Neurological Disorders in an Elderly Cohort Experienced Past Stressful Events: A Retrospective-prospective Study.

BACKGROUND: Psychological stress may be a risk factor for dementia, but the association between exposure to stressful life events and the development of cognitive dysfunction has not been conclusively demonstrated. We hypothesize that if a stressful event has an impact on the subjects, its effects would be different in the three diseases. OBJECTIVE: This study aims to assess the effects of stressful events in senior patients who later developed ischemic stroke, Alzheimer's, or Parkinson's disease. MATERIAL AND METHODS: Together with demographic variables (age, sex, race, socioeconomic and cultural levels), five types of past stressful events, such as death or serious illness of close relatives, job dismissal, change of financial status, retirement, and change of residence, were recorded in 1024 patients with Alzheimer's disease, Parkinson's disease, and ischemic stroke. Time-todiagnosis (months from the event to the first symptoms: retrospective study) and evolution time (years of follow-up of each patient: prospective study) were recorded. The variance and nonparametric methods were analyzed to the variables time-to-diagnosis and evolution time to analyze differences between these diseases. RESULTS: The demographic variables, such as age, sex, race, economic and cultural levels, were found to be statistically non-significant; differences in the economic level were significant (P<0.05). Significant differences (P<0.001) were found in the mean time-to-diagnosis between diseases (Alzheimer's disease>Parkinson's disease >Stroke), and minor differences (P<0.05) in evolution time. CONCLUSION: Differences in time-to-diagnosis between the diseases indicate that the stressful effect of having experienced the death or serious illness of a close relative has an impact on their emergence. The measurement of time-to-diagnosis and evolution time proves useful in detecting differences between diseases.

Effects of rotenone and pyridaben on complex I electron transfer and on mitochondrial nitric oxide synthase functional activity.

Rotenone and pyridaben were tested on activities and properties of rat brain mitochondria determining Ki (inhibitor concentration at half maximal inhibition) and Imax (% of inhibition at maximal inhibitor concentration). The assayed activities were complexes I, II and IV, respiration in states 3, 3u (uncoupled) and 4, biochemical and functional activities of mitochondrial nitric oxide synthase (mtNOS), and inner membrane potential. Selective inhibitions of complex I activity, mitochondrial respiration and membrane potential with malate-glutamate as substrate were observed, with a Ki of 0.28-0.36 nmol inhibitor/mg of mitochondrial protein. Functional mtNOS activity was half-inhibited at 0.70-0.74 nmol inhibitor/mg protein in state 3 mitochondria and at 2.52-2.98 nmol inhibitor/mg protein in state 3u mitochondria. This fact is interpreted as an indication of mtNOS being structurally adjacent to complex I with an intermolecular mtNOS-complex I hydrophobic bonding that is stronger at high Δψ and weaker at low Δψ.

Oxidative damage: the biochemical mechanism of cellular injury and necrosis in choline deficiency.

Oxidative stress and damage are characterized by decreased tissue antioxidant levels, consumption of tissue alpha-tocopherol, and increased lipid peroxidation. These processes occur earlier than necrosis in the liver, heart, kidney, and brain of weanling rats fed a choline deficient (CD) diet. In tissues, water-soluble antioxidants were analyzed as total reactive antioxidant potential (TRAP), alpha-tocopherol content was estimated from homogenate chemiluminescence (homogenate-CL), and lipid peroxidation was evaluated by thiobarbituric acid reactive substances (TBARS). Histopathology showed hepatic steatosis at days 1-7, tubular and glomerular necrosis in kidney at days 6 and 7, and inflammation and necrosis in heart at days 6 and 7. TRAP levels decreased by 18%, 48%, 56%, and 66% at day 7, with t(1/2) (times for half maximal change) of 2.0, 1.8, 2.5, and 3.0 days in liver, kidney, heart, and brain, respectively. Homogenate-CL increased by 97%, 113%, 18%, and 297% at day 7, with t(1/2) of 2.5, 2.6, 2.8, and 3.2 days in the four organs, respectively. TBARS contents increased by 98%, 157%, 104%, and 347% at day 7, with t(1/2) of 2.6, 2.8, 3.0, and 5.0 days in the four organs, respectively. Plasma showed a 33% decrease in TRAP and a 5-fold increase in TBARS at day 5. Oxidative stress and damage are processes occurring earlier than necrosis in the kidney and heart. In case of steatosis prior to antioxidant consumption and increased lipid peroxidation, no necrosis is observed in the liver.

