Oxidative stress in diabetes: implications for vascular and other complications

Improving effect of combined inorganic nitrate and nitric oxide synthase inhibitor on pancreatic oxidative stress and impaired insulin secretion in streptozotocin induced-diabetic rats

Purpose

The aim of this study was to evaluate the effect of dietary nitrate on secretory function of pancreatic islet and oxidative stress status in streptozotocin (STZ) induced type 1 diabetes in absence or presence of nitric oxide synthase inhibitor (L-NAME).

Methods

Fifty adult male sprague-dawly rats were divided into 5 groups: controls (C), diabetes (D), diabetes+nitrate (DN), diabetes +L-NAME (D + Ln), and diabetes+nitrate+L-NAME (DN + Ln) for 45 days. The concentrations of sodium nitrate and L-NAME were respectively 80 mg/L in drinking water and 5 mg/kg intraperitoneally. Body weight gain, plasma levels of glucose and insulin, islet insulin secretion and content, lipid peroxidation and antioxidant status in the pancreas of rats were determined.

Results

Compared to control group, the body weight gain and plasma insulin level were significantly decreased and plasma glucose and pancreatic NO and MDA concentrations and antioxidant enzymes activities were significantly increased in the STZ diabetic rats. In the diabetic rats, nitrate alone significantly reduced plasma glucose and increased pancreatic SOD and GPx activity. Reduced plasma glucose, pancreatic MDA and NO concentrations and increased plasma insulin level and pancreatic islet insulin secretion were observed in D + Ln and DN + Ln groups. Antioxidant enzymes activities were increased in diabetic rats which received combination of nitrate and L-NAME.

Conclusions

Our results showed that nitrate without effect on pancreatic islet insulin content and secretion decreased the blood glucose and slightly moderate oxidative stress and its effects in the presence of L-NAME on glucose hemostasis and pancreatic insulin secretion higher than those of nitrate alone.

Prefrontal cortex brain damage and glycemic control in patients with type 2 diabetes

BACKGROUND

This study examined brain tissue integrity in sites that controls cognition (prefrontal cortices; PFC) and its relationships to glycemic outcomes in adults with type 2 diabetes mellitus (T2DM).

METHODS

We examined 28 T2DM patients (median age 57.1 years; median body mass index [BMI] 30.6 kg/m2 ;11 males) and 47 healthy controls (median age 55.0 years; median BMI 25.8 kg/m2 ; 29 males) for cognition (Montreal Cognitive Assessment [MoCA]), glycemic control (hemoglobin A1c [HbA1c]), and PFC tissue status via brain magnetic resonance imaging (MRI). High-resolution T1-weighted images were collected using a 3.0-Tesla MRI scanner, and PFC tissue changes (tissue density) were examined with voxel-based morphometry procedures.

RESULTS

Reduced PFC density values were observed in T2DM patients compared to controls (left, 0.41 ± 0.02 mm3 /voxel vs 0.44 ± 0.02 mm3 /voxel, P < 0.001; right, 0.41 ± 0.03 mm3 /voxel vs 0.45 ± 0.02 mm3 /voxel, P < 0.001). PFC density values were positively correlated with cognition; left PFC region (r = 0.53, P = 0.005) and right PFC region (r = 0.56, P = 0.003), with age and sex as covariates. Significant negative correlations were found between PFC densities and HbA1c values; left PFC region (r = -0.39, P = 0.049) and right PFC region (r = -0.48, P = 0.01), with age and sex as covariates.

CONCLUSIONS

T2DM patients showed PFC brain tissue damage, which is associated with cognitive deficits and poor glycemic control. Further research is needed to identify causal relationships between HbA1c, cognition, and brain changes in T2DM and to evaluate the impact of interventions to prevent brain tissue injury or neuroregeneration in this high-risk patient population, to eventually preserve or enhance cognition and improve glucose outcomes.

Factors associated with oxidative stress status in pediatric patients with type 1 diabetes mellitus

Background Oxidative stress is implicated in both, the onset and the progression of type 1 diabetes mellitus (T1DM). There is accumulated evidence of increased biomarkers of oxidative stress in newly diagnosed, T1DM patients without complications, and in those with advanced disease. In this cross-sectional study, we investigated factors affecting oxidative stress status in pediatric patients with T1DM. Methods Advanced oxidation protein products (AOPP), prooxidant-antioxidant balance (PAB), total sulfhydryl (SH) groups, and superoxide dismutase (SOD) activity were determined in 170 children and adolescents with T1DM. Principal component analysis was used to investigate clustering of clinical and laboratory variables associated with elevated oxidative stress and reduced antioxidative defense biomarkers. Results Factor analysis extracted five factors, interpreted as (1) "weight status factor" including age, BMI, waist and hip circumferences; (2) "proatherogenic factor" that included LDL-cholesterol, non-HDL-cholesterol, and triglycerides; (3) "metabolic control factor" including glucose and HbA1c; (4) "renal marker factor" with positive loading of urinary albumin excretion rate and negative loading of GFR; and (5) "antiatherogenic factor" that included HDL-cholesterol. High AOPP levels were independently predicted by "proatherogenic" (OR: 2.32; 95% CI: 1.44-3.71; p < 0.001), "metabolic control" (OR: 2.24; 95% CI: 1.35-3.73; p < 0.01), and "renal marker" (OR: 1.65; 95% CI: 1.03-2.65; p < 0.05) factors. "Renal marker factor" was a significant predictor of PAB (OR: 0.52; 95% CI: 0.34-0.81; p < 0.01). Regarding antioxidative defense markers, reduced SH groups were predicted by "proatherogenic factor" (OR: 0.56; 95% CI: 0.34-0.94; p < 0.05), while "weight status factor" predicted lower SOD activity (OR: 1.66; 95% CI: 1.03-2.67; p < 0.05). Conclusions Cardiometabolic risk factors and renal function are associated with oxidative stress in pediatric T1DM patients.

Changes in the biochemical, hematological and histopathological parameters in STZ-Induced diabetic rats and the ameliorative effect of Kigelia africana fruit extract

Background

Biochemical, hematological and histological changes are major observable clinical and pathological factors associated with Diabetes mellitus. Derangement in the levels of these parameters increases the risk of the development of complications. In another hand, gastrointestinal intolerance due to the development of lactic acidosis on the gastrointestinal tract and the intestinal microbiome is the toxic side effect of various synthetic antidiabetic agents. The use of Kigelia africana fruit extract for the treatment of diabetes has been scientifically validated. This study therefore aimed at investigating changes in the biochemical, hematological and histological parameters as well as the determination of the functional groups present in the hexane fraction of the fruit.

Methods

The fruits were extracted with ethanol and partitioned with n-hexane to obtain the hexane fraction. Diabetic rats induced with streptozotocin (STZ) were divided into 5 groups of 5 animals each and treated with 100, 200 and 400 mg/kg body weight (BW) hexane fraction alongside reference standard; glibenclamide. Fasting blood glucose levels and their body weights were monitored weekly. Animals were sacrificed at the end of 28-day treatment. Blood, liver, and kidney were collected for biochemical, hematological and histopathological analyses. Fourier transform infrared resonance (FTIR) spectroscopic analysis was carried out on the hexane fraction for functional group determination.

Results

The hexane fraction of K. africana fruit extract decreased fasting blood glucose (FBG) levels significantly with ameliorative effects on the hematological parameters such as packed cell volume (PCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and red blood cells (RBC) etc. There were significant regenerative differences in the biochemical activities as well as the renal cortex and midzone sections of the rat's kidney and liver when compared with untreated diabetic rats. The presence of polyphenolic functional groups via FTIR analysis suggested high antioxidant activities of the fruit extract.

Conclusion

The use of Kigelia africana fruit extracts protects against biochemical, hematological and histological changes that are injurious to diabetic patients. Therefore, Kigelia africana fruit is a good hepatic- and nephroprotective agent and has a hemato-protective ability.

