Advanced oxidative and glycoxidative protein damage markers in the elderly with type 2 diabetes

Expressions of glycemic parameters, lipid profile, and thyroid hormone in patients with type 2 diabetes mellitus and their correlation

OBJECTIVE

This study aimed to investigate the expressions of glycemic parameters, lipid profile, and thyroid hormone in type 2 diabetes mellitus (T2DM) patients and their correlation.

METHODS

Eighty-four patients with T2DM in our hospital were included as the observation group. The T2DM patients were divided into mild group, moderate group, and severe group according to the fasting plasma glucose (FPG) level. Another 84 healthy subjects in the same period of health examination in our hospital were included as the control group. The levels of glycemic parameters, (HbA1c and FPG), lipid profile (TC, TG, LDL-C, and HDL-C) and thyroid hormone (FT3, TSH, and FT4) were measured by automatic biochemical analyzer. The correlation between glycemic parameters, lipid profile, and thyroid hormone was analyzed by Pearson correlation analysis.

RESULTS

The FPG, TC, TG, LDL-C, HbA1c, and TSH levels were significantly elevated, while the HDL-C and FT3 levels were significantly declined in the observation group versus to control group (p < .05). The levels of HbA1c, FPG, TC, LDL-C, and TSH were significantly increased, while the levels of HDL-C and FT3 were decreased in moderate and severe groups, when compared to mild group (p < .05). The levels of HbA1c, FPG, TC, LDL-C and TSH were higher, while the level of FT3 was lower in severe group than those in moderate group (p < .05). Pearson Correlation analysis showed that FT3 level in T2DM patients was positively correlated with FPG, HbAlc, TC, TG, and LDL-C levels (p < .05), but negatively correlated with HDL-C level (p < .05). TSH level was negatively correlated with FPG, HbAlc, TC, TG, and LDL-C levels (p < .05), while positively correlated with HDL-C level.

CONCLUSION

The thyroid hormone levels were of clinical significance in evaluating glycolipid metabolism and severity of T2DM. Clinical detection of glycolipid metabolism and thyroid hormone levels in T2DM patients is of great significance for diagnosis, evaluation, and targeted treatment of the disease.

Are Advanced Oxidation Protein Products (AOPPs) Levels Altered in Neuropsychiatric Disorders? An Integrative Review

Neuropsychiatric disorders such as major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ) are considered a public health problem since it interferes in personal relationships and at work. The pathophysiological mechanisms of these mental disorders are still not completely understood. The variety and heterogeneity of symptoms, as well as the absence of biomarkers, make the diagnosis, prognosis, and treatment of these disorders difficult. However, oxidative stress appears to play a role in the pathophysiology of these diseases. In this context, advanced oxidation protein products (AOPPs) are considered a biomarker of protein oxidative damage and have been associated with neuroinflammatory diseases. In patients with neuropsychiatric disorders, increased levels of AOPPs were associated with the severity of symptoms and decreased quality of life. Thus, the objective of this integrative review is to investigate and discuss the relationship between AOPPs levels and MDD, BD, and SZ. Different databases were consulted and approximately 112 scientific articles were found relating AOPPs and psychiatric disorders. In the majority of studies, the blood levels of AOPPs were increased in MDD, BD, and SZ and associated with the severity of the disorders. Although the association of this marker with the risk of developing one of these mental disorders is more uncertain, some studies have suggested this relationship. Of the twenty-four studies highlighted, only four did not find significant differences in AOPPs levels in patients with the disorders mentioned. In summary, it may be suggested that the assessment of AOPPs levels can be a useful tool in the evaluation of neuropsychiatric disorders, at least for prognostic evaluation. However, the role of this biomarker in the pathophysiology of mental disorders is still unclear, as well as whether reducing its levels represents a potential therapeutic strategy.

Circadian Rhythms, Chrononutrition, Physical Training, and Redox Homeostasis-Molecular Mechanisms in Human Health

A multitude of physiological processes, human behavioral patterns, and social interactions are intricately governed by the complex interplay between external circumstances and endogenous circadian rhythms. This multidimensional regulatory framework is susceptible to disruptions, and in contemporary society, there is a prevalent occurrence of misalignments between the circadian system and environmental cues, a phenomenon frequently associated with adverse health consequences. The onset of most prevalent current chronic diseases is intimately connected with alterations in human lifestyle practices under various facets, including the following: reduced physical activity, the exposure to artificial light, also acknowledged as light pollution, sedentary behavior coupled with consuming energy-dense nutriments, irregular eating frameworks, disruptions in sleep patterns (inadequate quality and duration), engagement in shift work, and the phenomenon known as social jetlag. The rapid evolution of contemporary life and domestic routines has significantly outpaced the rate of genetic adaptation. Consequently, the underlying circadian rhythms are exposed to multiple shifts, thereby elevating the susceptibility to disease predisposition. This comprehensive review endeavors to synthesize existing empirical evidence that substantiates the conceptual integration of the circadian clock, biochemical molecular homeostasis, oxidative stress, and the stimuli imparted by physical exercise, sleep, and nutrition.

Aging and Antithrombotic Treatment

Significance: Several aging-related pathophysiological mechanisms have been described to contribute to increased thrombotic risk in the elderly, including oxidative stress, endothelial dysfunction, and platelet and coagulation cascade activation. Antithrombotic treatment in the elderly should be individualized. Recent Advances: Recent studies have clarified some pathophysiological mechanisms of enhanced oxidative stress and thrombotic alterations in older adults. In the last decade, randomized trials have evaluated different antithrombotic strategies to reduce the risk of cardiovascular events in these patients. Critical Issues: The proportion of elderly patients included in clinical trials is generally low, thus not reflecting the daily clinical practice. There is no consensus on the most appropriate antithrombotic treatment in the elderly, also considering that bleeding risk management may be challenging in this high-risk subgroup of patients. Routine antiplatelet treatment is not a valid strategy for the primary prevention of cardiovascular events given the associated high risk of bleeding. In elderly patients with acute coronary syndrome, low-dose prasugrel or clopidogrel, shorter dual antiplatelet therapy, and no pretreatment before stent placement should be considered. Advanced age should not be the only reason for the underuse of oral anticoagulation in patients with atrial fibrillation, with direct oral anticoagulants preferred over warfarin for stroke prevention. Instead, a case-by-case clinical evaluation is warranted based on patient's bleeding risk also. Future Directions: There is a need for a structured tailored approach to manage thrombotic risk in elderly patients. The choice of the most appropriate antithrombotic treatment should balance efficacy and safety to reduce the risk of bleeding.

Assessment of health status and cardiovascular risk factors in a Roma population sample from South Bulgaria

OBJECTIVES

Roma population is one of the major ethnic groups in the Central and Eastern Europe, having high rates of chronic diseases and associated risk factors related to their poor social conditions, unhealthy lifestyle and low educational level. The purpose of our study was to assess the health status of Roma from South Bulgaria by means of blood indicators and determine the prevalence of some cardiovascular (CV) risk factors in the Roma population sample.

METHODS

The study group consisted of 60 Roma (23 men and 37 women), mean age 53.7 ± 15.9 years, and the control group consisted of 68 non-Roma from the majority population (29 men and 38 women), mean age 45.8 ± 12.2 years. The data were collected via questionnaire, anthropometric measures, and venous blood samples analyses after an overnight fasting.

RESULTS

The Roma population subjects were slightly but significantly older compared to the non-Roma group and both study groups included more women. The fasting glucose, body mass index (BMI), triglycerides (TG), total cholesterol (TC), and LDL-cholesterol (LDL-C) levels were significantly higher, and HDL-cholesterol (HDL-C) levels were significantly lower in Roma compared to the control non-Roma group. The values of cardiovascular risk markers such as TC/HDL-C and TG/HDL-C ratios, atherogenic index of plasma (AIP) and lipoprotein combine index (LCI) were significantly higher in Roma compared to non-Roma subjects. The prevalence of obesity in Roma was 35%, diabetes mellitus was recorded in 16.7% of the entire Roma sample, and hyperglycaemia in non-diabetics was recorded in 32%. Hypercholesterolaemia was found in 90% and hypertriglyceridaemia was found in 88.3%. The prevalence of cardiovascular diseases (CVD) was high and was encountered in 71.7% of the Roma participants and most of the subjects (96.7%) reported family history of CVD. The studied population showed high smoking rates with 33.3% active smokers.

CONCLUSIONS

Our study confirmed high prevalence of CV risk factors among Roma population, such as abnormal lipid profile parameters, obesity and heavy smoking and very high cardiovascular morbidity rate. Therefore, adequate measures and healthcare programmes aiming at the early identification, treatment and prevention of CVD risks among Roma are necessary.

