High glucose increases nitric oxide synthase expression and superoxide anion generation in human aortic endothelial cells

Nanoparticle-mediated delivery of tetrahydrobiopterin restores endothelial function in diabetic rats

Endothelial dysfunction, underlying the vascular complications of diabetes and other cardiovascular disorders, may result from uncoupling of endothelial nitric oxide synthase (eNOS) activity due to decreased levels of tetrahydrobiopterin (BH4), a critical co-factor for eNOS. Some clinical trials attempting to deliver exogenous BH4 as a potential therapeutic strategy in vascular disease states have failed due to oxidation of BH4 in the circulation. We sought to develop a means of protecting BH4 from oxidation while delivering it to dysfunctional endothelial cells. Polymeric and solid lipid nanoparticles (NPs) loaded with BH4 were delivered by injection or oral gavage, respectively, to streptozotocin-induced diabetic rats. BH4 was measured in coronary endothelial cells and endothelium-dependent vascular reactivity was assessed in vascular rings. Lymphatic uptake of orally delivered lipid NPs was verified by sampling mesenteric lymph. BH4-loaded polymeric NPs maintained nitric oxide production by cultured endothelial cells under conditions of oxidative stress. BH4-loaded NPs, delivered via injection or ingestion, increased coronary endothelial BH4 concentration and improved endothelium-dependent vasorelaxation in diabetic rats. Pharmacodynamics assessment indicated peak concentration of solid lipid NPs in the systemic bloodstream 6 hours after ingestion, with disappearance noted by 48 hours. These studies support the feasibility of utilizing NPs to deliver BH4 to dysfunctional endothelial cells to increase nitric oxide bioavailability. BH4-loaded NPs could provide an innovative tool to restore redox balance in blood vessels and modulate eNOS-mediated vascular function to reverse or retard vascular disease in diabetes.

Exploring the therapeutic potential of tetrahydrobiopterin for heart failure with preserved ejection fraction: A path forward

A large number of patients are affected by classical heart failure (HF) symptomatology with preserved ejection fraction (HFpEF) and multiorgan syndrome. Due to high morbidity and mortality rate, hospitalization and mortality remain serious socioeconomic problems, while the lack of effective pharmacological or device treatment means that HFpEF presents a major unmet medical need. Evidence from clinical and basic studies demonstrates that systemic inflammation, increased oxidative stress, and impaired mitochondrial function are the common pathological mechanisms in HFpEF. Tetrahydrobiopterin (BH4), beyond being an endogenous co-factor for catalyzing the conversion of some essential biomolecules, has the capacity to prevent systemic inflammation, enhance antioxidant resistance, and modulate mitochondrial energy production. Therefore, BH4 has emerged in the last decade as a promising agent to prevent or reverse the progression of disorders such as cardiovascular disease. In this review, we cover the clinical progress and limitations of using downstream targets of nitric oxide (NO) through NO donors, soluble guanylate cyclase activators, phosphodiesterase inhibitors, and sodium-glucose co-transporter 2 inhibitors in treating cardiovascular diseases, including HFpEF. We discuss the use of BH4 in association with HFpEF, providing new evidence for its potential use as a pharmacological option for treating HFpEF.

Attenuation of cannabis withdrawal symptoms by Prosopis farcta extract, its luteolin and melatonin in mice: Involvement of brain-derived neurotrophic factor and dopamine

The aim of this study was the identification of luteolin in Prosopis farcta extract (PFE) and melatonin to evaluate its effect on THC withdrawal syndrome in mice. Luteolin was identified by high-performance liquid chromatography (HPCL). Signs of toxicity of mice in PFE and luteolin were monitored for LD50 calculation. The behavioral symptoms of THC withdrawal (stereotypies, ambulation, and inactivity time) induced by the rimonabant challenge were illustrated in THC-dependent mice receiving PFE, luteolin, and melatonin. The expression of mature BDNF (mBDNF) was evaluated by Western blot analysis. The dopamine concentrations were measured using HPLC. PFE and luteolin LD50 were 650 and 220 mg/kg, respectively. PFE (300 mg/kg), all doses of luteolin, and melatonin increased significantly the mBDNF expression and decreased the dopamine concentration. The findings suggest that PFE, luteolin, and melatonin are mighty in reducing the signs of THC withdrawal. It seems these effects were due to a decrease in dopamine concentration level and an increase in mBDNF protein expression in mice brains.

Association between maternal diet, smoking, and the placenta MTHFR 677C/T genotype and global placental DNA methylation

INTRODUCTION

The placenta provides nutrients to the fetus, and it has protective effects against harmful substances. Unhealthy maternal diets and toxic agents might increase free radical (FR) production. Elevated FR levels are associated with a high risk of oxidative stress, which may cause DNA damage. DNA might be oxidized in the placenta, occasionally affecting its methylation profile due to 8-hidroxy-2'-deoxyguanosine formation.

METHODS

This study assessed 130 mothers and their children. The maternal's nutritional patterns were determined using the Food Frequency Questionnaire. Information on smoking and alcohol consumption was collected during the medical examination. Data on placental DNA were obtained to determine the MTHFR 677C/T genotype and the proportion of placental DNA methylation (pDNAm).

RESULTS

Consumption of vitamins and folic acid was above 85%. The pDNAm was found to be correlated with gestational age and coffee intake. Mothers with a smoking history had a low pDNAm. Placentas with the TT genotype had a higher but not significant pDNAm. In the placentas with the CC/CT genotype, the pDNAm was positively associated with carbohydrate and biotin intake. However, the TT genotype was negatively associated with folate and vegetable intake.

DISCUSSION

The pDNAm was positively associated with coffee intake, but not with macro-, and micronutrient intake. However, it was negatively associated with cigarette smoking. The placentas with the CC/CT genotype had a lower pDNAm than those with the TT genotype. In the placentas with the CC/CT or TT genotype, methylation was positively, and negatively associated with micro- or macronutrients, respectively.

Diabetes Modulates Iodothyronine Deiodinase 2 Expression in the Mouse Retina: A Role for Thyroid Hormone in the Pathogenesis of Diabetic Retinopathy

Purpose

Clinical investigations associate hypothyroidism with an increased risk for microvascular complications, yet the mechanism by which thyroid hormone regulates the development of diabetic retinopathy is not clearly understood. We investigated the role of iodothyronine deiodinase 2 (DIO2) in the pathogenesis of diabetic retinopathy.

Methods

Retinas from streptozotocin-induced diabetic and nondiabetic mice were evaluated by RNA sequencing, RT-PCR, and immunostaining. Media and cell lysates from mouse retinal microvascular endothelial cells and retinal astrocytes exposed to physiologic (5 mM) and high glucose (25 mM) containing media were assessed by liquid chromatography-tandem mass spectrometry to measure tetraiodothyronine (T4) and tri-iodothyronine (T3) concentrations and by Western blot analysis to determine the relationship of T4/T3 to oxidative stress and inflammatory mediators. Cell death was determined by Trypan Blue exclusion assay.

Results

At 12 weeks of diabetes duration, retinas from diabetic mice compared with nondiabetic mice demonstrated a significant decrease in Dio2 transcripts and Dio2 gene and protein (P < 0.05) expression. When cultured in the presence of high glucose, both mouse retinal astrocytes and microvascular endothelial cells demonstrated a significant reduction of DIO2 protein compared with cells cultured in physiologic glucose. High glucose inhibited generation of T3, leading to a significantly increased T4/T3 (P < 0.0079). Supplementation of cells with T3, but not T4, prevented the high glucose-induced rise in endothelial nitric oxide synthase, intercellular cell adhesion molecule 1, and endothelial cell death (P < 0.0079).

Conclusions

Decreased intraretinal T3 owing to diabetes-induced loss of DIO2 may lead to dysfunction and death of cells in the retina, thereby contributing to the pathogenesis of early diabetic retinopathy.

No acute hyperglycemia induced impairment in brachial artery flow-mediated dilation before or after aerobic exercise training in young recreationally active males

There is some evidence that transient endothelial dysfunction induced by acute hyperglycemia may be attenuated by a single bout of aerobic exercise. However, the impact of aerobic exercise training on acute hyperglycemia-induced endothelial dysfunction has not been explored. The purpose of this study was to determine the impact of aerobic exercise training on the endothelial function response to acute hyperglycemia. Brachial artery flow-mediated dilation (FMD) was assessed in 24 healthy males (21 ± 1 years) pre-, 60 and 90 min post ingestion of 75 g of glucose. Participants completed a four-week control (CON; n = 13) or exercise training (EX; n = 11) intervention. The EX group completed four weeks of cycling exercise (30 min, 4×/week at 65% work rate peak). Cardiorespiratory fitness ([Formula: see text]O2peak) increased and resting HR decreased in EX, but not CON post-intervention (p < 0.001). Glucose and insulin increased (p < 0.001) following glucose ingestion, with no significant difference pre- and post-intervention. In contrast to previous research, FMD was unaffected by glucose-ingestion, pre- and post-intervention in both groups. In conclusion, acute hyperglycemia did not impair endothelial function, before or after exercise training. Relatively high baseline fitness ([Formula: see text]O2peak ~ 46 mL/kg/min) and young age may have contributed to the lack of impairment observed. Further research is needed to examine the impact of exercise training on hyperglycemia-induced impairments in endothelial function in sedentary males and females.

