Presencia de las especies reactivas de oxígeno en la diabetes autoinmune del adulto

Se ha comprobado en los últimos años que las especies reactivas de oxígeno (ERO) participan en la destrucción de las células beta pancreáticas, lo cual influye en la diabetes mellitus (DM). La diabetes autoinmune del adulto (LADA) se manifiesta con una mezcla de características de la DM tipo I y la DM tipo 11.Se realizó un estudio de las variables indicadoras del estrés oxidativo en una población de 56 sujetos distribuidos de la siguiente forma, 32 individuos con LADA y 24 sujetos aparentemente sanos, grupo control para lo cual se determinaron las enzimas superóxido dismutasa (SOD) y catalasa (CAT), así como los niveles de malonildialdehído (MDA) y fructosamina obteniéndose como resultado disminuída la actividad de la SOD y aumentada la actividad de la CAT y los niveles de MDA en pacientes con LADA con respecto al grupo control.Se encontró en los pacientes con LADA una correlación entre los niveles de fructosamina y MDA y entre la actividad de la SOD y MDA (p î 0,05 y p î 0,01 respectivamente) sugiriendo que en estos diabéticos autoinmunes la peroxidación lipídica guarda una estrecha relación con los productos de glicosilación avanzada y la generación de radicales aniones superoxido y peróxido de hidrógeno. Estos resultados demuestran que en la diabetes autoinmunes del adulto hay presencia de estrés oxidativo. (AU)

Effect of Mangifera indica L. extract (QF808) on protein and hepatic microsome peroxidation.

The antioxidant activities of QF808, a steam bark extract of Mangifera indica L., were studied on hydroxyl-mediated oxidation of bovine serum albumin (BSA) and in a hepatic microsome system. The extract was effective in reducing the oxidation of BSA, since its half- maximal inhibition concentration (IC(50)) was 0.0049% w/v in the inhibition of carbonyl group formation and lower than 0.0025% w/v in the inhibition of sulfhydryl group loss. QF808 inhibited lipid peroxidation which was initiated enzymatically by reduced nicotinamide adenine dinucleotide phosphate (NADPH), IC(50)= 0.00075% w/v, or non-enzymatically by ascorbic acid, IC(50) = 0.0126% w/v. The extract tested did not inhibit NADPH-dependent cytochrome P-450 reductase activity, since it had no effect on the oxidation rate of NADPH. These results suggest that QF808 has an antioxidant activity, probably due to its ability to scavenge free radicals involved in microsome lipid peroxidation. In addition, QF808 antioxidant profile in vitro is probably similar to its principal polyphenolic component, mangiferin, a glycosylated xanthone.

Ozone treatment reduces markers of oxidative and endothelial damage in an experimental diabetes model in rats.

Ozone has been used as a therapeutical agent and beneficial effects have been observed. However so far only a few biochemical and pharmacodynamic mechanisms have been elucidated. We demonstrate that controlled ozone administration may promote an oxidative preconditioning or adaptation to oxidative stress, preventing the damage induced by reactive oxygen species (ROS). Taking into account that diabetes is a disorder associated with oxidative stress, we postulate that ozone treatment in our experimental conditions might protect antioxidant systems and maintain, at a physiological level, other markers of endothelial cell damage associated with diabetic complications. Five groups of rats were classified as follows: (1) control group treated only with physiological saline solution; (2) positive control group using streptozotocin (STZ) as a diabetes inductor; (3) ozone group, receiving 10 treatments (1.1 mg kg(-1)), one per day after STZ-induced diabetes; (4) oxygen group (26 mg kg(-1)), one per day, as in group 3 but using oxygen only; (5) control ozone group, as group 3, but without STZ. The ozone treatment improved glycemic control and prevented oxidative stress, the increase of aldose reductase, fructolysine content and advanced oxidation protein products. Nitrite and nitrate levels were maintained without changes with regard to non-diabetic control. The results of this study show that repeated administration of ozone in non-toxic doses might play a role in the control of diabetes and its complications.

Time course of oxidative damage in different brain regions following transient cerebral ischemia in gerbils.

The time course of oxidative damage in different brain regions was investigated in the gerbil model of transient cerebral ischemia. Animals were subjected to both common carotid arteries occlusion for 5 min. After the end of ischemia and at different reperfusion times (2, 6, 12, 24, 48, 72, 96 h and 7 days), markers of lipid peroxidation, reduced and oxidized glutathione levels, glutathione peroxidase, glutathione reductase, manganese-dependent superoxide dismutase (MnSOD) and copper/zinc containing SOD (Cu/ZnSOD) activities were measured in hippocampus, cortex and striatum. Oxidative damage in hippocampus was maximal at late stages after ischemia (48-96 h) coincident with a significant impairment in glutathione homeostasis. MnSOD increased in hippocampus at 24, 48 and 72 h after ischemia, coincident with the marked reduction in the activity of glutathione-related enzymes. The late disturbance in oxidant-antioxidant balance corresponds with the time course of delayed neuronal loss in the hippocampal CA1 sector. Cerebral cortex showed early changes in oxidative damage with no significant impairment in antioxidant capacity. Striatal lipid peroxidation significantly increased as early as 2 h after ischemia and persisted until 48 h with respect to the sham-operated group. These results contribute significant information on the timing and factors that influence free radical formation following ischemic brain injury, an essential step in determining effective antioxidant intervention.

