity

BACKGROUND AND PURPOSE

A previous study showed that low triglyceride concentration predicts higher mortality after stroke. The aim of our study was to determine whether serum triglyceride level is associated with stroke severity on admission.

METHODS

863 consecutive patients with acute ischemic stroke were included. Serum triglyceride level was measured within 36 hours after stroke onset. Stroke severity on admission was assessed using Scandinavian Stroke Scale (SSS). The patients were divided into 2 groups: those with severe stroke (SSS < or =25) and those with mild/moderate stroke (SSS >25).

RESULTS

Patients with severe stroke had significantly lower serum triglyceride level than patients with mild/moderate stroke (1.4+/-0.6 versus 1.7+/-1.3 mmol/L). After adjusting for age, sex, atrial fibrillation, diabetes mellitus, obesity, and ischemic heart disease, patients with triglyceride >2.3 mmol/L had lower risk of severe stroke than those with triglyceride < or =2.3 mmol/L (OR: 0.58; 95% CI: 0.35 to 0.95).

CONCLUSIONS

Our results suggest that lower level of triglyceride is associated with the more severe stroke.

Increases in serum non-high-density lipoprotein cholesterol may be beneficial in some high-functioning older adults: MacArthur studies of successful aging

objectives: To examine the association between changes in serum non-high-density lipoprotein cholesterol (non-HDL-C) over a 2.5-year period and risk of adverse health outcomes in the following 4.5 years in high-functioning older adults.

DESIGN

Prospective cohort, established in 1988, with a follow-up in 1991 and 1995.

SETTING

Population-based, community-dwelling men and women.

PARTICIPANTS

A random sample (n=267) from the MacArthur cohort (N=1,189). The cohort represented the highest-functioning tertile of 4,030 screened candidates aged 70 to 79.

MEASUREMENTS

Change in non-HDL-C between 1988 and 1991 was measured as a predictor of health outcomes between 1991 and 1995, including all-cause mortality, and among survivors, incident heart attack or stroke, development of new disability in basic activities of daily living, and decline in performance on the Short Portable Mental Status Questionnaire.

RESULTS

More-positive change in non-HDL-C between 1988 and 1991 was associated with fewer adverse outcomes between 1991 and 1995. In individuals whose total cholesterol at baseline was in the middle two quartiles (195-244 mg/dL), each 10-mg/dL increase in the 1988-to-1991 change in non-HDL-C was associated with an adjusted mortality odds ratio (OR) of 0.67 (95% confidence interval (CI)=0.51-0.88). In individuals without cardiovascular disease at baseline, the adjusted OR for new physical disability was 0.79 (95% CI=0.65-0.95) and for cognitive decline was 0.81 (95% CI=0.67-0.98).

CONCLUSION

Increases in cholesterol over time have beneficial associations in some older adults. The role of cholesterol changes in the health of older individuals needs further exploration.

Cooperative interaction between ascorbate and glutathione during mitochondrial impairment in mesencephalic cultures

A decrease in total glutathione, and aberrant mitochondrial bioenergetics have been implicated in the pathogenesis of Parkinson's disease. Our previous work exemplified the importance of glutathione (GSH) in the protection of mesencephalic neurons exposed to malonate, a reversible inhibitor of mitochondrial succinate dehydrogenase/complex II. Additionally, reactive oxygen species (ROS) generation was an early, contributing event in malonate toxicity. Protection by ascorbate was found to correlate with a stimulated increase in protein-glutathione mixed disulfide (Pr-SSG) levels. The present study further examined ascorbate-glutathione interactions during mitochondrial impairment. Depletion of GSH in mesencephalic cells with buthionine sulfoximine potentiated both the malonate-induced toxicity and generation of ROS as monitored by dichlorofluorescein diacetate (DCF) fluorescence. Ascorbate completely ameliorated the increase in DCF fluorescence and toxicity in normal and GSH-depleted cultures, suggesting that protection by ascorbate was due in part to upstream removal of free radicals. Ascorbate stimulated Pr-SSG formation during mitochondrial impairment in normal and GSH-depleted cultures to a similar extent when expressed as a proportion of total GSH incorporated into mixed disulfides. Malonate increased the efflux of GSH and GSSG over time in cultures treated for 4, 6 or 8 h. The addition of ascorbate to malonate-treated cells prevented the efflux of GSH, attenuated the efflux of GSSG and regulated the intracellular GSSG/GSH ratio. Maintenance of GSSG/GSH with ascorbate plus malonate was accompanied by a stimulation of Pr-SSG formation. These findings indicate that ascorbate contributes to the maintenance of GSSG/GSH status during oxidative stress through scavenging of radical species, attenuation of GSH efflux and redistribution of GSSG to the formation of mixed disulfides. It is speculated that these events are linked by glutaredoxin, an enzyme shown to contain both dehydroascorbate reductase as well as glutathione thioltransferase activities.