Association of the endothelial nitric oxide synthase (eNOS) 4a/b polymorphism with the risk of incident diabetic retinopathy in patients with type 2 diabetes mellitus: a systematic review and updated meta-analysis

OBJECTIVE

To conduct a systematic review and updated meta-analysis on the potential association between endothelial nitric oxide synthase (eNOS) 4a/b polymorphism and the risk of developing diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM) and to identify possible clinical biomarkers for early screening of DR.

MATERIALS AND METHODS

A meta-analysis based on case-control or cross-sectional studies was conducted to examine the correlation between eNOS 4a/b polymorphism and DR. Pooled odds ratio (OR) and 95% confidence interval (CI) were used to estimate the association strength.

RESULTS

We included 19 studies, covering 7838 subjects. An association was observed in Caucasians (allelic model: OR = 1.273, 95% CI: 1.006-1.610, p = .045; recessive model: OR = 0.575, 95% CI: 0.371-0.892, p = .014; dominant model: OR = 1.268, 95% CI: 1.052-1.528, p = .013; homozygote model: OR = 1.833, 95% CI: 1.176-2.856, p = .007). Moreover, population-based studies have indicated an association between eNOS 4a/b polymorphism and DR susceptibility.

CONCLUSIONS

The present study showed that intron 4a allele of eNOS 4a/b is a risk factor for DR in Caucasians with T2DM. Thus, eNOS 4a/b may be used as a biomarker for the early screening and diagnosis of DR in Caucasian T2DM patients.Key messagesEndothelial nitric oxide synthase 4a/b gene polymorphism is not associated with the risk of developing diabetic retinopathy in the overall population, Asians, or Chinese Han patients with type 2 diabetes. However, 4a is a risk factor for the development of diabetic retinopathy in Caucasians.Endothelial nitric oxide synthase 4a/b gene polymorphism is not associated with the type of diabetic retinopathy.

Advanced polymer hydrogels that promote diabetic ulcer healing: mechanisms, classifications, and medical applications

Diabetic ulcers (DUs) are one of the most serious complications of diabetes mellitus. The application of a functional dressing is a crucial step in DU treatment and is associated with the patient's recovery and prognosis. However, traditional dressings with a simple structure and a single function cannot meet clinical requirements. Therefore, researchers have turned their attention to advanced polymer dressings and hydrogels to solve the therapeutic bottleneck of DU treatment. Hydrogels are a class of gels with a three-dimensional network structure that have good moisturizing properties and permeability and promote autolytic debridement and material exchange. Moreover, hydrogels mimic the natural environment of the extracellular matrix, providing suitable surroundings for cell proliferation. Thus, hydrogels with different mechanical strengths and biological properties have been extensively explored as DU dressing platforms. In this review, we define different types of hydrogels and elaborate the mechanisms by which they repair DUs. Moreover, we summarize the pathological process of DUs and review various additives used for their treatment. Finally, we examine the limitations and obstacles that exist in the development of the clinically relevant applications of these appealing technologies. This review defines different types of hydrogels and carefully elaborate the mechanisms by which they repair diabetic ulcers (DUs), summarizes the pathological process of DUs, and reviews various bioactivators used for their treatment.

Unearthing of the Antidiabetic Potential of Aqueous Extract of Solanum betaceum Cav. Leaves

Solanum betaceum Cav., commonly known as tamarillo or Brazilian tomato, belongs to the Solanaceae family. Its fruit is used in traditional medicine and food crops due to its health benefits. Despite the numerous studies involving the fruit, there is no scientific knowledge about the tamarillo tree leaves. In this work, the phenolic profile of aqueous extract obtained from S. betaceum leaves was unveiled for the first time. Five hydroxycinnamic phenolic acids were identified and quantified, including 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, chlorogenic acid, caffeic acid and rosmarinic acid. While the extract displayed no effect on α-amylase, the extract inhibited the activity of α-glucosidase (IC₅₀ = 1617 mg/mL), and it was particularly effective for human aldose reductase (IC₅₀ = 0.236 mg/mL): a key enzyme in glucose metabolism. Moreover, the extract exhibited interesting antioxidant properties, such as a potent capacity to intercept the in vitro-generated reactive species O₂^•- (IC₅₀ = 0.119 mg/mL) and ^•NO (IC₅₀ = 0.299 mg/mL), as well as to inhibit the first stages of lipid peroxidation (IC₅₀ = 0.080 mg/mL). This study highlights the biological potential of S. betaceum leaves. The scarcity of research on this natural resource underscores the need for additional studies in order to fully explore its antidiabetic properties and to promote the value of a species currently at risk of extinction.

Hyperglycemic control in acute ischemic stroke patients undergoing endovascular treatment: post hoc analysis of the Stroke Hyperglycemia Insulin Network Effort trial

BACKGROUND

Hyperglycemia has been associated with poor outcomes in acute ischemic stroke patients undergoing endovascular treatment. We analyzed the effect of intensive glucose control on death and disability rates in patients with acute ischemic stroke undergoing endovascular treatment.

METHODS

We analyzed the effect of intensive (serum glucose <110 mg/dL) glucose treatment (compared with standard treatment, serum glucose <180 mg/dL) in patients who received endovascular treatment in the Stroke Hyperglycemia Insulin Network Effort (SHINE) trial. We further analyzed the effect of area under the curve (AUC) of serum glucose, proportion of the time blood glucose was <140 mg/dL, and glucose variability defined as the glucose range during 72 hours. The primary outcomes were neurological deterioration within 72 hours and outcome at 90 days.

RESULTS

A total of 146 patients (mean age 68.1±13.9 years, 50.7% men) underwent endovascular treatment for acute ischemic stroke; 72 and 74 patients were randomized to intensive and standard treatments, respectively. The rates of death (20.3% and 22.2%), favorable 90-day primary outcome (17.6% and 19.4%), and serious adverse events (41.9% and 56.98%) were similar between the two groups. The AUC of serum glucose was not associated with death within 90 days (OR 1, 95% CI 1 to 1) or favorable outcome at 90 days (OR 1, 95% CI 1 to 1). Glucose variability was not associated with death or favorable outcome at 90 days.

CONCLUSION

We did not identify any beneficial effect of intensive glucose reduction on rates of death or favorable outcomes at 90 days among acute ischemic stroke patients undergoing endovascular treatment.

Early Detection Is the Best Prevention-Characterization of Oxidative Stress in Diabetes Mellitus and Its Consequences on the Cardiovascular System

Previous studies demonstrated an important role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) in diabetic patients due to hyperglycemia. CVD remains the leading cause of premature death in the western world. Therefore, diabetes mellitus-associated oxidative stress and subsequent inflammation should be recognized at the earliest possible stage to start with the appropriate treatment before the onset of the cardiovascular sequelae such as arterial hypertension or coronary artery disease (CAD). The pathophysiology comprises increased reactive oxygen and nitrogen species (RONS) production by enzymatic and non-enzymatic sources, e.g., mitochondria, an uncoupled nitric oxide synthase, xanthine oxidase, and the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). Considering that RONS originate from different cellular mechanisms in separate cellular compartments, adequate, sensitive, and compartment-specific methods for their quantification are crucial for early detection. In this review, we provide an overview of these methods with important information for early, appropriate, and effective treatment of these patients and their cardiovascular sequelae.

A cross-sectional study to correlate antioxidant enzymes, oxidative stress and inflammation with prevalence of hypertension

AIMS

Hypertension a multifactorial consequence of environmental factors, life style and genetics is the well-recognized risk factor contributing to coronary heart diseases. The antioxidant imbalance, excessive reactive oxygen species (ROS) leads to oxidative stress which is pivotal in progression of hypertension. The present study aims to understand the complex interaction between oxidative stress, inflammation and antioxidant system which is crucial to maintain cellular homeostasis which further can exaggerate hypertension pathophysiology.

