Marcadores de estrés oxidativo en pacientes con esclerosis múltiple durante un brote y su remisión / Oxidative stress markers in patients with multiple sclerosis during an outbreak and its remission / Marcadores de estresse oxidativo em pacientes com esclerose múltipla durante um surto e sua remissão

La esclerosis múltiple remitente-recurrente (EM-RR) es una enfermedad desmielinizante del sistema nervioso central. A fin de entender la asociación del estrés oxidativo a nivel periférico con la recaída de la enfermedad se determinaron los niveles de marcadores de estrés oxidativo en plasma de pacientes en la recaída o brote y una semana después de la misma. Se analizaron muestras de 60 personas (20 pacientes con recaída, 20 pacientes sin recaída y 20 controles sanos). Se cuantificaron mediante métodos espectrofotométricos las actividades enzimáticas de óxido nítrico sintasa (ONS), glutatión peroxidasa (GPx), los niveles de lipoperóxidos y nitritos-nitratos y la fluidez de membrana. En el brote de la enfermedad aumentan significativamente los niveles de las actividades enzimáticas de ONS y GPx y los niveles de nitritos-nitratos y lipoperóxidos (p<0,01 en todos los casos), al ser comparados con los de individuos sanos. Dichos parámetros disminuyeron significativamente una semana después de iniciado el brote. Además, los parámetros evaluados se mantuvieron elevados en pacientes que no experimentaron un brote de la enfermedad cuando se los comparó con individuos sanos. La fluidez de membrana en los pacientes con y sin brote fue similar a la de los controles. En conclusión, el estrés oxidativo es un componente importante en los pacientes con esclerosis múltiple.

Recurrent-remitting multiple sclerosis (RR-MS) is a demyelinating disease of the central nervous system. In order to understand the association of oxidative stress at the peripheral level with the relapse of the disease, the levels of oxidative stress markers in plasma of patients in the relapse or outbreak and one week after relapse were determined. Samples of 60 subjects were analyzed (20 patients in relapse, 20 patients without relapse, and 20 healthy controls). The enzymatic activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), lipoperoxides and nitrite-nitrate levels and membrane fluidity were quantified by spectrophotometric methods. In relapse, the levels of enzymatic activities of NOS and GPx, and the levels of lipoperoxides and nitrites-nitrates were significantly increased (p<0.01, in all cases), compared with healthy individuals. These parameters decreased significantly 1 week after the start of the outbreak. In addition, the parameters evaluated remained high in patients who did not experience an outbreak of the disease compared to healthy subjects. The membrane fluidity in the patients with and without outbreak was similar to that of the controls. In conclusion, oxidative stress is an important component in patients with multiple sclerosis.

A esclerose múltipla recorrente-remitente (EM-RR) é uma doença desmielinizante do sistema nervoso central. Para compreender a associação do estresse oxidativo a nível periférico com a recaída da doença foram determinados os níveis de marcadores de estresse oxidativo em plasma de doentes na recaída ou surto e uma semana após a recaída. Foram analisadas a amostras de 60 pessoas (20 pacientes com recaída, 20 pacientes sem recaída e 20 controles saudáveis). As atividades enzimáticas de óxido nítrico sintase (ONS), glutationa peroxidase (GPX), os níveis de lipoperóxidos e nitritos-nitratos e a fluidez de membrana foram quantificadas por métodos espectrofotométricos. No surto da doença aumentam em forma significativa os níveis da atividade enzimática de ONS e GPX, e os níveis de nitritos-nitratos e lipoperóxidos (p<0,01 em todos os casos), em comparação com os indivíduos saudáveis. Esses parâmetros diminuíram significativamente uma semana após o início do surto. Além disso, os parâmetros avaliados permaneceram elevados em pacientes que não experimentaram um surto da doença quando comparados com indivíduos saudáveis. A fluência de membrana nos pacientes com e sem surto foi semelhante à dos controles. Em conclusão, o estresse oxidativo é um componente importante nos pacientes com esclerose múltipla.