Statins and stroke

An important issue for stroke prevention is the identification and treatment of risk factors such as hypercholesterolaemia. The 4 reasons to test if the statins have a role in stroke prevention are: (i) a statistical link between elevated low density lipoprotein-cholesterol or decreased high density lipoprotein-cholesterol and ischaemic stroke; (ii) a reduction in vascular risk with statins in randomised trials in patients with coronary heart disease; (iii) evidence of a decreased plaque progression under statins; and (iv) pooled analyses of primary and secondary prevention trials showing that reduction of total serum cholesterol reduces the incidence of stroke, especially with the highest rate of cholesterol reduction, and in patients with the highest risk of stroke (i.e. with statins in secondary prevention trials). The question of whether statins also have a neuroprotective effect in humans and reduce the risk of post-stroke dementia remains unsettled.

Hypolipemic agents for stroke prevention

An important issue for stroke prevention is identification and treatment of risk factors such as hypercholesterolemia. The four reasons to test hypolipidemic agents in stroke prevention are: (i) a statistical link between elevated low-density lipoprotein cholesterol (LDL-c) or decreased high-density lipoprotein cholesterol (HDL-c) and ischemic stroke; (ii) a reduction in vascular risk in randomized trials in patients with coronary heart disease; (iii) evidence of a decreased plaque progression under statins, (iv) pooled analyses of primary and secondary prevention trials showing that reduction of total serum cholesterol reduces the incidence of stroke, especially with the highest rate of cholesterol reduction, and in patients with the highest risk of stroke (i.e., with statins in secondary prevention trials), and (v) prophylactic neuroprotection induced by hypolipidemic agents in animal models of cerebral ischemia. Data provided by trials conducted in subjects with coronary heart disease and in asymptomatic individuals should now be confirmed in stroke patient.

Mitochondrial recycling of ascorbic acid from dehydroascorbic acid: dependence on the electron transport chain

Mitochondria can regenerate ascorbic acid from its oxidized forms, which may help to maintain the vitamin both in mitochondria and in the cytoplasm. In this work, we sought to determine the site and mechanism of mitochondrial ascorbate recycling from dehydroascorbic acid. Rat skeletal muscle mitochondria incubated for 3 h at 37 degrees C with 500 microM dehydroascorbic acid and energy substrates maintained ascorbate concentrations more than twice those observed in the absence of substrate. Succinate-dependent mitochondrial reduction of dehydroascorbic acid was blocked by inhibitors of mitochondrial Complexes II and III. Neither cytochrome c nor the outer mitochondrial membrane were necessary for the effect. The ascorbate radical was generated by mitochondria during treatment with dehydroascorbic acid and was abolished by ferricyanide, which does not penetrate the mitochondrial inner membrane. Together, these results show that energy substrate-dependent ascorbate recycling from dehydroascorbic acid involves an externally exposed portion of mitochondrial complex III.

Selective determination of mitochondrial chelatable iron in viable cells with a new fluorescent sensor

Mitochondrial chelatable ("redox-active") iron is considered to contribute to several human diseases, but has not yet been characterized in viable cells. In order to determine this iron pool, we synthesized a new fluorescent indicator, rhodamine B-[(1,10-phenanthrolin-5-yl)aminocarbonyl]benzyl ester (RPA). In a cell-free system, RPA fluorescence was strongly and stoichiometrically quenched by Fe(2+). RPA selectively accumulated in the mitochondria of cultured rat hepatocytes. The intramitochondrial RPA fluorescence was quenched when iron was added to the cells in a membrane-permeant form. It increased when the mitochondrial chelatable iron available to the probe was experimentally decreased by the membrane-permeant transition metal chelators pyridoxal isonicotinoyl hydrazone and 1,10-phenanthroline. The concentration of mitochondrial chelatable iron in cultured rat hepatocytes, quantified from the increase in RPA fluorescence after addition of pyridoxal isonicotinoyl hydrazone, was found to be 12.2 +/- 4.9 microM. Inhibition of haem synthesis with succinylacetone did not alter the signal obtained in hepatocytes, but a rapid increase in the concentration of mitochondrial chelatable iron was observed in human erythroleukaemia K562 cells. In conclusion, RPA enables the selective determination of the highly physiologically and pathophysiologically interesting mitochondrial pool of chelatable iron in intact cells and to record the time course of alterations of this pool.