Bone parameters in T1D and T2D assessed by DXA and HR-pQCT - A cross-sectional study: The DIAFALL study

INTRODUCTION/AIM

People with type 1 diabetes(T1D) and type 2 diabetes(T2D) have an increased risk of fractures due to skeletal fragility. We aimed to compare areal bone mineral density(aBMD), volumetric BMD(vBMD), cortical and trabecular measures, and bone strength parameters in participants with diabetes vs. controls.

METHODS

In a cross-sectional study, we included participants with T1D(n = 111), T2D(n = 106) and controls(n = 328). The study comprised of whole-body DXA and HR-pQCT scans, biochemistry, handgrip strength(HGS), Timed Up and GO(TUG), vibration perception threshold (VPT), questionnaires, medical histories, alcohol use, and previous fractures. Group comparisons were performed after adjustment for sex, age, BMI, diabetes duration, HbA1c, alcohol, smoking, previous fractures, postmenopausal, HGS, TUG, and VPT.

RESULTS

We found decreased aBMD in participants with T1D at the femoral neck(p = 0.028), whereas T2D had significantly higher aBMD at peripheral sites(legs, arms, p < 0.01) vs. controls. In T1D we found higher vBMD(p < 0.001), cortical vBMD (p < 0.001), cortical area(p = 0.002) and thickness(p < 0.001), lower cortical porosity(p = 0.008), higher stiffness(p = 0.002) and failure load(p = 0.003) at radius and higher vBMD(p = 0.003), cortical vBMD(p < 0.001), bone stiffness(p = 0.023) and failure load(p = 0.044) at the tibia than controls. In T2D we found higher vBMD(p < 0.001), cortical vBMD(p < 0.001), trabecular vBMD(p < 0.001), cortical area (p < 0.001) and thickness (p < 0.001), trabecular number (p = 0.024), lower separation(p = 0.010), higher stiffness (p < 0.001) and failure load (p < 0.001) at the radius and higher total vBMD(p < 0.001), cortical vBMD(p < 0.011), trabecular vBMD(p = 0.001), cortical area(p = 0.002) and thickness(p = 0.021), lower trabecular separation(p = 0.039), higher stiffness(p < 0.001) and failure load(p = 0.034) at tibia compared with controls.

CONCLUSION

aBMD measures were as expected but favorable bone microarchitecture and strength parameters were seen at the tibia and radius for T1D and T2D.

Modulation of Reactive Oxygen Species Homeostasis as a Pleiotropic Effect of Commonly Used Drugs

Age-associated diseases represent a growing burden for global health systems in our aging society. Consequently, we urgently need innovative strategies to counteract these pathological disturbances. Overwhelming generation of reactive oxygen species (ROS) is associated with age-related damage, leading to cellular dysfunction and, ultimately, diseases. However, low-dose ROS act as crucial signaling molecules and inducers of a vaccination-like response to boost antioxidant defense mechanisms, known as mitohormesis. Consequently, modulation of ROS homeostasis by nutrition, exercise, or pharmacological interventions is critical in aging. Numerous nutrients and approved drugs exhibit pleiotropic effects on ROS homeostasis. In the current review, we provide an overview of drugs affecting ROS generation and ROS detoxification and evaluate the potential of these effects to counteract the development and progression of age-related diseases. In case of inflammation-related dysfunctions, cardiovascular- and neurodegenerative diseases, it might be essential to strengthen antioxidant defense mechanisms in advance by low ROS level rises to boost the individual ROS defense mechanisms. In contrast, induction of overwhelming ROS production might be helpful to fight pathogens and kill cancer cells. While we outline the potential of ROS manipulation to counteract age-related dysfunction and diseases, we also raise the question about the proper intervention time and dosage.

Zinc status, insulin resistance and glycoxidative stress in elderly subjects with type 2 diabetes mellitus

Zinc deficiencies have been reported in numerous pathologies, such as diabetes mellitus, but also in the physiological process of ageing. Similarly, the end products of glycoxidation processes, advanced glycation end products (AGEs), are damaging compounds, a myriad of reports linking them to the development and progression of several age-associated chronic diseases. The aim of the present study was to analyze the relationships between zinc status, glycoxidative stress and insulin resistance (IR) in elderly subjects with type 2 diabetes mellitus (T2DM). A group of 52 non-smoking subjects (9 men and 43 women, aged 65-83 years) were enrolled in this cross-sectional study: 27 patients with T2DM, and 25 apparently healthy control subjects. Serum zinc (Zn) levels were assessed using a commercial kit based on an end-point colorimetric method, and serum AGEs were evaluated with a fluorimetric analytic procedure. The calculated glucose-to-zinc ratio (Gly/Zn), insulin-to-zinc ratio (Ins/Zn) and insulin-zinc resistance index (HOMA-IR/Zn) were further used to study the associations between serum Zn levels, secretory function of β-pancreatic cells and AGEs. T2DM patients presented significantly higher serum insulin and Zn levels, as compared to the controls. We found a significant inverse correlation between Zn and AGEs, and a strong positive correlation between AGEs and the Gly/Zn ratio, suggesting that both Zn and AGEs are biomarkers that could reflect the persistence of hyperglycemia. We identified new surrogate biomarkers useful for the assessment of glycemic control with great potential for the development of preventive and therapeutic strategies for elderly diabetics, based on the evaluation of serum Zn levels.

Quercetin improves myocardial redox status in rats with type 2 diabetes

Objective. Emerging data indicate that oxidative stress is closely associated with the pathogenesis of cardiovascular disease in type 2 diabetes mellitus (T2DM). The present study aimed to assess the effect of the most abundant flavonoid in the human diet quercetin (Q) on the myocardial redox status in rats with T2DM. Methods. T2DM was induced in male Wistar rats by a high caloric diet (for 14 weeks) and two streptozotocin (25 mg/kg b.w.) injections applied in four weeks of the diet, once a week for two weeks. The Q was administered intragastrically by gavage in a dose of 10 or 50 mg/kg of the body weight for 8 weeks starting from the 8th day after the last streptozotocin injection. The control rats received citrate buffer and seven days after the last STZ injection, basal glucose levels were measured in all animals. Results. Administration of Q increased insulin sensitivity in diabetic rats with more pronounced effect at a dose of 50 mg/kg b.w. The Q also decreased free radical oxidation in the heart mitochondria of diabetic animals, thus limiting the formation of advanced oxidation protein products in a dose-dependent manner and normalized the activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione reductase) in cardiac mitochondria independently of the dose used. In addition, the Q in both doses prevented the development of oxidative stress in the T2DM rats cardiomyocytes by reducing NADPH oxidase and xanthine oxidase activities. Conclusions. The findings demonstrate that Q in both doses 10 mg/kg and 50 mg/kg can protect from the development of oxidative stress in cardiomyocytes in the diabetic rats. The present data indicate that the use of Q may contribute to the amelioration of cardiovascular risk in patients with T2DM.

Therapeutic Potentials of Colocasia affinis Leaf Extract for the Alleviation of Streptozotocin-Induced Diabetes and Diabetic Complications: In vivo and in silico-Based Studies

INTRODUCTION

Hypoglycemia in diabetes mellitus (DM) correlates with hepatic impairment, nephropathy, lipid abnormalities, and oxidative stress and subsequently complicates the disease pathogenesis. Medicinal plants have been used for the management of diabetes since ancient times. In this study, we explored the potentials of Colocasia affinis (CA), a plant known to possess anti-allergic and anti-inflammatory activities, as a remedy for diabetes and related complications.

METHODS

We induced diabetes in rats using a single intraperitoneal dose (65 mg/kg) of streptozotocin (STZ). We next treated the rats with an ethanolic extract of leaves of CA to reveal its antidiabetic and organ-protective potentials. Biomarkers of diabetes, inflammation, and oxidative stress were measured using biochemical and histopathological analysis. We also performed molecular docking for three major phytochemicals (kaempferol, myricetin, and rosmarinic acid) of CA.

RESULTS

Oral administration of the CA leaves extract at 250 mg/kg and 500 mg/kg doses decreased blood glucose level significantly (p<0.05) in STZ-induced diabetic rats. The extract also considerably attenuated plasma HbA1c levels and normalized blood lipids, glycogen, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Additionally, treatment with the extract improved kidney complications by decreasing serum creatinine and blood urea nitrogen (BUN) levels. Furthermore, CA leaves extract normalized nitric oxide (NO) and advance oxidative protein products (AOPP) in diabetic rats. The extract also showed significant improvement of the antioxidant enzymes glutathione dismutase (GSH) and superoxide dismutase (SOD) at a dose of 500 mg/kg. Besides, histological investigation demonstrated attenuation of inflammation of the vital organs, including the liver and the kidney. In silico studies revealed that three major phytochemicals (kaempferol, myricetin, and rosmarinic acid) of the ethanolic extract of leaves of CA can inhibit several molecular targets of diabetes and inflammation.

