Chronic melatonin treatment improves obesity by inducing uncoupling of skeletal muscle SERCA-SLN mediated by CaMKII/AMPK/PGC1α pathway and mitochondrial biogenesis in female and male Zücker diabetic fatty rats.

Melatonin acute treatment limits obesity of young Zücker diabetic fatty (ZDF) rats by non-shivering thermogenesis (NST). We recently showed melatonin chronically increases the oxidative status of vastus lateralis (VL) in both obese and lean adult male animals. The identification of VL skeletal muscle-based NST by uncoupling of sarcoendoplasmic reticulum Ca2+-ATPase (SERCA)- sarcolipin (SLN) prompted us to investigate whether melatonin is a SERCA-SLN calcium futile cycle uncoupling and mitochondrial biogenesis enhancer. Obese ZDF rats and lean littermates (ZL) of both sexes were subdivided into two subgroups: control (C) and 12 weeks orally melatonin treated (M) (10 mg/kg/day). Compared to the control groups, melatonin decreased the body weight gain and visceral fat in ZDF rats of both sexes. Melatonin treatment in both sex obese rats restored the VL muscle skin temperature and sensitized the thermogenic effect of acute cold exposure. Moreover, melatonin not only raised SLN protein levels in the VL of obese and lean rats of both sexes; also, the SERCA activity. Melatonin treatment increased the SERCA2 expression in obese and lean rats (both sexes), with no effects on SERCA1 expression. Melatonin increased the expression of thermogenic genes and proteins (PGC1-α, PPARγ, and NRF1). Furthermore, melatonin treatment enhanced the expression ratio of P-CaMKII/CaMKII and P-AMPK/AMPK. In addition, it rose mitochondrial biogenesis. These results provided the initial evidence that chronic oral melatonin treatment triggers the CaMKII/AMPK/PGC1α axis by upregulating SERCA2-SLN-mediated NST in ZDF diabetic rats of both sexes. This may further contribute to the body weight control and metabolic benefits of melatonin.

Seroprevalence of Leishmania infection among asymptomatic renal transplant recipients from southern Spain.

BACKGROUND: The aim of this article is to assess the seroprevalence of Leishmania infection among asymptomatic renal transplant recipients in a population in the south of Spain. METHODS: Serum samples were screened for immunoglobulin-G antibodies against Leishmania with an indirect fluorescent antibody test. RESULTS: Of 625 examined serum samples, 30 (4.8%) samples were positive for Leishmania antibodies. Thirteen samples showed titers of 1:80, 15 samples showed titers of 1:160, and 2 samples showed titers of 1:320. None of the patients with positive serology to Leishmania showed signs or symptoms compatible with leishmaniasis. CONCLUSION: The prevalence of Leishmania infection found among asymptomatic renal transplant patients reinforces the need for attention in evaluation of these patients in endemic areas.

Melatonin increases intracellular calcium in the liver, muscle, white adipose tissues and pancreas of diabetic obese rats.

Melatonin, a widespread substance with antioxidant and anti-inflammatory properties, has been found to act as an antidiabetic agent in animal models, regulating the release and action of insulin. However, the molecular bases of this antidiabetic action are unknown, limiting its application in humans. Several studies have recently shown that melatonin can modify calcium (Ca(2+)) in diabetic animals, and Ca(2+) has been reported to be involved in glucose homeostasis. The objective of the present study was to assess whether the antidiabetic effect of chronic melatonin at pharmacological doses is established via Ca(2+) regulation in different tissues in an animal model of obesity-related type 2 diabetes, using Zücker diabetic fatty (ZDF) rats and their lean littermates, Zücker lean (ZL) rats. After the treatments, flame atomic absorption spectrometry was used to determine Ca(2+) levels in the liver, muscle, main types of internal white adipose tissue, subcutaneous lumbar fat, pancreas, brain, and plasma. This study reports for the first time that chronic melatonin administration (10 mg per kg body weight per day for 6 weeks) increases Ca(2+) levels in muscle, liver, different adipose tissues, and pancreas in ZDF rats, although there were no significant changes in their brain or plasma Ca(2+) levels. We propose that this additional peripheral dual action mechanism underlies the improvement in insulin sensitivity and secretion previously documented in samples from the same animals. According to these results, indoleamine may be a potential candidate for the treatment of type 2 diabetes mellitus associated with obesity.

