Insulin polymers in the plasma of obese subjects are associated with elevated levels of carbonyl groups and are decreased by (-)-epicatechin.

We investigated whether oxidative damage and insulin polymerization at a systemic level are associated with the insulin resistance (IR) observed in obese subjects. We evaluated 3 groups (n=16/each) divided according to body mass index (BMI): Normal weight (NW) with a BMI of 18.5-24.9, obese 1 (O1) 30-34.9, and obese 3 (O3)>40 kg/m(2). IR and oxidative damage status of the groups were established by HOMA value and the analysis of biomarkers of oxidative stress in plasma. Insulin polymers in systemic circulation were detected using an antibody specific coupled to magnetic beads, which were incubated in plasma from the study groups. Analysis of magnetic beads by electrophoresis on polyacrylamide gel and silver stain assessed the presence of insulin polymers. The inhibition of polymers formation was studied by the presence of (-)-epicatechin. We demonstrated that O1 and O3 subjects with IR showed higher oxidative damage to their plasma lipids and proteins than NW subjects. This oxidative damage was associated with the presence of insulin polymers in the plasma of the O1 and O3 subjects. This polymer showed a high concentration of carbonyl groups by Western blot, suggesting the participation of oxidative damage in the generation of the polymer. The antioxidant (-)-epicatechin decreased the formation of the insulin polymer, indicating that the prevention of oxidative damage can inhibit insulin polymerization. Our study revealed an association between the presence of carbonyl stress, IR, and insulin polymer formation in obese subjects. This study also demonstrates that the antioxidant (-)-epicatechin inhibits insulin polymerization.

Influence of the AT(2) receptor on the L-arginine-nitric oxide pathway and effects of (-)-epicatechin on HUVECs from women with preeclampsia.

Pregnancy is a state of vasodilation mediated by nitric oxide (NO). This vasodilation is impaired in women with preeclampsia, and an alteration in the L-arginine-NO pathway may be a causal factor. The production of NO and arginase activity were investigated in plasma and human umbilical vein endothelial cells (HUVECs) from women with preeclampsia, which were associated with arginase II, eNOS, caveolin, angiotensin 1 and 2 receptor expression (AT1R and AT2R, respectively). The effect of (-)-epicatechin on arginase activity and production of anion superoxide in HUVEC also were investigated. Healthy volunteer non-pregnant (HV), normal pregnant (NP) and preeclamptic (PE) women were recruited for this study. Higher values of nitrite/nitrate (NO(2)/NO(3)) were detected in the plasma from PE women as opposed to HV and NP. Lower arginase activity in PE versus HV or NP women was observed. HUVECs from PE women showed lower values of NO(2)/NO(3), higher activity of arginase and higher expression of AT(1)R and AT(2)R than HUVECS from NP women. Interestingly, arginase activity was associated with AT(2)R stimulation; indeed this activity and the high NADPH (nicotinamide adenine dinucleotide phosphate) oxidase activity in HUVECs from PE women can uncouple the production or inactivation of NO. However, we demonstrated that (-)-epicatechin could lead to a decrease in the activity of both enzymes.

Oxidative stress present in the blood from obese patients modifies the structure and function of insulin.

Obesity and its associated disorders constitute a growing epidemic across the world. Numerous studies have demonstrated the presence of systemic oxidative stress in patients with obesity. In this study, we show the effects of oxidative stress present in the blood from obese patients on recombinant human insulin. Insulin was incubated with whole blood (WB) from overweight subjects (OW), obese 1 patients (O1), or normal weight volunteers (NW) (n=16 for each group). Whole blood from OW and O1, unlike WB from NW, increased the carbonyl content of insulin; however, only whole blood from O1 patients increased the amount of formazan present in the hormone. Interestingly, the incubation of insulin with WB from O1 provoked a decrease in the hypoglycemic activity of the hormone (18%), an effect due to insulin polymerization. In addition, we showed that the formation of the insulin polymer generated the formation of new epitopes and the development of a new immunogenicity. These observations show that oxidative stress present in the WB of O1 patients can result in abolition of the biological activity of insulin and contribute to the development of an immune response to the hormone.

[Effect of antioxidant supplementation over oxidative stress and quality of life in cervical cancer]. / Efecto de la suplementación con antioxidantes sobre el estrés oxidativo y la calidad de vida durante el tratamiento oncológico en pacientes con cáncer cérvico uterino.