MATERIALS AND METHODS

The metabolic profile of hypertensive and normotensive subjects from Malwa region, Punjab was compared by estimating lipid profile, cardiac, hepatic and renal markers. The oxidative stress markers (protein carbonyls and lipid peroxidation), inflammatory markers (Nitric oxide, Myeloperoxidase and advanced oxygen protein products), and antioxidant enzymes (Superoxide Dismutase, Catalase, and Total Antioxidant Capacity) were analyzed.

KEY FINDINGS

It is observed that the metabolic markers are altered in hypertensive subjects which further these subjects showed increased oxidative, inflammatory profile and compromised antioxidant status when compared with normotensive subjects. Co-relation analysis validated the involvement of inflammation and oxidative stress in impaired endothelial function and vital organ damage.

SIGNIFICANCE OF STUDY

These markers may act as early indicators of hypertension which usually do not show any physical symptoms, thus can be diagnosed and treated at the earliest. The current study suggests that disturbed homeostasis, a consequence of altered interaction between antioxidant system and inflammatory events raises the oxidative stress levels which eventually leads to hypertension and associated complications. These indicators can serve as early indicators of future chronic complications of hypertension.

Oxidative Regulation of Vascular Cav1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders

Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca²⁺ (Ca_v1.2) channel in small arteries and arterioles plays an essential role in regulating Ca²⁺ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Ca_v1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Ca_v1.2 and potential roles of ROS-mediated Ca_v1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.

In Vitro Modeling of Diabetes Impact on Vascular Endothelium: Are Essentials Engaged to Tune Metabolism?

Angiopathy is a common complication of diabetes mellitus. Vascular endothelium is among the first targets to experience blood-borne metabolic alterations, such as hyperglycemia and hyperlipidemia, the hallmarks of type 2 diabetes. To explore mechanisms of vascular dysfunction and eventual damage brought by these pathologic conditions and to find ways to protect vasculature in diabetic patients, various research approaches are used including in vitro endothelial cell-based models. We present an analysis of the data available from these models that identifies early endothelial cell apoptosis associated with oxidative stress as the major outcome of mimicking hyperglycemia and hyperlipidemia in vitro. However, the fate of endothelial cells observed in these studies does not closely follow it in vivo where massive endothelial damage occurs mainly in the terminal stages of diabetes and in conjunction with comorbidities. We propose that the discrepancy is likely in missing essentials that should be available to cultured endothelial cells to adjust the metabolic state and withstand the immediate apoptosis. We discuss the role of carnitine, creatine, and AMP-activated protein kinase (AMPK) in suiting the endothelial metabolism for long-term function in diabetic type milieu in vitro. Engagement of these essentials is anticipated to expand diabetes research options when using endothelial cell-based models.

Methylglyoxal-Modified Human Serum Albumin Binds to Leukocyte Myeloperoxidase and Inhibits its Enzymatic Activity

Hyperglycemia in diabetes mellitus induces modification of proteins by glucose and its derivative methylglyoxal (MG). Neutrophils perform their bactericidal activity mainly via reactive halogen (RHS) and oxygen (ROS) species generation catalyzed by myeloperoxidase (MPO) stored in neutrophil azurophilic granules (AGs) and membrane NADPH oxidase, respectively. Herein, we study the binding of human serum albumin (HSA) modified with MG (HSA-MG) to MPO and its effects on MPO activity and release by neutrophils. Peroxidase activity of MPO was registered by oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, and chlorinating activity by decolorization of Celestine blue B dye. Binding of HSA-MG to MPO was studied by affinity chromatography, disc-electrophoresis, ligand Western blotting and enzyme-linked solid phase immunoassay using monoclonal antibodies (mAbs) to MPO. ROS and RHS generation were detected by lucigenin (Luc) and luminol (Lum) chemiluminescence (CL), respectively. Neutrophil degranulation was assessed by flow cytometry using fluorescent labeled antibodies to the marker proteins CD63 from AGs and CD11b from peroxidase-negative granules (PNGs). NETosis was assayed by quantifying DNA network-like structures (NET-like structures) in blood smears stained by Romanowsky. HSA-MG bound to MPO, giving a stable complex (Kd = 1.5 nM) and competing with mAbs, and non-competitively inhibited peroxidase and chlorinating MPO activity and induced degranulation of PNGs but not of AGs. HSA-MG enhanced Luc-CL per se or following PMA, unlike Lum-CL, and did not affect spontaneous or PMA-stimulated NETosis. Thus, HSA modified under hyperglycemia-like conditions stimulated NADPH oxidase of neutrophils but dampened their functions dependent on activity of MPO, with no effect on its release via degranulation or NETosis. This phenomenon could underlie the downregulation of bactericidal activity of MPO and neutrophils, and hence of innate immunity, giving rise to wound healing impairment and susceptibility to infection in patients with hyperglycemia.

The Ultrastructure of Skeletal Muscle Capillaries of Streptozotocin Diabetic Rats and the Therapeutic Effect of Benfluorex

Diabetes mellitus is a serious disease worldwide and causes other associated diseases. In this study, we observed the effect of streptozotocin (STZ)-induced diabetes and benfluorex treatment on muscular capillary ultrastructure. Adult male rats were used as the test subjects and each individual was intraperitoneally injected with one dose of STZ (45 mg/kg) to induce diabetes. Doses (50 mg/kg) of benfluorex were given to the subjects with tap water by intragastric gavage application once daily for 21 days. At the end of day 21, muscle tissues were obtained from animals and examined under transmission electron microscopy. From the data obtained with the electron microscope, it was observed that the control group had typical continuous capillary vascular structures in their muscles, while STZ caused disruptive disorder of the muscle cells in the capillary wall of the STZ-diabetic group. Additionally, the thickening of the basement membrane around endothelial cells, loss of mitochondrial crista in the muscle cells, enlarged endothelial cells, and narrowed vessel lumen were observed in the muscle tissue. The findings of our study revealed that STZ-induced diabetes disrupted the vascular structure, while benfluorex partially improved it.

The Problem of Wound Healing in Diabetes—From Molecular Pathways to the Design of an Animal Model

Chronic wounds are becoming an increasingly common clinical problem due to an aging population and an increased incidence of diabetes, atherosclerosis, and venous insufficiency, which are the conditions that impair and delay the healing process. Patients with diabetes constitute a group of subjects in whom the healing process is particularly prolonged regardless of its initial etiology. Circulatory dysfunction, both at the microvascular and macrovascular levels, is a leading factor in delaying or precluding wound healing in diabetes. The prolonged period of wound healing increases the risk of complications such as the development of infection, including sepsis and even amputation. Currently, many substances applied topically or systemically are supposed to accelerate the process of wound regeneration and finally wound closure. The role of clinical trials and preclinical studies, including research based on animal models, is to create safe medicinal products and ensure the fastest possible healing. To achieve this goal and minimize the wide-ranging burdens associated with conducting clinical trials, a correct animal model is needed to replicate the wound conditions in patients with diabetes as closely as possible. The aim of the paper is to summarize the most important molecular pathways which are impaired in the hyperglycemic state in the context of designing an animal model of diabetic chronic wounds. The authors focus on research optimization, including economic aspects and model reproducibility, as well as the ethical dimension of minimizing the suffering of research subjects according to the 3 Rs principle (Replacement, Reduction, Refinement).

The Association of Oxidative and Antioxidant Potential with Cardiometabolic Risk Profile in the Group of 60- to 65-Year-Old Seniors from Central Poland

Pathogenesis of cardiovascular diseases is caused by, inter alia, oxidative stress. On the other hand, cardiovascular risk factors may cause redox imbalance. The pathological pathways between those components are to be determined. In the group comprised of 300 sex-matched subjects, we evaluated a number of cardiovascular risk factors: blood pressure, body mass, lipids, glucose, homocysteine, uric acid, von Willebrand factor (vWF), VCAM-1 and ICAM-1. The presence of cardiovascular diseases and drugs for their treatment were examined. Secondly, we assessed total antioxidative status (TAS), total oxidative status (TOS) and other markers of oxidative stress. TAS was inversely related to LDL cholesterol. TOS was positively associated with BMI and female sex, but negatively associated with the use of angiotensin II receptor antagonists. Plasma lipid peroxides concentration was positively related to ICAM-1 and presence of stroke, whereas platelet lipid peroxides were positively associated with vWF. Platelets proteins thiol groups were in a positive relationship with vWF, but in a negative relationship with uric acid and diagnosed lipid disorders. Both free thiol and amino groups were positively associated with plasma glucose. Platelets free amino groups were related to platelets count. Superoxide generation by blood platelets (both with and without homocysteine) was positively connected to glucose level. Among women, oxidative markers appear to be more related to glucose level, whereas among men they are related to body mass indices. TAS, TOS and oxidative markers are largely related to modifiable cardiovascular risk factors such as body mass, and intake of drugs such as angiotensin II receptor blockers. Plasma and platelet oxidation markers appear to be especially associated with glucose concentration. The presented analyses unanimously indicate strong connections between cardiovascular risk factors and redox potential and specify how cardiometabolic interventions may counter-balance oxidative stress.