Introduction of vincristine mini-bags and an assessment of the subsequent risk of extravasation.

INTRODUCTION: Numerous international organisations have advocated the preparation of vincristine in small volume intravenous bags in order to eliminate inadvertent intrathecal administration. However, the risk of extravasation is a significant deterrent, and adoption of this practice has been variable and only hesitantly accepted in the clinical setting. PURPOSE: We carried out a study with the aims of establishing the incidence of reported extravasation of vincristine administration to paediatric and adult patients in mini-bags; here we describe motivating factors and barriers faced by clinical staff. The secondary aim was to support the need for change and implementation of the international recommendations. METHODS: Chemotherapy-certified nurses completed a survey spanning August 2009 to August 2011, to ascertain the incidence of extravasation associated with the administration of vincristine in mini-bags. RESULTS: This period captured 421 occasions of vincristine administration in 25-ml or 50-ml mini-bags (in 0.9% sodium chloride). The median age of patients was 13 years (range 2.5 months to 99 years). Vincristine was administered through peripheral lines (26.4%), portacath (52.0%), PICC line (15.9%) and Hickman line (5.7%). The majority of infusions were over at least 10 minutes (50.1%). There were no cases of extravasation reported. CONCLUSIONS: The administration of vincristine in small volume intravenous bags was safe, practical, and feasible in all patient groups. The successful implementation of the international recommendations for vincristine administration in mini-bags to eliminate potential inadvertent intrathecal administration was dependent on stakeholder buy-in.

Estudio de la influencia de la nutrición y genética maternas sobre la programación del desarrollo del tejido adiposo fetal (Estudio PREOBE) / Study of maternal nutrition and genetic on the foetal adiposity programming (The PREOBE study)

Introducción: La genética y la alimentación de la madre antes y durante el embarazo, las distintas patologías metabólicas maternas, así como la ingesta de nutrientes en los primeros meses de vida del recién nacido parecen estar implicados en la etiología de la obesidad y sus consecuencias a largo plazo. La posible contribución de estos y otros factores, los mecanismos y sus efectos en el metabolismo y desarrollo de la enfermedad están aún en fase de investigación. Objetivo: Obtener un mayor conocimiento del desarrollo del tejido adiposo fetal y la influencia de factores genéticos, dietéticos y ambientales sobre el riesgo a largo plazo de padecer obesidad. Metodología: Se han establecido cuatro grupos de estudio de 30 madres gestantes cada uno: 1) grupo control; 2) madres con intolerancia a la glucosa/diabetes gestacional; 3) madres con escasa ganancia ponderal durante el embarazo, y 4) madres con sobrepeso/obesidad al inicio del embarazo. Se realizará un análisis de los siguientes parámetros: 1) ingesta dietética; 2) hábitos y estilo de vida; 3) actividad física; 4) antropometría y composición corporal; 5) estudio hematológico; 6) estudio bioquímico (biomarcadores lipídicos y metabólicos); 7) perfil inmunológico; 8) perfil psicológico; 9) marcadores genéticos, y 10) marcadores microbiológicos; todos ellos relacionados con la formación del tejido adiposo fetal en las primeras etapas de la vida y el riesgo de padecer obesidad en el futuro. Conclusión: En este proyecto, coordinado por el Departamento de Pediatría de la Facultad de Medicina de la Universidad de Granada y que cuenta con la participación de otros grupos de investigación de larga y acreditada experiencia, se pretende obtener un mayor conocimiento de los orígenes de la obesidad en la infancia y posterior desarrollo de esta enfermedad en etapas posteriores de la vida (AU)

Background: Maternal genetics and feeding before and during pregnancy, different maternal metabolic pathologies, as well as nutrient intakes of newborns in their first months of life may be involved in the obesity aetiology and its long-term consequences. The possible role of these and others factors, the mechanisms and the effects on the metabolism, and the development of this disease need further research. Objective: To acquire more knowledge about foetal adipose tissue development and the influence of genetic, dietetic and environmental factors on the risk to suffer from obesity. Methodology: Four study groups have been established with 30 pregnant women in each one: 1) control group; 2) mothers with glucose intolerance/gestational diabetes; 3) women with low weight gain during pregnancy, and 4) women with overweight/obesity at the beginning of the pregnancy. The magnitudes to be studied are: 1) dietary intake; 2) life-style habits; 3) physical activity; 4) anthropometry and body composition; 5) haematological study; 6) biochemical study (lipid and metabolic biomarkers); 7) immune function profile related to nutritional status; 8) psychological profile; 9) genetic biomarkers, and 10) microbiological markers; all of them in relation to the development of the foetal adipose tissue in the first stages of life and the risk of suffering from obesity in the future. Conclusion: This project, coordinated by the Department of Paediatrics of the School of Medicine in the University of Granada, and with the collaboration of well-known and expert research groups, tries to contribute to the knowledge about the obesity aetiology in infancy and its subsequent development in later periods of life (AU)