The involvement of transition metal ions on iron-dependent lipid peroxidation.

The metals iron (Fe) and copper (Cu) are considered trace elements, and the metals cobalt (Co) and nickel (Ni) are known as ultra-trace elements, considering their presence in low to very low quantity in humans. The biologic activity of these transition metals is associated with the presence of unpaired electrons that favor their participation in redox reactions. They are part of important enzymes involved in vital biologic processes. However, these transition metals become toxic to cells when they reach elevated tissue concentrations and produce cellular oxidative damage. Phospholipid liposomes (0.5 mg/ml, phosphatidylcholine (PC)/phosphatidylserine (PS), 60/40) were incubated for 60 min at 37 degrees C with 25 microM of Fe2+ in the absence and in the presence of Cu2+, Co2+, and Ni2+ (0-100 microM) with and without the addition of hydrogen peroxide (H2O2, 5-50 microM). Iron-dependent lipid peroxidation in PC/PS liposomes was assessed by thiobarbituric acid-reactive substances (TBARS) production. Metal transition ions promoted lipid peroxidation by H2O2 decomposition and direct homolysis of endogenous hydroperoxides. The Fe2+-H2O2-mediated lipid peroxidation takes place by a pseudo-second order process, and the Cu2+-mediated process by a pseudo-first order reaction. Co2+ and Ni2+ alone do not induce lipid peroxidation. Nevertheless, when they are combined with Fe2+, Fe2+-H2O2-mediated lipid peroxidation was stimulated in the presence of Ni2+ and was inhibited in the presence of Co2+. The understanding of the effects of transition metal ions on phospholipids is relevant to the prevention of oxidative damage in biologic systems.

Role of Oxidative Stress in Lithium-Induced Nephropathy.

Long-term lithium treatment was associated with chronic kidney disease and renal failure although the underlying pathogenic mechanisms are not certainty known. The aim of this study was to evaluate changes in oxidative stress measures as well as renal functional and structural alterations associated with chronic use of lithium in rats. Forty Wistar male rats were randomized into four groups: control groups fed ad libitum powered standard diet for 1 and 3 months and experimental groups fed ad libitum the same diet supplemented with 60 mmol/kg diet for 1 and 3 months. Histopathological changes, laboratory parameters, and oxidative stress measurements were assessed at months 1 and 3. The experimental animals showed alteration of the cortical tubules from the first month of lithium-treatment and a decrease in the glomerular filtration rate and in the glomerular area at the third month. There was an increase in thiobarbituric acid reactive substances and carbonyls, as well as an increase in reduced glutathione, in the kidney of rats exposed to lithium. These changes were evident from the first month of treatment and remained throughout the experiment. Our results suggest that, oxidative stress could be one of the pathogenic mechanisms involved in the structural and functional alterations of the kidney associated with prolonged use of lithium. The study of the pathogenic mechanisms involved in lithium-induced nephropathy is a critical issue for the development of new strategies for prevention and/or early detection.

Copper(II) and iron(III) ions inhibit respiration and increase free radical-mediated phospholipid peroxidation in rat liver mitochondria: Effect of antioxidants.

Rat liver mitochondria (1.5-2.1mg protein·mL-1) supplemented with either 25 and 100µM Cu2+ or 100 and 500µM Fe3+ show inhibition of active respiration (O2 consumption in state 3) and increased phospholipid peroxidation . Liver mitochondria were supplemented with the antioxidants reduced glutathione, N-acetylcysteine or butylated hydroxitoluene, to evaluate their effects on the above-mentioned alterations. Although the mitochondrial dysfunction is clearly associated to phospholipid peroxidation, the different responses to antioxidant supplementation indicate that the metal ions have differences in their mechanisms of toxicity. Mitochondrial phospholipid peroxidation through the formation of hydroxyl radical by a Fenton/Haber-Weiss mechanism seems to precede the respiratory inhibition and to be the main fact in Fe-induced mitochondrial dysfunction. In the case of Cu2+, it seems that the ion oxidizes glutathione, and low molecular weight protein thiol groups in a direct reaction, as part of its intracellular redox cycling. The processes involving phospholipid peroxidation, protein oxidation and mitochondrial respiratory inhibition characterize a redox dyshomeostatic situation that ultimately leads to cell death. However, Cu2+ exposure involves an additional, yet unidentified, toxic event as previous reduction of the metal with N-acetylcysteine has only a minor effect in preventing the mitochondrial damage.