Antidiabetic potential of seaweed and their bioactive compounds: a review of developments in last decade

Diabetes Mellitus is a public health problem worldwide due to high morbidity and mortality rate associated with it. Diabetes can be managed by synthetic hypoglycemic drugs, although their persistent uses have several side effects. Hence, there is a paradigm shift toward the use of natural products having antidiabetic potential. Seaweeds, large marine benthic algae, are an affluent source of various bioactive compounds, including phytochemicals and antioxidants thus exhibiting various health promoting properties. Seaweed extracts and its bioactive compounds have antidiabetic potential as they inhibit carbohydrate hydrolyzing enzymes in vitro and exhibit blood glucose lowering effect in random and post prandial blood glucose tests in vivo. In addition, they have been associated with reduced weight gain in animals probably by decreasing mRNA expression of pro-inflammatory cytokines with concomitant increase in mRNA expression levels of anti-inflammatory cytokines. Their beneficial effect has been seen in serum and hepatic lipid profile and antioxidant enzymes indicating the protective role of seaweeds against free radicals mediated oxidative stress induced hyperglycemia and associated hyperlipidemia. However, the detailed and in-depth studies of seaweeds as whole, their bioactive isolates and their extracts need to be explored further for their health benefits and wide application in food, nutraceutical and pharmaceutical industries.

Association Between Insulin Resistance, Oxidative Stress, Sympathetic Activity and Coronary Microvascular Function in Patients With Early Stage Impaired Glucose Metabolism

BACKGROUND

Although acute hyperglycemia and insulin resistance (IR) are risk factors for atherosclerosis development through oxidative stress and sympathetic activation in diabetes mellitus, the association of these factors with coronary microvascular function in the early diabetic stage remains controversial.Methods and Results:Using transthoracic echocardiography, coronary flow velocity (CFV) and its reserve (CFVR) as parameters of coronary microvascular function were measured before and 1 h after an oral glucose tolerance test (OGTT) in 40 patients (aged 59±12 years) without diagnosed diabetes mellitus or coronary artery disease. Plasma glucose, insulin and thiobarbituric acid reactive substance (TBARS; an oxidative stress marker) were measured during the OGTT. IR was evaluated as homeostasis model assessment of IR (HOMA-R). Sympathetic activity was evaluated by using plasma catecholamines after OGTT. CFVR decreased after an OGTT (P<0.0001) mainly because of an increased baseline CFV (P<0.0001). Although the change in CFVR was not associated with the change in TBARS and catecholamines, it was independently associated with HOMA-R on the multivariate regression analysis (β=-0.40, P=0.01). Another multivariate regression analysis revealed that change in baseline CFV was independently associated with HOMA-R (β=0.35, P=0.03).

CONCLUSIONS

IR, rather than oxidative stress and sympathetic activity, was associated with an increase in baseline CFV and a decline in CFVR during acute hyperglycemia. IR might play an important role in increased myocardial oxygen demand and coronary microvascular dysfunction.

The Potential Therapeutic Role of Celastrol in Patients With Heart Failure With Preserved Ejection Fraction

Analysis of left ventricular systolic dysfunction remained at the centre of heart failure research for many years (also known as heart failure with reduced ejection fraction, HFrEF). Although more than 50% of all heart failure patients experience a form of heart failure characterised by preserved ejection fraction (HFpEF), the pathophysiological mechanisms leading to this form of heart failure remain not well-understood. Several evidence-based treatments for HFrEF are in routine use, but there are limited evidence-based therapies for HFpEF. The effects of these remain controversial, with current treatment options being limited to managing the associated symptoms and conditions. Accumulating evidence demonstrates that pro-inflammatory and oxidative stress pathways play key roles in the development and progression of HFpEF, such as the Unfolded Protein Response (UPR) and inducible nitric oxide synthase. Celastrol, derived from medicinal plants, is a bioactive compound with strong anti-inflammatory properties, which could deem it as fruitful in overcoming the effects of such dysregulated UPR. This literature review therefore focuses on Celastrol's anti-inflammatory and antioxidant activities, alongside its other potential therapeutic activities, and its ability to impede the pathways that are thought to be involved in the development of HFpEF, such as the JAK2/STAT pathway, to elucidate the potential therapeutic role of this bioactive compound, in the treatment of HFpEF.

Impact of glucose variability on coronary plaque vulnerability in patients with dysglycemia: A whole coronary analysis with multislice computed tomography

BACKGROUND

Dysglycemia is associated with an increased risk of acute coronary syndrome caused by the disruption of vulnerable plaques. The relationship between glycemic variability (GV), which is a component of impaired glucose metabolism, and coronary plaque vulnerability has not been fully elucidated. This study investigated the impact of GV on whole coronary plaque vulnerability using multislice computed tomography (MSCT).

METHODS

We analyzed 88 patients with dysglycemia who underwent 24 h blood glucose monitoring and MSCT. The mean amplitude of glycemic excursion (MAGE) was calculated as an index of the GV. We defined a CT-derived vulnerable plaque as a plaque with a remodeling index > 1.10 and a mean CT density < 30 HU. We calculated the percentage of low-attenuation plaque (% LAP) as the ratio of the low-attenuation component (CT density < 30HU) volume to the total vessel volume.

RESULTS

Vulnerable plaques were detected in 27 patients (31%). Patients with vulnerable plaques had higher MAGE (110.0 ± 40.7 vs. 71.7 ± 21.7, p < 0.01) than patients without vulnerable plaques. A univariate logistic regression analysis showed that vulnerable plaques were associated with the MAGE [odds ratio (OR) 1.04, 95% confidence interval (CI), 1.02-1.07, p < 0.01]. In a multivariate model, the MAGE (OR 1.05, 95% CI 1.02-1.07) remained a significant predictor of vulnerable plaque presence. Patients with multivessel-vulnerable plaques had higher MAGE values than those with single-vessel involvement or no vulnerable plaques (132.3 ± 39.4 vs. 102.2 ± 39.7, vs. 71.7 ± 21.7, p < 0.01). The regression analysis showed a positive correlation between MAGE levels and the % LAP (r = 0.55, p < 0.01). In a multiple linear regression analysis, the MAGE was independently associated with the % LAP (β = 0.42, p < 0.01).

CONCLUSIONS

Increased GV is associated with the presence and extent of vulnerable plaques.

Repeated administration of inorganic nitrate on blood pressure and arterial stiffness: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

We aim to synthesize effects of repeated administration (≥3 days) of inorganic nitrate on blood pressure and arterial stiffness measures.

METHODS

We conducted a systematic review and meta-analysis of randomized controlled trials with at least 3 days treatment of inorganic nitrate on blood pressure and arterial stiffness in individuals with or without elevated cardiovascular disease risk. MEDLINE, EMBASE and the Cochrane Library were searched through 2 July 2019. Two independent reviewers extracted relevant study data. Data were pooled using the generic inverse variance method with random-effects model, and expressed as mean differences with 95% confidence intervals. Certainty in the evidence was assessed using GRADE.

RESULTS

Forty-seven trials were included (n = 1101). Administration of inorganic nitrate significantly lowered SBP [mean difference: -2.91 mmHg, 95% confidence interval (95% CI): -3.92 to -1.89, I = 76%], DBP (mean difference: -1.45 mmHg, 95% CI: -2.22 to -0.68, I = 78%], central SBP (mean difference: -1.56 mmHg, 95% CI: -2.62 to -0.50, I = 30%) and central DBP (mean difference: -1.99 mmHg, 95% CI: -2.37 to -1.60, I = 0%). There was no effect on 24-h blood pressure, augmentation index or pulse wave velocity. Certainty in the evidence was graded moderate for central blood pressure, pulse wave velocity and low for peripheral blood pressure, 24-h blood pressure and augmentation index.

CONCLUSION

Repeated administration (≥3 days) of inorganic nitrate lower peripheral and central blood pressure. Results appear to be driven by beneficial effects in healthy and hypertensive individuals. More studies are required to increase certainty in the evidence.