[Study of maternal nutrition and genetic on the foetal adiposity programming (The PREOBE study)]. / Estudio de la influencia de la nutrición y genética maternas sobre la programación del desarrollo del tejido adiposo fetal (Estudio PREOBE).

BACKGROUND: Maternal genetics and feeding before and during pregnancy, different maternal metabolic pathologies, as well as nutrient intakes of newborns in their first months of life may be involved in the obesity aetiology and its long-term consequences. The possible role of these and others factors, the mechanisms and the effects on the metabolism, and the development of this disease need further research. OBJECTIVE: To acquire more knowledge about foetal adipose tissue development and the influence of genetic, dietetic and environmental factors on the risk to suffer from obesity. METHODOLOGY: Four study groups have been established with 30 pregnant women in each one: 1) control group; 2) mothers with glucose intolerance/gestational diabetes; 3) women with low weight gain during pregnancy, and 4) women with overweight/obesity at the beginning of the pregnancy. The magnitudes to be studied are: 1) dietary intake; 2) life-style habits; 3) physical activity; 4) anthropometry and body composition; 5) haematological study; 6) biochemical study (lipid and metabolic biomarkers); 7) immune function profile related to nutritional status; 8) psychological profile; 9) genetic biomarkers, and 10) microbiological markers; all of them in relation to the development of the foetal adipose tissue in the first stages of life and the risk of suffering from obesity in the future. CONCLUSION: This project, coordinated by the Department of Paediatrics of the School of Medicine in the University of Granada, and with the collaboration of well-known and expert research groups, tries to contribute to the knowledge about the obesity aetiology in infancy and its subsequent development in later periods of life.

Increased susceptibility to plasma lipid peroxidation in untrained subjects after an extreme mountain bike challenge at moderate altitude.

The purpose of this study was to determine whether acute strenuous physical exercise, partially performed under moderate altitude, influences the susceptibility of plasma lipids to peroxidation. Eleven male amateur cyclists took part in a 95-km mountain bike challenge with a cumulative altitude difference of 2340 m. Blood samples were obtained before and immediately after the race in order to determine plasma lipid and lipoprotein concentrations, and to assess the susceptibility of the former to peroxidation. Neither plasma lipid nor lipoprotein levels changed significantly after the race. However, the susceptibility of plasma lipids to peroxidation increased by 71.8 %. We concluded that strenuous physical exercise partially performed under hypoxic conditions increases the susceptibility of plasma lipids to peroxidation in untrained subjects.

[Lipid peroxidation in adult epileptic patients treated with valproic acid]. / Peroxidación lipídica en pacientes epilépticos adultos tratados con ácido valproico.

INTRODUCTION: Free radicals play an important role as regulatory mediators in cellular signalling processes; however, when overproduced or when antioxidant defence systems are weakened, they are cause of cellular damage. Excessive amount of free radical production has been related with a variety conditions, like aging, different kind of diseases, and xenobiotics biotransformation; this last process includes the metabolism of lipid soluble drugs. An increase in oxidative stress has been described in series of treated epileptic patients. OBJECTIVE: To evaluate the susceptibility to plasma lipid peroxidation in samples from epileptic patients treated with valproic acid monotherapy, studying if the formation of lipid peroxides was related with plasma drug concentration, patients' sex or the kind of epilepsy suffered. PATIENTS AND METHODS: Peroxidated lipids (LPO) were measured by spectrofluorometry before and after induction of an oxidative Fenton reaction in 76 epileptic patients and 4 healthy subjects. RESULTS: After induction of the Fenton reaction, but not in basal conditions, lipid peroxidation showed a lineal relationship with valproate plasma levels. Oxidized LPO values were also significantly higher in samples from patients with partial epilepsies than in those with generalized epilepsies. Likewise, a significant gender effect was observed, being values from epileptic women noticeably higher than those of epileptic men. CONCLUSIONS: Plasma from epileptic patients receiving valproic acid evidences an increased vulnerability to lipid peroxidation which seems to be related with drug amount in the body, subject's sex, and epilepsy type.