Açaí seed extract prevents the renin-angiotensin system activation, oxidative stress and inflammation in white adipose tissue of high-fat diet-fed mice

The role of the renin-angiotensin system (RAS), oxidative stress, and inflammation on the development of obesity and its comorbidities has been extensively addressed. Euterpe oleracea Mart. (açaí) seed extract (ASE), with antioxidant and anti-inflammatory properties and capable to modulate plasma renin levels, has been evidenced as a potential regulator of body mass. We hypothesized that the supplementation with ASE might exert beneficial effects on obesity-related white adipose tissue changes and metabolic disorders by interfering with the local adipose tissue overexpression of RAS, inflammation, and oxidative stress in C57BL/6 mice fed a high-fat (HF) diet. The animals were fed a standard diet (10% fat, control), 60% fat (HF), HF + ASE (300 mg/kg per day) and HF + ENA (enalapril, 30 mg/kg per day) for 12 weeks. ASE and ENA prevented weight gain and adiposity, adipocyte hypertrophy, dyslipidemia, and insulin resistance. In adipose tissue, ASE increased the insulin receptor expression and reduced renin and AT1 receptor expression, which was associated with decreased plasma levels of renin and angiotensin II. Differently, ENA increased the expression of angiotensin-conversing enzyme 2, AT2, B2, and Mas receptors in adipose tissue. Also, ASE but not ENA decreased malondialdehyde and 8-isoprostane levels in adipose tissue. Finally, ASE and ENA reduced the adipose tissue inflammatory markers tumor necrosis factor alpha and interleukin 6. These results demonstrate that ASE prevented the adipocyte hypertrophy, obesity, hyperlipidemia, hyperglycemia, and insulin resistance in HF diet-fed mice. The downregulation of RAS in adipose tissue, reducing oxidative stress and inflammation, may contribute to the prevention of obesity-related disorders.

Lack of lymphocytes impairs macrophage polarization and angiogenesis in diabetic wound healing

AIMS

This study aimed to investigate the effect of lymphocytes in wound healing and the underlying mechanisms, in diabetic and non-diabetic mice, using Balb/c recombination activating gene (Rag)-2 and interleukin 2 receptor gamma (IL-2Rγ) double knockout (KO) (RAG2^-/- IL-2Rγ^-/-) mice.

MAIN METHODS

Wound healing in vivo was performed in control and STZ-induced diabetic mice, in both KO and WT mice. Inflammation and ROS production were evaluated by immunofluorescence microscopy analysis, antioxidant enzymes and angiogenesis were evaluated by quantitative PCR and immunofluorescence microscopy analysis, and wound closure kinetics evolution was evaluated by measurement of acetate tracing of the wound area.

KEY FINDINGS

Wound closure was significantly delayed in KO mice, where the M1/M2 macrophage ratio and basal ROS levels were significantly increased, while antioxidant defenses and angiogenesis were significantly decreased. Moreover, the expected increase in matrix metallopeptidase (MMP)-9 protein levels in diabetic conditions was not observed in KO mice, suggesting that the mechanisms leading to the increase in MMP-9 observed in diabetic wounds may in part be lymphocyte-dependent.

SIGNIFICANCE

Our results indicate that lack of lymphocytes compromises wound healing independent of diabetes. The lack of these cells, even in non-diabetic mice, mimics the phenotype observed in wounds under diabetic conditions. Moreover, the combination of diabetes and the lack of lymphocytes, further impair the wound healing conditions, indicating that when the innate regulatory function is lost in these KO mice, excessive M1 polarization, poor angiogenesis and impaired wound healing are worsen.

The Anti-Inflammatory Effects of Glucagon-Like Peptide Receptor Agonist Lixisenatide on the Retinal Nuclear and Nerve Fiber Layers in an Animal Model of Early Type 2 Diabetes

This study explored the anti-inflammatory effects of a glucagon-like peptide-1 receptor agonist (GLP-1RA), known as lixisenatide, on the eyes of early type 2 diabetic mice. Diabetic (db/db) mice were divided into three groups: GLP-1RA [lixisenatide (LIX)], insulin (INS) with controlled hyperglycemia based on the glucose concentration of lixisenatide, and diabetic control (D-CON). Nondiabetic control mice (db/dm) were also characterized for comparison. After 8 weeks of treatment, mRNA levels of inflammatory markers, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, immunohistochemical staining; Western blot of glial fibrillary acidic protein (GFAP) and thioredoxin-interacting protein; and retinal thickness were assessed in the central and peripheral neurosensory retina. LIX showed decreased immunohistochemical staining for both thioredoxin-interacting protein and GFAP in the central and peripheral neurosensory retina compared with D-CON and INS, and decreased expression of these proteins in the neurosensory retina and immunohistochemical staining in the optic nerve head for GFAP compared with D-CON. The inner nuclear layer in the peripheral retina in LIX was only thinner than those of D-CON and INS. In an early type 2 diabetic mouse model, lixisenatide treatment showed superior anti-inflammatory effects on the retina and optic nerve head independent of hyperglycemia. Thus, the neuroprotective effects of lixisenatide treatment in the peripheral inner nuclear layer should be evaluated in early type 2 diabetic retinopathy.

Isopulegol Mitigates Hyperglycemia Mediated Oxidative and Endoplasmic Reticulum Stress in HFD/STZ Induced Diabetic Rats

BACKGROUND

Oxidative and endoplasmic reticulum stresses contribute to the pathogenesis of β-cell dysfunction in diabetes mellitus. This study investigates the effect of isopulegol on the above stresses in HFD/STZ induced diabetic rats.

METHODS

Animals in group I and II were placed in normal pellet diet and group II was treated with isopulegol at 200 mg/kg b.w. Animals in groups III-V were placed in HFD for 4 weeks and made diabetic with single intraperitoneal injection of STZ (35 mg/kg b.w) in 0.1 M citrate buffer (pH 4.5). Group III served as diabetic control while animals in group IV and V were treated with isopulegol (100 mg/kg b.w) and metformin (25 mg/kg b.w) respectively for 28 d.

RESULTS

The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione sulphur transferase (GST), glutathione reductase (GR) and the levels of vitamin-E, vitamin-C, reduced glutathione (GSH) were significantly (p <0.05) decreased in plasma and tissues of diabetic rats. Thiobarbituric acid reactive acid substances (TBARS) and lipid hydroperoxides (LHP), indices of lipid peroxidation were also significantly (p <0.05) increased in diabetic rats. In pancreatic tissue ER stress markers PERK, elf2α, ATF4 and in hepatic tissue oxidative stress marker UCP-2 expression was significantly (p <1.0) increased in diabetic rats. Administration of isopulegol significantly improved antioxidant status and decreased oxidative and ER stress markers in diabetic treated rats. Histopathological studies on liver and kidney supported the above findings. The results are comparable with the standard drug metformin.

CONCLUSIONS

Isopulegol a naturally occurring monoterpene alcohol attenuated oxidative and ER stress in HFD/STZ induced diabetic rats.

Urinary Excretion of 6-Sulfatoxymelatonin, the Main Metabolite of Melatonin, and Mortality in Stable Outpatient Renal Transplant Recipients

Melatonin is a multifaceted hormone which rises upon the onset of darkness. Pineal synthesis of melatonin is known to be disturbed in patients with end-stage renal disease, but it is not known if its production is restored to normal after successful renal transplantation. We hypothesized that urinary excretion of 6-sulfatoxymelatonin, the major metabolite of melatonin, is lower in renal transplant recipients (RTRs) compared to healthy controls and that this is associated with excess mortality. Urinary 6-sulfatoxymelatonin was measured via LC-MS/MS in 701 stable outpatient RTRs and 285 healthy controls. Median urinary 6-sulfatoxymelatonin in RTR was 13.2 nmol/24 h, which was 47% lower than in healthy controls. Urinary 6-sufatoxymelatonin appeared undetectable in the majority of 36 RTRs with diabetic nephropathy as primary renal disease. Therefore, this subgroup was excluded from further analyses. Of the remaining 665 RTRs, during 5.4 years of follow-up, 110 RTRs died, of whom 38 died due to a cardiovascular cause. In Cox-regression analyses, urinary 6-sulfatoxymelatonin was significantly associated with all-cause mortality (0.60 (0.44–0.81), p = 0.001) and cardiovascular mortality (0.49 (0.29–0.84), p = 0.009), independent of conventional risk factors and kidney function parameters. Based on these results, evaluation and management of melatonin metabolism could be considered for improvement of long-term outcomes in RTRs.

Antioxidant Effects and Mechanisms of Medicinal Plants and Their Bioactive Compounds for the Prevention and Treatment of Type 2 Diabetes: An Updated Review

Diabetes mellitus is a metabolic disorder that majorly affects the endocrine gland, and it is symbolized by hyperglycemia and glucose intolerance owing to deficient insulin secretory responses and beta cell dysfunction. This ailment affects as many as 451 million people worldwide, and it is also one of the leading causes of death. In spite of the immense advances made in the development of orthodox antidiabetic drugs, these drugs are often considered not successful for the management and treatment of T2DM due to the myriad side effects associated with them. Thus, the exploration of medicinal herbs and natural products as therapeutic sources for the treatment of T2DM is promoted because they have little or no side effects. Bioactive molecules isolated from natural sources have been proven to lower blood glucose levels via regulating one or more of the following mechanisms: improvement of beta cell function, insulin resistance, glucose (re)absorption, and glucagon-like peptide-1 homeostasis. In recent times, the mechanisms of action of different bioactive molecules with antidiabetic properties and phytochemistry are gaining a lot of attention in the area of drug discovery. This review article presents an update of the findings from clinical research into medicinal plant therapy for T2DM.