Dysregulation of nitric oxide synthases during early and late pathophysiological conditions of diabetes mellitus leads to amassing of microvascular impedement

Diabetes is a major killer worldwide and its unprecedented rise poses a serious threat to mankind. According to recent estimation, 387 million people worldwide are affected from the disease with a prevalence rate of 8.3 and 46.3 % still remains undiagnosed. Important characteristics of diabetes are abnormalities of the physiological signalling functions of reactive oxygen species and reactive nitrogen species. Increased oxidative stress contributes to the activation of stress-sensitive intracellular signalling pathways and the development of gene products that trigger cellular damage and contribute to the vascular complications of diabetes. Growing evidence from studies into many diseases suggests that the pathogenesis of diabetes, obesity, cancer, ageing, inflammation, neurodegenerative disorders, hypertension, apoptosis, cardiovascular diseases, and heart failure are correlated with oxidative stress. This leads to cell metabolism and cell-cell homeostasis to be complexly dysregulated. This review focuses to investigate the status of oxidative stress, nitric oxide and reactive species in early and diabetes. Significance of nitric oxide synthases Evidences has accumulated indicating that the generation of reactive oxygen species (oxidative stress) may play an important role in the etiology of diabetic complications thus attention was given on the reactive oxygen and reactive nitrogen species and their potential role in pathogenesis. Additionally, the therapeutic advances in diabetes management are included. Nanotechnology, statins and stem cell technology are some techniques which can be considered to have a possible future in the treatment sector of diabetes.

Role of oxidative stress in calcific aortic valve disease and its therapeutic implications

Calcific aortic valve disease (CAVD) is the end result of active cellular processes that lead to the progressive fibrosis and calcification of aortic valve leaflets. In western populations, CAVD is a significant cause of cardiovascular morbidity and mortality, and in the absence of effective drugs, it will likely represent an increasing disease burden as populations age. As there are currently no pharmacological therapies available for preventing, treating, or slowing the development of CAVD, understanding the mechanisms underlying the initiation and progression of the disease is important for identifying novel therapeutic targets. Recent evidence has emerged of an important causative role for reactive oxygen species (ROS)-mediated oxidative stress in the pathophysiology of CAVD, inducing the differentiation of valve interstitial cells into myofibroblasts and then osteoblasts. In this review, we focus on the roles and sources of ROS driving CAVD and consider their potential as novel therapeutic targets for this debilitating condition.

Parenteral Nutrition and Cardiotoxicity

Parenteral nutrition (PN) is a life-saving nutritional therapy for those situations when patients are unable to receive enteral nutrition. However, despite a multitude of benefits offered by PN, it is associated with a variety of side effects, most notably parenteral nutrition-associated liver disease (PNALD). Adverse effects of PN on other organ systems, such as brain and cardiovascular system, have been poorly studied. There have been several case reports, studies, and a recent animal study highlighting cardiotoxic effects of PN; however, much remains unclear about the underlying mechanisms causing cardiac damage. In this review, we propose a series of potential mechanisms behind PN-associated heart injury, and we provide an overview of therapeutic strategies and recent scientific advances.

Cellular and Functional Effects of Insulin Based Therapies and Exercise on Endothelium

Endothelial dysfunction is a hallmark of type 2 diabetes that can have severe consequences on vascular function, including hypertension and changes in blood flow, as well as exercise performance. Because endothelium is also the barrier for insulin movement into tissues, it acts as a gatekeeper for transport and glucose uptake. For this reason, endothelial dysfunction is a tempting area for pharmacological and/or exercise intervention with insulin-based therapies. In this review, we describe the current state of drugs that can be used to treat endothelial dysfunction in type 2 diabetes and diabetes-related diseases (e.g., obesity) at the molecular levels, and also discuss their role in exercise.

Influence of Administering Watermelon Rind Water Extract (Citrullus vulgaris Schard) on Glucose Level of Male White Rats (Rattus norvegicus) Induced with Streptozotosin

Watermelon rind water extract contain of citrulline. Citrulline is a precursor of generating Nitric Oxide (NO). NO possibly reduced the level of blood glucose in streptozotosin-induced diabetic rats. This study was a laboratory experimental study completely randomized design. A number of 30 male albino Wistar rats weighting 100 – 200 gr were devided into six groups (N=5), with group 1 served as normal control group. The other groups were given streptozotosin to induced diabetes mellitus. The rats in control diabetic group were given CMC 0,5%, the others were given watermelon rind extracs for 8 days with different doses for each group. The results showed that serum glucose levels in posttest control group was significantly different, from that group of the watermelon rind extract 250 mg/kg bw/day (p = 0,000), groups of watermelon rind extract 500 mg/kgbw/day (p = 0,000) and groups of watermelon rind extract 1000 mg/kgbw/day (p = 0,000). The level of triglyceride in postest control was significantly different from that group of the watermelon rind extract 250 mg/kg bw/day (p = 0,000), groups of watermelon rind extract 500 mg/kgbw/day (p = 0,000) and groups of watermelon rind extract 1000 mg/kgbw/day (p = 0,000).The conclusion, the watermelon rind water extrac can be used to reduced glucose serum level (250, 500, 1000mg/kg bw) with the optimal dose was 500 mg /kgbw/day with the optimal dose was 1000 mg /kgbw/day. 

Cutaneous Vasculopathy and Pulmonary Thromboembolism in an Unstable Diabetic Cat

A 6-year-old, male-neutered, domestic short-haired cat was referred for further management of a 3-month history of uncontrolled diabetes mellitus. The cat visited the hospital on 3 occasions during a 3-week time period. Hyperglycemia was documented at all visits. The cat initially presented with evidence of hypovolemia, cranial abdominal pain, and dehydration. Moderate hyperglycemia, mild ketonemia, and severe hypokalemia were documented. A 3 × 2 cm skin lesion with associated alopecia and erythema was first noticed at a routine follow-up examination (visit 2) 1 week later. A diagnosis of diabetic ketoacidosis was made 6 days later. The previously identified skin lesion now measured 6 × 2.5 cm. Two episodes of respiratory distress were identified at this visit, with no evidence of cardiac or pulmonary pathology. The cat developed a moderate anemia (packed cell volume 16 %, total solids 7.9 g/dL) on the fifth day of hospitalization. Fluid therapy, electrolyte supplementation, regular insulin, anti-emetic, and analgesia medications were administered during visits 1 and 3. Due to development of anemia, suspected pulmonary thromboembolism events and progression of skin lesions, euthanasia was elected. A diagnosis of cutaneous vasculopathy with secondary ischemic necrosis was made postmortem and pulmonary thromboembolism was confirmed. To the authors' knowledge, this is the first report of cutaneous vasculopathy and pulmonary thromboembolism in a cat with confirmed diabetes mellitus, warranting further research to assess if hypercoagulability is common in this patient population, as routine thromboprophylaxis and anticoagulation may be potentially indicated.

Endothelial Dysfunction: A Contributor to Adverse Cardiovascular Remodeling and Heart Failure Development in Type 2 Diabetes beyond Accelerated Atherogenesis

Endothelial dysfunction, associated with depressed nitric oxide (NO) bioavailability, is awell-recognized contributor to both accelerated atherogenesis and microvascular complications intype 2 diabetes (DM). However, growing evidence points to the comorbidities-driven endothelialdysfunction within coronary microvessels as a key player responsible for left ventricular (LV)diastolic dysfunction, restrictive LV remodeling and heart failure with preserved ejection fraction(HFpEF), the most common form of heart failure in DM. In this review we have described: (1)multiple cellular pathways which may link depressed NO bioavailability to LV diastolicdysfunction and hypertrophy; (2) hemodynamic consequences and prognostic effects of restrictiveLV remodeling and combined diastolic and mild systolic LV dysfunction on cardiovascularoutcomes in DM and HFpEF, with a focus on the clinical relevance of endothelial dysfunction; (3)novel therapeutic strategies to improve endothelial function in DM. In summary, beyondassociations with accelerated atherogenesis and microvascular complications, endothelialdysfunction supplements the multiple interwoven pathways affecting cardiomyocytes, endothelialcells and the extracellular matrix with consequent LV dysfunction in DM patients. The associationamongst impaired endothelial function, reduced coronary flow reserve, combined LV diastolic anddiscrete systolic dysfunction, and low LV stroke volume and preload reserve-all of which areadverse outcome predictors-is a dangerous constellation of inter-related abnormalities, underlyingthe development of heart failure. Nevertheless, the relevance of endothelial effects of novel drugsin terms of their ability to attenuate cardiovascular remodeling and delay heart failure onset in DMpatients remains to be investigated.