Peroxidación lipídica en pacientes epilépticos adultos tratados con ácido valproico / Lipid peroxidation in adult epileptic patients treated with valproic acid

Introducción. Aunque los radicales libres son mediadores importantes en la regulación de algunos procesos celulares, pueden causar citotoxicidad cuando se producen en exceso o las defensas antioxidantes disminuyen, y se han implicado en la patogenia de numerosas enfermedades. Asimismo, los fármacos, fundamentalmente a través de la producción de metabolitos intermediarios, pueden aumentar el estrés oxidativo; en este sentido, diversos autores han observado alteraciones del metabolismo oxidativo en pacientes epilépticos tratados. Objetivo. Evaluar la susceptibilidad a la peroxidación lipídica en epilépticos adultos tratados con ácido valproico (VPA), y comprobar si ésta guarda relación con la concentración plasmático del fármaco, el sexo del enfermo o el tipo de epilepsia padecido. Pacientes y métodos. Los lípidos peroxidados (LPO) se midieron mediante espectrofluorometría antes y después de la inducción de una reacción oxidativa de tipo Fenton en el plasma de 76 pacientes epilépticos y 48 sujetos sanos. Resultados. La formación de LPO tras la oxidación mostró una relación lineal positiva con las concentraciones plasmáticas de VPA. Asimismo, fue superior en los pacientes con epilepsias parciales que en aquellos con epilepsias generalizadas. Se observó también un efecto significativo del sexo, puesto que los valores de LPO se elevaron más en las mujeres que en los varones epilépticos. Conclusiones. En el plasma de los pacientes tratados con VPA se aprecia una vulnerabilidad al estrés oxidativo directamente proporcional a la concentración plasmática del fármaco, más acentuada en las mujeres que en los hombres. Ésta, por otra parte, parece ser mayor en los pacientes con epilepsias parciales (AU)

Introduction. Free radicals play an important role as regulatory mediators in cellular signalling processes; however, when overproduced or when antioxidant defence systems are weakened, they are cause of cellular damage. Excessive amount of free radical production has been related with a variety conditions, like aging, different kind of diseases, and xenobiotics biotransformation; this last process includes the metabolism of lipid soluble drugs. An increase in oxidative stress has been described in series of treated epileptic patients. Objective. To evaluate the susceptibility to plasma lipid peroxidation in samples from epileptic patients treated with valproic acid monotherapy, studying if the formation of lipid peroxides was related with plasma drug concentration, patients’ sex or the kind of epilepsy suffered. Patients and methods. Peroxidated lipids (LPO) were measured by spectrofluorometry before and after induction of an oxidative Fenton reaction in 76 epileptic patients and 4 healthy subjects. Results. After induction of the Fenton reaction, but not in basal conditions, lipid peroxidation showed a lineal relationship with valproate plasma levels. Oxidized LPO values were also significantly higher in samples from patients with partial epilepsies than in those with generalized epilepsies. Likewise, a significant gender effect was observed, being values from epileptic women noticeably higher than those of epileptic men. Conclusions. Plasma from epileptic patients receiving valproic acid evidences an increased vulnerability to lipid peroxidation which seems to be related with drug amount in the body, subject’s sex, and epilepsy type (AU)

Hydroxy-urea protects erythrocytes against oxidative damage.

Hydroxy-urea (OH-U) is used to treat sickle cell anemia by increasing hemoglobin fetal-fraction. It has been suggested that the sickle cell mutations lead to the formation of unstable HbS and release of iron, which can result in lipid peroxidation (LPO), and eventual cell damage. Since oxidative processes might be involved in pathogenesis of sickle cell disease, we investigated the antioxidant property of OH-U in a red blood cell (RBC) model. Intact RBCs or RBC membranes were exposed to t-butyl hydroperoxide (t-BHP, 0.75 mM) or iron (ferrous sulfate; 100 microM) at 37 degrees C for 60 min in the presence or absence of OH-U (1.25 mM). The extent of oxidative damage was measured by LPO (as thiobarbituric acid reactive substances, TBARS), hemoglobin oxidation (as percent of methemoglobin, metHb %), and decrease in the activities of membrane-bound Na+/K+-ATPase and Ca2+-ATPases. Our results show that OH-U inhibited t-BHP-induced LPO in fresh RBC membranes significantly (P <0.01). OH-U significantly inhibited t-BHP-mediated LPO (P <0.01) and metHb formation (P <0.01) in intact RBC. Also, OH-U inhibited iron-induced LPO and metHb formation in intact RBC (P <0.01). In addition, OH-U blocked t-BHP-mediated changes in membrane ATPase activities. Furthermore, OH-U blocked iron-mediated hydroxyl radical generation in a dose-dependent fashion. In conclusion, the observed antioxidant properties of OH-U might contribute to its therapeutic action in sickle cell disease.