NAD(P)H, a directly operating antioxidant?

Endogenous oxygen- and nitrogen-centered free radicals are considered to play a decisive role in a variety of diseases such as neurodegenerative disorders, atherosclerosis, or cancer. Directly operating antioxidants limit the action of freely diffusing radicals by scavenging the attacking, oxidizing radical and re-reducing the oxidized biomolecule, i.e., the biomolecule-derived radical. From textbooks of biochemistry it is understood that NAD(P)H acts as a hydride (hydrogen anion) donor in a variety of enzymatic processes. One example is the re-reduction of GSSG to GSH, catalyzed by glutathione reductase. Because of this reaction, NADPH has been suggested to also act as an indirectly operating antioxidant, thus maintaining the antioxidative power of glutathione. To the best of our knowledge, however, neither NADPH nor NADH has been considered to be directly operating antioxidants. Based on recently published data, new experiments, and theoretical considerations, we propose that NAD(P)H represents a decisive, directly operating antioxidant that should be considered of major importance in the mitochondrial compartment. NAD(P)H fulfills this task both by scavenging toxic free radicals and repairing biomolecule-derived radicals.

Mitochondrial Uptake and Recycling of Ascorbic Acid

Mitochondria generate reactive oxygen species as by-products of oxidative metabolism. Since ascorbic acid can scavenge such destructive species, we studied the ability of mitochondria from rat liver and muscle to take up, recycle, and oxidize ascorbate. Freshly prepared mitochondria contain ascorbate, as do mitoplasts that lack the outer mitochondrial membrane. Both mitochondria and mitoplasts rapidly take up oxidized ascorbate as dehydroascorbic acid and reduce it to ascorbate. Ascorbate concentrations in mitochondria and mitoplasts rise into the low millimolar range during dehydroascorbic acid uptake, although uptake and reduction is opposed by ascorbate efflux. Mitochondrial dehydroascorbic acid reduction depends mainly on GSH, but mitochondrial thioredoxin reductase may also contribute. Reactive oxygen species generated within mitochondria oxidize ascorbate more readily than they do GSH and alpha-tocopherol. These results show that mitochondria can recycle ascorbate, which in turn might help to prevent deleterious effects of oxidant stress in the organelle.

Fourier-transform infrared spectroscopy: a pharmacotoxicologic tool for in vivo monitoring radical aggression

Among the physico-chemical methods that can be used to investigate induced peroxidation in living cells, Fourier transform infrared (FT-IR) spectroscopy appears to be a valuable technique as it is non-destructive and sensitive for monitoring changes in the vibrational spectra of samples. We examined microsomal fractions from rat liver and brain by FT-IR to study the effect of radical aggression induced in vivo by carbon tetrachloride (CCl4). The length of the acyl chains was increased as a consequence of peroxidation induced by the xenobiotic. Moreover, an enhanced level of cholesterol esters and an increase in phospholipids were observed in the liver and the brain, respectively. The conformational structure of the membrane proteins was changed in both the liver and the brain. In the polysaccharide region, we observed an important loss in glucidic structures, such as a decrease in liver glycogen and in some brain glycolipids. These alterations are probably due to the interactions between cells and CCl4and the metabolic changes caused by CCl4. Thus, FT-IR spectroscopy appears to be an useful tool and an accurate means for rapidly investigating the in vivo biochemical alterations induced by CCl4in microsomes, and for correlating them with biochemical and physiological data.Key words: brain, carbon tetrachloride, FT-IR, liver, microsomes.

Pharmacologic application of fourier transform IR spectroscopy: in vivo toxicity of carbon tetrachloride on rat liver

Microsomal fractions from rat liver were examined by means of Fourier transform IR (FTIR) spectroscopy to study the in vivo toxic effect of carbon tetrachloride administered by intraperitoneal injection. Lipid content was significantly enhanced in the liver of treated rats compared with untreated ones. The level of saturated fatty acids largely increased while that of unsaturated acids slightly decreased as a consequence of lipid peroxidation induced by the xenobiotic compound. The conformational structure of membrane proteins was changed, which was shown by the large decrease in the alpha-helical configuration. In the polysaccharide region we observed an important loss in glucidic structures that could be related to the metabolic changes caused by carbon tetrachloride intoxication. Thus, FTIR spectroscopy appears to be a useful tool to rapidly investigate the chemical alterations induced by this drug in liver microsomes and to correlate them with biochemical and physiological data.