Effects of Nigella sativa on endothelial dysfunction in diabetes mellitus: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Endothelial dysfunction is involved in lesion generation by the promotion of both early and late mechanism(s) of atherosclerosis such as adhesion molecules up-regulation, increased chemokine secretion and leukocyte adherence, increased cell permeability, enhanced low-density lipoprotein oxidation, cytokine elaboration, platelet activation and vascular smooth muscle cell migration, and proliferation. Nigella sativa is from the Ranunculaceae family which is used in some countries for various medicinal purposes. Nigella sativa seed has been widely used in traditional medicine for the treatment of diabetes.

AIM OF THE REVIEW

This review article summarized the therapeutic effects of Nigella sativa on endothelial dysfunction.

METHODS

Databases such as PubMed, Web of Science, Google Scholar, Scopus, and Iran Medex were considered. The search terms were " Nigella sativa " or "endothelium" and " Diabetes"," endothelial dysfunction ", " Thymoquinone " and " anti-inflammatory effect ".

RESULTS

The current review shows that Nigella sativa and Thymoquinone have a protective effect on endothelial dysfunction induced by diabetes. This is done by several mechanisms such as reduction of inflammatory and apoptotic markers, improving hyperglycemia, hyperlipidemia and antioxidant function, inhibiting platelet aggregation, and regulating eNOS, VCAM-1 and LOX-1 genes expression that involve in the endothelial dysfunction. Thymoquinone also reduces expression and secretion of some cytokines such as MCP-1, interleukin-1β, TNF-α, NF-κB, and Cox-2 that result in anti-inflammation effect.

CONCLUSION

Thymoquinone, the main phenolic terpene found in Nigella sativa, has several important properties such as antidiabetic, anti-inflammatory, and antioxidant activity. Therefore, Nigella sativa can improve endothelial dysfunction.

Diastolic dysfunction in men with severe obstructive sleep apnea syndrome but without cardiovascular or oxidative stress-related comorbidities

Background:

We aimed to evaluate whether the severity of obstructive sleep apnea syndrome (OSAS) per se affects the prevalence of left ventricular (LV) diastolic dysfunction in patients without comorbidities.

Methods:

A total of 42 patients with first-diagnosed severe OSAS [apnea–hypopnea index (AHI) > 30] and 25 controls (AHI < 5), having been referred for snoring to the Sleep Laboratory Department of our tertiary Hospital, were enrolled in the study. Inclusion criteria were absence of any cardiovascular or oxidative stress-related comorbidities, and age between 20 and 70 years. Clinical, laboratory, echocardiographic, and polysomnographic data were recorded prospectively. Diastolic dysfunction diagnosis and grading was based on 2016 ASE/EACVI recommendations.

Results:

Severe OSAS was associated with significantly increased prevalence and degree of diastolic dysfunction (26/42; 61.9%) compared with controls (7/25; 28%) (p = 0.007). AHI ⩾ 55 (dichotomous value of severe OSAS subset) was also characterized by greater prevalence and degree of diastolic dysfunction compared with 30 < AHI < 55 patients (p = 0.015). In the severe OSAS subset, age >45 years-old, height <1.745 m, body-mass index (BMI) >27.76 kg m⁻², OSAS severity (AHI > 57.35), oxidative stress (overnight reduction of reduced to oxidized glutathione ratio < 18.44%), and BMI/height ratio > 16.155 kg m⁻³ (an index describing ‘dense’, short-heavy patients) presented significant diagnostic utility in identifying diastolic dysfunction in ROC-curve analysis (0.697 ⩾ AUC ⩾ 0.855, 0.001 ⩽ p ⩽ 0.018). In binary logistic regression model, advanced age (OR 1.23, 95% CI 1.025–1.477; p = 0.026) and AHI (OR 1.123, 95% CI 1.007–1.253; p = 0.036) showed independent association with diastolic dysfunction in severe OSAS.

Conclusions:

The present prospective study may suggest that severe OSAS is significantly associated with LV diastolic dysfunction; OSAS clinical severity exerts a positive influence on (and possibly constitutes an independent risk factor of) LV diastolic dysfunction.

The reviews of this paper are available via the supplementary material section.

Evaluation of ameliorative effect of sodium nitrate in experimental model of streptozotocin-induced diabetic neuropathy in male rats

OBJECTIVE

Diabetes induces sensory symptoms of neuropathy as positive (hyperalgesia), negative (hypoalgesia), or both.

METHODS

In the present study, fifty male Wistar rats were allocated to five groups: control, control+nitrate, diabetes, diabetes+insulin, and diabetes+nitrate. Thirty days after diabetes confirmation, insulin (2-4 U/day) was injected subcutaneously in diabetes+insulin group and nitrate (100 mg/l) was added into drinking water of the control+nitrate and diabetes+nitrate groups for a period of 2 months. In order to assess the mechanical and thermal algesia, tail immersion, hot plate, and von Frey tests were performed. The serum insulin levels were determined with insulin ELISA Kit. Serum level of NOx was determined by the Griess method.

RESULTS

Both thermal and mechanical nociceptive thresholds showed a significant decrease (p<0.05) which was followed by a significant increase (p<0.01) in the thermal nociceptive threshold in the diabetes group. Chronic nitrate or insulin treatment led to a significant decrease (p<0.01) in blood glucose levels, as well as a significant (p<0.05) increase in the body weight and serum NOx. Moreover, nitrate treatment significantly increased serum insulin levels (p<0.001) compared to the other groups.

CONCLUSION

Chronic nitrate treatment modified the thermal and mechanical sensitivities in diabetic animals.

Regulation of carbohydrate metabolism by nitric oxide and hydrogen sulfide: Implications in diabetes

Nitric oxide (NO) and hydrogen sulfide (H₂S) are two gasotransmitters that are produced in the human body and have a key role in many of the physiological activities of the various organ systems. Decreased NO bioavailability and deficiency of H₂S are involved in the pathophysiology of type 2 diabetes and its complications. Restoration of NO levels have favorable metabolic effects in diabetes. The role of H₂S in pathophysiology of diabetes is however controversial; H₂S production is decreased during development of obesity, diabetes, and its complications, suggesting the potential therapeutic effects of H₂S. On the other hand, increased H₂S levels disturb the pancreatic β-cell function and decrease insulin secretion. In addition, there appear to be important interactions between NO and H₂S at the levels of both biosynthesis and signaling pathways, yet clear an insight into this relationship is lacking. H₂S potentiates the effects of NO in the cardiovascular system as well as NO release from its storage pools. Likewise, NO increases the activity and the expression of H₂S-generating enzymes. Inhibition of NO production leads to elimination/attenuation of the cardioprotective effects of H₂S. Regarding the increasing interest in the therapeutic applications of NO or H₂S-releasing molecules in a variety of diseases, particularly in the cardiovascular disorders, much is to be learned about their function in glucose/insulin metabolism, especially in diabetes. The aim of this review is to provide a better understanding of the individual and the interactive roles of NO and H₂S in carbohydrate metabolism.

CTRP13 Preserves Endothelial Function by Targeting GTP Cyclohydrolase 1 in Diabetes

Endothelial dysfunction plays a crucial role in the progress of diabetic vasculopathy. C1q/tumor necrosis factor-related protein 13 (CTRP13) is a secreted adipokine that can ameliorate atherosclerosis and vascular calcification. However, the role of CTRP13 in regulating endothelial function in diabetes has yet to be explored. In this study, CTRP13 treatment improved endothelium-dependent relaxation in the aortae and mesenteric arteries of both db/db mice and streptozotocin-injected mice. CTRP13 supplement also rescued the impaired endothelium-dependent relaxation ex vivo in the db/db mouse aortae and in high glucose (HG)-treated mouse aortae. Additionally, CTRP13 treatment reduced reactive oxygen species overproduction and improved nitric oxide (NO) production and endothelial NO synthase (eNOS) coupling in the aortae of diabetic mice and in HG-treated human umbilical vein endothelial cells. Mechanistically, CTRP13 could increase GTP cyclohydrolase 1 (GCH1) expression and tetrahydrobiopterin (BH4) levels to ameliorate eNOS coupling. More importantly, CTRP13 rescued HG-induced inhibition of protein kinase A (PKA) activity. Increased PKA activity enhanced phosphorylation of the peroxisome proliferator-activated receptor α and its recruitment to the GCH1 promoter, thus activating GCH1 transcription and, ultimately, endothelial relaxation. Together, these results suggest that CTRP13 preserves endothelial function in diabetic mice by regulating GCH1/BH4 axis-dependent eNOS coupling, suggesting the therapeutic potential of CTRP13 against diabetic vasculopathy.