CONCLUSION

Collectively, our results demonstrated the therapeutic potentials of CA for the mitigation of diabetes and diabetic complications.

Nuclear-mitochondrial communication involving miR-181c plays an important role in cardiac dysfunction during obesity

AIMS

In cardiomyocytes, there is microRNA (miR) in the mitochondria that originates from the nuclear genome and matures in the cytoplasm before translocating into the mitochondria. Overexpression of one such miR, miR-181c, can lead to heart failure by stimulating reactive oxygen species (ROS) production and increasing mitochondrial calcium level ([Ca²⁺]_m). Mitochondrial calcium uptake 1 protein (MICU1), a regulatory protein in the mitochondrial calcium uniporter complex, plays an important role in regulating [Ca²⁺]_m. Obesity results in miR-181c overexpression and a decrease in MICU1. We hypothesize that lowering miR-181c would protect against obesity-induced cardiac dysfunction.

METHODS AND RESULTS

We used an in vivo mouse model of high-fat diet (HFD) for 18 weeks and induced high lipid load in H9c2 cells with oleate-conjugated bovine serum albumin in vitro. We tested the cardioprotective role of lowering miR-181c by using miR-181c/d^-/- mice (in vivo) and AntagomiR against miR-181c (in vitro). HFD significantly upregulated heart levels of miR-181c and led to cardiac hypertrophy in wild-type mice, but not in miR-181c/d^-/- mice. HFD also increased ROS production and pyruvate dehydrogenase activity (a surrogate for [Ca²⁺]_m), but the increases were alleviated in miR-181c/d^-/- mice. Moreover, miR-181c/d^-/- mice fed a HFD had higher levels of MICU1 than did wild-type mice fed a HFD, attenuating the rise in [Ca²⁺]_m. Overexpression of miR-181c in neonatal ventricular cardiomyocytes (NMVM) caused increased ROS production, which oxidized transcription factor Sp1 and led to a loss of Sp1, thereby slowing MICU1 transcription. Hence, miR-181c increases [Ca²⁺]_m through Sp1 oxidation and downregulation of MICU1, suggesting that the cardioprotective effect of miR-181c/d^-/- results from inhibition of Sp1 oxidation.

CONCLUSION

This study has identified a unique nuclear-mitochondrial communication mechanism in the heart orchestrated by miR-181c. Obesity-induced overexpression of miR-181c increases [Ca²⁺]_m via downregulation of MICU1 and leads to cardiac injury. A strategy to inhibit miR-181c in cardiomyocytes can preserve cardiac function during obesity by improving mitochondrial function. Altering miR-181c expression may provide a pharmacologic approach to improve cardiomyopathy in individuals with obesity/type 2 diabetes.

Middle-Aged Indians with Type 2 Diabetes Are at Higher Risk of Biological Ageing with Special Reference to Serum CDKN2A

Sedentary lifestyle and high visceral adiposity have elevated the risk of type 2 diabetes (T2DM) among Indians at younger age. In this study, we aimed to investigate the association of oxidative stress and chronic inflammatory mediators with ageing with special reference to the biological ageing marker cyclin-dependent kinase inhibitor 2A (CDKN2A) among middle-aged (31-50 years) Indian healthy and T2DM subjects. Malondialdehyde (MDA), oxidized LDL (oxLDL), interleukin-6 (IL-6), interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and CDKN2A were measured in T2DM patients (n = 80) and controls (n = 80) aged 31-50 years, further grouped into G1: 31-40 years and G2: 41-50 years. IL-6, TNF-α, MCP-1, and CDKN2A showed a significant association with ageing among both T2DM patients and controls. But the strength of the association of MCP-1 and CKDN2A with ageing was significantly stronger in T2DM patients than the controls. All the oxidative stress and proinflammatory mediators showed nonsignificant associations with CDKN2A in the controls. However, IL-6, TNF-α, and MCP-1 showed a strong association with CDKN2A in T2DM patients. An increased risk of high levels of CDKN2A was found in G1 T2DM patients (OR: 3.484 (95% CI: 1.246-9.747) p = 0.017) and G2 T2DM patients (OR: 5.000 (95% CI: 1.914-13.061), p = 0.001) with reference to the respective control groups. Our study reveals that the middle-aged Indians with T2DM are at higher risk of biological ageing. The development of T2DM is more common among middle-aged Indians. T2DM may exacerbate the ageing process and may subsequently predispose Indians to various age-related complications at a much early age.

Preclinical and clinical results regarding the effects of a plant-based antidiabetic formulation versus well established antidiabetic molecules

Diabetes mellitus (DM) is a complex syndrome with debilitating long-term complications, comprising alterations of carbohydrate, protein and lipid metabolisms, along increased oxidative stress and chronic low-grade inflammation. Diet management and plant-based formulations can improve the metabolic status of patients, being used as adjuvants of classic antidiabetic therapy. The purpose of our study was to evaluate the impact of a plant-based antidiabetic formulation (PBAF), containing Vaccinium myrtillus, Ribes nigrum, Rosa canina and Capsicum annuum, on the increased oxidative burden found in diabetes mellitus, comparing it with the effects of metformin and gliclazide. Firstly, we characterized the individual plant-derived components of this formulation and also assessed their in vitro radical scavenging capacity. We devised a preclinical study protocol to examine the impact of the PBAF, along metformin and gliclazide, on tissue histology as well as on the redox status of tissue, mitochondria, serum and serum lipoproteins of alloxan-induced diabetic Wistar rats. Subsequently, we assessed their long-term impact on the redox status of serum and isolated serum lipoproteins of type 2 DM (T2DM) patients, taking into consideration their cardiometabolic profile. In the preclinical stage, we found that PBAF was able to enhance total serum antioxidant defense, while metformin yielded the best results regarding the advanced glycation and protein/lipid oxidation of serum and of serum lipoproteins. The latter also improved overall serum redox status and HDL redox function. Also, antidiabetic treatment seemed to increase mitochondrial redox activity, without overturning overall tissue redox balance. Histologically, liver and brain tissues of treated diabetic rats were fairly similar to those of non-diabetic rats. In T2DM patients, the most striking results involved the effects on serum lipoproteins. The tested PBAF exerted protective antioxidant effects on low-density and, especially, on high density lipoproteins. We conclude that this formulation might constitute a good addition to the well-established pharmacological approach of DM, contributing to the reduction of overall oxidative burden.

A mitochondrial-targeted peptide ameliorated podocyte apoptosis through a HOCl-alb-enhanced and mitochondria-dependent signalling pathway in diabetic rats and in vitro

Mitochondria play important roles in the development of diabetic kidney disease (DKD). The SS peptide is a tetrapeptide that is located and accumulated in the inner mitochondrial membrane; it reduces reactive oxygen species (ROS) and prevents mitochondrial dysfunction. Podocytes are key cellular components in DKD progression. However, whether the SS peptide can exert renal protection through podocytes and the mechanism involved are unknown. In the present study, we explored the mechanisms of the SS peptide on podocyte injury in vivo and in vitro. Compared with the control group, the glomerular podocyte number and expression of WT1 were significantly reduced and TUNEL-positive podocytes were significantly increased in renal tissues in the diabetic rat. These effects were further exacerbated by hypochlorite-modified albumin (HOCl-alb) challenge but prevented by SS-31. In vitro, SS-31 blocked apoptosis in podocyte cell line induced by HOCl-alb. SS-31 prevented oxidative stress and mitochondria-dependent apoptosis signalling by HOCl-alb in vivo and in vitro, as evidenced by the release of cytochrome c (cyt c), binding of apoptosis activated factor-1 (Apaf-1) and caspase-9, and activation of caspases. These data suggest that SS-31 may prevent podocyte apoptosis, exerting renal protection in diabetes mellitus, probably through an apoptosis-related signalling pathway involving oxidative stress and culminating in mitochondria.

Beyond LDL-c: The importance of serum oxidized LDL in predicting risk for type 2 diabetes in the middle-aged Asian Indians

AIMS

Oxidized low-density lipoprotein (OxLDL) as the residual lipid plays a crucial role in cardiovascular complications and type 2 diabetes. This study aimed to evaluate the relationship of OxLDL with the conventional risk markers and to find the association of OxLDL with the risk of development of type 2 diabetes in middle-aged (30-50 years) Asian Indians.