Isolation of ani-hepatotoxic principle form the juice of Ecballium elaterium.

The antihepatotoxic activity of elaterium (dried juice of the fruits of Ecballium elaterium, Cucurbitaceae) and cucurbitacin B (isolated from the juice) was studied against CCl4-induced hepatotoxicity. Pre- and posttreatment with elaterium and cucurbitacin B reduced CCl4-hepatotoxicity, as shown reduction in the anormally increased sGPT levels. Posttreatment caused a significant reduction in the degree of steatosis observed inthe control group, treated only with CCl4. In conclusion, elaterium and cucurbitacin B had preventive and curative effects against CCl4-induced hepatotoxicity.

Vitamin A status in acute exacerbations of cystic fibrosis.

Vitamin A is an essential nutrient for epithelial cell maintenance and repair, and it is known that infectious stresses may depress plasma vitamin A concentrations. Patients with cystic fibrosis are at risk for vitamin A deficiency because of fat malabsorption as well as for the inflammatory stresses of pulmonary exacerbations of their underlying disease. We therefore hypothesized that acute pulmonary exacerbations of CF would depress plasma retinol concentrations, and that these concentrations would return to baseline values when clinical symptoms improved. We prospectively studied 35 CF patients (mean age: 24.2 y) consecutively admitted with pulmonary exacerbations. Plasma retinol, vitamin E, retinol binding protein (RBP), and C-reactive protein (CRP) concentrations were measured on hospital admission and discharge. Dietary intake was measured by using a semiquantitative food-frequency questionnaire. Regression analysis was used to identify significant clinical and laboratory correlates of retinol concentrations. On admission, mean (+/- SD) concentrations of plasma retinol were 1.14 +/- 0.5 mumol/L compared with 1.70 +/- 0.6 mumol/L on discharge (P = 0.0001). Of 35 subjects, 8 (22.9%) had plasma retinol concentrations considered to be in the deficient range (< 0.70 mumol/L). Concurrently, mean concentrations of plasma RBP increased during hospital admission (from 1.46 to 2.24 mumol/L, P = 0.003), and the mean CRP concentration declined (from 25.7 to 9.8 mg/L, P = 0.002). Significant positive correlations were found between plasma retinol concentrations at admission and age, weight, body mass index, triceps-skinfold-thickness percentile, midupper arm circumference percentile, plasma vitamin E, and RBP concentration, thus suggesting that better-nourished patients had more optimal vitamin A status. At admission, plasma retinol concentrations were negatively correlated with maximum body temperature and CRP concentrations, which indicated that the body's acute-phase response was associated with the depression in retinol concentrations. We conclude that plasma retinol concentrations are depressed in acute pulmonary exacerbations of cystic fibrosis, and that concentrations considered to be in the deficient range are common. Vitamin A metabolism during acute inflammatory stress deserves further study.

Effects of a single bout of ultraendurance exercise on lipid levels and susceptibility of lipids to peroxidation in triathletes.

