Total plasma antioxidants in first-degree relatives of patients with insulin-dependent diabetes

Therapeutic Potential and Immunomodulatory Role of Coenzyme Q10 and Its Analogues in Systemic Autoimmune Diseases

Coenzyme Q₁₀ (CoQ₁₀) is a mitochondrial electron carrier and a powerful lipophilic antioxidant located in membranes and plasma lipoproteins. CoQ₁₀ is endogenously synthesized and obtained from the diet, which has raised interest in its therapeutic potential against pathologies related to mitochondrial dysfunction and enhanced oxidative stress. Novel formulations of solubilized CoQ₁₀ and the stabilization of reduced CoQ₁₀ (ubiquinol) have improved its bioavailability and efficacy. Synthetic analogues with increased solubility, such as idebenone, or accumulated selectively in mitochondria, such as MitoQ, have also demonstrated promising properties. CoQ₁₀ has shown beneficial effects in autoimmune diseases. Leukocytes from antiphospholipid syndrome (APS) patients exhibit an oxidative perturbation closely related to the prothrombotic status. In vivo ubiquinol supplementation in APS modulated the overexpression of inflammatory and thrombotic risk-markers. Mitochondrial abnormalities also contribute to immune dysregulation and organ damage in systemic lupus erythematosus (SLE). Idebenone and MitoQ improved clinical and immunological features of lupus-like disease in mice. Clinical trials and experimental models have further demonstrated a therapeutic role for CoQ₁₀ in Rheumatoid Arthritis, multiple sclerosis and type 1 diabetes. This review summarizes the effects of CoQ₁₀ and its analogs in modulating processes involved in autoimmune disorders, highlighting the potential of these therapeutic approaches for patients with immune-mediated diseases.

The Intrinsic Virtues of EGCG, an Extremely Good Cell Guardian, on Prevention and Treatment of Diabesity Complications

The pandemic proportion of diabesity—a combination of obesity and diabetes—sets a worldwide health issue. Experimental and clinical studies have progressively reinforced the pioneering epidemiological observation of an inverse relationship between consumption of polyphenol-rich nutraceutical agents and mortality from cardiovascular and metabolic diseases. With chemical identification of epigallocatechin-3-gallate (EGCG) as the most abundant catechin of green tea, a number of cellular and molecular mechanisms underlying the activities of this unique catechin have been proposed. Favorable effects of EGCG have been initially attributed to its scavenging effects on free radicals, inhibition of ROS-generating mechanisms and upregulation of antioxidant enzymes. Biologic actions of EGCG are concentration-dependent and under certain conditions EGCG may exert pro-oxidant activities, including generation of free radicals. The discovery of 67-kDa laminin as potential EGCG membrane target has broaden the likelihood that EGCG may function not only because of its highly reactive nature, but also via receptor-mediated activation of multiple signaling pathways involved in cell proliferation, angiogenesis and apoptosis. Finally, by acting as epigenetic modulator of DNA methylation and chromatin remodeling, EGCG may alter gene expression and modify miRNA activities. Despite unceasing research providing detailed insights, ECGC composite activities are still not completely understood. This review summarizes the most recent evidence on molecular mechanisms by which EGCG may activate signal transduction pathways, regulate transcription factors or promote epigenetic changes that may contribute to prevent pathologic processes involved in diabesity and its cardiovascular complications.