MATERIALS AND METHODS

A total of 78 type 2 diabetes patients and 78 age-matched controls were recruited. The serum OxLDL concentration was assessed by enzyme-linked immunosorbent assay (ELISA). Other anthropometric and biochemical measures were also carried out. Multiple logistic regression was used to determine the association of OxLDL and OxLDL to non-oxidized lipoproteins with the occurrence of type 2 diabetes.

RESULTS

OxLDL was significantly higher in type 2 diabetes cases than controls (p < 0.001) even though there was no significant difference in LDL cholesterol (LDL-c) between type 2 diabetes patients and controls. OxLDL correlated significantly with fasting plasma glucose (FPG) and insulin resistance (HOMA-IR). OxLDL did not show any significant correlation with LDL-c. Multiple logistic regression showed a significant association of OxLDL, OxLDL/LDL-c and OxLDL/HDL-c with type 2 diabetes (p < 0.001). LDL-c showed no association with type 2 diabetes. ROC-AUC curve analyses showed OxLDL/HDL-c to have highest discriminatory power for type 2 diabetes (AUC: 0.710 with 95% CI: 0.629-0.791, p < 0.001).

CONCLUSION

Our findings highlight the possibly more attention has to be given to OxLDL for managing lipids and diabetes progression as well as reducing cardiac risk in middle-aged type 2 diabetes patients.

Agmatine Prevents Oxidative-nitrative Stress in Blood Leukocytes Under Streptozotocin-induced Diabetes Mellitus

Changes in cellular metabolism, development of oxidative-nitrative stress and intensification of glycation and lipid peroxidation (LPO), are significant processes that occur during diabetes mellitus (DM)-associated chronic hyperglycemia. These processes contribute to deviations in the structural organization and functional activity of leukocytes. The development of oxidative-nitrative stress in peripheral blood cells during DM can be prevented by agmatine, an endogenous metabolite of L-arginine, which is a nitric oxide synthase (NOS) inhibitor, and possesses hypoglycemic properties. The administration of agmatine to animals with DM lead to the inhibition of both constitutive and inducible NOS in leukocytes, which in turn decreased total nitrite/nitrate (NOx) levels. Additionally, we observed corresponding increases in reduced glutathione content and activity of antioxidant enzymes (SOD, CAT, GPx, GR), along with decreased levels of the thiobarbituric acid reactive substance, advanced oxidation protein products (AOPPs) and advanced glycosylation end-products (AGEs) as compared to the non-treated diabetic group. Our results indicate that treatment of diabetic animals with agmatine restores redox homeostasis and a balances antioxidant defence system enzymes in leukocytes. This corrective effect on the functional capacity of leukocytes is exerted by preventing oxidative-nitrative stress in animals with DM.

Antioxidative Efficacy of a Pistacia Lentiscus Supplement and Its Effect on the Plasma Amino Acid Profile in Inflammatory Bowel Disease: A Randomised, Double-Blind, Placebo-Controlled Trial

Oxidative stress is present in patients with Inflammatory Bowel Disease (IBD), and natural supplements with antioxidant properties have been investigated as a non-pharmacological approach. The objective of the present study was to assess the effects of a natural Pistacia lentiscus (PL) supplement on oxidative stress biomarkers and to characterise the plasma-free amino acid (AA) profiles of patients with active IBD (Crohn's disease (CD) N = 40, ulcerative colitis (UC) N = 20). The activity was determined according to 5 ≤ Harvey Bradshaw Index ≤ 16 or 2 ≤ Partial Mayo Score ≤ 6. This is a randomised, double-blind, placebo-controlled clinical trial. IBD patients (N = 60) were randomly allocated to PL (2.8 g/day) or to placebo for 3 months being under no treatment (N = 21) or under stable medical treatment (mesalamine N = 24, azathioprine N = 14, and corticosteroids N = 23) that was either single medication (N = 22) or combined medication (N = 17). Plasma oxidised, low-density lipoprotein (oxLDL), total serum oxidisability, and serum uric acid were evaluated at baseline and follow-up. OxLDL/LDL and oxLDL/High-Density Lipoprotein (HDL) ratios were calculated. The plasma-free AA profile was determined by applying a gas chromatography/mass spectrometry analysis. oxLDL (p = 0.031), oxLDL/HDL (p = 0.020), and oxLDL/LDL (p = 0.005) decreased significantly in the intervention group. The mean change differed significantly in CD between groups for oxLDL/LDL (p = 0.01), and, in the total sample, both oxLDL/LDL (p = 0.015) and oxLDL/HDL (p = 0.044) differed significantly. Several changes were reported in AA levels. PL ameliorated a decrease in plasma-free AAs seen in patients with UC taking placebo. In conclusion, this intervention resulted in favourable changes in oxidative stress biomarkers in active IBD.

The Consumption of Beef Burgers Prepared with Wine Grape Pomace Flour Improves Fasting Glucose, Plasma Antioxidant Levels, and Oxidative Damage Markers in Humans: A Controlled Trial

Wine grape pomace flour (WGPF) is a fruit byproduct that is high in fiber and antioxidants. We tested whether WGPF consumption could affect blood biochemical parameters, including oxidative stress biomarkers. In a three-month intervention study, 27 male volunteers, each with some components of metabolic syndrome, consumed a beef burger supplemented with 7% WGPF containing 3.5% of fiber and 1.2 mg gallic equivalents (GE)/g of polyphenols (WGPF-burger), daily, during the first month. The volunteers consumed no burgers in the second month, and one control-burger daily in the third month. At baseline and after these periods, we evaluated the metabolic syndrome components, plasma antioxidant status (i.e., 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity (DPPH), vitamin E, vitamin C), and oxidative damage markers (i.e., advanced oxidation protein products (AOPPs), oxidized low-density lipoproteins (oxLDLs), malondialdehyde (MDA)). The WGPF-burger intake significantly reduced glycemia and homeostatic model assessment-based measurement of insulin resistance. Vitamin C increased and decreased during the consumption of the WGPF-burger and control-burger, respectively. The WGPF-burger intake significantly decreased AOPP and oxLDL levels. Vitamin E and MDA levels showed no significant changes. In conclusion, the consumption of beef burgers prepared with WGPF improved fasting glucose and insulin resistance, plasma antioxidant levels, and oxidative damage markers. Therefore, this functional ingredient has potential as a dietary supplement to manage chronic disease risk in humans.

Analysis of Postprandial Glycemia in Relation to Metabolic Compensation and Other Observed Parameters of Outpatients with Type 2 Diabetes Mellitus in the Czech Republic

INTRODUCTION

The goal of the study was to determine the level of metabolic compensation expressed by glycosylated hemoglobin, fasting plasma glucose, and postprandial glucose as determined after a standardized breakfast; further, to evaluate interrelationships between the studied parameters and postprandial glucose levels.

METHODS

The study included 1055 patients with type 2 diabetes mellitus. Their fasting plasma glucose and postprandial glucose were measured before and after a standardized breakfast. Attending diabetologists completed a uniform questionnaire that included demographic data, type of antidiabetic treatment, duration of diabetes, latest glycosylated hemoglobin value, presence of dyslipidemia, and organic complications.

RESULTS

Glycosylated hemoglobin < 53 mmol/mol was achieved in 363 (34.2%), postprandial glucose < 7.5 mmol/l in 211 (19.9%), and fasting plasma glucose < 6 mmol/l in 251 (23.7%) patients. Excellent metabolic compensation, indicated by all the above mentioned glycosylated hemoglobin, fasting plasma glucose, and postprandial glucose values simultaneously, was achieved in only 71 (6.7%) patients. Comparable to fasting plasma glucose and postprandial glucose values, correlation with glycosylated hemoglobin levels is statistically significant; however, there is no difference at different glycosylated hemoglobin levels. There was a significant correlation between dyslipidemia and postprandial glycemia (p = 0.013).

CONCLUSION

The objective of care for patients with diabetes mellitus is to improve their long-term metabolic compensation; to that end, both fasting plasma glucose and postprandial glucose deserve equal attention.