Arginase activity and nitric oxide levels in patients with obstructive sleep apnea syndrome

OBJECTIVE: Obstructive sleep apnea syndrome is characterized by repetitive obstruction of the upper airways, and it is a risk factor for cardiovascular diseases. There have been several studies demonstrating low levels of nitric oxide in patients with obstructive sleep apnea syndrome compared with healthy controls. In this study, we hypothesized that reduced nitric oxide levels would result in high arginase activity. Arginase reacts with L-arginine and produces urea and L-ornithine, whereas L-arginine is a substrate for nitric oxide synthase, which produces nitric oxide. METHODS: The study group consisted of 51 obstructive sleep apnea syndrome patients (M/F: 43/8; mean age 49±10 years of age) and 15 healthy control subjects (M/F: 13/3; mean age 46±14 years of age). Obstructive sleep apnea syndrome patients were divided into two subgroups based on the presence or absence of cardiovascular disease. Nitric oxide levels and arginase activity were measured via an enzyme-linked immunosorbent assay of serum samples. RESULTS: Serum nitric oxide levels in the control subjects were higher than in the obstructive sleep apnea patients with and without cardiovascular diseases (p<0.05). Arginase activity was significantly higher (p<0.01) in obstructive sleep apnea syndrome patients without cardiovascular diseases compared with the control group. Obstructive sleep apnea syndrome patients with cardiovascular diseases had higher arginase activity than the controls (p<0.001) and the obstructive sleep apnea syndrome patients without cardiovascular diseases (p<0.05). CONCLUSION: Low nitric oxide levels are associated with high arginase activity. The mechanism of nitric oxide depletion in sleep apnea patients suggests that increased arginase activity might reduce the substrate availability of nitric oxide synthase and thus could reduce nitric oxide levels. .

Effect of cervical sympathetic block on cerebral vasospasm after subarachnoid hemorrhage in rabbits

PURPOSE: Cerebral vasospasm (CVS) is a major complication after subarachnoid hemorrhage (SAH) induced by the rupture of intracranial aneurysms. The aim of the present study was to investigate the effect and mechanism of cervical sympathetic block on cerebral vasospasm of the rabbits after SAH. METHODS: After successful modeling of cervical sympathetic block, 18 healthy male white rabbits were randomly divided into three groups (n=6), ie, sham operation group (Group A), SAH group (Group B) and SAH with cervical sympathetic block group (Group C). Models of delayed CVS were established by puncturing cisterna magna twice with an injection of autologous arterial blood in Groups B and C. A sham injection of blood through cisterna magna was made in Group A. 0.5 ml saline was injected each time through a catheter for cervical sympathetic block after the first injection of blood three times a day for 3 d in Group B (bilateral alternating). 0.5 ml of 0.25% bupivacaine was injected each time through a catheter for cervical sympathetic block after the first injection of blood three times a day for 7 d in Group B. 2 ml venous blood and cerebrospinal fluid were obtained before (T1), 30 min (T2) and 7 d (T3) after the first injection of blood, respectively, and conserved in a low temperature refrigerator. Basilar artery value at T1, T2 and T3 was measured via cerebral angiography. The degree of damage to nervous system at T1 and T3 was recorded. RESULTS: There was no significant difference in diameter of basilar artery at T1 among three groups. The diameters of basilar artery at T2 and T3 of Groups B and C were all smaller than that in Group A, which was smaller than Group C, with a significant difference. There was no significant difference in NO and NOS in plasma and cerebrospinal fluid among three groups. The NO and NOS contents at T2 and T3 of Groups B and C were all lower than Group A; Group C was higher than Group B, with a significant difference. The nerve function at T3 of Groups B and C were all lower than Group A and that of Group C higher than Group B, with a significant difference. CONCLUSION: Cervical sympathetic block can relieve cerebral vasospasm after subarachnoid hemorrhage and increase NO content and NOS activity in plasma and cerebrospinal fluid to promote neural functional recovery.

Oxido nítrico y circulación / Nitric oxide and circulation

Nitric oxide (NO) is a fascinating ubiquitous molecule with multiple complex roles in biological systems, such as intra and inter cell communications. Endothelial physiology relies on its endothelium derived relaxing factor (EDRF) properties as originally described. NO exhibits physiological vasodilator effects, mediated in part by its binding to the heme group of guanylyl cyclase to produce cGMP that relaxes vascular smooth muscle by lowering cytoplasmic Ca2' levels. So me experiments from several laboratories have very recently established that red blood cells provide a novel vasodilator activity NO mediated in which hemoglobin acts as an O2 sensor and O2-responsive NO signal transducer, thereby regulating both peripheral and pulmonary vascular tone. Haemoglobin through its oxygen binding function adjusts NO bioavailability at the microcirculation and in turn, red blood cells can cause microvessels to dila­te or constrict, with S-nitroso-haemoglobin as an intermediate. But other groups demonstrated that SNO­Hb is not essential for the physiologic coupling of erythrocyte deoxygenation with increased NO bioactivity in vivo. A third group emphasized the role of nitrites and the nitrite reductase activity of hemoglobin as the source of vasodilators in the microcirculation. As blood transfusion in the setting of acute coronary syndromes seemed to be associated with higher mortality, some authors linked those phenomena to the S-nitrosohemoglobin deficiency in banked blood, a mechanism that could explain its loss of physiological activity. In adition to the peripheric actions, the regulatory function of NO on cardiac efficiency also contributes to its key role in the circulation.