Rat liver mitochondrial dysfunction by addition of copper(II) or iron(III) ions.

Increased copper (Cu) and iron (Fe) levels in liver and brain are associated to oxidative stress and damage with increased phospholipid oxidation process. The aim of this work was to assess the toxic effects of Cu2+ and Fe3+ addition to rat liver mitochondria by determining mitochondrial respiration in states 3 (active respiration) and 4 (resting respiration), and phospholipid peroxidation. Both, Cu2+ and Fe3+ produced decreases in O2 consumption in a concentration-dependent manner in active state 3: both ions by 42% with malate-glutamate as complex I substrate (concentration for half maximal response (C50) 60µM Cu2+ and 1.25mM Fe3+), and with succinate as complex II substrate: 64-69% with C50 of 50µM Cu2+ and with C50 of 1.25mM of Fe3+. Respiratory control decreased with Cu2+ (C50 50µM) and Fe3+ (C50 1.25-1-75mM) with both substrates. Cu2+ produced a 2-fold increase and Fe3+ a 5-fold increase of thiobarbituric acid-reactive substances (TBARS) content from 25µM Cu2+ (C50 40µM) and from 100µM Fe3+ (C50 1.75mM). Supplementations with Cu2+ and Fe3+ ions induce mitochondrial dysfunction with phospholipid peroxidation in rat liver mitochondria. Although is proved that a Fenton/Haber Weiss mechanism of oxidative damage occurs in metal-ion induced mitochondrial toxicity, slightly different responses to the metal ions suggest some differences in the mechanism of intracellular toxicity. The decreased rates of mitochondrial respiration and the alteration of mitochondrial function by phospholipid and protein oxidations lead to mitochondrial dysfunction, cellular dyshomeostasis and cell death.

Evidence of oxidative stress in familial amyloidotic polyneuropathy type 1.

OBJECTIVE: To evaluate the oxidative state in patients with familial amyloidotic polyneuropathy type 1 (FAP1). DESIGN: From 3 unrelated families, patients with FAP1 carrying a transthyretin Met-30 mutation were studied. The diagnosis was confirmed by genetic analysis. Eleven of 21 patients carried the mutation; all were symptomatic and were clinically assessed using a clinical score. All of the patients were evaluated for copper-zinc superoxide dismutase type 1 activity in red blood cells using spectrophotometry. Plasma total reactive antioxidant potential was studied using a chemiluminescent method. The results were compared with those obtained from an age-matched control group. SETTING: A public and academic multidisciplinary research clinic. RESULTS: Six of the 11 FAP1-positive patients disclosed superoxide dismutase type 1 activity values greater than 55 U/mg of protein (upper control limit), whereas 9 of 10 patients in whom total reactive antioxidant potential was measured had values below the lower limit of the control group. No relationship was found between the levels of superoxide dismutase type 1 activity and the severity of the clinical involvement. CONCLUSIONS: Oxidative stress may be part of the mechanisms leading to tissue damage in patients with FAP1. The lack of correlation between the laboratory findings and the severity of clinical involvement may signal that oxidative processes are at work throughout the natural history of the disease.

Brain antioxidant responses to acute iron and copper intoxications in rats.