Early-Life Persistent Vitamin D Deficiency Alters Cardiopulmonary Responses to Particulate Matter-Enhanced Atmospheric Smog in Adult Mice

Early life nutritional deficiencies can lead to increased cardiovascular susceptibility to environmental exposures. Thus, the purpose of this study was to examine the effect of early life persistent vitamin D deficiency (VDD) on the cardiopulmonary response to a particulate matter-enhanced photochemical smog. Mice were fed a VDD or normal diet (ND) after weaning. At 17 weeks of age, mice were implanted with radiotelemeters to monitor electrocardiogram, heart rate (HR), and heart rate variability (HRV). Ventilatory function was measured throughout the diet before and after smog exposure using whole-body plethysmography. VDD mice had lower HR, increased HRV, and decreased tidal volume compared with ND. Regardless of diet, HR decreased during air exposure; this response was blunted by smog in ND mice and to a lesser degree in VDD. When compared with ND, VDD increased HRV during air exposure and more so with smog. However, smog only increased cardiac arrhythmias in ND mice. This study demonstrates that VDD alters the cardiopulmonary response to smog, highlighting the possible influence of nutritional factors in determining responses to air pollution. The mechanism of how VDD induces these effects is currently unknown, but modifiable factors should be considered when performing risk assessment of complex air pollution atmospheres.

Adiponectin: possible link between metabolic stress and oxidative stress in the elderly

OBJECTIVE

The aim of this study was to evaluate the relationships between the serum levels of adiponectin and systemic oxidative stress exerted on lipids, proteins, as well as endothelial function and cardiovascular diseases (CVD) risk markers, in elderly subjects with metabolic syndrome (MS).

METHODS

The serum advanced glycation and oxidation protein products, low-density lipoprotein susceptibility to oxidation (oxLDL), nitric oxide metabolic pathway products (NOx), serum lipid peroxidation, as well as total antioxidant/oxidative capacity (TAC/TOC), were analyzed in elderly subjects with MS (n = 44), compared to aged-matched control (n = 39).

RESULTS

We pointed out significantly lower levels of adiponectin in elderly MS subjects concomitantly with significantly higher levels of oxidative stress and CVD risk markers. Significant positive correlations were found between serum adiponectin levels and HDL-cholesterol (p < 0.05) and the total cholesterol/LDL-cholesterol ratio (p < 0.01). Additionally, adiponectin levels were significantly inversely associated with insulin resistance index (HOMA-IR, r = -0.348; p < 0.05) and serum lipid peroxidation (r = -0.337; p < 0.05), and significantly positively with the antioxidant capacity (TAC, r = 0.339; p < 0.05). Conversely, adiponectin levels were significantly negatively (r = -0.310; p < 0.05) associated with serum uric acid concentration.

CONCLUSIONS

The major protective role of adiponectin versus stress related to an impaired glucose and lipid metabolism suggests that adiponectin plays a critical role in adiposity-related metabolic stress and redox homeostasis.

Advanced oxidation protein products promote NADPH oxidase-dependent β-cell destruction and dysfunction through the Bcl-2/Bax apoptotic pathway

The accumulation of plasma advanced oxidation protein products (AOPPs) has been linked with diverse disorders, including diabetes, chronic kidney disease, obesity, and metabolic syndrome. The aim of the present study was to evaluate the pathophysiological relevance of AOPPs in β-cell destruction and dysfunction. Exposure of cultured rat β-cells (INS-1) to AOPPs induced an increase in Bax expression, caspase-3 activity, and apoptosis as well as a decrease in Bcl-2 expression in a dose- and time-dependent manner. AOPP challenge rapidly increased the production of intracellular superoxide by activation of NADPH oxidases, demonstrated by p47^phox translocation and interaction with p22^phox and gp91^phox, and this in turn led to apoptosis. AOPPs treatment resulted in β-cell apoptosis, AOPPs accumulation, and decreased insulin content in pancreas and plasma in unilateral nephrectomized rats. Chronic inhibition of NADPH oxidase by apocynin prevented β-cell apoptosis and ameliorated insulin deficiency in AOPP-challenged rats. This study demonstrates for the first time that accumulation of AOPPs promotes NADPH oxidase-dependent β-cell destruction and dysfunction by the Bcl-2/Bax-caspase apoptotic pathway. This finding may provide a mechanistic explanation for β-cell destruction and dysfunction in patients with diverse disorders.

Coefficient of Friction at the Fingertips in Type II Diabetics Compared to Healthy Adults

Clinical observations suggest that type II diabetes patients are more susceptible to skin changes, which may be associated with reduced coefficient of friction at the fingertips. Reduced coefficient of friction may explain recent reports of fine motor dysfunction in diabetic patients. Coefficient of friction was evaluated using slip force evaluation in a cross-sectional cohort of diabetic patients and age- and sex-matched healthy controls. Covariates of tactile sensation, disease duration, glycated hemoglobin, and clinical diagnosis of peripheral neuropathy were also assessed. A significant decrease in fingertip coefficient of friction in the diabetic group was found as compared to controls. Health state covariates did not alter the strength of between-group differences in statistical analyses. This finding of between-group differences for fingertip frictional properties suggests that causative factors of reported manual motor dysfunction lie in both the distal and proximal portions of the nervous system.

Molecular mechanisms of ROS production and oxidative stress in diabetes

Oxidative stress and chronic inflammation are known to be associated with the development of metabolic diseases, including diabetes. Oxidative stress, an imbalance between oxidative and antioxidative systems of cells and tissues, is a result of over production of oxidative-free radicals and associated reactive oxygen species (ROS). One outcome of excessive levels of ROS is the modification of the structure and function of cellular proteins and lipids, leading to cellular dysfunction including impaired energy metabolism, altered cell signalling and cell cycle control, impaired cell transport mechanisms and overall dysfunctional biological activity, immune activation and inflammation. Nutritional stress, such as that caused by excess high-fat and/or carbohydrate diets, promotes oxidative stress as evident by increased lipid peroxidation products, protein carbonylation and decreased antioxidant status. In obesity, chronic oxidative stress and associated inflammation are the underlying factors that lead to the development of pathologies such as insulin resistance, dysregulated pathways of metabolism, diabetes and cardiovascular disease through impaired signalling and metabolism resulting in dysfunction to insulin secretion, insulin action and immune responses. However, exercise may counter excessive levels of oxidative stress and thus improve metabolic and inflammatory outcomes. In the present article, we review the cellular and molecular origins and significance of ROS production, the molecular targets and responses describing how oxidative stress affects cell function including mechanisms of insulin secretion and action, from the point of view of possible application of novel diabetic therapies based on redox regulation.

Plasma Markers of Oxidative Stress in Patients with Gestational Diabetes Mellitus in the Second and Third Trimester

Objective. To determine plasma markers of oxidative stress during the second and third trimester of pregnancy in patients with gestational diabetes mellitus (GDM). Study Design. We conducted a prospective nested case-control study involving 400 pregnant women, 22 of whom developed GDM. As control group, 30 normal pregnant women were chosen randomly. Plasma samples were analyzed for 8-iso-prostaglandin F2α (8-iso-PGF2α), advanced oxidative protein products (AOPPs), protein carbonyl (PCO), glutathione peroxidase-3 (GPX-3), and paraoxonase-1 (PON1) at 16–20 weeks, 24–28 weeks, and 32–36 weeks of gestation. Results. Compared to control subjects, the plasma levels of PCO, AOPPs, and 8-iso-PGF2α were elevated at 16–20 weeks' and 32–36 weeks' gestation in GDM. There was no significant difference in PCO and 8-iso-PGF2α at 24–28 weeks in GDM. GPX-3 was statistically significantly increased at 16–20 weeks and 32–36 weeks in GDM. PON1 reduced in patients with GDM. No significant differences were found at 24–28 and 32–36 weeks between the GDM and control groups. In GDM, PCO, AOPPs, and 8-iso-PGF2α levels were higher and GPX-3 and PON1 levels were lower in the second than the third trimester. Conclusion. Oxidation status increased in GDM, especially protein oxidation, which may contribute to the pathogenesis of GDM.

Glucagon-like peptide-1 attenuates advanced oxidation protein product-mediated damage in islet microvascular endothelial cells partly through the RAGE pathway

Advanced oxidation protein products (AOPPs) are knownt to play a role in the pathogenesis of diseases and related complications. However, whether AOPPs affect the survival of islet microvascular endothelial cells (IMECs) has not been reported to date, at least to the best of our knowledge. In this study, we aimed to investigate the mechanisms underlying AOPP-mediated damage in IMECs and the protective role of glucagon-like peptide-1 (GLP-1), which has been suggested to exert beneficial effects on the cardiovascular system. IMECs were treated with AOPPs (0-200 µg/ml) for 0-72 h in the presence or absence of GLP-1 (100 nmol/l). Apoptosis, cell viability and reactive oxygen species (ROS) production were examined, the expression levels of p53, Bax, receptor for advanced glycation end-products (RAGE) and NAD(P)H oxidase subunit were determined, and the activity of NAD(P)H oxidase, caspase-9 and caspase-3 was also determined. The results revealed that AOPPs increased the expression of RAGE, p47phox and p22phox; induced NAD(P)H oxidase-dependent ROS generation, increased p53 and Bax expression, enhanced the activity of caspase-9 and caspase-3, and induced cell apoptosis. Treatment with GLP-1 decreased the expression of RAGE, inhibited NAD(P)H oxidase activity, decreased cell apoptosis and increased cell viability. On the whole, our findings indicate that AOPPs induce the apoptosis of IMECs via the RAGE-NAD(P)H oxidase-dependent pathway and that treatment with GLP-1 effectively reverses these detrimental effects by decreasing AOPP-induced RAGE expression and restoring the redox balance. Our data may indicate that GLP-1 may prove to be beneficial in attenuating the progression of diabetes mellitus.