The Protective Effect of Antioxidants Consumption on Diabetes and Vascular Complications

Obesity and diabetes is generally accompanied by a chronic state of oxidative stress, disequilibrium in the redox balance, implicated in the development and progression of complications such as micro- and macro-angiopathies. Disorders in the inner layer of blood vessels, the endothelium, play an early and critical role in the development of these complications. Blunted endothelium-dependent relaxation and/or contractions are quietly associated to oxidative stress. Thus, preserving endothelial function and oxidative stress seems to be an optimization strategy in the prevention of vascular complications associated with diabetes. Diet is a major lifestyle factor that can greatly influence the incidence and the progression of type 2 diabetes and cardiovascular complications. The notion that foods not only provide basic nutrition but can also prevent diseases and ensure good health and longevity is now attained greater prominence. Some dietary and lifestyle modifications associated to antioxidative supply could be an effective prophylactic means to fight against oxidative stress in diabesity and complications. A significant benefit of phytochemicals (polyphenols in wine, grape, teas), vitamins (ascorbate, tocopherol), minerals (selenium, magnesium), and fruits and vegetables in foods is thought to be capable of scavenging free radicals, lowering the incidence of chronic diseases. In this review, we discuss the role of oxidative stress in diabetes and complications, highlight the endothelial dysfunction, and examine the impact of antioxidant foods, plants, fruits, and vegetables, currently used medication with antioxidant properties, in relation to the development and progression of diabetes and cardiovascular complications.

Inactivation of Protein Tyrosine Phosphatases Enhances Interferon Signaling in Pancreatic Islets

Type 1 diabetes (T1D) is the result of an autoimmune assault against the insulin-producing pancreatic β-cells, where chronic local inflammation (insulitis) leads to β-cell destruction. T cells and macrophages infiltrate into islets early in T1D pathogenesis. These immune cells secrete cytokines that lead to the production of reactive oxygen species (ROS) and T-cell invasion and activation. Cytokine-signaling pathways are very tightly regulated by protein tyrosine phosphatases (PTPs) to prevent excessive activation. Here, we demonstrate that pancreata from NOD mice with islet infiltration have enhanced oxidation/inactivation of PTPs and STAT1 signaling compared with NOD mice that do not have insulitis. Inactivation of PTPs with sodium orthovanadate in human and rodent islets and β-cells leads to increased activation of interferon signaling and chemokine production mediated by STAT1 phosphorylation. Furthermore, this exacerbated STAT1 activation-induced cell death in islets was prevented by overexpression of the suppressor of cytokine signaling-1 or inactivation of the BH3-only protein Bim. Together our data provide a mechanism by which PTP inactivation induces signaling in pancreatic islets that results in increased expression of inflammatory genes and exacerbated insulitis.

Biobreeding rat islets exhibit reduced antioxidative defense and N-acetyl cysteine treatment delays type 1 diabetes

Islet-level oxidative stress has been proposed as a trigger for type 1 diabetes (T1D), and release of cytokines by infiltrating immune cells further elevates reactive oxygen species (ROS), exacerbating β cell duress. To identify genes/mechanisms involved with diabetogenesis at the β cell level, gene expression profiling and targeted follow-up studies were used to investigate islet activity in the biobreeding (BB) rat. Forty-day-old spontaneously diabetic lymphopenic BB DRlyp/lyp rats (before T cell insulitis) as well as nondiabetic BB DR+/+ rats, nondiabetic but lymphopenic F344lyp/lyp rats, and healthy Fischer (F344) rats were examined. Gene expression profiles of BB rat islets were highly distinct from F344 islets and under-expressed numerous genes involved in ROS metabolism, including glutathione S-transferase (GST) family members (Gstm2, Gstm4, Gstm7, Gstt1, Gstp1, and Gstk1), superoxide dismutases (Sod2 and Sod3), peroxidases, and peroxiredoxins. This pattern of under-expression was not observed in brain, liver, or muscle. Compared with F344 rats, BB rat pancreata exhibited lower GST protein levels, while plasma GST activity was found significantly lower in BB rats. Systemic administration of the antioxidant N-acetyl cysteine to DRlyp/lyp rats altered abundances of peripheral eosinophils, reduced severity of insulitis, and significantly delayed but did not prevent diabetes onset. We find evidence of β cell dysfunction in BB rats independent of T1D progression, which includes lower expression of genes related to antioxidative defense mechanisms during the pre-onset period that may contribute to overall T1D susceptibility.