Individual susceptibility to vernal keratoconjunctivitis and ameliorative effects of antioxidants on its symptoms

An allergic response is associated by an increase in the expression and activity of the inducible nitric oxide synthase [iNOS] an inducible enzyme present endothelial cells and polymorphonuclear leucocytes [PMN] and moncytes. Vernal keratoconjunctivitis [VKC], is a recurrent or chronic ocular allergic eye disease affecting young individual living in a hot climate. This study was designed to test a hypothesis that the immune changes seen in Vernal keratoconjunctivitis during the summer or spring season is a function of the effect of hot weather on the of polymorphonuclear leucocytes [PMN] and monocytes in susceptible individuals, by evaluating the role of nitric oxide [NO] and NO-synthase [iNOS] in the pathogenesis of allergic conjunctivitis and the effect of supplementing those patients with antioxidants in order to ameliorate ocular allergic effects. 40 patients with typical VKC were divided into two groups. Antioxidants were given as a supplement to one group [n=20], while the second group did not [n=20]. Both groups were followed up periodically for clinical picture and status and were compared with a third healthy age and socio-economic matching control group. Blood samples were obtained before treatment, after one month and at the end of the whole follow up period. Blood markers of oxidative stress including: protein carbonyls, nitrite. DNA fragmentation and apoptosis in circulating lymphocytes of VKC before and after antioxidant therapy during the severity of the disease were evaluated. Also neutrophil's individual ability to express iNOS was assessed. Vernal Keratoconjunctivitis patients exhibited increased individual ability in the production and expression of nitric oxide by their stimulated neutrophils [4.5 +/- 0.05 nmol/ 10[5] cell vs. 2.5 +/- 0.09 nmol/ 10[5] cell] compared to controls. Both biochemical and clinical picture proved that a supplement of antioxidants to the traditional topical treatment would significantly improve the patients ocular allergic symptoms even after seizure of topical treatment, while recurrence of symptoms and signs occurred in group two after stoppage of the topical steroidal treatment. The antioxidant supplemented group exhibited decreased markers of oxidative stress at the end of the first month follow-up period compared to those patients that were not supplemented with antioxidants: Protein carbonyls [0.57 +/- 0.34 vs. 0.93 +/- 0.05]; Percentage of DNA fragmentation per total DNA in combined plasma and leucocytes after one month [0.7% +/- 0.09 vs. 0.93 +/- 0.05] and plasma nitrite after one month [2.4 +/- 0.5 vs. 3 +/- 0.19 nMol/ml] in VKC patients compared to controls respectively. The associated immunological and inflammatory systemic condition of VKC recommends the use of antioxidant mixture in order to emeliorate the ocular allergic effects associated with VKC. Antioxidant use proved its efficiency and prevent recurrence of VKC even after stoppage of the steroid. Also individuals with increased neutrophil's activity have higher individual susceptibility to develop VKC

Preliminary study on the production of nitric oxide and expression of nitric oxide synthase by camel macrophages [with one table and one figure]

Nitric Oxide is produced by macrophage when activated or invaded by certain antigens or microbes. In the present study, camel peripheral blood leukocytes were obtained by ficoll cushion. Monocytes were separated and grown to macrophages. The mature macrophages were exposed to E. coli LPS as well as sheep pox virus antigen. Nitric oxide [NO] production, by stimulated macrophages as well as the mRNA specific for production of inducible nitric oxide syntheses [iNOS], were investigated. Production of NO was stimulated by both pox antigen and LPS and was more with the latter. The obtained results indicated the similarity in the tested parameters between camel macrophages and those of other mammals tested so far viz mice