Analysis of Hemoglobin Glycation Using Microfluidic CE-MS: A Rapid, Mass Spectrometry Compatible Method for Assessing Diabetes Management

Diabetes has become a significant health problem worldwide with the rate of diagnosis increasing rapidly in recent years. Measurement of glycated blood proteins, particularly glycated hemoglobin (HbA1c), is an important diagnostic tool used to detect and manage the condition in patients. Described here is a method using microfluidic capillary electrophoresis with mass spectrometry detection (CE-MS) to assess hemoglobin glycation in whole blood lysate. Using denaturing conditions, the hemoglobin (Hb) tetramer dissociates into the alpha and beta subunits (α- and β-Hb), which are then separated via CE directly coupled to MS detection. Nearly baseline resolution is achieved between α-Hb, β-Hb, and glycated β-Hb. A second glycated β-Hb isomer that is partially resolved from β-Hb is detected in extracted ion electropherograms for glycated β-Hb. Glycation on α-Hb is also detected in the α-Hb mass spectrum. Additional modifications to the β-Hb are detected, including acetylation and a +57 Da species that could be the addition of a glyoxal moiety. Patient blood samples were analyzed using the microfluidic CE-MS method and a clinically used immunoassay to measure HbA1c. The percentage of glycated α-Hb and β-Hb was calculated from the microfluidic CE-MS data using peak areas generated from extracted ion electropherograms. The values for glycated β-Hb were found to correlate well with the HbA1c levels derived in the clinic, giving a slope of 1.20 and an R(2) value of 0.99 on a correlation plot. Glycation of human serum albumin (HSA) can also be measured using this technique. It was observed that patients with elevated glycated Hb levels also had higher levels of HSA glycation. Interestingly, the sample with the highest HbA1c levels did not have the highest levels of glycated HSA. Because the lifetime of HSA is shorter than Hb, this could indicate a recent lapse in glycemic control for that patient. The ability to assess both Hb and HSA glycation has the potential to provide a more complete picture of a patient's glycemic control in the months leading up to blood collection. The results presented here demonstrate that the microfluidic CE-MS method is capable of rapidly assessing Hb and HSA glycation from low volumes of whole blood with minimal sample preparation and has the potential to provide more information in a single analysis step than current technologies.

Aging-associated oxidized albumin promotes cellular senescence and endothelial damage

Increased levels of oxidized proteins with aging have been considered a cardiovascular risk factor. However, it is unclear whether oxidized albumin, which is the most abundant serum protein, induces endothelial damage. The results of this study indicated that with aging processes, the levels of oxidized proteins as well as endothelial microparticles release increased, a novel marker of endothelial damage. Among these, oxidized albumin seems to play a principal role. Through in vitro studies, endothelial cells cultured with oxidized albumin exhibited an increment of endothelial damage markers such as adhesion molecules and apoptosis levels. In addition, albumin oxidation increased the amount of endothelial microparticles that were released. Moreover, endothelial cells with increased oxidative stress undergo senescence. In addition, endothelial cells cultured with oxidized albumin shown a reduction in endothelial cell migration measured by wound healing. As a result, we provide the first evidence that oxidized albumin induces endothelial injury which then contributes to the increase of cardiovascular disease in the elderly subjects.

Molecular biomarkers of oxidative stress and role of dietary factors in gasoline station attendants

Exposure to benzene promotes oxidative stress through the production of ROS, which can damage biological structures with the formation of new metabolites which can be used as markers of oxidant/antioxidant imbalance. This study aims to assess modifications in circulating levels of advanced oxidation protein products (AOPP), advanced glycation end-products (AGE) and serum reactive oxygen metabolites (ROMs) in a group of gasoline station attendants exposed to low-dose benzene and to evaluate the influence of antioxidant food intake on these biomarkers of oxidative stress. The diet adopted by the population examined consisted of compounds belonging to the classes of terpenoids, stilbenes and flavonoids, notably resveratrol, lycopene and apigenin. Ninety one gasoline station attendants occupationally exposed to benzene and 63 unexposed male office workers were recruited for this study. Urinary trans, trans-muconic acid (t,t-MA) concentration, determined to assess individual exposure level, resulted significantly higher in exposed workers. In subjects exposed to benzene, we observed a significant increase (p < 0.001) in ROMs and AOPP levels, which were also negatively correlated with fruit and vegetables consumption. By contrast, AGE did not show a significant increase and consequently any relation with antioxidant food intake. Only ROMs, representing a global biomarker of oxidative status, resulted correlated to t,t-MA levels (p < 0.01), probably due to low-dose exposure. Increase of ROS induced by reactive benzene metabolites may promote specific biochemical pathways with a major production of AOPP, which seem to represent a more sensitive biochemical marker of oxidative stress in workers exposed to benzene compared to AGE. Furthermore, this is the first study demonstrating ROMs increment in subject exposed to benzene. These biomarkers may be useful for screening purposes in gasoline station workers and other subjects exposed to low-dose benzene. Moreover, a diet rich in fruits and vegetables demonstrated an inverse association with the levels of oxidative stress markers, suggesting a protective role of antioxidant food intake in workers exposed to oxidant agents.

Hypochlorite-Modified Albumin Upregulates ICAM-1 Expression via a MAPK-NF-κB Signaling Cascade: Protective Effects of Apocynin

Hypochlorite-modified albumin (HOCl-alb) has been linked to endothelial dysfunction, which plays an important role in the development of hypertension, diabetes, and chronic kidney disease. However, whether HOCl-alb induces endothelial dysfunction via vascular inflammation and whether a signaling pathway is involved are unknown and have not been investigated. HOCl-alb was found to upregulate ICAM-1 expression in human umbilical vein endothelial cells (HUVECs) in a time- and dose-dependent manner. HOCl-alb time-dependently phosphorylated ERK1/2 and p38(MAPK). HOCl-alb also activated NF-κB. ICAM-1 expression was dose-dependently inhibited by U0126 (a specific inhibitor of MEK1/2, a signal upstream from ERK1/2), SB203580 (a specific inhibitor of p38(MAPK)), and SN50 (a specific inhibitor of NF-κB). U0126 and SB203580 both counteracted the activation of NF-κB, whereas the phosphorylation of ERK1/2 and p38(MAPK) was not blocked by SN50. ERK1/2 phosphorylation was blocked by U0126 but not by SB203580, and p38(MAPK) activity was reduced by SB203580 but not by U0126. Apocynin, a specific NADPH oxidase (NOX) inhibitor, inhibited ICAM-1 expression and the activity of ERK1/2, p38(MAPK), and NF-κB. These results indicate that HOCl-alb-induced ICAM-1 expression is caused by the activation of a redox-sensitive intracellular signal cascade involving ERK1/2 and p38(MAPK), culminating in the activation of NF-κB and involving NOXs among the upstream signals.

Using Serum Advanced Glycation End Products-Peptides to Improve the Efficacy of World Health Organization Fasting Plasma Glucose Criterion in Screening for Diabetes in High-Risk Chinese Subjects

The efficacy of using fasting plasma glucose (FPG) alone as a preferred screening test for diabetes has been questioned. This study was aimed to evaluate whether the use of serum advanced glycation end products-peptides (sAGEP) would help to improve the efficacy of FPG in diabetes screening among high-risk Chinese subjects with FPG <7.0 mmol/L. FPG, 2-h plasma glucose (2h-PG), serum glycated haemoglobin A1c (HbA1c), and sAGEP were measured in 857 Chinese subjects with risk factors for diabetes. The areas under receiver operating characteristic (ROC) curves generated by logistic regression models were assessed and compared to find the best model for diabetes screening in subjects with FPG <7.0 mmol/L. The optimal critical line was determined by maximizing the sum of sensitivity and specificity. Among the enrolled subjects, 730 of them had FPG <7.0 mmol/L, and only 41.7% new diabetes cases were identified using the 1999 World Health Organization FPG criterion (FPG ≥7.0 mmol/L). The area under ROC curves generated by the model on FPG-sAGEP was the largest compared with that on FPG-HbA1c, sAGEP, HbA1c or FPG in subjects with FPG <7.0 mmol/L. By maximizing the sum of sensitivity and specificity, the optimal critical line was determined as 0.69×FPG + 0.14×sAGEP = 7.03, giving a critical sensitivity of 91.2% in detecting 2h-PG ≥11.1 mmol/L, which was significantly higher than that of FPG-HbA1c or HbA1c. The model on FPG-sAGEP improves the efficacy of using FPG alone in detecting diabetes among high-risk Chinese subjects with FPG <7.0 mmol/L, and is worth being promoted for future diabetes screening.