BACKGROUND: Mexico has a high rate of cervical cancer which represents an important public health issue. The treatment for this disease depends on the extension of the tumor; for the initial stages surgery is recommended, and for locally advanced tumors, a combination of chemotherapy and radiotherapy is used. All this process affects natural antioxidant consumption and Quality of Life (QoL). OBJECTIVE: To find out the effect that supplementation with antioxidants (ß-carotene, vitamin C y vitamin E) has on oxidative stress, and quality of life in patient diagnosed with cervical cancer during treatments with cisplatin and radiotherapy. MATERIALS AND METHODS: We conducted a randomized, blind clinical trial in women with cervical cancer whose antineoplasic treatment was radiotherapy in and radiotherapy with cisplatin. Patients were randomly assigned to receive antioxidant therapy or a placebo. Plasma concentrations of malondialdehyde (MDA), free carbonyls, dityrosines, and carbonyl/protein rate in two different moments, before oncologic therapy, and after finishing oncology treatment, we also evaluated food consumption by using a validated food frequency questionnaire and a QOL questionnaire before treatment and after it was over. The effect of the antioxidant treatment was assessed by the use t-student test for independent and paired samples, as well as frequencies and X² for categorical variables. RESULTS: We evaluated 103 patients who were randomly assigned to receive treatment with antioxidants 49 (47.60%) and placebo 54 (52.40%). We did not find statistically significant differences in food or antioxidant consumption according to the food frequency questionnaires. Most of the patients consumed more energy than needed to meet their requirement, but they did not consume enough of most of the antioxidants according to the Recommended Dailiy Allowance (RDA) recommendation. Serum levels of plasma free carbonyls and carbonil/mg of protein ratio were statistically significant (p < 0.009) which shows protein protection regarding oxidative stress in the supplemented group, this information was similar to the one found in the QOL questionnaire, which showed that Global QOL was better in the supplemented group (p < 0.025). Most of the patients had lower α-tocopherol and retinol plasma levels than the recommended values. CONCLUSIONS: Antioxidant supplementation showed to be effective in reducing oxidative stress in proteins, but it did not on food ingestion, patients did not meet their antioxidants requirement in their diets, in spite of an excess in energy consumption. Antioxidant plasma levels in most of the patients were lower than normal. QoL score was better in the supplemented group.

Anticonvulsant drugs, oxidative stress and nitric oxide.

Nitric Oxide (NO) is thought to play a fundamental role in the genesis and the spreading of epileptiform hyperactivity, although its function is unclear and controversial. As a free radical, NO may cause oxidative stress, which is emerging as an important mechanism in the etiology of seizure-induced neuronal death. Here we investigated the role of NO in seizure mechanisms through oxidative stress generation by studying the effect of anticonvulsant drugs such as amino oxyacetic acid (AAOA), valproate (VALP), diazepam (DIAZ) and gabapentin (GBPTNA) on oxidative stress in the brain, estimated as free carbonyls by the method of Dalle and Rossi, and by measuring NO by the indirect method based on the Griess reaction. Results show that, except for AAOA and VALP, anticonvulsants did not significantly affect or decreased free carbonyls, but reversed the oxidative stress produced by pentylenetetrazole (PTZ) induced convulsions. Anticonvulsants except AAOA diminished NO levels and with the exception of VALP, counteracted the increase in NO generated by PTZ. Anticonvulsants decreased oxidative stress and NO especially in hippocampus (HI) and cortex (CX), and reversed PTZ effects on both parameters. PTZ diminished NO in HI, which could be explained since PTZ caused an increase on endothelial NO synthase but a decrease in neuronal NOS expression in this brain area. Since the drugs studied are modulating GABA levels, our results suggest that seizures generated by alterations in GABAergic transmission produce oxidative stress caused by NO, which can be reversed by anticonvulsants. The effects described differ among the brain regions studied and the NO synthase isoform affected.

Cardiovascular risk factors in the urban Mexican population: the FRIMEX study.

BACKGROUND: Atherosclerotic ischaemic heart disease is the second leading cause of general mortality in Mexico due to the growing prevalence of atherosclerotic risk factors in our society. The data of the FRIMEX study (Factores de Riesgo en México, Risk Factors in Mexico), considered together with those of other contemporary epidemiological surveys, will aid in our comprehension of the current state of cardiovascular epidemics in Mexico. METHODS: Frequencies of obesity, hypertension and smoking, and total cholesterol and glucose in capillary blood were estimated in a non-probabilistic sample comprised of 140017 individuals (aged 44+/-13 years; 42% men and 58% women), from six Mexican cities (Mexico City, Guadalajara, Monterrey, Puebla, Leon and Tijuana). RESULTS: Obesity or overweight status was found in 71.9% of participants. Hypertension was found in 26.5%, and the proportions of awareness, treatment and control for this disease were 49.3, 73 and 36%, respectively. Prevalence of hypertension increased with age; while it was higher in men under 60 years of age, in the more aged individuals it was higher in women. Hypercholesterolaemia was found in 40% of the individuals and cholesterolaemia > or =240 mg/dl was significantly higher in women. Thirty-five and a half percent of men and 18.1% of women were smokers. Type 2 diabetes mellitus was found in 10.4% of participants. There was significant Pearson's correlation between body mass index and blood pressure, between hypertension and glucose levels, and between hypertension and total cholesterol concentrations. CONCLUSIONS: We conclude that this population has a high cardiovascular risk profile and a high probability of the occurrence of metabolic syndrome.