Evidence for augmented oxidative stress in the subjects with type 1 diabetes and their siblings: a possible preventive role for antioxidants

BACKGROUND/OBJECTIVES

Oxidative stress (OS) is thought to be involved in both development of type 1 diabetes (T1D) and its further complications. In this study, certain biomarkers of OS were compared among the subjects with T1D, their non-diabetic siblings and unrelated healthy controls.

SUBJECTS/METHODS

Known cases of T1D from both sexes aged 5-25 years were enrolled in a case-control study (n(1)=60). There were two control groups; non-diabetic siblings (n(2)=60) and unrelated apparently healthy subjects (n(3)=60). Anthropometric, dietary and laboratory assessments were done.

RESULTS

There was no significant difference in dietary data among the groups. Total antioxidant capacity was significantly lower in T1D than both related and unrelated controls (1.6 ± 0.05, 1.7 ± 0.05 and 1.8 ± 0.06 mmol BSA equivalent/l, respectively, P=0.044). Both T1D subjects and their siblings showed lower glutathione peroxidase (GSH-px) levels (median (interquartile range): 22.2 (28.6), 29.9 (23) and 41.8 (73.6) U/ml, respectively, P=0.006). On the contrary, superoxide dismutase concentrations were significantly higher in T1D group and the siblings than unrelated healthy controls (243 (45.3), 157.8 (176.9) and 27.9 (8.7) U/l, respectively, P<0.001). Serum concentrations of GSH correlated with energy intake in the siblings (r=0.521, P<0.001) and unrelated controls (r=0.268, P=0.042) but not in T1D group. The associations remained significant after controlling for blood glucose (r=0.437, P=0.001 and r=0.420, P=0.011, respectively) in both the groups.

CONCLUSION

Augmented OS in the siblings may indicate an increased requirement for antioxidants in genetically diabetes-prone subjects.

L-arginine is essential for pancreatic β-cell functional integrity, metabolism and defense from inflammatory challenge

In this work, our aim was to determine whether L-arginine (a known insulinotropic amino acid) can promote a shift of β-cell intermediary metabolism favoring glutathione (GSH) and glutathione disulfide (GSSG) antioxidant responses, stimulus-secretion coupling and functional integrity. Clonal BRIN-BD11 β-cells and mouse islets were cultured for 24 h at various L-arginine concentrations (0-1.15  mmol/l) in the absence or presence of a proinflammatory cytokine cocktail (interleukin 1β, tumour necrosis factor α and interferon γ). Cells were assessed for viability, insulin secretion, GSH, GSSG, glutamate, nitric oxide (NO), superoxide, urea, lactate and for the consumption of glucose and glutamine. Protein levels of NO synthase-2, AMP-activated protein kinase (AMPK) and the heat shock protein 72 (HSP72) were also evaluated. We found that L-arginine at 1.15  mmol/l attenuated the loss of β-cell viability observed in the presence of proinflammatory cytokines. L-arginine increased total cellular GSH and glutamate levels but reduced the GSSG/GSH ratio and glutamate release. The amino acid stimulated glucose consumption in the presence of cytokines while also stimulating AMPK phosphorylation and HSP72 expression. Proinflammatory cytokines reduced, by at least 50%, chronic (24 h) insulin secretion, an effect partially attenuated by L-arginine. Acute insulin secretion was robustly stimulated by L-arginine but this effect was abolished in the presence of cytokines. We conclude that L-arginine can stimulate β-cell insulin secretion, antioxidant and protective responses, enabling increased functional integrity of β-cells and islets in the presence of proinflammatory cytokines. Glucose consumption and intermediary metabolism were increased by L-arginine. These results highlight the importance of L-arginine availability for β-cells during inflammatory challenge.