A review of potential metabolic etiologies of the observed association between red meat consumption and development of type 2 diabetes mellitus

Epidemiological studies suggest that red and processed meat consumption is related to an increased risk of type 2 diabetes. However, it is not clearly understood which components of red and processed meat contribute to this increased risk. This review examines potential mechanisms addressing the role of saturated fatty acid, sodium, advanced glycation end products (AGEs), nitrates/nitrites, heme iron, trimethylamine N-oxide (TMAO), branched amino acids (BCAAs) and endocrine disruptor chemicals (EDCs) in the development of type 2 diabetes based on data from published clinical trials and animal models. TMAO which is derived from dietary carnitine and choline by the action of bacterial enzymes followed by oxidation in the liver may be a strong candidate molecule mediating the risk of type 2 diabetes. BCAAs may induce insulin resistance via the mammalian target of rapamycin complex 1 (mTORC1) and ribosomal protein S6 kinase β 1 (S6k1)-associated pathways. The increased risk associated with processed meat compared with red meat suggests that there are interactions between the saturated fat, salt, and nitrates in processed meat and iron, AGEs and TMAO. Intervention studies are required to clarify potential mechanisms and explore interactions among components, in order to make firm recommendations on red and processed meat consumption.

Advanced glycation end-products: modifiable environmental factors profoundly mediate insulin resistance

Advanced glycation end-products are toxic by-products of metabolism and are also acquired from high-temperature processed foods. They promote oxidative damage to proteins, lipids and nucleotides. Aging and chronic diseases are strongly associated with markers for oxidative stress, especially advanced glycation end-products, and resistance to peripheral insulin-mediated glucose uptake. Modifiable environmental factors including high levels of refined and simple carbohydrate diets, hypercaloric diets and sedentary lifestyles drive endogenous formation of advanced glycation end-products via accumulation of highly reactive glycolysis intermediates and activation of the polyol/aldose reductase pathway producing high intracellular fructose. High advanced glycation end-products overwhelm innate defenses of enzymes and receptor-mediated endocytosis and promote cell damage via the pro-inflammatory and pro-oxidant receptor for advanced glycation end-products. Oxidative stress disturbs cell signal transduction, especially insulin-mediated metabolic responses. Here we review emerging evidence that restriction of dietary advanced glycation end-products significantly reduces total systemic load and insulin resistance in animals and humans in diabetes, polycystic ovary syndrome, healthy populations and dementia. Of clinical importance, this insulin sensitizing effect is independent of physical activity, caloric intake and adiposity level.

Are reactive oxygen species still the basis for diabetic complications?

Despite the wealth of pre-clinical support for a role for reactive oxygen and nitrogen species (ROS/RNS) in the aetiology of diabetic complications, enthusiasm for antioxidant therapeutic approaches has been dampened by less favourable outcomes in large clinical trials. This has necessitated a re-evaluation of pre-clinical evidence and a more rational approach to antioxidant therapy. The present review considers current evidence, from both pre-clinical and clinical studies, to address the benefits of antioxidant therapy. The main focus of the present review is on the effects of direct targeting of ROS-producing enzymes, the bolstering of antioxidant defences and mechanisms to improve nitric oxide availability. Current evidence suggests that a more nuanced approach to antioxidant therapy is more likely to yield positive reductions in end-organ injury, with considerations required for the types of ROS/RNS involved, the timing and dosage of antioxidant therapy, and the selective targeting of cell populations. This is likely to influence future strategies to lessen the burden of diabetic complications such as diabetes-associated atherosclerosis, diabetic nephropathy and diabetic retinopathy.

Oxidized LDL and NO synthesis--Biomarkers of endothelial dysfunction and ageing

Oxidized LDL (oxLDL) and nitric oxide (NO) exert contradictory actions within the vascular endothelium microenvironment influencing key events in atherogenesis. OxLDL and NO are so far regarded as representative parameters of oxidative stress and endothelial dysfunction, new targets in prevention, diagnosis and therapy of cardiovascular diseases, and also as candidate biomarkers in evaluating the human biological age. The aim of this review is to explore recent literature on molecular mechanisms and pathophysiological relationships between LDL oxidation, NO synthesis and vascular endothelium function/dysfunction in ageing, focusing on the following aspects: (1) the impact of metabolic status on both LDL oxidation and NO synthesis in relation with oxidative stress, (2) the use of oxidized LDL and NO activity as biomarkers in human studies reporting on cardiovascular outcomes, and (3) evidences supporting the importance of oxidized LDL and NO activity as relevant biomarkers in vascular ageing and age-related diseases.

Natural products and the aging process

Abstract Literature surveys show that the most of the research that have been conducted on the effect of herbal remedies on many tissue pathologies, including metabolic disturbances, cardiovascular decline, neurodegeneration, cataract, diabetic retinopathy and skin inflammation, all lead to an accelerated aging process. The increased carbonylation of proteins (carbonyl stress) disturbing their function has been indicated as an underlying mechanism of cellular senescence and age-related diseases. Because it is also linked to the carbonyl stress, aging chronic disease and inflammation plays an important role in understanding the clinical implications of cellular stress response and relevant markers. Greater knowledge of the molecular and cellular mechanisms involved in several pathologies associated with aging would provide a better understanding to help us to develop suitable strategies, use specific targets to mitigate the effect of human aging, prevent particularly chronic degenerative diseases and improve quality of life. However, research is lacking on the herbal compounds affecting cellular aging signaling as well as studies regarding the action mechanism(s) of natural products in prevention of the age-related disease. This review provides leads for identifying new medicinal agents or potential phytochemical drugs from plant sources for the prevention or delaying cellular aging processes and the treatment of some disorders related with accelerated body aging.

Acute exercise increases resistance to oxidative stress in young but not older adults

A single bout of acute exercise increases oxidative stress and stimulates a transient increase in antioxidant enzymes. We asked whether this response would induce protection from a subsequent oxidative challenge, different from that of exercise, and whether the effects were affected by aging. We compared young (20 ± 1 years, n = 8) and older (58 ± 6 years, n = 9) healthy men and women. Resistance to oxidative stress was measured by the F2-isoprostane response to forearm ischemia/reperfusion (I/R) trial. Each participant underwent the I/R trial twice, in random order; once after performing 45 min of cycling on the preceding day (IRX) and a control trial without any physical activity (IRC). Baseline F2-isoprostane levels were significantly lower at IRX compared to IRC (P < 0.05) and not different between groups. F2-isoprostane response to IRX was significantly lower compared to IRC in young (P < 0.05) but not different in the older group. Superoxide dismutase activity in response to acute exercise was significantly higher in young compared to older adults (P < 0.05). These data suggest that signal transduction of acute exercise may be impaired with aging. Repeated bouts of transient reactive oxygen species production as seen with regular exercise may be needed to increase resistance to oxidative stress in older individuals.

Elevated risk of type 2 diabetes for development of Alzheimer disease: a key role for oxidative stress in brain

Alzheimer disease (AD) is the most common form of dementia among the elderly and is characterized by progressive loss of memory and cognition. Epidemiological data show that the incidence of AD increases with age and doubles every 5 years after 65 years of age. From a neuropathological point of view, amyloid-β-peptide (Aβ) leads to senile plaques, which, together with hyperphosphorylated tau-based neurofibrillary tangles and synapse loss, are the principal pathological hallmarks of AD. Aβ is associated with the formation of reactive oxygen (ROS) and nitrogen (RNS) species, and induces calcium-dependent excitotoxicity, impairment of cellular respiration, and alteration of synaptic functions associated with learning and memory. Oxidative stress was found to be associated with type 2 diabetes mellitus (T2DM), which (i) represents another prevalent disease associated with obesity and often aging, and (ii) is considered to be a risk factor for AD development. T2DM is characterized by high blood glucose levels resulting from increased hepatic glucose production, impaired insulin production and peripheral insulin resistance, which close resemble to the brain insulin resistance observed in AD patients. Furthermore, growing evidence suggests that oxidative stress plays a pivotal role in the development of insulin resistance and vice versa. This review article provides molecular aspects and the pharmacological approaches from both preclinical and clinical data interpreted from the point of view of oxidative stress with the aim of highlighting progresses in this field.