"Mangifera indica L. extract (QF808) reduces ischaemia-induced neuronal loss and oxidative damage in the gerbil brain".

The effect of oral administration of Mangifera indica L. extract (QF808) on ischemia-reperfusion-induced neuronal death in the gerbil hippocampal CA1 sector was examined. Oral administration of QF808 for 7 days dose-dependently protected against neuronal cell death following transient ischaemia and reperfusion as assessed by histopathology. In addition, locomotor activity assessment prior to ischaemia and 7 days after correlated well with the histological results. To evaluate redox alterations by reactive oxygen species, total sulfhydryl, non-protein sulfhydryl groups (NPSH), malondialdehyde + 4-hydroxyalkenals and total nitrogen oxide levels were assayed in hippocampus and cortex homogenates. QF808 treatment attenuated NPSH loss, nitrogen oxide levels and lipid peroxidation in the hippocampus. These results suggest that orally administered QF808 is absorbed across the blood-brain barrier and attenuates neuronal death of the hippocampal CA1 area after ischaemia-reperfusion. These protective effects are most likely due to the antioxidant activity of QF808.

Evaluation of the in vitro antioxidant activity of Mangifera indica L. extract (Vimang).

An extract of Mangifera indica L. (Vimang) was tested in vitro for its antioxidant activity using commonly accepted assays. It showed a powerful scavenger activity of hydroxyl radicals and hypochlorous acid and acted as an iron chelator. The extract also showed a significant inhibitory effect on the peroxidation of rat-brain phospholipid and inhibited DNA damage by bleomycin or copper-phenanthroline systems.

Effect of ozone treatment on reactive oxygen species and adenosine production during hepatic ischemia-reperfusion.

This study investigates whether ozone could confer protection from hepatic ischemia reperfusion by modifying the accumulation of adenosine and xanthine during ischemia. A significant increase in both adenosine and xanthine accumulation was observed as a consequence of ATP degradation during hepatic ischemia. Adenosine exerts a protective effect on hepatic ischemia reperfusion injury since the elimination of endogenous adenosine accumulation with adenosine deaminase increased the hepatic injury associated with this process. On the other hand, the high xanthine levels observed after ischemia could exert deleterious effects during reperfusion due to reactive oxygen species generation from xanthine oxidase. The administration of allopurinol, an inhibitor of xanthine oxidase, attenuated the increase in reactive oxygen species and transaminase levels observed after hepatic reperfusion. Ozone treatment in liver maintained adenosine levels similar to those found after ischemia but led to a marked reduction in xanthine accumulation. In order to evaluate the role of both adenosine and xanthine, we tried to modify the protection confered by ozone, by modifying the concentrations of adenosine and xanthine. The metabolization of endogenous adenosine after ischemia abolished the protective effect conferred by ozone. When xanthine was administered previous to ozone treatment, the protection conferred by adenosine disappeared, showing both postischemic reactive oxygen species and transaminase levels similar to those found after hepatic ischemia reperfusion. Ozone would confer protection against the hepatic ischemia reperfusion injury by the accumulation of adenosine that in turns benefits the liver and by blocking the xanthine/xanthine oxidase pathway for reactive oxygen species generation.

Protective effect of ozone treatment on the injury associated with hepatic ischemia-reperfusion: antioxidant-prooxidant balance.

The effects of ozone treatment on the injury associated to hepatic ischemia-reperfusion (I/R) was evaluated. Ozone treatment (1 mg/kg daily during 10 days by rectal insufflation) is shown to be protective as it attenuated the increases in transaminases (AST, ALT) and lactate levels observed after I/R. I/R leads to a decrease in endogenous antioxidant (SOD and glutathione) and an increase in reactive oxygen species (H2O2) with respect to the control group. However, ozone treatment results in a preservation (glutathione) or increase (SOD) in antioxidant defense and maintains H2O2 at levels comparable to those in the control group. The present study reports a protective effect of ozone treatment on the injury associated to hepatic I/R. The effectiveness of ozone could be related to its action on endogenous antioxidants and prooxidants balance in favour of antioxidants, thus attenuating oxidative stress.

Prevention of renal injury after induction of ozone tolerance in rats submitted to warm ischaemia.