Dose- and time-dependent antioxidant responses to Fe (0-60 mg kg(-1)) and Cu overloads (0-30 mg kg(-1)) in rat brains are described by the C50 and the t1/2, the brain metal concentration and the time for half maximal oxidative responses. Brain GSH and the GSH/GSSG ratio markedly decreased after Fe and Cu treatments (50-80%) with a t1/2 of 9-10 h for GSH and of 4 h for GSH/GSSG for both metals. The GSH/GSSG ratio was the most sensitive indicator of brain oxidative stress. The decrease of GSH and the increase of in vivo chemiluminescence had similar time courses. The C50 for brain chemiluminescence, GSH and hydrophilic and lipophilic antioxidants were in similar ranges (32-36 µg Fe g(-1) brain and 10-18 µg Cu g(-1) brain), which indicated a unique free-radical mediated process for each metal. The brain concentration of hydrophilic and lipophilic antioxidants decreased after Fe and Cu loads; hydrophilic antioxidants decreased by 46-68% with a t1/2 of 10-11 h and lipophilic antioxidants decreased by 75-45% with a t1/2 of 10-12 h. Cu,Zn-SOD and CAT activities and the protein expression were adaptively increased (100-90% after Fe and Cu loads), with a t1/2 of 8-12 h. GPx-4 activity decreased after both metal loads by 73-27% with a t1/2 of 8-4 h with decreased protein expression.

Rat liver antioxidant response to iron and copper overloads.

The rat liver antioxidant response to Fe and Cu overloads (0-60mg/kg) was studied. Dose- and time-responses were determined and summarized by t1/2 and C50, the time and the liver metal content for half maximal oxidative responses. Liver GSH (reduced glutathione) and GSSG (glutathione disulfide) were determined. The GSH content and the GSH/GSSG ratio markedly decreased after Fe (58-66%) and Cu (79-81%) loads, with t1/2 of 4.0 and 2.0h. The C50 were in a similar range for all the indicators (110-124µgFe/g and 40-50µgCu/g) and suggest a unique free-radical mediated process. Hydrophilic antioxidants markedly decreased after Fe and Cu (60-75%; t1/2: 4.5 and 4.0h). Lipophilic antioxidants were also decreased (30-92%; t1/2: 7.0 and 5.5h) after Fe and Cu. Superoxide dismutase (SOD) activities (Cu,Zn-SOD and Mn-SOD) and protein expression were adaptively increased after metal overloads (Cu,Zn-SOD: t1/2: 8-8.5h and Mn-SOD: t1/2: 8.5-8.0h). Catalase activity was increased after Fe (65%; t1/2: 8.5h) and decreased after Cu (26%; t1/2: 8.0h), whereas catalase expression was increased after Fe and decreased after Cu overloads. Glutathione peroxidase activity decreased after metal loads by 22-39% with a t1/2 of 4.5h and with unchanged protein expression. GSH is the main and fastest responder antioxidant in Fe and Cu overloads. The results indicate that thiol (SH) content and antioxidant enzyme activities are central to the antioxidant defense in the oxidative stress and damage after Fe and Cu overloads.

Oxidative damage to rat brain in iron and copper overloads.

This study reports on the acute brain toxicity of Fe and Cu in male Sprague-Dawley rats (200 g) that received 0 to 60 mg kg(-1) (ip) FeCl2 or CuSO4. Brain metal contents and time-responses were determined for rat survival, in situ brain chemiluminescence and phospholipid and protein oxidation products. Metal doses hyperbolically defined brain metal content. Rat survival was 91% and 60% after Fe and Cu overloads. Brain metal content increased from 35 to 114 µg of Fe per g and from 3.6 to 34 µg of Cu per g. Brain chemiluminescence (10 cps cm(-2)) increased 3 and 2 times after Fe and Cu overloads, with half maximal responses (C50) of 38 µg of Fe per g of brain and 15 µg of Cu per g of brain, and with half time responses (t1/2) of 12 h for Fe and 20 h for Cu. Phospholipid peroxidation increased by 56% and 31% with C50 of 40 µg of Fe per g and 20 µg of Cu per g and with t1/2 of 9 h and 14 h. Protein oxidation increased by 45% for Fe with a C50 of 40 µg of Fe per g and 18% for Cu with a C50 of 10 µg of Cu per g and a t1/2 of 12 h for both metals. Fe and Cu brain toxicities are likely mediated by Haber-Weiss type HO˙ formation with subsequent oxidative damage.