Oxidative stress and redox modulation potential in type 1 diabetes

Redox reactions are imperative to preserving cellular metabolism yet must be strictly regulated. Imbalances between reactive oxygen species (ROS) and antioxidants can initiate oxidative stress, which without proper resolve, can manifest into disease. In type 1 diabetes (T1D), T-cell-mediated autoimmune destruction of pancreatic β-cells is secondary to the primary invasion of macrophages and dendritic cells (DCs) into the islets. Macrophages/DCs, however, are activated by intercellular ROS from resident pancreatic phagocytes and intracellular ROS formed after receptor-ligand interactions via redox-dependent transcription factors such as NF-κB. Activated macrophages/DCs ferry β-cell antigens specifically to pancreatic lymph nodes, where they trigger reactive T cells through synapse formation and secretion of proinflammatory cytokines and more ROS. ROS generation, therefore, is pivotal in formulating both innate and adaptive immune responses accountable for islet cell autoimmunity. The importance of ROS/oxidative stress as well as potential for redox modulation in the context of T1D will be discussed.

Role of increased ROS dissipation in prevention of T1D

Protection of pancreatic beta cells is an approach to prevent autoimmune type 1 diabetes (T1D) and to protect transplanted islets. Reactive oxygen species (ROS) are important mediators of beta cell death during the development of T1D. We have examined the role of elevated ROS dissipation in the prevention of T1D using the ALR mouse strain. The selection of ALR, for resistance against alloxan-induced free radical-mediated diabetes, led to a strain of mice with an elevated systemic as well as pancreatic ROS dissipation. Independent genetic mapping studies have identified ALR-derived diabetes protective loci. Conplastic and congenic mouse as well as cell line studies have confirmed the genetic mapping and demonstrated that the elevated ROS dissipation protects ALR beta cells from autoimmune destruction. Our data support the hypothesis that elevated ROS dissipation protects beta cells against autoimmune destruction and prevents T1D development.

Glutathione-s-transferase M1 and T1 polymorphisms and associations with type 1 diabetes age-at-onset

Type 1 diabetes (T1D) is an autoimmune disease characterized by pancreatic beta cell destruction involving auto-reactive T-cells, pro-inflammatory cytokines, reactive oxygen species (ROS) and loss of insulin. Monozygotic twin studies show a 20-60% concordance with T1D indicating there may be an environmental component to the disease. Glutathione (GSH) is the major endogenous antioxidant produced by the cell. GSH participates directly in the neutralization of free radicals and plays a role in the immune response. Glutathione-s-transferases (GSTs) conjugate GSH to free-radicals or xenobiotics. GST activity depletes GSH levels and may either detoxify or enhance the toxicity of a compound. Glutathione-s-transferase mu 1 (GSTM1) and glutathione-s-transferase theta 1 (GSTT1) have polymorphic homozygous deletion (null) genotypes resulting in complete absence of enzyme activity. GSTM1 and GSTT1 null genotypes in Caucasian populations have frequencies of approximately 40-60% and 15-20%, respectively. GST null genotypes have been associated with susceptibility to cancer and protection against chronic pancreatitis. The aim of this study was to investigate associations with GSTM1 and GSTT1 polymorphisms in a group T1D patients and control subjects 0-35 years old who participated in the Combined Swedish Childhood Diabetes Registry and Diabetes Incidence Study (1986-1988). Results show that the presence of the GSTM1 and not the null genotype (OR, 2.13 95% CI, 1.23-3.70, p-value, 0.007, Bonferroni corrected p-value, 0.035) may be a susceptibility factor in T1D 14-20 years old. These results suggest that the GSTM1 null genotype is associated with T1D protection and T1D age-at-onset and that susceptibility to T1D may involve GST conjugation.

The use of pholasin as a probe for the determination of plasma total antioxidant capacity

BACKGROUND AND OBJECTIVES

Total antioxidant capacity (TAC) reflects the capacity of plasma, or other body fluid, to resist oxidation. The aim of the present study was to assess the prognostic value of Pholasin as a probe for the determination of plasma TAC.