Is exposure to family member incarceration during childhood linked to diabetes in adulthood? Findings from a representative community sample

Objectives:

Diabetes is a prevalent and serious public health problem, particularly among older adults. A robust literature has shown that adverse childhood experiences contribute to the development of health problems in later life, including diabetes. Family member incarceration during childhood is an under-investigated yet increasingly common adverse childhood experience in the United States. The purpose of this study was to investigate the relationship between family member incarceration during childhood and diabetes in adulthood, while considering the role of gender as well as the impact of a range of potential confounds.

Methods:

A large representative community sample of adults aged 40 and older (n = 8790 men, 14,255 women) was drawn from the Behavioral Risk Factor Surveillance System 2012 optional adverse childhood experiences module to investigate the association between family member incarceration during childhood and diabetes. For each gender, nine logistic regression analyses were conducted using distinct clusters of variables (e.g. socioeconomic status and health behaviors).

Results:

Among males, the odds of diabetes among those exposed to family member incarceration during childhood ranged from 2.00 to 1.59. In the fully adjusted model, they had elevated odds of 1.64 (95% confidence interval = 1.27, 2.11). Among women, the odds of diabetes was much lower, hovering around 1.00.

Conclusion:

Findings suggest that family member incarceration during childhood is associated with diabetes in men, even after adjusting for a wide range of potential risk factors (e.g. sociodemographics, health behaviors, healthcare access, and childhood risk factors). Future research should explore the mechanisms linking family member incarceration during childhood and long-term negative health outcomes in men.

Hepatic insulin resistance induced by mitochondrial oxidative stress can be ameliorated by sphingosine 1-phosphate

The bioactive lipid mediator sphingosine 1-phosphate (S1P) is considered to be involved in the development of insulin resistance (IR) via effects on oxidative stress; the mechanism however is not yet fully revealed. To this end, we investigated the role and mechanism of S1P on hepatic IR. We found that treatment of the normal human liver cell LO2 with 1000 nM insulin for 48 h reduced glucose uptake and increased serine phosphorylation of insulin receptor substrate-1, indicating a reduction in insulin receptor signaling. Moreover, the same concentration of insulin caused accumulation of reactive oxygen species (ROS) in the cytosol and mitochondria, and enhanced expression of the antioxidant transcription factor (Nrf2) and upregulated Nrf2 nuclear translocation. Using known inhibitors and donors of ROS (H₂O₂, ·O₂-, ·OH), the results demonstrated the differential roles for the specific ROS in regulating IR in LO2 cells, with H₂O₂ having a more significant inhibitory role compared with ·O₂^- and ·OH. Cell treatment with S1P at 0.1-5.0 μM reversed the effects of high insulin concentrations on ROS generation, glucose uptake, and insulin signaling. H₂O₂ also reversed the beneficial effects of S1P in alleviating IR. These results show that H₂O₂ signaling plays a key determinant in hepatic IR induced by insulin. S1P can ameliorate hepatic IR by reducing mitochondrial ROS generation, and the possible anti-IR effect mechanism may be involved in H₂O₂ signaling.

Heparin-binding epidermal growth factor (EGF)-like growth factor in pediatric patients with type 1 diabetes mellitus

Heparin-binding EGF-like growth factor (HB-EGF) is involved in atherosclerosis progression. We investigated association between plasma HB-EGF levels and lipid, oxidative stress and inflammatory biomarkers in pediatric patients with type 1 diabetes mellitus (T1DM). Levels of HB-EGF, high-sensitive C-reactive protein (hsCRP), prooxidant-antioxidant balance (PAB), total antioxidant status (TAS), oxidized low-density lipoproteins (oxLDL), metabolic control and serum lipid parameters and paraoxonase 1 (PON1) activity were determined in 74 patients and 40 controls. In comparison to controls, patients had significantly higher levels (p < 0.01) of HB-EGF, hsCRP, PAB and oxLDL particles (p < 0.001), but lower levels of TAS and PON1 activity. In T1DM group, HB-EFG levels were positively associated with hsCRP, PAB and oxLDL levels. hsCRP and oxLDL levels were independent predictors of HB-EGF concentration. We demonstrated that oxidative modifications of LDL particles and low-grade inflammation are main determinants of increased plasma HB-EGF levels, which indicates an interactive role of oxidative stress, dyslipidemia and inflammation.

Effects of Zamzam water on glycemic status, lipid profile, redox homeostasis, and body composition in rats

Objectives

Previous studies have demonstrated that Zamzam water exerts beneficial effects on several ailments such as diabetes mellitus, nephrotoxicity, hepatotoxicity, and stress. The present study aimed to assess the effects of Zamzam water on glycemic status, lipid profile, redox homeostasis, and body composition in healthy rats.

Methods

Twenty-four rats were divided into two equal groups. Rats were fed a chow diet along with either tap or Zamzam water as the only fluid source. After ten weeks, fasting blood glucose, serum insulin, insulin resistance, low density lipoproteins (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, superoxide dismutase, and lipid peroxidation were measured. Adipose pads and carcass (musculoskeletal only) were weighed and residual body weight was calculated. The groups were compared using independent sample t test (unpaired).

Results

The following parameters were significantly reduced in the Zamzam water group compared to the tap water group: fasting blood sugar, 96.5 vs. 147.1 mg/dl (p = 0.00); serum insulin, 0.44 vs. 1.31 μU/l (p = 0.00); and insulin resistance, 1.89 vs. 8.40 (p = 0.00). LDL cholesterol, HDL cholesterol, superoxide dismutase, lipid peroxidation, weight of the body, fat pads, and carcass, as well as residual body weight (both absolute and relative) showed no significant changes.

Conclusion

Zamzam water intake for ten weeks decreases fasting blood sugar, serum insulin, and insulin resistance. However, Zamzam water has no effect on lipid profile, redox homeostasis, and body composition.

Downregulation of BK channel function and protein expression in coronary arteriolar smooth muscle cells of type 2 diabetic patients

Aims

Type 2 diabetes (T2D) is strongly associated with cardiovascular morbidity and mortality in patients. Vascular large conductance Ca2+-activated potassium (BK) channels, composed of four pore-forming α subunits (BK-α), and four regulatory β1 subunits (BK-β1), are densely expressed in coronary arterial smooth muscle cells (SMCs) and play an important role in regulating vascular tone and myocardial perfusion. However, the role of BK channels in coronary microvascular dysfunction of human subjects with diabetes is unclear. In this study, we examined BK channel function and protein expression, and BK channel-mediated vasodilation in freshly isolated coronary arterioles from T2D patients.

Methods and results

Atrial tissues were obtained from 16 patients with T2D and 25 matched non-diabetic subjects during cardiopulmonary bypass procedure. Microvessel videomicroscopy and immunoblot analysis were performed in freshly dissected coronary arterioles and inside-out single BK channel currents was recorded in enzymatically isolated coronary arteriolar SMCs. We found that BK channel sensitivity to physiological Ca2+ concentration and voltage was downregulated in the coronary arteriolar SMCs of diabetic patients, compared with non-diabetic controls. BK channel kinetics analysis revealed that there was significant shortening of the mean open time and prolongation of the mean closed time in diabetic patients, resulting in a remarkable reduction of the channel open probability. Functional studies showed that BK channel activation by dehydrosoyasaponin-1 was diminished and that BK channel-mediated vasodilation in response to shear stress was impaired in diabetic coronary arterioles. Immunoblot experiments confirmed that the protein expressions of BK-α and BK-β1 subunits were significantly downregulated, but the ratio of BK-α/BK-β1 was unchanged in the coronary arterioles of T2D patients.

Conclusions

Our results demonstrated for the first time that BK channel function and BK channel-mediated vasodilation were abnormal in the coronary microvasculature of diabetic patients, due to decreased protein expression and altered intrinsic properties of BK channels.