Better outcome after stroke with higher serum cholesterol levels

OBJECTIVE

To examine whether serum cholesterol levels have any prognostic value in the first month following acute ischemic stroke.

BACKGROUND

Although the association between serum cholesterol levels and cerebrovascular disorders has been extensively studied, the relationship between cholesterol levels and outcome following ischemic stroke has not been investigated.

METHODS

Using data from 3,273 consecutive patients with first-ever ischemic stroke, the authors compared poor functional outcome (severe disability or death) at 1 month in patients with high cholesterol (total serum cholesterol greater than 6.5 mmol/L or 250 mg/dL) and normal cholesterol (level equal to or less than 6.5 mmol/L or 250 mg/dL). Data were analyzed by univariate and multivariate analysis.

RESULTS

In comparison with patients with normal cholesterol levels, patients with high cholesterol levels had a 2.2-fold lower risk of death (p = 0.002) and a 2.1-fold lower risk of poor functional outcome at 1 month (p < 0.001). After adjustment for known confounding variables, multivariate analysis showed that higher cholesterol levels remained an independent predictor of better functional outcome (OR 0.48, CI 0. 34 to 0.69, p < 0.001).

CONCLUSIONS

The authors' findings suggest that higher levels of cholesterol are associated with a better outcome in the early phase after ischemic stroke.

A unifying hypothesis of Alzheimer's disease. III. Risk factors

Normal ageing and Alzheimer's disease (AD) have many features in common and, in many respects, both conditions only differ by quantitative criteria. A variety of genetic, medical and environmental factors modulate the ageing-related processes leading the brain into the devastation of AD. In accordance with the concept that AD is a metabolic disease, these risk factors deteriorate the homeostasis of the Ca(2+)-energy-redox triangle and disrupt the cerebral reserve capacity under metabolic stress. The major genetic risk factors (APP and presenilin mutations, Down's syndrome, apolipoprotein E4) are associated with a compromise of the homeostatic triangle. The pathophysiological processes leading to this vulnerability remain elusive at present, while mitochondrial mutations can be plausibly integrated into the metabolic scenario. The metabolic leitmotif is particularly evident with medical risk factors which are associated with an impaired cerebral perfusion, such as cerebrovascular diseases including stroke, cardiovascular diseases, hypo- and hypertension. Traumatic brain injury represents another example due to the persistent metabolic stress following the acute event. Thyroid diseases have detrimental sequela for cerebral metabolism as well. Furthermore, major depression and presumably chronic stress endanger susceptible brain areas mediated by a host of hormonal imbalances, particularly the HPA-axis dysregulation. Sociocultural and lifestyle factors like education, physical activity, diet and smoking may also modulate the individual risk affecting both reserve capacity and vulnerability. The pathophysiological relevance of trace metals, including aluminum and iron, is highly controversial; at any rate, they may adversely affect cellular defences, antioxidant competence in particular. The relative contribution of these factors, however, is as individual as the pattern of the factors. In familial AD, the genetic factors clearly drive the sequence of events. A strong interaction of fat metabolism and apoE polymorphism is suggested by intercultural epidemiological findings. In cultures, less plagued by the 'blessings' of the 'cafeteria diet-sedentary' Western lifestyle, apoE4 appears to be not a risk factor for AD. This intriguing evidence suggests that, analogous to cardiovascular diseases, apoE4 requires a hyperlipidaemic lifestyle to manifest as AD risk factor. Overall, the etiology of AD is a key paradigm for a gene-environment interaction. Copyright 2000 John Wiley & Sons, Ltd.