Potential roles of Citrulline and watermelon extract on metabolic and inflammatory variables in diabetes mellitus, current evidence and future directions: A systematic review

OBJECTIVE

Diabetes mellitus is a prevalent endocrine disorder worldwide. Citrulline is an α-amino acid, which is abundant in watermelon, and a precursor of arginine and nitric oxide. Decreased bioavailability of nitric oxide is associated with insulin resistance. The present systematic review focused on the existing evidence of citrulline and watermelon extract effects on metabolic and inflammatory parameters in diabetes mellitus.

METHODS

A systematic search of the databases PubMed, Scopus, EMBASE, ProQuest and Google Scholar was conducted for relevant papers published from inception until October 2018. All clinical trials, animal and in vitro studies published in the English language that assessed the role of citrulline and watermelon extract on diabetes mellitus, were eligible. Studies providing inadequate information were excluded.

RESULTS

Out of 1262 articles we found, only eight articles met the inclusion criteria for analysis. In three studies an increase in the synthesis of nitric oxide was reported with citrulline and watermelon extract supplementation. Four studies showed a significant reduction in blood glucose after supplementation with watermelon extract, and two studies reported a decrease in a number of inflammatory biomarkers following citrulline supplementation. Although citrulline intake caused a significant reduction in HOMA-IR in one study, inconsistent results were revealed on the effects of citrulline and watermelon extract on insulin levels and lipid profile.

CONCLUSION

Citrulline and watermelon extract could improve nitric oxide synthesis, glycaemic status and inflammation in diabetes mellitus. However, further studies are required to shed light on the underlying mechanisms.

Thymol polymeric nanoparticle synthesis and its effects on the toxicity of high glucose on OEC cells: involvement of growth factors and integrin-linked kinase

Background

Nowadays, the drug delivery system is important in the treatment of diseases.

Purpose

A polymeric nanoparticle modified by oleic acid (NPMO) as a Thymol (Thy) drug release system was synthesized from Thymbra spicata and its neurotrophic and angiogenic effects on rat’s olfactory ensheathing cells (OECs) in normal (NG) and high glucose (HG) conditions were studied.

Methods

The NPMO was characterized by using different spectroscopy methods, such as infrared, HNMR, CNMR, gel permeation chromatography, dynamic light scattering, and atomic force microscopy. Load and releasing were investigated by HPLC. The toxicity against OECs diet-induced by MTT assay. ROS and generation of nitric oxide (NO) were evaluated using dichloro-dihydro-fluorescein and Griess method, respectively. The expression of protein integrin-linked kinase (ILK), vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) were evaluated by Western blotting.

Results

ThyNPMO is desirable for transferring drug as a carrier. The amount of Thy and extract (E) loaded on NPMO estimated at 43±2.5% and 41±1.8%, respectively. Then, 65% and 63% of the drug load were released, respectively. Thy, ThyNPMO, E, and ENPMO prevented HG-induced OECs cell death (EC50 33±1.5, 22±0.9, 35±1.8, and 25±1.1 μM, respectively). Incubation with Thy, ThyNPMO, E ,and ENPMO at high concentrations increased cell death with LC50 105±3.5, 82±2.8, 109±4.3, and 86±3.4 μM, respectively in HG states.

Conclusion

OECs were protected by ThyNPMO and ENPMO in protective concentrations by reducing the amount of ROS and NO, maintaining ILK, reducing VEGF, and increasing BDNF and NGF. The mentioned mechanisms were totally reversed at high concentrations.

Formononetin ameliorates high glucose‑induced endothelial dysfunction by inhibiting the JAK/STAT signaling pathway

High glucose‑induced endothelial Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling is associated with the development and progression of the vascular complications of diabetes. The present study aimed to investigate whether formononetin, a biologically active compound isolated from Astragalus membranaceus (Fisch.) Bge, was able to regulate the JAK/STAT signaling pathway, improving endothelial function. In the present study, formononetin was identified to act as a JAK2 inhibitor, similarly to tyrphostin AG 490 (AG490), by significantly inhibiting the phosphorylation and the mRNA expression levels of JAK2 and STAT in HUVECs exposed to high glucose levels. In addition, formononetin and AG490 improved the viability of HUVECs and inhibited the protein expression levels of caspase‑3. Furthermore, formononetin and AG490 attenuated the inflammatory response in HUVECs by downregulating the protein and mRNA expression levels of interleukin (IL)‑1β and intercellular adhesion molecule 1 (ICAM‑1). Formononetin and AG490 also restored nitric oxide (NO) synthesis in HUVECs. Notably, formononetin was able to reverse the abnormal levels of phosphorylated (p)‑JAK2, p‑STAT3, IL‑1β, ICAM‑1 and NO induced by cotreatment with high glucose and IL‑6, an agonist of the JAK/STAT signaling pathway. Additionally, the present results suggested that formononetin restored phenylephrine‑mediated contraction and acetylcholine‑induced relaxation in aortic tissues of rats fed a high‑glucose diet, in a dose‑dependent manner. Collectively, formononetin could improve endothelial function under glucose stress in vivo and in vitro, suggesting that formononetin may represent a novel potential therapeutic compound to treat diabetic vascular complications.

Molecular Dysfunction and Phenotypic Derangement in Diabetic Cardiomyopathy

The high incidence and poor prognosis of heart failure (HF) patients affected with diabetes (DM) is in part related to a specific cardiac remodeling currently recognized as diabetic cardiomyopathy (DCM). This cardiac frame occurs regardless of the presence of coronary artery diseases (CAD) and it can account for 15–20% of the total diabetic population. The pathogenesis of DCM remains controversial, and several molecular and cellular alterations including myocardial hypertrophy, interstitial fibrosis, oxidative stress and vascular inflammation, have been postulated. The main cardio-vascular alterations associated with hyperglycemia comprise endothelial dysfunction, adverse effects of circulating free fatty acids (FFA) and increased systemic inflammation. High glucose concentrations lead to a loss of mitochondrial networks, increased reactive oxygen species (ROS), endothelial nitric oxide synthase (eNOS) activation and a reduction in cGMP production related to protein kinase G (PKG) activity. Current mechanisms enhance the collagen deposition with subsequent increased myocardial stiffness. Several concerns regarding the exact role of DCM in HF development such as having an appearance as either dilated or as a concentric phenotype and whether diabetes could be considered a causal factor or a comorbidity in HF, remain to be clarified. In this review, we sought to explain the different DCM subtypes and the underlying pathophysiological mechanisms. Therefore, the traditional and new molecular and signal alterations and their relationship with macroscopic structural abnormalities are described.

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.

The influence of acute hyperglycaemia on brachial artery flow-mediated dilatation in the early and late follicular phases of the menstrual cycle

NEW FINDINGS

What is the central question of the study? This is the first study to examine the impact of acute hyperglycaemia on endothelial function [flow-mediated dilatation (FMD)] in premenopausal women across the early and late follicular (EF and LF) phases of the menstrual cycle. What is the main finding and its importance? Flow-mediated dilatation was impaired 90 min after glucose ingestion, with no significant difference between phases. This indicates that women are susceptible to acute hyperglycaemia-induced endothelial dysfunction in both the EF and LF phases of the menstrual cycle, despite potentially vasoprotective elevations in estradiol levels during the LF phase.

ABSTRACT

Acute hyperglycaemia transiently impairs endothelial function in healthy men when assessed via flow-mediated dilatation (FMD). However, research in female participants is lacking, and the impact of menstrual phase [early follicular (EF) and late follicular (LF)] on vulnerability to acute hyperglycaemia-induced endothelial dysfunction is unknown. Seventeen healthy, naturally menstruating women [21 ± 1 years old (mean ± SD)] participated in three visits. During two visits (EF_Glucose and LF_Glucose ), brachial artery FMD was assessed before and 60, 90 and 120 min after an oral glucose challenge (75 g glucose). During an additional EF visit, participants ingested 300 ml of water (EF_TimeControl ). Blood glucose and insulin increased 30 min after glucose ingestion (P < 0.001), with no difference between phases. Flow-mediated dilatation did not change in EF_TimeControl (P = 0.748) but was reduced 90 min after glucose ingestion (Pre, 8.5 ± 2.5%; Post90, 6.6 ± 2.4%, P = 0.001; Cohen's d = 0.82), with no difference between phases (main effect of phase, P = 0.506; phase by time interaction, P = 0.391). To account for individual variability in the time course of the impact of hyperglycaemia, the maximal hyperglycaemia-induced impairment in FMD was determined in each participant and compared between phases, revealing no significant phase differences (EF_Glucose , -3.1 ± 2.8%; LF_Glucose , -2.4 ± 2.1%, P = 0.181; d = 0.34). These results indicate that, similar to findings in men, acute hyperglycaemia results in FMD impairment in young women. We did not detect significant protection from acute hyperglycaemia-induced endothelial dysfunction in the LF 'high-oestrogen' phase in this sample, and further research is needed to examine the potential for a protective effect of oestrogen exposure, including oral contraceptive pills and hormone replacement therapy.