Oxidised Met147 of human serum albumin is a biomarker of oxidative stress, reflecting glycaemic fluctuations and hypoglycaemia in diabetes

Oxidative stress has been linked to a number of chronic diseases, and this has aroused interest in the identification of clinical biomarkers that can accurately assess its severity. We used liquid chromatography-high resolution mass spectrometry (LC-MS) to show that oxidised and non-oxidised Met residues at position 147 of human serum albumin (Met¹⁴⁷) can be accurately and reproducibly quantified with stable isotope-labelled peptides. Met¹⁴⁷ oxidation was significantly higher in patients with diabetes than in controls. Least square multivariate analysis revealed that glycated haemoglobin (HbA_1c) and glycated albumin (GA) did not significantly influence Met¹⁴⁷ oxidation, but the GA/HbA_1c ratio, which reflects glycaemic excursions, independently affected Met¹⁴⁷ oxidation status. Continuous glucose monitoring revealed that Met¹⁴⁷ oxidation strongly correlates with the standard deviation of sensor glucose concentrations and the time spent with hypoglycaemia or hyperglycaemia each day. Thus, glycaemic variability and hypoglycaemia in diabetes may be associated with greater oxidation of Met¹⁴⁷. Renal function, high-density lipoprotein-cholesterol and serum bilirubin were also associated with the oxidation status of Met¹⁴⁷. In conclusion, the quantification of oxidised and non-oxidised Met¹⁴⁷ in serum albumin using our LC-MS methodology could be used to assess the degree of intravascular oxidative stress induced by hypoglycaemia and glycaemic fluctuations in diabetes.

Spironolactone reversed hepato-ovarian triglyceride accumulation caused by letrozole-induced polycystic ovarian syndrome: tissue uric acid-a familiar foe

Polycystic ovarian syndrome (PCOS) is a complex endocrine disease among women of reproductive age and is one of the main causes of infertility. Non-alcoholic fatty liver disease (NAFLD), the most prominent chronic liver disease in adults, is characterized by excess hepatic triglyceride (TG) accumulation. PCOS women have increased risk of NAFLD and uric acid has been documented to have a positive correlation with subclinical tissue damage and might be the link in the cystic. Spironolactone (SPL) is a mineralocorticoid receptor (MR) blocker that has been in wide clinical use for some decades. In this research, we investigated the effects of SPL on ovarian and hepatic tissue damage in experimental PCOS rats induced by letrozole (LET). A total of eighteen adult female Wistar rats were used for this study and the animals divided into 3 groups are treated with vehicle, LET (1 mg/kg), and LET+SPL (SPL; 0.25 mg/kg), p.o. once daily respectively for 21 uninterrupted days. Results showed that LET treatment induced features of PCOS characterized by increased plasma testosterone (T) and luteinizing hormone (LH) together with increased body weight. Abnormal ovarian and hepatic histomorphological changes were also observed with elevated uric acid (UA) and TG accumulation in both tissues respectively. Treatment with SPL however attenuated the elevated testosterone in the LET-induced PCOS model accompanied with a reversal in the observed ovarian and hepatic UA, TG accumulation, and altered histomorphological changes. Taken together, spironolactone reversed the PCOS-induced ovarian and hepatic tissue damage by suppressing tissue UA and TG accumulation.

Aqueous humor and serum 25-Hydroxyvitamin D levels in patients with cataracts

Background

Serum 25-hydroxyvitamin D (25 (OH) D) levels are associated with various pathologic ocular conditions. Few studies have assessed 25 (OH) D concentrations in non-serum specimens, and none to date has assessed 25 (OH) D concentrations in human aqueous humor and their association with ocular diseases. This study investigated the possible correlations between 25 (OH) D concentrations in aqueous humor and serum and whether vitamin D concentrations in aqueous humor were associated with cataract.

Methods

This study prospectively enrolled 136 patients, including 87 with senile cataract and 49 with diabetic cataract, who underwent cataract surgery from January to November 2017. 25 (OH) D was measured in aqueous humor and serum specimens collected from all patients, and their correlation was analyzed statistically. Clinical and laboratory data, including the results of ophthalmologic examinations, were compared in the two groups of cataract patients.

Results

No correlation was observed between 25 (OH) D concentrations in aqueous humor and serum (P = 0.381). 25 (OH) D concentrations in aqueous humor were significantly higher in patients with diabetic than senile cataract (P = 0.006). Multivariate logistic regression analysis showed that the adjusted odds ratio for diabetic cataract for the highest compared with the lowest quartile of 25 (OH) D concentration in aqueous humor was 4.36 ng/ml (95% confidence interval [CI]: 1.33–14.34 ng/ml; P = 0.015). Multivariate linear regression analysis showed that 25(OH) D concentration in aqueous humor was 2.68 ng/ml (95% CI: 0.34–5.01 ng/ml; P = 0.025) higher in patients with diabetic than senile cataract.

Conclusions

25(OH) D concentrations in aqueous humor and serum did not correlate with each other. Higher 25(OH) D level in aqueous humor was associated with diabetic cataract. These findings suggest that studies of vitamin D levels in patients with ocular conditions should include measurements of vitamin D levels in aqueous humor.

In vitro α-glucosidase inhibition by honeybush (Cyclopia genistoides) food ingredient extract—potential for dose reduction of acarbose through synergism

Synergistic in vitro inhibition of intestinal α-glucosidase by acarbose and xanthones indicates potential for reducing the effective dose of acarbose.

Inhibition of Hypothalamic Inhibitor κB Kinase β/Nuclear Transcription Factor κB Pathway Attenuates Metabolism and Cardiac Dysfunction in Type 2 Diabetic Rats

BACKGROUND

Inflammation and oxidative stress play important roles in energy imbalance and its complications. Recent research indicates that hypothalamic inflammation may contribute to the pathogenesis of metabolic syndrome and cardiac dysfunction, but the mechanisms remain unclear. We hypothesized that suppression of the proinflammatory IKKβ/NF-κB pathway in the hypothalamus can improve energy balance and cardiac function in type 2 diabetic (T2D) rats.

METHODS

Normal and T2D rats received bilateral hypothalamic arcuate nucleus (ARC) infusions of the IKKβ inhibitor SC-514 or vehicle via osmotic minipump. Metabolic phenotyping, immunohistochemical analyses, and biochemical analyses were used to investigate the outcomes of inhibition of the hypothalamic IKKβ. Echocardiography and glucometer were used for measuring cardiac function and blood glucose, respectively. Blood samples were collected for the evaluation of circulating proinflammatory cytokines. Heart was harvested for cardiac morphology evaluations. The ARC was harvested and analyzed for IKKβ, NF-κB, proinflammatory cytokines, reactive oxygen species (ROS), and NAD(P)H (gp91phox, p47phox) oxidase activity levels and neuropeptides.

RESULTS

Compared with normal rats, T2D rats were characterized by hyperglycemia, hyperinsulinemia, glucose intolerance, cardiac dysfunction, as well as higher ARC levels of IKKβ, NF-κB, proinflammatory cytokines, ROS, gp91phox, and p47phox. ARC infusion of the IKKβ inhibitor SC-514 attenuated all these changes in T2D rats, but not in normal rats.

CONCLUSIONS

Our results indicate that the hypothalamic IKKβ/NF-κB pathway plays a key role in modulating energy imbalance and cardiac dysfunction, suggesting its potential therapeutic role during type 2 diabetes mellitus.

The impact of air pollution on the incidence of diabetes and survival among prevalent diabetes cases

PURPOSE

Growing evidence implicates ambient air pollutants in the development of major chronic diseases and premature mortality. However, epidemiologic evidence linking air pollution to diabetes remains inconclusive. This study sought to determine the relationships between selected air pollutants (nitrogen dioxide [NO₂], fine particulate matter [PM_2.5], ozone [O₃], and oxidant capacity [Ox; the redox-weighted average of O₃ and NO₂]) and the incidence of diabetes, as well as the risk of cardiovascular or diabetes mortality among individuals with prevalent diabetes.

RESEARCH DESIGN AND METHODS

We followed two cohorts, which included 4.8 million Ontario adults free of diabetes and 452,590 Ontario adults with prevalent diabetes, from 2001 to 2015. Area-level air pollution exposures were assigned to subjects' residential areas, and outcomes were ascertained using health administrative data with validated algorithms. We estimated hazard ratios for the association between each air pollutant and outcome using Cox proportional hazards models, and modelled the shape of the concentration-response relationships.

RESULTS

Over the study period, 790,461 individuals were diagnosed with diabetes. Among those with prevalent diabetes, 26,653 died from diabetes and 64,773 died from cardiovascular diseases. For incident diabetes, each IQR increase in NO₂ had a hazard ratio of 1.04 (95% CI: 1.03-1.05). This relationship was relatively robust to all sensitivity analyses considered, and exhibited a near-linear shape. There were also positive associations between incident diabetes and PM_2.5, O₃, and Ox, but these estimates were somewhat sensitive to different models considered. Among those with prevalent diabetes, almost all pollutants were associated with increased diabetes and cardiovascular mortality risk. The strongest association was observed between diabetes mortality and exposure to NO₂ (HR = 1.08, 95% CI: 1.02-1.13).

