Erythrocyte glutathione concentration and production during hyperinsulinemia, hyperglycemia, and endotoxemia in healthy humans

Iodine Redistribution During Trauma, Sepsis, and Hibernation: An Evolutionarily Conserved Response to Severe Stress

OBJECTIVE

We performed these studies to learn how iodine in the form of free iodide behaves during stress.

DESIGN

Prospective observational trial using samples obtained from human trauma patients and retrospective observational study using remnant samples from human sepsis patients and arctic ground squirrels. Preclinical interventional study using hind-limb ischemia and reperfusion injury in mice.

SETTING

Level I trauma center emergency room and ICU and animal research laboratories.

SUBJECTS

Adult human sepsis and trauma patients, wild-caught adult arctic ground squirrels, and sexually mature laboratory mice.

INTERVENTIONS

Ischemia and reperfusion injury was induced in mice by temporary application of tourniquet to one hind-limb. Iodide was administered IV just prior to reperfusion.

MEASUREMENTS AND MAIN RESULTS

Free iodide was measured using ion chromatography. Relative to iodide in plasma from normal donors, iodide was increased 17-fold in plasma from trauma patients and 26-fold in plasma from sepsis patients. In arctic ground squirrels, iodide increases over three-fold during hibernation. And during ischemia/reperfusion injury in mice, iodide accumulates in ischemic tissue and reduces both local and systemic tissue damage.

CONCLUSIONS

Iodide redistributes during stress and improves outcome after injury. Essential functions of iodide may have contributed to its evolutionary selection and be useful as a therapeutic intervention for human patients.

Obesity induced alterations in redox homeostasis and oxidative stress are present from an early age

Objectives

Oxidative stress and inflammation have been postulated as underlying mechanisms for the development of obesity-related insulin resistance. This association however, remains elusive especially in childhood. We sought to investigate this relation by measuring oxidative stress and antioxidant response biomarkers, before and during an oral glucose tolerance test (OGTT), in different biological samples from obese children.

Subjects

24 children were recruited for the study, (18 obese and 6 controls). After OGTT, the obese group was subdivided in two, according to whether or not carbohydrate metabolic impairment (Ob.IR+, Ob.IR-; respectively) was found. Different biomarkers were analyzed after fasting (T = 0) and during an OGTT (T = 60 and 120 min). Lipoperoxides were measured in plasma, erythrocytes, and urine; while advanced glycation end products were determined in plasma, and redox status (GSH/GSSG ratio) in erythrocytes.

Results

We found marked differences in the characterization of the oxidative status in urine and erythrocytes, and in the dynamics of the antioxidant response during OGTT. Specifically, Ob.IR+ children show increased oxidative stress, deficient antioxidant response and a significant imbalance in redox status, in comparison to controls and Ob.IR- children.

Conclusion

Obese children with insulin resistance show increased levels of oxidative stress biomarkers, and a stunted antioxidant response to an OGTT leading to increased oxidative stress after a single glucose load, as detected in erythrocytes, but not in plasma. We propose erythrocytes as sensors of early and acute changes in oxidative stress associated with insulin resistance in childhood obesity. This is a pilot study, performed with a limited sample size, so data should be interpreted with caution until reproduced.

Acute blood glucose fluctuations can decrease blood glutathione and adiponectin levels in patients with type 2 diabetes

INTRODUCTION

Glutathione appears to have apparent antioxidant activity to counter regulate hyperglycemia induced oxidative stress. Adiponectin also plays a role in the suppression of the metabolic derangements in type 2 diabetes mellitus (DM). The aim of this study was to determine whether blood glucose fluctuations can alter blood levels of glutathione and adiponectin.

METHODS

We enrolled 34 patients with type 2 DM. As a measure of short-term glycemic variability, the mean amplitude of glycemic excursions (MAGE) was computed from a continuous glucose monitor system (CGMS), and data were recorded over 72 h. For long-term glycemic variability, we calculated the standard deviation (SD) of HbA1c over a 2-year period. Glutathione and adiponectin levels were measured after completing the 72-h CGMS data collection.