DESIGN AND METHODS

Plasma samples either oxidised using the free radical generator 2'-azobis-(2-amidinopropane) hydrochloride (AAPH) at 60 degrees C for 180 min or obtained from diabetic (type 1 and type 2) patients (n = 61 and 124, respectively) with or without polyneuropathy (PN) and/or cardiovascular autonomic neuropathy (CAN) and control subjects (n = 70) were analysed for TAC status. TAC was assessed using two versions of Analysis By Emitted Light (ABEL) tests including quenching of Pholasin chemiluminescence (QPC) with peroxynitrite (ONOO(-)-QPC) and with superoxide anion (O2(-)-QPC).

RESULTS

The utilisation of AAPH to induce peroxyl radical mediated plasma oxidation produced a significant decrease in TAC as assessed by ONOO(-)-QPC and O2(-)-QPC assays in a time-dependent manner. Type 1 and type 2 diabetic patients without PN and/or CAN had lower TAC (ONOO(-)-QPC and O2(-)-QPC) than in control subjects. Further alterations in TAC were noted in the presence of PN and/or CAN. Correlations were found between TAC (ONOO(-)-QPC and O2(-)-QPC) values on duration of diabetes and neurological impairment score-lower limb (NIS-LL) in type 1 diabetic patients.

CONCLUSIONS

This study has established that the ONOO(-)-QPC and O2(-)-QPC versions of the ABEL test fulfil the criteria in terms of simplicity, sensitivity and reliability for the measurement of plasma TAC. These biomarkers may prove useful in studies evaluating the impact of therapeutic drugs or antioxidant interventions aimed at delaying the onset of complications in clinical conditions associated with oxidative stress.

Parameters of antioxidative defense in type 2 diabetic patients with cardiovascular complications

OBJECTIVE

Diabetes-associated oxidative stress is a consequence of both increased production of free radicals and reduced capacity of antioxidative defense. Prolonged hyperglycemia is the major factor in the pathogenesis of atherosclerosis in diabetes which can lead to cardiovascular complications. The aim of this study was to test the parameters of antioxidative defense in type 2 diabetic patients.

METHODS

A total of 117 type 2 diabetics with and without cardiovascular complications were examined in order to find out the influence of hyperglycemia, type and duration of complications and duration of diabetes on the extent of disorder of antioxidative parameter values: superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and total antioxidant status (TAS).

RESULTS

Compared to healthy control subjects, type 2 diabetic patients with cardiovascular complications (CVC) had significantly lower SOD (P<0.0001), GSH-Px (P<0.0001), GR ( P = 0.0002) and TAS values (P<0.0001). In type 2 diabetic subjects with CVC, males had significantly lower SOD (778.7+/-103.2 U/gHb, P<0.01) and GR activities (52.2+/-8.9 U/L, P<0.001) compared to females (839.3+/-94.9 U/gHb; 58.5+/-9.1 U/L). Significant and positive correlation was found between glucose levels and SOD (r = 0.375 for P<0.05) and GSH-Px (r = 0.384, P<0.05 ) activity in the group of complications-free diabetics, while significant negative correlation between glucose and GSH-Px values (r = -0.382, P<0.05) was found in the group of type 2 diabetics with coronary artery disease (CAD) and hypertension (HTA) and with CAD and acute myocardial infarction (AMI) (r = -0.860 P<0.05), and highly negative correlation between glucose and SOD levels (r = -0.590, P<0.05) in the group of diabetic subjects with CAD, AMI and HTA. Likewise, there was highly significant negative correlation of SOD (r = -0.949, P<0.05) and TAS (r = -0.393 for P = 0.038) with duration of diabetes in the group of diabetics with CAD and HTA.

CONCLUSION

Our results confirm the hypothesis that there is reduced antioxidative defense in type 2 diabetics with prominent cardiovascular complications, which negatively correlates with glucose concentrations and duration of diabetes and cardiovascular complications.