CONCLUSIONS

Selected air pollutants, especially NO₂, were linked to an increased risk of incident diabetes, as well as risk of cardiovascular or diabetes mortality among persons with prevalent diabetes. As NO₂ is frequently used as a proxy for road traffic exposures, this result may indicate that traffic-related air pollution has the strongest effect on diabetes etiology and survival after diabetes development.

Effects of Nigella Sativa on Type-2 Diabetes Mellitus: A Systematic Review

Diabetes mellitus is one of the most prevalent metabolic disorders that affect people of all genders, ages, and races. Medicinal herbs have gained wide attention from researchers and have been considered to be a beneficial adjuvant agent to oral antidiabetic drugs because of their integrated effects. Concerning the various beneficial effects of Nigella sativa, this systematic review aims to provide comprehensive information on the effects of Nigella sativa on glucose and insulin profile status in humans. A computerized database search performed through Scopus and Medline via Ebscohost with the following set of keywords: Nigella Sativa OR black seed oil OR thymoquinone OR black cumin AND diabetes mellitus OR hyperglycemia OR blood glucose OR hemoglobin A1C had returned 875 relevant articles. A total of seven articles were retrieved for further assessment and underwent data extraction to be included in this review. Nigella sativa was shown to significantly improve laboratory parameters of hyperglycemia and diabetes control after treatment with a significant fall in fasting blood glucose, blood glucose level 2 h postprandial, glycated hemoglobin, and insulin resistance, and a rise in serum insulin. In conclusion, these findings suggested that Nigella sativa could be used as an adjuvant for oral antidiabetic drugs in diabetes control.

Selenium and iodine in diabetes mellitus with a focus on the interplay and speciation of the elements

Diabetes mellitus is a chronic metabolic disease caused by insulin deficiency (type I) or dysfunction (type II). Diabetes is a threatening public health concern. It is considered as one of the priority non-communicable diseases, due to its high and increasing incidence, the associated healthcare costs, and threatening medical complications. Two trace elements selenium (Se) and iodine (I) were intensively discussed in the context of diabetic pathology and, possibly, etiology. It seems there is a multilayer involvement of these essential nutrients in glucose tolerance, energy metabolism, insulin signaling and resistance, which are mainly related to the antioxidant selenoenzymes and the thyroid hormones. Other factors might be related to (auto)immunity, protection against endoplasmic reticulum stress, and leptin signaling. The aim of the current review is to evaluate the current understanding of the role of selenium and iodine in diabetes with a focus on the biochemical interplay between the elements, their possible role as biomarkers, and their chemical speciation. Possible impacts from novel analytical techniques related to trace element speciation and isotopic analysis are outlined.

Eicosapentaenoic acid prevents salt sensitivity in diabetic rats and decreases oxidative stress

OBJECTIVES

Salt sensitivity (SS) is associated with increased cardiovascular risk in patients with Type 2 diabetes mellitus (T2-DM) due to an increase in renal oxidation. ω-3 polyunsaturated fatty acids have shown antioxidant effects, but a typical Western diet contains limited content. In particular, ω-3 polyunsaturated fatty acids are able to activate nuclear factor erythroid 2-related factor 2 (Nrf-2) to prevent diabetes mellitus-related complications by mitigating oxidative stress. Therefore, we hypothesized that eicosapentaenoic acid (EPA; ω-3) modulates SS in rats with T2-DM by decreasing renal oxidative stress via Nrf-2 activation and enhancing the antiinflammatory response via interleukin (IL) 6 modulation.

METHODS

Three-month-old male rats (n = 40) were fed with a Normal Na-diet (NNaD) and randomly selected into four groups: Healthy Wistar nondiabetic rats (Wi), diabetic controls (eSS), arachidonic acid-treated eSS (AA; ω-6), and EPA-treated eSS (ω-3). After 1 year, rats were placed in metabolic cages for 7 d and fed a NNaD, followed by a 7-d period with a High Na-diet (HNaD). Systolic blood pressure, body weight, serum IL-6 and reactive oxygen species (ROS) levels were determined at the end of each 7-d period. Glycated hemoglobin (HbA1c), triacylglycerol, creatinine, and cholesterol levels were determined. ROS levels and Nrf-2 expression in kidney lysates were also assayed. Histologic changes were evaluated. A t test or analysis of variance was used for the statistical analysis.

RESULTS

After a HNaD, systolic blood pressure increased in both the control eSS and AA groups, but not in the EPA and Wi groups. However, HbA1c levels remained unchanged by the treatments, which suggests that the observed beneficial effect was independent of HbA1c levels. The IL-6 levels were higher in the eSS and AA groups, but remained unaltered in EPA and Wi rats after a HNaD diet. Interestingly, EPA protected against serum ROS in rats fed the HNaD, whereas AA did not. In kidney lysates, ROS decreased significantly in the EPA group compared with the eSS group, and Nrf-2 expression was consistently higher compared with the AA and eSS groups. Diabetic rats presented focal segmental sclerosis, adherence to Bowman capsule, and mild-to-moderate interstitial fibrosis. EPA and AA treatment prevented kidney damage.

CONCLUSIONS

An adequate ω3-to-ω6 ratio prevents SS in diabetic rats by a mechanism that is independent of glucose metabolism but associated with the prevention of renal oxidative stress generation. These data suggest that EPA antioxidant properties may prevent the development of hypertension or kidney damage.

Relationship between aldose reductase enzyme and the signaling pathway of protein kinase C in an in vitro diabetic retinopathy model

Protein kinase C (PKC) and aldose reductase (AR) enzyme activities are increased in diabetes and complications are include retinopathy, nephropathy, and neuropathy. However, the relationship between PKC and AR and the underlying molecular mechanisms is still unclear. We aimed to evaluate the relationship between these two enzymes and clarify the underlying molecular mechanisms by the related signaling molecules. The effects of hyperglycemia and oxidative stress on AR and PKC enzymes and the signaling molecules such as nuclear factor-kappa B (NF-κB), inhibitor kappa B-alpha (IkB-α), total c-Jun, phospho c-Jun, and stress-activated protein kinases (SAPK)/Jun amino-terminal kinases (JNK) were evaluated in human retinal pigment epithelial cells (ARPE-19). AR, PKC protein levels, and related signaling molecules increased with hyperglycemia and oxidative stress. The AR inhibitor sorbinil decreased PKC expression and activity and all signaling molecule protein levels. Increased AR expression during hyperglycemia and oxidative stress was found to be correlated with the increase in PKC expression and activity in both conditions. Decreased expression and activity of PKC and the protein levels of related signaling molecules with the AR inhibitor sorbinil showed that AR enzyme may play a key role in the expression of PKC enzyme and oxidative stress during diabetes.

Protective effects of Salidroside on spermatogenesis in streptozotocin induced type-1 diabetic male mice by inhibiting oxidative stress mediated blood-testis barrier damage

Spermatogenic dysfunction is one of the major secondary complications of male diabetes. Salidroside (SAL) is the important active ingredients isolated from Herba Cistanche, which exhibits numerous pharmacological activities such as antioxidant, anti-diabetic, and anti-inflammatory effects. The present study was designed to determine whether SAL contributes to the recovery from spermatogenic dysfunction in streptozotocin (STZ) induced type-1 diabetic mice. SAL (25, 50, or 100 mg/kg) and Clomiphene citrate (CC, 5 mg/kg) were orally administered to male type-1 diabetic mice for 10 weeks. Testis tissues were collected for histopathological and biochemical analysis. Moreover, reproductive organ weight, sperm parameters, and testicular cell DNA damage were estimated. The results revealed that SAL significantly improved the weight of the reproductive organs, sperm parameters and testicular morphology to different degrees in type-1 diabetic mice. Furthermore, reactive oxygen species (ROS) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), markedly increased in the testicular tissue after SAL treatment. In addition, our data also showed a marked downregulation the fluorescence expressions of p38 MAPK phosphorylation and upregulation the protein expressions of ZO-1, Occludin, Claudin-11 and N-cadherin after SAL administration (100 mg/kg) compared with the type-1 diabetic group. In conclusion, these results demonstrated that SAL exerts protective effects on type-1 diabetes-induced male spermatogenic dysfunction, which is likely mediated by inhibiting oxidative stress-mediated blood testis barrier damage.

Autophagy protects peripheral blood mononuclear cells against inflammation, oxidative and nitrosative stress in diabetic dyslipidemia

BACKGROUND

Type 2 diabetes mellitus (T2DM) results in severe oxidative and nitrosative stress and inflammation when associated with hyperlipidemia. In this study, we have attempted to explore the role of autophagy in T2DM subjects with or without dyslipidemia.