Decreased susceptibility to lipid peroxidation of Goto-Kakizaki rats: relationship to mitochondrial antioxidant capacity

The respiratory function and the antioxidant capacity of liver mitochondrial preparations isolated from Goto-Kakizaki non-insulin dependent diabetic rats and from Wistar control rats, with the age of 6 months, were compared. It was found that Goto-Kakizaki mitochondrial preparations presented a higher coupling between oxidative and phosphorylative systems, compared to non-diabetic preparations. Goto-Kakizaki mitochondria presented a lower susceptibility to lipid peroxidation induced by ADP/Fe2+, as evaluated by the formation of thiobarbituric acid substances. The decreased susceptibility to peroxidation in diabetic rats was correlated with an increase in mitochondrial vitamin E (alpha-tocopherol) content and GSH/GSSG ratio. Moreover, the glutathione reductase activity was significantly increased, whereas the glutathione peroxidase was decreased. Superoxide dismutase activity was unchanged in diabetic rats. Fatty acid analyses showed that the content in polyunsaturated fatty acids of Goto-Kakizaki mitochondrial membranes was significantly higher compared to controls. These results indicate that the lower susceptibility to lipid peroxidation of mitochondria from diabetic rats was related to their antioxidant defense systems, and may correspond to an adaptative response of the cells against oxidative stress in the early phase of diabetes.

Antioxidant systems in rat epididymal spermatozoa

Mammalian caput and cauda epididymidal spermatozoa exhibit diverse stages of maturation, and their plasma membrane shows diverse composition and stability levels, thus enabling these spermatozoa to undergo the acrosomal reaction after transit through the epididymis. As a result, the study of antiperoxidative mechanisms is quite relevant, since epididymal spermatozoa must be properly protected against agents such as reactive oxygen species, which can impair the complex maturation process. We considered activities of certain enzymes (glutathione peroxidase [GPx], phospholipid hydroperoxide glutathione peroxidase [PHGPx], glutathione reductase [GR], superoxide dismutase [SOD], and catalase [CAT]) and the vitamin E content in isolated rat caput and cauda epididymidal spermatozoa. The results indicate that caput epididymidal sperm have significantly greater PHGPx (3.5x), GPx (2.4x), and SOD (1.7x) activities, as well as a greater amount of vitamin E (3.8x). There were no detectable differences in the GR and CAT activities of caput and cauda epididymidal spermatozoa. The substantial drop in PHGPx activity during epididymal transit is discussed in relation to an additional function of this enzyme: the use of caput sperm protamines as a sulfhydryl substrate. In vitro peroxidation of the two sperm populations by the free radical generator (azo-initiator) 2,2'-azobis(2-amidinopropane) dihydrochloride revealed that only about 13% of the vitamin E content of the caput epididymidal spermatozoa was consumed, which contrasts with the greater consumption (about 70%) of the vitamin in cauda epididymidal spermatozoa. Selective inhibition of PHGPx, SOD, or CAT did not change this picture. The higher susceptibility of cauda epididymidal spermatozoa to radicals is discussed in relation to the diverse enzymatic activities, vitamin E content, and peroxidative response. These factors are correlated with the different stages of sperm cell maturation, which are characterized-from caput to cauda epididymidis-by progressive destabilization of the plasma and acrosomal membranes.

Influence of vitamin E succinate on retinal cell survival

In this study, we analyzed the influence of vitamin E succinate (5-80 microM), supplemented in the culture medium, on the survival of cultured retinal cells. The release of lactate dehydrogenase (LDH) was decreased in the presence of low concentrations (10-20 microM) of vitamin E succinate, whereas high concentrations (80 microM) induced a significant increase (about 2-fold) in the release of LDH, indicating a reduction of plasma membrane integrity. Supplementing with vitamin E succinate (80 microM) greatly enhanced its cellular content, as compared to vitamin E acetate (80 microM), and the membrane order of the retinal cells, as evaluated by the fluorescence anisotropy (r) of TMA-DPH (1-(4-(trimethylammonium)-phenyl)-6-phenylhexa-1,3,5-triene), was not altered. Furthermore, vitamin E succinate was more potent than vitamin E acetate in reducing thiobarbituric acid reactive substances (TBARS) formation upon ascorbate-Fe2+-induced oxidative stress (TBARS formation after cell oxidation decreased by about 15-fold or 1.6 fold, respectively, in the presence of 20 microM vitamin E succinate or 20 microM vitamin E acetate). A decrease in MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction induced by supplementing with vitamin E succinate (80 microM), to 35.99 +/- 1.96% as compared to the control, but not by vitamin E acetate (80 microM), suggests that vitamin E succinate may affect the mitochondrial activity. Vitamin E succinate also reduced significantly the ATP:ADP ratio in a dose-dependent manner, indicating that vitamin E succinate-mediated cytotoxic effects involve a decrement of mitochondrial function.