Comparison of spectrophotometric and enhanced chemiluminescent assays of serum antioxidant capacity

BACKGROUND

Over recent years, interest in total antioxidant capacity measurement in biological fluids has increased. A number of assays are now available, and we wished to compare an enhanced chemiluminescence (ECL) method to a spectrophotometric method, the total antioxidant status (TAS) assay.

METHODS

Serum urate concentration, ECL and TAS were measured in 34 healthy subjects. Additionally, 10 subjects participated in a two-way, randomised crossover study, and received urate 1000 mg or vitamin C 1000 mg intravenously over 1 h. Serum ECL and TAS were measured at 0, 15, 30, 45, 60, 90 and 120 min after commencing infusion.

RESULTS

Baseline measurements were poorly correlated between ECL and TAS assays, and between serum urate concentration and each antioxidant assay. There was good correlation between the change in antioxidant capacity detected by both assays during urate infusion (R=0.79, p<0.001, n=60), but not vitamin C infusion.

CONCLUSIONS

ECL and TAS measures of serum antioxidant capacity correlate poorly in a healthy population, although both are sensitive to increases in circulating urate concentrations. Therefore, ECL and TAS appear sensitive to different factors. The comparative strengths and weaknesses of various antioxidant assays should be reviewed.

Prevention strategies for type 1 diabetes mellitus: current status and future directions

Type 1 diabetes mellitus affects about 1 in 300 people in North America and Europe. Epidemiological studies indicate that the incidence and thus prevalence of type 1 diabetes is rising worldwide. Intervention in autoimmune type 1a diabetes could occur at the time of diagnosis or, preferably, prior to clinical presentation during the 'prediabetic' period (e.g. prevention). Prediabetes is best recognised by the detection of islet autoantibodies in the serum. Promising intervention strategies include monoclonal antibody therapies (e.g. anti-CD3, anti-CD25, anti-CD52 or anti-CD20 monoclonal antibodies), immunosuppression (e.g. calcineurin inhibitors, B7 blockade, glucocorticoids, sirolimus (rapamycin), azathioprine or mycophenolate mofetil), immunomodulatory therapies (e.g. plasmapheresis, intravenous immunoglobulin, cytokine administration, adoptive cellular gene therapy) and tolerisation interventions (e.g. autoantigen administration or avoidance, altered peptide ligand or peptide-based therapies). To date, islet and pancreas transplantation have essentially been reserved for patients with long-standing diabetes who have complications and are also in need of a concurrent kidney transplant. None of the therapies attempted to date has produced long-term remissions in new-onset type 1 diabetes patients and no therapies have been shown to prevent the disease. Nevertheless, with advances in our understanding of basic immunology and the cellular and molecular mechanisms of tolerance induction and maintenance, successful intervention therapies will be developed. The balance between safety and efficacy is critical. Higher rates of adverse events might be more tolerable in new-onset type 1 diabetes patients if the therapy is extremely effective at inducing a permanent remission. However, therapies must not harm the beta-cells themselves or any organ system that is a potential target of diabetes complications, such as the nervous system, retina, cardiovascular system or kidney. In the treatment of prediabetes, successful therapies should provide a level of safety similar to that of currently used vaccines and a high level of efficacy.

Systemic uric acid administration increases serum antioxidant capacity in healthy volunteers

Oxidative stress plays an important role in the development of atherosclerosis and contributes to tissue damage that occurs as a consequence, particularly in myocardial infarction and acute stroke. Antioxidant properties of uric acid have long been recognized and, as a result of its comparatively high serum concentrations, it is the most abundant scavenger of free radicals in humans. Elevation of serum uric acid concentration occurs as a physiologic response to increased oxidative stress-for example, during acute exercise-thus providing a counter-regulatory increase in antioxidant defenses. In view of its antioxidant properties, uric acid may have potentially important and beneficial effects within the cardiovascular system. We wished to investigate whether administration of uric acid was feasible and if it could have an impact on antioxidant function in vivo. We have, therefore, performed a randomized, placebo-controlled double-blind study of the effects of systemic administration of uric acid, 1,000 mg, in healthy volunteers, compared with vitamin C, 1,000 mg. We observed a significant increase in serum free-radical scavenging capacity from baseline during uric acid and vitamin C infusion, using two methodologically distinct antioxidant assays. The effect of uric acid was substantially greater than that of vitamin C.