METHODS

Experiments were carried out in isolated Peripheral blood mononuclear cells (PBMC) from study subjects and insulin resistant HepG2 cells utilizing flow cytometry, confocal microscopy and molecular biology techniques like western blotting, immunofluorescence and real time PCR.

RESULTS

In case of T2DM with dyslipidemia, higher population of autophagy positive cell was detected compared to T2DM which may have been originated due to higher stress. Flow cytometric data indicated autophagy to be triggered by both oxidative and nitrosative stress in PBMC of diabetic dyslipidemic patients, which is a novel finding of our work. Expression of LC3 puncta, a hallmark of autophagy was observed at periphery of PBMC and Hep G2 cells in case of diabetic dyslipidemic condition. Increased expression of ATG5, LC3B and Beclin1 supports the autophagic pathway in both PBMC and Hep G2 cells. Upon blocking autophagy by 3-methyl adenine (3MA), the apoptotic cell population increased significantly. Autophagy was also been evidenced to control oxidative stress mediated up-regulation of inflammatory markers like IL-6, TNF-α.

CONCLUSION

Induction of autophagy emerged to be a protective mechanism for the diabetic cells coupled with dyslipidemia. Not only Reactive oxygen species, but also reactive nitrogen species was involved in autophagy induction process. Moreover inhibition study documented autophagy to have a protective role in pro-inflammatory responses. Thus, enhancing autophagic activity may be an efficient mechanism leading to new therapeutic strategy to restore the glycemic regulation.

Protective effects of raspberry on the oxidative damage in HepG2 cells through Keap1/Nrf2-dependent signaling pathway

The aim of the present study was to explore the protective effects of raspberry and its bioactive compound cyanidin 3-O-glucoside against H2O2-induced oxidative stress in HepG2 cells. We established a model of oxidative stress in HepG2 cells induced by H2O2 and examined the protein expression of Keap1/Nrf2. The antioxidant activity of raspberry extract was carried out measuring the level of reactive oxygen species (ROS), and the changes of phase II detoxification elements such as GSH level and CAT activity. Also the expression of proteins related to the Keap1/Nrf2 signaling was tested. The results revealed that raspberry extract significantly reduced the ROS levels in oxidative injured cells, increased GSH content and CAT activity, and activated the expression of proteins Keap1, Nrf2, HO-1, NQO1, and γ-GCS. These results taken together indicated that raspberry treatment could ameliorate H2O2-induced oxidative stress in HepG2 cells via Keap1/Nrf2 pathway.

Effect of olive leaves extract on the antidiabetic effect of glyburide for possible herb-drug interaction

The concomitant use of olive leaves (OL) and glyburide (GLB) is a possible therapy for diabetic patients. However, there is no report about the effect of OL on the antidiabetic effect of GLB till now. In the current study, the possible interaction of olive leaves extract (OLE) with GLB was assessed to determine if there was any pharmacological benefit over GLB alone. Seven groups of male Sprague Dawley rats were used. Normal rats of the 1st group treated with 2 mL/kg of 3% Tween 80 (vehicle). The 2nd–5th groups were diabetic rats received vehicle, GLB (5 mg/kg), OLE low dose and OLE high dose respectively, while the 6th–7th groups administered combinations of GLB plus OLE low dose and GLB plus OLE high dose, respectively. All treatments were administered orally once daily for 8 weeks.

The use of GLB+OLE-500 obviously improved fasting blood glucose (FBG), insulin and glycated hemoglobin (HbA1c) in diabetic rats (95.5 ± 5.55 mg/dL, 6.8 ± 0.16 mg/dL and 6.1 ± 0.29%, respectively) compared to those treated with GLB monotherapy (140.0 ± 6.36 mg/dL, 5.4 ± 0.19 mg/dL and 7.0 ± 0.20%, respectively). The lipid profile [triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C)] was significantly improved in diabetic rats exposed to GLB+OLE-500 (35.6 ± 1.51 mg/dL, 48.5 ± 2.74 mg/dL, 25.1 ± 1.21 mg/dL and 17.0 ± 0.82 mg/dL, respectively) in comparison with diabetic group exposed to GLB alone (43.2 ± 2.15 mg/dL, 56.8 ± 2.14 mg/dL, 18.6 ± 0.96 mg/dL, 23.0 ± 1.26 mg/dL, respectively). Additionally, the benefit impacts of GLB+OLE-500GLB+OLE-500 therapy on the antioxidant and lipid peroxidation parameters in the pancreatic tissues of diabetic rats were higher than those of GLB monotherapy. Moreover, GLB plus OLE-500 combination had the greatest effect on restoration of the insulin content of Beta (β) cells and reduction of the glucagon and somatostatin of Alpha (α) and Delta (δ) endocrine cells in the pancreatic islets among the different treatment. The current study suggests that OL and GLB combination could cause herb-drug interactions through modulation of insulin receptor (INR), glucose transporter 2 (Slc2a2) and peroxisome proliferator-activated receptor α (PPAR-α) genes expression in the liver of diabetic rats.

Oxidative Stress, NF-κB-Mediated Inflammation and Apoptosis in the Testes of Streptozotocin-Induced Diabetic Rats: Combined Protective Effects of Malaysian Propolis and Metformin

Oxidative stress, inflammation and apoptosis are major complications that trigger organ failure in diabetes mellitus (DM), and are proven to adversely affect the male reproductive system. Clinical and experimental studies have demonstrated the promising protective effects of propolis in DM and its associated systemic effects. Herein, we investigated the effect of Malaysian propolis (MP) on testicular oxidative stress, inflammation and apoptosis in diabetic rats. Further, the possibility of a complementary effect of MP with the anti-hyperglycaemic agent, metformin (Met), was studied with the idea of recommending its use in the event that Met alone is unable to contain the negative effects of DM on the male reproductive system in mind. Male Sprague-Dawley rats were either gavaged distilled water (normoglycaemic control and diabetic control groups), MP (diabetic rats on MP), Met (diabetic rats on Met) or MP+Met (diabetic rats on MP+Met), for 4 weeks. MP decreased oxidative stress by up-regulating (p < 0.05) testicular mRNA levels of nuclear factor erythroid 2-related factor 2, superoxide dismutase, catalase and glutathione peroxidase; increasing (p < 0.05) the activities of antioxidant enzymes; and decreasing (p < 0.05) lipid peroxidation in the testes and epididymis of diabetic rats. Further, MP down-regulated (p < 0.05) testicular mRNA and protein levels of pro-inflammatory mediators (nuclear factor kappa B, inducible nitric oxide synthase, tumour necrosis factor-α and interleukin (IL)-1β), decreased (p < 0.05) the nitric oxide level, and increased (p < 0.05) IL-10 mRNA and protein levels. MP also down-regulated (p < 0.05) Bax/Bcl-2, p53, casapase-8, caspase-9 and caspase-3 genes, and increased (p < 0.05) testicular germ cell proliferation. MP's effects were comparable to Met. However, the best results were achieved following co-administration of MP and Met. Therefore, we concluded that administration of the MP+Met combination better attenuates testicular oxidative stress, inflammation and apoptosis in DM, relative to MP or Met monotherapy, and may improve the fertility of males with DM.

Dynamic thiol/disulfide homeostasis and oxidant status in patients with hypoparathyroidism

Background

In this study, we aimed at determining the dynamic thiol/disulfide homeostasis and oxidant balance, and investigating the relation of these parameters to the severity of the disease and the serum calcium levels.

Methods

55 patients with iatrogenic hypoparathyroidism follow-ups and 40 healthy volunteers were included in the study. The blood dynamic thiol/sulfide balance, Total Antioxidant Status (TAS), Total Oxidant Status (TOS), Paraoxonase Enzyme Activity (PON) levels were measured in serum samples.

Results

In our study, it was found that the disulfide, disulfide/native thiol, disulfide/total thiol levels were higher in the hypoparathyroidism group. A negative correlation was found between 25-hydroxy vitamin D (25-OH vitamin D) and disulfide, disulfide/native thiol and disulfide/total thiol, and a positive correlation was found between native thiol and total thiol ratio; and the corrected calcium levels and PON levels were negatively correlated.

Conclusions

Consequently, a change in favour of disulfide was found in the dynamic thiol-disulfide homeostasis in the hypoparathyroidism group in our study.