RESULTS

The blood levels of glutathione were significantly and negatively correlated with MAGE (r = -0.543; P < 0.001), but not with HbA1c and SD of HbA1c. Adiponectin levels were also significantly and negatively correlated with MAGE and SD of HbA1c (r = -0.64 and r = -0.55, respectively; P < 0.001). Using generalized estimating equations, multivariate regression analysis revealed that MAGE is an independent predictor of serum levels of adiponectin (P = 0.002) and glutathione (P = 0.004).

CONCLUSIONS

We found strong associations between acute blood glucose variability, glutathione, and adiponectin in type 2 diabetic patients treated with oral hypoglycemic agent therapy.

Acute changes in blood glucose do not alter blood glutathione synthesis in adolescents with poorly controlled type 1 diabetes mellitus

Depletion of blood glutathione (GSH), a key antioxidant, is associated with type 1 diabetes mellitus (T1D) and contributes to the pathophysiology of diabetes complications. The aim of the current study was to determine whether acute normalization of blood glucose would restore GSH kinetics in adolescents with poorly controlled T1D. Ten 16.9 ± 1.5-year-old (SE) adolescents who had had T1D for 8.5 ± 1.9 years and were free of complications but were in poor control (hemoglobin A(1c), 9.2% ± 0.5%) received two 5-hour intravenous infusions of L-[3,3-(2)H(2)]cysteine in the postabsorptive state on 2 separate days after blood glucose had been maintained overnight at 246 ± 24 mg/dL (hyperglycemia) or 118 ± 23 mg/dL (euglycemia) using intravenous insulin infusion. Blood GSH fractional synthesis rates were determined by mass spectrometry from (2)H(2)-cysteine incorporation into GSH. Neither blood GSH (551 ± 169 vs 541 ± 232 μmol/L, P = .629) nor GSH fractional synthesis rate (84% ± 30% vs 82% ± 33% d(-1), P = .965) was altered by the short-term change in glycemic control. This finding suggests that, in adolescents with poorly controlled T1D, either (a) blood glucose per se does not regulate GSH metabolism or (b) GSH may only respond to sustained, more chronic changes in blood glucose level.

Deficient synthesis of glutathione underlies oxidative stress in aging and can be corrected by dietary cysteine and glycine supplementation

BACKGROUND

Aging is associated with oxidative stress, but underlying mechanisms remain poorly understood.

OBJECTIVE

We tested whether glutathione deficiency occurs because of diminished synthesis and contributes to oxidative stress in aging and whether stimulating glutathione synthesis with its precursors cysteine and glycine could alleviate oxidative stress.

DESIGN

Eight elderly and 8 younger subjects received stable-isotope infusions of [2H(2)]glycine, after which red blood cell (RBC) glutathione synthesis and concentrations, plasma oxidative stress, and markers of oxidant damage (eg, F(2)-isoprostanes) were measured. Elderly subjects were restudied after 2 wk of glutathione precursor supplementation.

RESULTS

Compared with younger control subjects, elderly subjects had markedly lower RBC concentrations of glycine (486.7 ± 28.3 compared with 218.0 ± 23.7 μmol/L; P < 0.01), cysteine (26.2 ± 1.4 compared with 19.8 ± 1.3 μmol/L; P < 0.05), and glutathione (2.08 ± 0.12 compared with 1.12 ± 0.18 mmol/L RBCs; P < 0.05); lower glutathione fractional (83.14 ± 6.43% compared with 45.80 ± 5.69%/d; P < 0.01) and absolute (1.73 ± 0.16 compared with 0.55 ± 0.12 mmol/L RBCs per day; P < 0.01) synthesis rates; and higher plasma oxidative stress (304 ± 16 compared with 346 ± 20 Carratelli units; P < 0.05) and plasma F(2)-isoprostanes (97.7 ± 8.3 compared with 136.3 ± 11.3 pg/mL; P < 0.05). Precursor supplementation in elderly subjects led to a 94.6% higher glutathione concentration, a 78.8% higher fractional synthesis rate, a 230.9% higher absolute synthesis rate, and significantly lower plasma oxidative stress and F(2)-isoprostanes. No differences in these measures were observed between younger subjects and supplemented elderly subjects.

CONCLUSIONS

Glutathione deficiency in elderly humans occurs because of a marked reduction in synthesis. Dietary supplementation with the glutathione precursors cysteine and glycine fully restores glutathione synthesis and concentrations and lowers levels of oxidative stress and oxidant damages. These findings suggest a practical and effective approach to decreasing oxidative stress in aging.