Brain oxidative reactions and nitric oxide relation to the pro-and anticonvulsive activity of nitric oxide synthase modulators in pentylenetetrazol seizure model in mice

This study was carried out to investigate the possible effects and relation of brain levels of nitric oxide [NO], malondialdehyde [MDA] and glutathione [GSH], using the NO donor L-arginine [L-Arg, 75-1200 mg/kg] and the NO inhibitor, NG-nitro-L-arginine methyl ester [L- NAME, 25-150 mg/kg] and flunarizine [Flu, 10-40 mg/kg] and calcium channel blocker alone and in different combinations on pentylenetetrazol [PTZ] seizure severity, latency and threshold in mice. L-NAME decreased PTZ seizure threshold and caused a significant dose-dependent proconvulsant effect, which was partially antagonized by Flu [20 mg/kg]. Meanwhile, L-Arg produced a significant anti- convulsant activity and increased the FTZ threshold. Mortality was decreased by pretreatment with L-NAME, while all animals receiving protective doses of L-Arg did not show any mortality. In PTZ treated animals, MDA levels were increased, while GSH levels were decreased; this change was not related directly to the decreased brain NO levels by L-NAME. However, L-Arg significantly increased the formation of NO, which was associated with decreased lipid peroxidation. Moreover, it prevented the effect of PTZ on MDA and GSH. Flu failed to alter brain NO levels, but it caused about 10 folds increase in MDA and 2.5 folds increase in GSH when combined with L-Arg

Interrelationship between nitric oxide synthase and myocardial tumor necrosis factor-alpha effect on cardiac contractile function in preconditioned anesthetized dogs

Brief periods of myocardial ischemia and reperfusion render the myocardium tolerant to a subsequent sustained ischemia. This phenomenon has been known as ischemic preconditioning [PC]. It has recently become apparent that ischemic PC consists of two phases: an early phase, which occurs within minutes and disappears within 2 to 4 hours from the PC ischemia, and a late phase, which becomes manifest 24 hours later. The purpose of the present study was to test the hypothesis that the protective effect of ischemic PC is mediated by augmented nitric oxide [NO] formation. This study also aims at examining the effect of ischemic PC on postischemic myocardial tumor necrosis factor-alpha [TNF-alpha] production. This study was carried out on 38 healthy adult dogs of either sex. Six dogs were sacrificed and left ventricular myocardium was excised, homogenized and cardiac TNF-alpha homogenate was determined by chemiluminescence. Thirty-two dogs were randomized into 4 equal groups; Group I [preconditioned group], Group II [ischemic control group], Group III [preconditioned N-nitro-L-arginine methyl-ester [L-NA] treated group] and Group IV [ischemic L-NA treated group]. All groups were allowed 3 hours of reperfusion thereafter. Left ventricular systolic pressure [LVSP] and cardiac output [COP] were measured before and after left anterior descending coronary artery [LAD] occlusion reperfusion [O/R] in the four studied groups. After the three hours of reperfusion, TNF-alpha was measured in the cardiac homogenate of all groups. There was no statistically significant difference in LVSP and COP when comparing the four groups after LAD O/R However, there was a significant drop in both parameters in each of the four studied groups after LAD O/R. The absent short-term beneficial role of PC on myocardial contractility following O/R could be attributed to stunning of the myocardium: Furthermore, inhibition of NO synthesis did not attenuate myocardial stunning in preconditioned and ischemic anesthetized dogs. The present study also demonstrated that O/R increases cardiac TNF-alpha levels and that ischemic PC decreases ischemia-induced cardiac TNF-alpha production, which is still significantly higher in the preconditioned groups, compared with control group. This drop in myocardial TNF-alpha following ischemic PC did not improve postischemic functional recovery in anesthetized dogs. The absent short-term beneficial role of pretreatment with a NOS inhibitor could be explained by the fact that inducible NO synthase [iNOS] mediated only the late dysfunction induced by TNF-alpha

Negative inotropic effect of chagasic IGG mediated by nitric oxide

In this paper we analyse the interaction of IgG from T. cruzi infected patients with cardiac muscarinic acetycholine receptors (mAChRs). Human chagasic IgG, activating M2 mAChR simulated the agonist actions excerting negative inotropic effect and simulation of nitric oxide synthase (NOS). Inhibitos of phospholipase C, protein Kinase C, calcium/calmodulin, NOS and guanylate cyclase activities prevented the chagasis effects upon contractility and NOS activity.