Insights on the Use of α-Lipoic Acid for Therapeutic Purposes

α-lipoic acid (ALA, thioctic acid) is an organosulfur component produced from plants, animals, and humans. It has various properties, among them great antioxidant potential and is widely used as a racemic drug for diabetic polyneuropathy-associated pain and paresthesia. Naturally, ALA is located in mitochondria, where it is used as a cofactor for pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase complexes. Despite its various potentials, ALA therapeutic efficacy is relatively low due to its pharmacokinetic profile. Data suggests that ALA has a short half-life and bioavailability (about 30%) triggered by its hepatic degradation, reduced solubility as well as instability in the stomach. However, the use of various innovative formulations has greatly improved ALA bioavailability. The R enantiomer of ALA shows better pharmacokinetic parameters, including increased bioavailability as compared to its S enantiomer. Indeed, the use of amphiphilic matrices has capability to improve ALA bioavailability and intestinal absorption. Also, ALA's liquid formulations are associated with greater plasma concentration and bioavailability as compared to its solidified dosage form. Thus, improved formulations can increase both ALA absorption and bioavailability, leading to a raise in therapeutic efficacy. Interestingly, ALA bioavailability will be dependent on age, while no difference has been found for gender. The present review aims to provide an updated on studies from preclinical to clinical trials assessing ALA's usages in diabetic patients with neuropathy, obesity, central nervous system-related diseases and abnormalities in pregnancy.

Hyperglycemia exacerbates acetaminophen-induced acute liver injury by promoting liver-resident macrophage proinflammatory response via AMPK/PI3K/AKT-mediated oxidative stress

Although diabetes mellitus/hyperglycemia is a risk factor for acute liver injury, the underlying mechanism remains largely unknown. Liver-resident macrophages (Kupffer cells, KCs) and oxidative stress play critical roles in the pathogenesis of toxin-induced liver injury. Here, we evaluated the role of oxidative stress in regulating KC polarization against acetaminophen (APAP)-mediated acute liver injury in a streptozotocin-induced hyperglycemic murine model. Compared to the controls, hyperglycemic mice exhibited a significant increase in liver injury and intrahepatic inflammation. KCs obtained from hyperglycemic mice secreted higher levels of the proinflammatory factors, such as TNF-α and IL-6, lower levels of the anti-inflammatory factor IL-10. Furthermore, enhanced oxidative stress was revealed by increased levels of reactive oxygen species (ROS) in KCs from hyperglycemic mice post APAP treatment. In addition, ROS inhibitor NAC resulted in a significant decrease of ROS production in hyperglycemic KCs from mice posttreated with APAP. We also analyzed the role of hyperglycemia in macrophage M1/M2 polarization. Interestingly, we found that hyperglycemia promoted M1 polarization, but inhibited M2 polarization of KCs obtained from APAP-exposed livers, as evidenced by increased MCP-1 and inducible NO synthase (iNOS) gene induction but decreased Arg-1 and CD206 gene induction accompanied by increased STAT1 activation and decreased STAT6 activation. NAC restored Arg-1, CD206 gene induction, and STAT6 activation. To explore the mechanism how hyperglycemia regulates KCs polarization against APAP-induced acute liver injury, we examined the AMPK/PI3K/AKT signaling pathway and found decreased AMPK activation and increased AKT activation in liver and KCs from hyperglycemic mice post APAP treatment. AMPK activation by its agonist AICAR or PI3K inhibition by its antagonist LY294002 inhibited ROS production in KCs from hyperglycemic mice post APAP treatment and significantly attenuated APAP-induced liver injury in the hyperglycemic mice, compared to the control mice. Our results demonstrated that hyperglycemia exacerbated APAP-induced acute liver injury by promoting liver-resident macrophage proinflammatory response via AMPK/PI3K/AKT-mediated oxidative stress.

Aldose reductase regulates hyperglycemia-induced HUVEC death via SIRT1/AMPK-α1/mTOR pathway

Although hyperglycemia-mediated death and dysfunction of endothelial cells have been reported to be a major cause of diabetes associated vascular complications, the mechanisms through which hyperglycemia cause endothelial dysfunction is not well understood. We have recently demonstrated that aldose reductase (AR, AKR1B1) is an obligatory mediator of oxidative and inflammatory signals induced by growth factors, cytokines and hyperglycemia. However, the molecular mechanisms by which AR regulates hyperglycemia-induced endothelial dysfunction is not well known. In this study, we have investigated the mechanism(s) by which AR regulates hyperglycemia-induced endothelial dysfunction. Incubation of human umbilical vein endothelial cells (HUVECs) with high glucose (HG) decreased the cell viability and inhibition of AR prevented it. Further, AR inhibition prevented the HG-induced ROS generation and expression of BCL-2, BAX and activation of Caspase-3 in HUVECs. AR inhibition also prevented the adhesion of THP-1 monocytes on HUVECs, expression of iNOS and eNOS and adhesion molecules ICAM-1 and VCAM-1 in HG-treated HUVECs. Further, AR inhibition restored the HG-induced depletion of SIRT1 in HUVECs and increased the phosphorylation of AMPKα1 along-with a decrease in phosphorylation of mTOR in HG-treated HUVECs. Fidarestat decreased SIRT1 expression in HUVECs pre-treated with specific SIRT1 inhibitor but not with the AMPKα1 inhibitor. Similarly, knockdown of AR in HUVECs by siRNA prevented the HG-induced HUVECs cell death, THP-1 monocyte adhesion and SIRT1 depletion. Furthermore, fidarestat regulated the phosphorylation of AMPKα1 and mTOR, and expression of SIRT1 in STZ-induced diabetic mice heart and aorta tissues. Collectively, our data suggest that AR regulates hyperglycemia-induced endothelial death and dysfunction by altering the ROS/SIRT1/AMPKα1/mTOR pathway.

Inositol and antioxidant supplementation: Safety and efficacy in pregnancy

Pregnancies complicated by diabetes have largely increased in number over the last 50 years. Pregnancy is characterized by a physiologic increase in insulin resistance, which, associated with increased oxidative stress and inflammations, could induce alterations of glucose metabolism and diabetes. If not optimally controlled, these conditions have a negative impact on maternal and foetal outcomes. To date, one can resort only to diet and lifestyle to treat obesity and insulin resistance during pregnancy, and insulin remains the only therapeutic option to manage diabetes during pregnancy. However, in the last years, in a variety of experimental models, inositol and antioxidants supplementation have shown insulin-sensitizing, anti-inflammatory, and antioxidant properties, which could be mediated by some possible complementary mechanism of action. Different isomers and multiple combinations of these compounds are presently available: Aim of the present review article is to examine the existing evidence in order to clarify and/or define the effects of different inositol- and antioxidant-based supplements during pregnancy complicated by insulin resistance and/or by diabetes. This could help the clinician's evaluation and choice of the appropriate supplementation regimen.

Obeticholic acid protects against diabetic cardiomyopathy by activation of FXR/Nrf2 signaling in db/db mice

Diabetic cardiomyopathy (DCM) is one of the major cardiac complications in diabetic patients and a major reason for the death of diabetic patients. Obeticholic acid (OCA) is a semi-synthetic bile acid analogue. The objective of the present study was to investigate the possible cardio-protective effect of OCA against DCM. db/db diabetic mice were given OCA with or without injection of LV-short hairpin farnesoid X receptor (shFXR), and general glucose and lipid metabolism, myocardial morphology and function, myocardial fibrosis, inflammation and oxidative stress were evaluated. We found that OCA significantly ameliorated metabolic dysfunctions. Moreover, OCA attenuated morphological injury of cardiac tissue, restored the abnormal changes of hemodynamic variables and echocardiographic parameters. The Sirius-Red staining of cardiac tissue and mRNA expression of fibrotic biomarkers, including connective tissue growth factor, osteopontin, Transforming growth factor-β1, atrial natriuretic peptide, Collagen Ⅰ, and Collagen Ⅲ were decreased by OCA. Systemic levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were reduced by OCA. Moreover, OCA decreased oxidant products and increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression and the expression and activities of antioxidant enzymes. Injection of LV-shFXR downregulated FXR expression and inhibited all these beneficial effects of OCA. FXR is major target that mediated that beneficial effect of OCA. In summary, FXR/Nrf2 signaling was involved in OCA-induced amelioration of metabolic disorder, oxidative stress, inflammation, fibrosis and myocardial dysfunction. Our findings provide new evidence for the interaction of FXR and Nrf2 signaling and novel option for the intervention of DCM.

Alkaline Ceramidase Mediates the Oxidative Stress Response in Drosophila melanogaster Through Sphingosine

Alkaline ceramidase (Dacer) in Drosophila melanogaster was demonstrated to be resistant to paraquat-induced oxidative stress. However, the underlying mechanism for this resistance remained unclear. Here, we showed that sphingosine feeding triggered the accumulation of hydrogen peroxide (H2O2). Dacer-deficient D. melanogaster (Dacer mutant) has higher catalase (CAT) activity and CAT transcription level, leading to higher resistance to oxidative stress induced by paraquat. By performing a quantitative proteomic analysis, we identified 79 differentially expressed proteins in comparing Dacer mutant to wild type. Three oxidoreductases, including two cytochrome P450 (CG3050, CG9438) and an oxoglutarate/iron-dependent dioxygenase (CG17807), were most significantly upregulated in Dacer mutant. We presumed that altered antioxidative activity in Dacer mutant might be responsible for increased oxidative stress resistance. Our work provides a novel insight into the oxidative antistress response in D. melanogaster.