Oxidative markers in diabetic ketoacidosis

Oxidative stress has been implicated in the pathogenesis of the chronic complications of diabetes mellitus but little is known in diabetic ketoacidosis (DKA). The aim of this work was to determine whether lipid peroxidation, as assessed by measuring malondialdehyde (MDA, a prooxidant) and antioxidant status (TAS, an index of antioxidant defenses), is modified in DKA, and also whether any observed abnormalities were related to metabolic disturbances.

METHODS

four groups of patients were studied, comprising 19 patients with DKA, massive ketonuria and plasma standard bicarbonate levels below 16 mmol/l (group 1); 20 patients with poorly controlled diabetes, glycated hemoglobin (HbA1c) above 8% and plasma bicarbonate levels above 16 mmol/l (group 2); 11 patients with well-controlled diabetes and HbA1c below 8% (group 3); and 10 non-diabetic, non-obese control subjects (group 4). Metabolic parameters, MDA levels and TAS were assessed in the plasma of the four groups of subjects.

RESULTS

mean plasma MDA and TAS values were significantly different among the four groups (respectively p < 0.001 and p < 0.01). Mean plasma MDA value was significantly higher in group 1 than in group 3 (p < 0.02) and group 4 (p < 0.001) but was not different from that in group 2. Mean plasma MDA value in group 2 was significantly lower than that in group 4 (p = 0.002). Mean plasma TAS value in group 1 was significantly lower than in groups 3 (p < 0.002) and 4 (p < 0.05). Mean plasma TAS value was significantly lower in group 2 than in group 4 (p<0.05). Plasma MDA values in the diabetic patients (groups 1+2+3) were not related to any clinical characteristics (BMI, age, duration of the disease) or metabolic parameters (glycemia, HbA1c bicarbonates, blood urea nitrogen, phosphatemia, lipids), while plasma TAS values correlated negatively with glycemia, osmolality and HbA1c. A significant relationship was also found between TAS and HbA1c in group 1 (p < 0.05) and between MDA and HbA1c in group 3 (p < 0.05). Correlations were also found between TAS and phosphatemia in group 1 (p < 0.01) and between MDA and phosphatemia in group 2 (p < 0.01). A positive relationship between MDA and cholesterol levels was found in group 1 (p < 0.01). In conclusion, MDA values are increased and TAS values decreased in DKA and poorly controlled diabetes, and tend to correlate more with markers of diabetic imbalance than with markers of acute metabolic disturbances of DKA.

Unaltered antioxidant activity of plasma in subjects at increased risk for IDDM

Evidence suggests that free oxygen radicals are involved in the destruction of islet beta-cells in insulin-dependent diabetes mellitus (IDDM). Therefore, we determined the plasma antioxidant activity in 51 healthy unaffected children and adolescents randomly chosen from a study of beta-cell autoimmunity in schoolchildren in northern Finland. Twenty-two subjects tested positive for one or more IDDM-associated autoantibodies and 9 subjects had at least two of the three antibodies tested (antibodies against islet cells, ICA; glutamic acid decarboxylase, GADA; insulin, IAA). There was no significant association of total plasma antioxidant potential, plasma concentrations of alpha-tocopherol, ascorbic acid, protein thiols, or uric acid with the presence of ICA, GADA, or IAA. A reduced first-phase insulin response to intravenous glucose was also not associated with reduced plasma antioxidant activity. These results indicate that the plasma antioxidant activity is not decreased in subjects at increased risk for IDDM. Furthermore, the results suggest that the clinical onset of IDDM is not preceded by signs of increased systemic oxidative stress in plasma.