On the basis that ozone (O3) can upregulate cellular antioxidant enzymes, a morphological, biochemical and functional renal study was performed in rats undergoing a prolonged treatment with O3 before renal ischaemia. Rats were divided into four groups: (1) control, a medial abdominal incision was performed to expose the kidneys; (2) ischaemia, in animals undergoing a bilateral renal ischaemia (30 min), with subsequent reperfusion (3 h); (3) O3 + ischaemia, as group 2, but with previous treatment with O3 (0.5 mg/kg per day given in 2.5 ml O2) via rectal administration for 15 treatments; (4) O2 + ischaemia, as group 3, but using oxygen (O2) alone. Biochemical parameters as fructosamine level, phospholipase A, and superoxide dismutases (SOD) activities, as well as renal plasma flow (RPF) and glomerular filtration rate (GFR), were measured by means of plasma clearance of p-amino-hippurate and inulin, respectively. In comparison with groups 1 and 3, the RPF and GFR were significantly decreased in groups 2 and 4. Interestingly, renal homogenates of the latter groups yielded significantly higher values of phospholipase A activity and fructosamine level in comparison with either the control (1) and the O3 (3) treated groups. Moreover renal SOD activity showed a significant increase in group 3 without significant differences among groups 1, 2 and 4. Morphological alterations of the kidney were present in 100%, 88% and 30% of the animals in groups 2, 4 and 3, respectively. It is proposed that the O3 protective effect can be ascribed to the substantial possibility of upregulating the antioxidant defence system capable of counteracting the damaging effect of ischaemia. These findings suggest that, whenever possible, ozone preconditioning may represent a prophylactic approach for minimizing renal damage before transplantation.

Ozone oxidative preconditioning: a protection against cellular damage by free radicals.

There is some anecdotal evidence that oxygen-ozone therapy may be beneficial in some human diseases. However so far only a few biochemical and pharmacodynamic mechanisms have been elucidated. On the basis of preliminary data we postulated that controlled ozone administration would promote an oxidative preconditioning preventing the hepatocellular damage mediated by free radicals. Six groups of rats were classified as follows: (1) negative control, using intraperitoneal sunflower oil; (2) positive control using carbon tetrachloride (CCl4) as an oxidative challenge; (3) oxygen-ozone, pretreatment via rectal insufflation (15 sessions) and after it, CCl4; (4) oxygen, as group 3 but using oxygen only; (5) control oxygen-ozone, as group 3, but without CCl4; group (6) control oxygen, as group 5, but using oxygen only. We have evaluated critical biochemical parameters such as levels of transaminase, cholinesterase, superoxide dismutase, catalase, phospholipase A, calcium dependent ATPase, reduced glutathione, glucose 6 phosphate dehydrogenase and lipid peroxidation. Interestingly, in spite of CCl4 administration, group 3 did not differ from group 1, while groups 2 and 4 showed significant differences from groups 1 and 3 and displayed hepatic damage. To our knowledge these are the first experimental results showing that repeated administration of ozone in atoxic doses is able to induce an adaptation to oxidative stress thus enabling the animals to maintain hepatocellular integrity after CCl4 poisoning.

Prostanoids and free radicals in Cl4C-induced hepatotoxicity in rats: effect of astilbin.

A beneficial effect of flavonoids in Cl(4)C-induced hepatoxicity in rats has been reported. In this communication we have evaluated the protective effect of astilbin, an active flavonoid isolated from a crude extract of Hymenaea martiana, as well as its action on liver arachidonate metabolism in Cl(4)C-treated rats. The following groups of rats were studied: Group I = controls; Group II = Astilbine-treated animals (40 mg/Kg); Group III = Cl(4)C-treated at 1 ml/kg; Group IV = Astilbine + ClC4 and Group V = Vitamine E (50 mg/Kg) + Cl(4)C-treated animals. Histological findings, superoxide dismutase activity, lipoperoxides and prostanoid profiling studies revealed that the hepatoprotective effect of astilbine was higher than that of vitamin E. Astilbine was capable to restore lipoperoxides and tissue prostanoids to basal values.

Tissular prostanoid release, phospholipase A2 activity, and lipid peroxidation in pancreas transplantation.

Free radical species have been implicated as important agents in ischemia-reperfusion injury associated to transplantation procedures. This study was carried out to investigate the possible relationship between phospholipase A2 activity (PLA2), lipoperoxidation, and the changes in arachidonic acid metabolism during ischemia reperfusion injury in pancreas transplantation, as well as the effect of a free radical scavenger such as superoxide dismutase on these changes. For this purpose male Lewis rat groups (n = 7) were classified as follows: group I--control; group II--syngenic pancreas transplantation after 15 min preservation in Collins solution at 4 degrees C; group III--syngenic pancreas transplantation after 18 hr preservation in the same conditions; group IV--same as III but with administration of SOD (i.v.) immediately before revascularization in the recipient rat. The results indicate that significant increases in PLA2 activity and lipoperoxide levels occur concomitantly with an increase of thromboxane B2 (TXB2) and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) in pancreatic tissue after pancreas transplantation. The counteracting effect of a free radical scavenger such as SOD supports the role of oxygen free radicals (OFR) mediating activation of PLA2 and subsequent formation of eicosanoids in pancreas transplantation.