Dietary (-)-epicatechin affects NF-κB activation and NADPH oxidases in the kidney cortex of high-fructose-fed rats

Inflammation involves the activation of redox-sensitive transcription factors, e.g., nuclear factor κB (NF-κB). Administration of (-)-epicatechin to high-fructose-fed rats prevented NF-κB activation and up-regulation of the NADPH oxidase 4 (NOX4) in the kidney cortex. These results add mechanistic insights into the action of (-)-epicatechin diminishing inflammatory responses.

Correlation of Oxidative Stress Biomarkers and Hematological Parameters in Blood Cancer Patients from Sardinia, Italy

Background: Over the last few decades, there has been a dramatic increase in hematological malignancies (HMs) in the population of Sardinia. It is accepted that oxidative stress biomarkers have been demonstrated to be prognostically important in various neoplastic diseases. The aim of this study is to evaluate serum vitamin E, total antioxidant capacity (TAC), Malondialdehyde (MDA) and reactive oxygen species (ROS) levels in 80 Sardinian patients with different HMs [acute myeloid leukemia (AML)(n=20), myelodysplastic syndromes (MDS) (n=20), Hodgkin lymphoma (HL) (n=20) and non-Hodgkin lymphoma (NHL) (n=20)] on the day of their diagnosis. Materials and Methods: Samples from all participants were obtained after an overnight fast (at least 10 hours). This study was approved and conducted in accordance with Good Clinical Practice guidelines and the Declaration of Helsinki. Patients and controls provided written, informed consent before entering the study. All study participants' medical history and their medication were documented upon enrolling. Results: Lower levels of TAC and Vitamin E were observed in most of the studied groups compared to healthy controls (0.41-0.49 mmol/L vs. 0.56 mmol/L) (19.55-28.55 μmol/L vs. 34.51 μmol/L). Moreover, higher average MDA levels were observed in HL and NHL patients compared to healthy controls (16.6 ng/ml-17.8 ng/ml vs. 7.4 ng/ml). Additionally, the ROS values of all studied groups were found elevated. Serum TAC showed significant negative correlations with MDA values (R= -0.51; P<0.001). Statistical significance was observed in all hematological parameters, producing either positive or negative correlation with at least one OS biomarker. Conclusion: The present data suggest that Sardinian patients with HL and NHL on the day of their diagnosis presented the highest OS in comparison to AML and healthy subjects. Moreover, MDS patients presented high OS status. Likewise, our results also indicated that changes in their hematological indices are eminent of their oxidative and antioxidative status.

Evaluation of a flavonoids library for inhibition of pancreatic α-amylase towards a structure-activity relationship

α-Amylase has been considered an important therapeutic target for the management of type 2 diabetes mellitus (T2DM), decreasing postprandial hyperglycaemia (PPHG). In the present work, a panel of 40 structurally related flavonoids was tested, concerning their ability to inhibit α-amylase activity, using a microanalysis screening system, an inhibitory kinetic analysis and molecular docking calculations. From the obtained results, it was possible to observe that the flavone with a -Cl ion at 3-position of C-ring, an –OH group at 3′- and 4′- positions of B-ring and at 5- and 7- positions of A-ring and the C2 = C3 double bond, was the most active tested flavonoid, through competitive inhibition. In conclusion, some of the tested flavonoids have shown promising inhibition of α-amylase and may be considered as possible alternatives to the modulation of T2DM.

Oxidative stress and DNA damage in peripheral blood mononuclear cells from normal, obese, prediabetic and diabetic persons exposed to adrenaline in vitro

Diabetes represents one of the major health concerns, especially in developed countries. Some hormones such as the stress hormone adrenaline can induce reactive oxygen species (ROS) and may worsen the diabetes. Therefore, the main aim of the investigation was to find out whether peripheral blood mononuclear cells (PBMCs) from normal persons have less DNA damage induced by adrenaline (0.1, 1 and 10 μM) in comparison to PBMCs from obese, prediabetic and diabetic patients. Also, the biochemical parameters of oxidative stress (TBARS, catalase) and lactate dehydrogenase were monitored. It was observed that higher concentrations of adrenaline (1 and 10 μM) induced DNA damage in the obese, prediabetic and diabetic groups. In healthy individuals only the highest concentration of adrenaline caused significant increase in the DNA damage. In summary, total comet score (TCS) comparison has shown significant differences between groups, and DNA damaging effects of adrenaline were most evident in diabetic patients. The results of the biochemical analysis also demonstrate that adrenaline exerts most obvious effects in diabetic individuals which is manifested as significant change of parameters of oxidative stress. In summary, the obtained results demonstrated that diabetics are more sensitive to genotoxic effects of adrenaline and this effect probably resulted from decreased antioxidative defence mechanisms in various stages of progression through diabetes. Therefore, these results could contribute to a better understanding of a role of endocrine factors to damage of cellular biomolecules which could be useful in finding novel therapeutic approaches and lifestyle changes with an aim to lower the possibility of diabetes complications.

ROS- and HIF1α-dependent IGFBP3 upregulation blocks IGF1 survival signaling and thereby mediates high-glucose-induced cardiomyocyte apoptosis

The prevalence of chronic hyperglycemia and its complications, imposing a critical burden on the worldwide economy and the global healthcare system, is a pressing issue. Mounting evidence indicates that oxidative stress and hypoxia, two noticeable features of hyperglycemia, play a joint crucial role in mediating cellular apoptosis. However, the underlying detailed molecular mechanism remains elusive. Triggered by the observation that insulin-like growth factor (IGF1)-binding protein 3 (IGFBP3) can mediate, in renal cells, high-glucose-induced apoptosis by elevating oxidative stress, we wish to, in this study, know whether or not the similar scenario holds in cardiac cells and, if so, to find its relevant molecular key players, thereby dissecting the underlying molecular pathway. Specifically, we used a combination of three different cellular sources (H9c2 cells, diabetic rats, and neonatal rat ventricular cardiomyocytes) as our model systems of study. We made use of Co-IP assay and western blot analysis in conjunction with loss-of-function reasoning, gain-of-function logic, and inhibitor treatment as our main analytical tools. As a result, briefly, our main findings are that hyperglycemia can induce cardiac IGFBP3 overexpression and secretion, that high levels of IGFBP3 can sequester IGF1 from IGF1 survival pathway, leading to apoptosis, and that IGFBP3 gene upregulation is hypoxia-inducible factor (HIF)1α-dependent and reactive oxygen species dependent. Piecing these findings together allows us to propose the improved molecular regulatory mechanism. In conclusion, we have established the molecular roles of IGFBP3, HIF1, and prolyl hydroxylase domain in connecting oxidative stress with hypoxia and in cellular apoptosis under hyperglycemia.

Therapeutic Options Targeting Oxidative Stress, Mitochondrial Dysfunction and Inflammation to Hinder the Progression of Vascular Complications of Diabetes

Type 2 diabetes mellitus is a leading cause of morbidity and mortality worldwide, given its serious associated complications. Despite constant efforts and intensive research, an effective, ubiquitous treatment still eludes the scientific community. As such, the identification of novel avenues of research is key to the potential discovery of this evasive "silver bullet." We focus on this review on the matter of diabetic injury to endothelial tissue and some of the pivotal underlying mechanisms, including hyperglycemia and hyperlipidemia evoked oxidative stress and inflammation. In this sense, we revisited the most promising therapeutic interventions (both non-pharmacological and antidiabetic drugs) targeting oxidative stress and inflammation to hinder progression of vascular complications of diabetes. This review article gives particular attention to the relevance of mitochondrial function, an often ignored and understudied organelle in the vascular endothelium. We highlight the importance of mitochondrial function and number homeostasis in diabetic conditions and discuss the work conducted to address the aforementioned issue by the use of various therapeutic strategies. We explore here the functional, biochemical and bioenergetic alterations provoked by hyperglycemia in the endothelium, from elevated oxidative stress to inflammation and cell death, as well as loss of tissue function. Furthermore, we synthetize the literature regarding the current and promising approaches into dealing with these alterations. We discuss how known agents and therapeutic behaviors (as, for example, metformin, dietary restriction or antioxidants) can restore normality to mitochondrial and endothelial function, preserving the tissue's function and averting the aforementioned complications.