Symplocos cochinchinensis attenuates streptozotocin-diabetes induced pathophysiological alterations of liver, kidney, pancreas and eye lens in rats

The beneficial effects of hydroethanol extract of Symplocos cochinchinensis (SCE) has been explored against hyperglycemia associated secondary complications in streptozotocin induced diabetic rat model. The experimental groups consist of normal control (NC), diabetic control (DC), DC + metformin 100 mg kg(-1) bwd, DC + SCE 250 and DC + SCE 500. SCEs and metformin were administered daily for 21 days and sacrificed on day 22. Oral glucose tolerance test, plasma insulin, % HbA1c, urea, creatinine, aspartate aminotransferase, alanine aminotransferase, albumin, total protein etc. were analysed. Aldose reductase (AR) activity in the eye lens was also checked. On day 21, DC rats showed significantly abnormal glucose response, HOMA-IR, % HbA1c, decreased activity of antioxidant enzymes and GSH, elevated AR activity, hepatic and renal oxidative stress markers like malondialdehyde, protein carbonyls compared to NC. DC rats also exhibited increased level of plasma urea and creatinine. Treatment with SCE protected from the deleterious alterations of biochemical parameters in a dose dependent manner including histopathological alterations in pancreas. SCE 500 exhibited 46.28% of glucose lowering effect and decreased HOMA-IR (2.47), % HbA1c (6.61), lens AR activity (15.99%), and hepatic, renal oxidative stress and function markers compared to DC group. Considerable amount of liver and muscle glycogen was replenished by SCE treatment in diabetic animals. Although metformin showed better effect, the activity of SCE was very much comparable with this drug.

Role of lipid peroxidation products, plasma total antioxidant status, and Cu-, Zn-superoxide dismutase activity as biomarkers of oxidative stress in elderly prediabetics

The relationship between hyperglycemia and oxidative stress in diabetes is well known, but the influence of metabolic disturbances recognized as prediabetes, in elderly patients especially, awaits for an explanation. Methods. 52 elderly persons (65 years old and older) with no acute or severe chronic disorders were assessed: waist circumference (WC), body mass index (BMI), percentage of body fat (FAT), and arterial blood pressure. During an oral glucose tolerance test (OGTT) fasting (0′) and 120-minute (120′) glycemia and insulinemia were determined, and type 2 diabetics (n = 6) were excluded. Subjects were tested for glycated hemoglobin HbA1c, plasma lipids, total antioxidant status (TAS), thiobarbituric acid-reacting substances (TBARS), and activity of erythrocyte superoxide dismutase (SOD-1). According to OGTT results, patients were classified as normoglycemics, (NGT, n = 18) and prediabetics, (PRE, n = 28). Results. Both groups did not differ with their lipids, FAT, and TBARS. PRE group had higher WC (P < 0.002) and BMI (P < 0.002). Lower SOD-1 activity (P < 0.04) and TAS status (P < 0.04) were found in PRE versus NGT group. Significance. In elderly prediabetics, SOD-1 and TAS seem to reflect the first symptoms of oxidative stress, while TBARS are later biomarkers of oxidative stress.

Neuroprotective effect of ginger in the brain of streptozotocin-induced diabetic rats

Diabetes mellitus results in neuronal damage caused by increased intracellular glucose leading to oxidative stress. Recent evidence revealed the potential of ginger for reducing diabetes-induced oxidative stress markers. The aim of this study is to investigate, for the first time, whether the antioxidant properties of ginger has beneficial effects on the structural brain damage associated with diabetes. We investigated the observable neurodegenerative changes in the frontal cortex, dentate gyrus, and cerebellum after 4, 6, and 8 weeks of streptozotocin (STZ)-induced diabetes in rats and the effect(s) of ginger (500 mg/kg/day). Sections of frontal cortex, dentate gyrus, and cerebellum were stained with hematoxylin and eosin and examined using light microscopy. In addition, quantitative immunohistochemical assessments of the expression of inducible NO synthase (iNOS), tumor necrosis factor (TNF)-α, caspase-3, glial fibrillary acidic protein (GFAP), acetylcholinesterase (AChE), and Ki67 were performed. Our results revealed a protective role of ginger on the diabetic brain via reducing oxidative stress, apoptosis, and inflammation. In addition, this study revealed that the beneficial effect of ginger was also mediated by modulating the astroglial response to the injury, reducing AChE expression, and improving neurogenesis. These results represent a new insight into the beneficial effects of ginger on the structural alterations of diabetic brain and suggest that ginger might be a potential therapeutic strategy for the treatment of diabetic-induced damage in brain.

Effect of the herbal combination Canephron N on diabetic nephropathy in patients with diabetes mellitus: results of a comparative cohort study

OBJECTIVES

Diabetic nephropathy (DN) is a serious and common complication of diabetes mellitus leading to end-stage renal disease in up to 30% of diabetic patients. The first manifestation of DN in humans is microalbuminuria, which arises from the increased passage of albumin through the glomerular filtration barrier. Reactive oxygen species, inflammatory cytokines, and growth factors are key players in the context of damage to the glomerular filtration barrier.

INTERVENTIONS

In this study the herbal combination Canephron(®) N, containing lovage root, rosemary leaves, and centaury herb, was administered to patients with DN to study the effects on microalbuminuria and overall oxidant/antioxidant status. An open study involving 59 patients with DN was performed to compare the effects of Canephron N administered concomitantly with standard antidiabetic therapy and an angiotensin-converting enzyme (ACE) inhibitor, with the standard therapy and ACE inhibitor treatment alone.

RESULTS

After 6 months of therapy the level of microalbuminuria decreased significantly in the study group compared with the control group. Canephron N had a positive effect on the antioxidant defense status and lipid peroxidation levels. In addition, liver aminotransferase levels did not change.

CONCLUSIONS

With respect to the excellent tolerability, the study results encourage use of the herbal combination as an add-on therapy in patients with DN.

NAD(P)H oxidase isoforms as therapeutic targets for diabetic complications

The development of macro- and microvascular complications is accelerated in diabetic patients. While some therapeutic regimes have helped in delaying progression of complications, none have yet been able to halt the progression and prevent vascular disease, highlighting the need to identify new therapeutic targets. Increased oxidative stress derived from the NADPH oxidase (Nox) family has recently been identified to play an important role in the pathophysiology of vascular disease. In recent years, specific Nox isoforms have been implicated in contributing to the development of atherosclerosis of major vessels, as well as damage of the small vessels within the kidney and the eye. With the use of novel Nox inhibitors, it has been demonstrated that these complications can be attenuated, indicating that targeting Nox derived oxidative stress holds potential as a new therapeutic strategy.

Monitoring of glycation, oxidative stress and inflammation in relation to the occurrence of vascular complications in patients with type 2 diabetes mellitus

The study aimed to evaluate if the monitoring of advanced glycation end products (AGEs), advanced oxidation protein products (AOPP), lipoperoxides (LPO) and interleukin-6 (IL-6) in plasma could help to predict development of diabetic complications (DC). Clinical and biochemical parameters including AGEs, AOPP, LPO and IL-6 were investigated in patients with type 2 diabetes mellitus (DM2) with (+DC) and without (-DC) complications. AGEs were significantly higher in both diabetic groups compared to controls. AGEs were also significantly higher in group +DC compared to -DC. AGEs significantly correlated with HbA1c. We observed significantly higher AOPP in both diabetic groups in comparison with controls, but the difference between -DC and +DC was not significant. LPO significantly correlated with BMI. IL-6 were significantly increased in both diabetic groups compared to controls, but the difference between -DC and +DC was not significant. There was no significant correlation between IL-6 and clinical and biochemical parameters. These results do not exclude the association between IL-6 and onset of DC. We suggest that the measurement of not only HbA1c, but also AGEs may be useful to predict the risk of DC development in clinical practice. Furthermore, the measurement of IL-6 should be studied as adjunct to HbA1c monitoring.

Markers of Oxidative Stress during Diabetes Mellitus

The prevalence of diabetes mellitus is rising all over the world. Uncontrolled state of hyperglycemia due to defects in insulin secretion/action leads to a variety of complications including peripheral vascular diseases, nephropathy, neuropathy, retinopathy, morbidity, and/or mortality. Large body of evidence suggests major role of reactive oxygen species/oxidative stress in development and progression of diabetic complications. In the present paper, we have discussed the recent researches on the biomarkers of oxidative stress during type 2 diabetes mellitus.