The protective effect of menhaden oil in the oxidative damage and renal necrosis due to dietary choline deficiency.

Weanling rats fed a choline-deficient diet develop kidney oxidative damage, tubular and cortical kidney necrosis, renal failure and animal death. The effect of dietary menhaden oil was assayed on the mentioned sequence correlating oxidative stress with renal structure and function. Rats were fed ad libitum 4 different diets: (a) a choline-deficient diet with corn oil and sunflower hydrogenated oil as a source of fatty acids; (b) the same diet supplemented with choline; (c) a choline-deficient diet with menhaden oil as a source of fatty acids; and (d) the previous diet supplemented with choline. Animals were sacrificed at days 0, 2, 4 and 7. The histopathological study of the kidneys showed that renal necrosis was only observed at day 7 in choline-deficient rats receiving the vegetable oil diet, simultaneously with increased creatinine plasma levels. Homogenate chemiluminescence (BOOH-initiated chemiluminescence) and phospholipid oxidation indicate the development of oxidative stress and damage in choline-deficient rats fed vegetable oils as well as the protective effect of menhaden oil. Rats fed with the fish oil diet showed that oxidative stress and damage develop later, as compared with vegetable oil, with no morphological damage during the experimental period.

The acute toxicity of iron and copper: biomolecule oxidation and oxidative damage in rat liver.

The transition metals iron (Fe) and copper (Cu) are needed at low levels for normal health and at higher levels they become toxic for humans and animals. The acute liver toxicity of Fe and Cu was studied in Sprague Dawley male rats (200 g) that received ip 0-60 mg/kg FeCl(2) or 0-30 mg/kg CuSO(4). Dose and time-responses were determined for spontaneous in situ liver chemiluminescence, phospholipid lipoperoxidation, protein oxidation and lipid soluble antioxidants. The doses linearly defined the tissue content of both metals. Liver chemiluminescence increased 4 times and 2 times after Fe and Cu overloads, with half maximal responses at contents (C(50%)) of 110 µgFe/g and 42 µgCu/g liver, and with half maximal time responses (t(1/2)) of 4h for both metals. Phospholipid peroxidation increased 4 and 1.8 times with C(50%) of 118 µg Fe/g and 45 µg Cu/g and with t(1/2) of 7h and 8h. Protein oxidation increased 1.6 times for Fe with C(50%) at 113 µg Fe/g and 1.2 times for Cu with 50 µg Cu/g and t(1/2) of 4h and 5h respectively. The accumulation of Fe and Cu in liver enhanced the rate of free radical reactions and produced oxidative damage. A similar free radical-mediated process, through the formation HO(•) and RO(•) by a Fenton-like homolytic scission of H(2)O(2) and ROOH, seems to operate as the chemical mechanism for the liver toxicity of both metals.

Type 2 diabetes and/or its treatment leads to less cognitive impairment in Alzheimer's disease patients.

AIM: To evaluate the cognitive performance of a homogeneous population of Alzheimer's disease (AD), non-demented Type 2 Diabetes Mellitus (DIAB), demented with concomitant diseases (AD+DIAB) and healthy control subjects. AD is a progressive dementia disorder characterized clinically by impairment of memory, cognition and behavior. Recently, a major research interest in AD has been placed on early evaluation. Diabetes is one of the clinical conditions that represent the greatest risk of developing oxidative stress and dementia. Glucose overload, leading to the development of impaired-induced insulin secretion in DIAB and has been suggested to slow or deter AD pathogenesis. METHODS: The degree of cognitive impairment was determined on the Alzheimer Disease Assessment Scale-Cognitive (ADAS-Cog) and the Folstein's Mini Mental State Examination (MMSE); the severity of dementia was quantified applying the Clinical Dementia Rating (CDR) test; the Hamilton test was employed to evaluate depressive conditions; the final population studied was 101 subjects. RESULTS: The cognitive deterioration is statistically significantly lower (p<0.05) in AD+DIAB patients as compared with AD patients. CONCLUSIONS: In this longitudinal study the superimposed diabetic condition was associated with a lower rate of cognitive decline, while diabetic non-demented patients and controls present normal scores.