OBJECTIVE: To determine the effects of a single bout of ultraendurance exercise, as a model for physiologic stress, on lipid and lipoprotein levels, and oxidative susceptibility of lipids in highly trained athletes. DESIGN: Observational trial. POPULATION AND SETTING: Thirty-nine volunteer subjects (26 mean, 13 women; mean age, 38 +/- 10 years) who competed in and completed the 1994 Hawaii Ironman World Championship Triathlon consisting of a consecutive 3.9-km (2.4-mi) swim, 180.2-km (112-mi) bike ride, and a 42.2-km (26.2-mi) run. Subjects answered questionnaires and had blood samples obtained 2 days prior to and within 15 minutes of completion of the triathlon. MAIN OUTCOME MEASURES: Prerace vs postrace changes in lipid and lipoprotein levels, and susceptibility of lipids to peroxidation. RESULTS: The mean duration of exercise was 753 +/- 128 minutes. With exercise, plasma volume-corrected levels of triglycerides decreased 39% from 1.58 +/- 0.83 to 0.97 +/- 0.68 mmol/L (139.6 +/- 73.6 to 85.8 +/- 60.5 mg/dL) (P < .001). Levels of total cholesterol decreased 9% from 4.94 +/- 0.88 to 4.50 +/- 0.79 mmol/L (190.8 +/- 33.8 to 173.8 +/- 30.6 mg/dL) (P < .001), low-density lipoprotein cholesterol decreased 11% from 2.59 +/- 0.77 to 2.30 +/- 0.86 mmol/L (100.1 +/- 29.9 to 88.7 +/- 33.3 mg/dL) (P = .02), and apolipoprotein B decreased 10% from 0.91 +/- 0.20 to 0.82 +/- 0.18 g/L (90.7 +/- 20.0 to 82.0 +/- 17.9 mg/dL) (P < .001). High-density lipoprotein cholesterol and apolipoprotein A-I increased with exercise but not significantly. The susceptibility of lipids to peroxidation decreased significantly (4.51 +/- 1.91 micromol/L, preexercise, vs 2.42 +/- 2.27 micromol/L, postexercise, P < .001), an effect that was not related to antioxidant use or levels of vitamins A, C, or E. Serum iron, a potential pro-oxidant, also decreased by 45% with exercise from 15.75 +/- 5.55 to 8.59 +/- 4.30 micromol/L (88 +/- 31 to 48 +/- 24 micrograms/dL) (P < .001), an effect that was weakly correlated with changes in lipid peroxidation (P = .05). CONCLUSIONS: These data suggest that a single bout of prolonged exercise can reduce lipid and lipoprotein risk factors for developing cardiovascular disease. Moreover, susceptibility of lipids to peroxidation is reduced by exercise, thereby adding to the benefits of physical activity. This effect appears to be independent of antioxidant supplement use and may be mediated by induction of endogenous antioxidants. These observations may explain in part the reduced risk of developing vascular and other diseases in individuals who are physically active.

Superoxide production and LDL oxidation by diabetic neutrophils.

The mechanism(s) resulting in the premature atherosclerosis of diabetes is unknown. Increased phagocyte release of reactive oxygen species such as superoxide anion (O2.-), resulting in low-density lipoprotein (LDL) oxidation, could be one possible cause. The purpose of the present study was to compare the abilities of polymorphonuclear leukocytes (PMN) from 12 non-insulin-dependent diabetes mellitus (NIDDM) subjects free of vascular disease to produce O2.- anion and oxidize LDL with PMN from age- and gender-matched normoglycemic controls. PMN were activated with phorbol 12-myristate 13-acetate (PMA) to measure O2.- production. In addition, the PMN were activated with PMA and opsonized zymosan (OZ) to assess LDL oxidation over 5 hours. LDL oxidation was measured by conjugated diene formation and apolipoprotein B (apo B) fluorescence. PMN superoxide production stimulated by PMA was similar between groups. LDL oxidation by PMN was also not different between the NIDDM and control groups. The results of this study indicate that PMN O2.- production and LDL oxidation are not enhanced in NIDDM subjects without vascular disease. Other factors, such as reduced antioxidant concentrations and non-enzymatic glycation of LDL, may play a greater role in the premature atherosclerosis of diabetes.

Plasma oxidizability in Mexican-Americans and non-Hispanic whites.

Several lines of evidence support an atherogenic role for oxidized low-density lipoprotein (LDL). Previous studies have suggested that although Mexican-Americans have an increased rate of diabetes, obesity, elevated triglyceride levels, and low high-density lipoprotein (HDL) cholesterol levels, their rates of coronary heart disease (CHD) are similar or possibly lower than in non-Hispanic whites. Mexican-Americans have smaller, denser LDL than non-Hispanic whites. On the basis of this latter observation, we postulated that lipid peroxide (LPO) levels would be increased in Mexican-Americans. We examined the oxidizability of plasma in 50 Mexican-Americans and 50 non-Hispanic whites from the San Antonio Heart Study, a population-based study of diabetes and cardiovascular disease, at baseline and after coincubation with a metal-independent system (2'2'-azobis-2-amidinopropane hydrochloride [AAPH]) and a metal-dependent system (Fe2+/H2O2) of oxidation. LPO levels were measured by a modified fluorimetric assay. Vitamin E and plasma fatty acid composition were also determined. We found significantly higher LPO levels at baseline and after AAPH coincubation in Mexican-Americans than in non-Hispanic whites (baseline, 2.75 +/- .09 v 2.07 +/- .09 micromol/L, P < .001; post-AAPH, 5.49 +/- .14 v 5.07 +/-. .04 micromol/L, P = .037). However, no significant ethnic differences were seen after coincubation with Fe2+/H2O2. Diabetes and cigarette-smoking were also associated with higher LPO levels. Mexican-Americans also had lower levels of vitamin E (the predominant lipid-soluble antioxidant in plasma) than non-Hispanic whites, although these differences only partially explained the differences in susceptibility to oxidation. Plasma fatty acids were similar in Mexican-Americans and non-Hispanic whites, suggesting only small differences in diet composition. We conclude that LPO levels are higher in Mexican-Americans than in non-Hispanic whites, and that these results are only partially related to differences in vitamin E levels.

Plasma oxidizability in subjects with normal glucose tolerance, impaired glucose tolerance, and NIDDM.

OBJECTIVE: Several lines of evidence support an atherogenic role for oxidized low-density lipoprotein (LDL). Studies on LDL oxidation in diabetes to date have examined LDL isolated from plasma, but have failed to evaluate the other pro- and antioxidant factors present in vivo, the balance of which could be crucial in determining the susceptibility of LDL to lipid peroxidation. RESEARCH DESIGN AND METHODS: We examined the oxidizability of plasma from Mexican-Americans in the San Antonio Heart Study. The oxidizability of plasma in 75 subjects with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and non-insulin-dependent diabetes mellitus (NIDDM) was studied after co-incubation with a free radical initiator, 2,2'-azobis-2-amidinopropane hydrochloride (AAPH). Lipid peroxide (LPO) levels were measured by a modified fluorimetric assay. RESULTS: Baseline LPO levels (mumol/l; means +/- SE) were similar in the three glucose tolerance categories (NGT, 1.99 +/- 0.07; IGT, 1.88 +/- 0.07; NIDDM, 1.97 +/- 0.07; P = 0.521). However, after incubation with AAPH (NGT, 4.30 +/- 0.20; IGT, 4.45 +/- 0.20; NIDDM, 5.35 +/- 0.20; P = 0.003), the diabetic plasma had significantly greater amounts of LPOs compared with the other two groups. There was no significant difference in LPOs between the NGT and IGT groups. The statistical significance of increased oxidizability of the diabetic plasma persisted after exclusion of patients who smoked cigarettes (n = 15) or who had vascular disease (n = 4). CONCLUSIONS: In conclusion, this study shows that the plasma of Mexican-American subjects with NIDDM is more prone to lipid peroxidation than that of non-Hispanic whites.

Susceptibility of plasma to ferrous iron/hydrogen peroxide-mediated oxidation: demonstration of a possible Fenton reaction.

The aim of our study was to evaluate a model system by using iron in the peroxidation of plasma. Lipid peroxidation was monitored by fluorometric measurement of lipid peroxides (LPO). Plasma coincubated with Fe2+ and H2O2 had a 268% increase in plasma LPO after 1 h. The optimum concentrations were 0.42 mmol/L Fe2+ and 0.73 mol/L H2O2. Coincubation of plasma with these concentrations of Fe2+ and H2O2 separately resulted in no increase in plasma LPO. The increase in plasma LPO after oxidation with Fe2+/H2O2 was paralleled by a decrease in plasma polyunsaturated fatty acids, an increase in the relative electrophoretic mobility of low-density lipoprotein (LDL), and decreases in apolipoprotein (apo) B-100 and apo A-I immunoreactivity. In vitro oxidation of LDL and high-density lipoprotein separately with this system produced increases of LPO of 246% and 128%, respectively. LPO formation in plasma was inhibited by catalase, desferrioxamine, and mannitol, but not by superoxide dismutase. Hydroxyl radical generation with Fe2+/H2O2 was evidenced by fragmentation of deoxyribose. We conclude that the Fe2+/H2O2 system, possibly by a Fenton reaction mechanism, resulted in significant plasma oxidation. This model system may be useful for examining lipid peroxidation in clinical investigations.