Altered bioavailability of epoxyeicosatrienoic acids is associated with conduit artery endothelial dysfunction in type 2 diabetic patients

Background

This pathophysiological study addressed the hypothesis that soluble epoxide hydrolase (sEH), which metabolizes the vasodilator and anti-inflammatory epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs), contributes to conduit artery endothelial dysfunction in type 2 diabetes.

Methods and results

Radial artery endothelium-dependent flow-mediated dilatation in response to hand skin heating was reduced in essential hypertensive patients (n = 9) and type 2 diabetic subjects with (n = 19) or without hypertension (n = 10) compared to healthy subjects (n = 36), taking into consideration cardiovascular risk factors, flow stimulus and endothelium-independent dilatation to glyceryl trinitrate. Diabetic patients but not non-diabetic hypertensive subjects displayed elevated whole blood reactive oxygen species levels and loss of NO release during heating, assessed by measuring local plasma nitrite variation. Moreover, plasma levels of EET regioisomers increased during heating in healthy subjects, did not change in hypertensive patients and decreased in diabetic patients. Correlation analysis showed in the overall population that the less NO and EETs bioavailability increases during heating, the more flow-mediated dilatation is reduced. The expression and activity of sEH, measured in isolated peripheral blood mononuclear cells, was elevated in diabetic but not hypertensive patients, leading to increased EETs conversion to DHETs. Finally, hyperglycemic and hyperinsulinemic euglycemic clamps induced a decrease in flow-mediated dilatation in healthy subjects and this was associated with an altered EETs release during heating.

Conclusions

These results demonstrate that an increased EETs degradation by sEH and altered NO bioavailability are associated with conduit artery endothelial dysfunction in type 2 diabetic patients independently from their hypertensive status. The hyperinsulinemic and hyperglycemic state in these patients may contribute to these alterations.

Trial registration NCT02311075. Registered December 8, 2014.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0843-z) contains supplementary material, which is available to authorized users.

The impact of intraday glucose variability on coronary artery spasm in patients with dysglycemia

Impaired glucose metabolism is associated with an increased risk of cardiovascular complications, and coronary artery spasm is thought to underlie the development of coronary artery disease. Intraday glucose variability (GV) accelerates oxidative stress and inflammatory cytokine release, but its impact on coronary artery spasm remains unclear. This study investigated the relationship between intraday GV and coronary artery spasm. The study included 50 patients with dysglycemia and suspected coronary spastic angina. GV was analyzed by 24-h monitoring of the blood glucose concentration using a flash glucose monitoring system. The mean amplitude of glycemic excursion (MAGE) was calculated as an index of GV. Coronary artery spasm was assessed using the intracoronary acetylcholine provocation test. Coronary spasm was defined as acetylcholine-induced total or subtotal coronary occlusion. Changes in vessel diameter in response to acetylcholine were evaluated with quantitative coronary angiography. Coronary artery spasms were observed in 21 patients (42%). MAGE was significantly higher in patients with spasms compared to those without spasms (127.5 ± 33.5 vs. 91.4 ± 37.6, p < 0.01). Regression analysis showed a positive correlation between MAGE levels and coronary diameter changes induced by acetylcholine (r = 0.47, p < 0.01). In multiple regression analysis, MAGE was independently associated with acetylcholine-induced coronary diameter change (β = 0.47, p < 0.01). Intraday GV was associated with coronary artery spasm in patients with dysglycemia.

Early Effects of Hyperbaric Oxygen on Inducible Nitric Oxide Synthase Activity/Expression in Lymphocytes of Type 1 Diabetes Patients: A Prospective Pilot Study

This study aimed at examining the early effects of hyperbaric oxygen therapy (HBOT) on inducible nitric oxide synthase (iNOS) activity/expression in lymphocytes of type 1 diabetes mellitus (T1DM) patients. A group of 19 patients (mean age: 63 ± 2.1) with T1DM and with the peripheral arterial disease were included in this study. Patients were exposed to 10 sessions of HBOT in the duration of 1 h to 100% oxygen inhalation at 2.4 ATA. Blood samples were collected for the plasma C-reactive protein (CRP), plasma free fatty acid (FFA), serum nitrite/nitrate, and serum arginase activity measurements. Expression of iNOS and phosphorylation of p65 subunit of nuclear factor-κB (NFκB-p65), extracellular-regulated kinases 1/2 (ERK1/2), and protein kinase B (Akt) were examined in lymphocyte lysates by Western blot. After exposure to HBOT, plasma CRP and FFA were significantly decreased (p < 0.001). Protein expression of iNOS and serum nitrite/nitrate levels were decreased (p < 0.01), while serum arginase activity was increased (p < 0.05) versus before exposure to HBOT. Increased phosphorylation of NFκB-p65 at Ser⁵³⁶ (p < 0.05) and decreased level of NFκB-p65 protein (p < 0.001) in lymphocytes of T1DM patients were observed after HBOT. Decreased phosphorylation of ERK1/2 (p < 0.05) and Akt (p < 0.05) was detected after HBOT. Our results indicate that exposure to HBO decreased iNOS activity/expression via decreasing phosphorylation of ERK1/2 and Akt followed by decreased activity of NFκB.

Investigative Study on Nitric Oxide Production in Human Dermal Fibroblast Cells under Normal and High Glucose Conditions

Diabetic foot ulcers (DFU) are a major health problem associated with diabetes mellitus. Impaired nitric oxide (NO) production has been shown to be a major contributor to the dysregulation of healing in DFU. The level of impairment is not known primarily due to challenges with measuring NO. Herein, we report the actual level of NO produced by human dermal fibroblasts cultured under normal and high glucose conditions. Fibroblasts produce the extracellular matrix, which facilitate the migration of keratinocytes to close wounds. The results show that NO production was significantly higher in normal glucose compared to high glucose conditions. The real-time NO detected was compared to the nitrite present in the culture media and there was a direct correlation between real-time NO and nitrite in normal glucose conditions. However, real-time NO detection and nitrite measurement did not correlate under high glucose conditions. The inducible nitric oxide synthase (iNOS) enzyme responsible for NO production was upregulated in normal and high glucose conditions and the proliferation rate of fibroblasts was not statistically different in all the treatment groups. Relying only on nitrite to assess NO production is not an accurate determinant of the NO present in the wound bed in pathological states such as diabetes mellitus.

Perivascular adipose tissue (PVAT) in atherosclerosis: a double-edged sword

Perivascular adipose tissue (PVAT), the adipose tissue that surrounds most of the vasculature, has emerged as an active component of the blood vessel wall regulating vascular homeostasis and affecting the pathogenesis of atherosclerosis. Although PVAT characteristics resemble both brown and white adipose tissues, recent evidence suggests that PVAT develops from its own distinct precursors implying a closer link between PVAT and vascular system. Under physiological conditions, PVAT has potent anti-atherogenic properties mediated by its ability to secrete various biologically active factors that induce non-shivering thermogenesis and metabolize fatty acids. In contrast, under pathological conditions (mainly obesity), PVAT becomes dysfunctional, loses its thermogenic capacity and secretes pro-inflammatory adipokines that induce endothelial dysfunction and infiltration of inflammatory cells, promoting atherosclerosis development. Since PVAT plays crucial roles in regulating key steps of atherosclerosis development, it may constitute a novel therapeutic target for the prevention and treatment of atherosclerosis. Here, we review the current literature regarding the roles of PVAT in the pathogenesis of atherosclerosis.

Connexin 43 Hemichannel Activity Promoted by Pro-Inflammatory Cytokines and High Glucose Alters Endothelial Cell Function

The present work was done to elucidate whether hemichannels of a cell line derived from endothelial cells are affected by pro-inflammatory conditions (high glucose and IL-1β/TNF-α) known to lead to vascular dysfunction. We used EAhy 926 cells treated with high glucose and IL-1β/TNF-α. The hemichannel activity was evaluated with the dye uptake method and was abrogated with selective inhibitors or knocking down of hemichannel protein subunits with siRNA. Western blot analysis, cell surface biotinylation, and confocal microscopy were used to evaluate total and plasma membrane amounts of specific proteins and their cellular distribution, respectively. Changes in intracellular Ca²⁺ and nitric oxide (NO) signals were estimated by measuring FURA-2 and DAF-FM probes, respectively. High glucose concentration was found to elevate dye uptake, a response that was enhanced by IL-1β/TNF-α. High glucose plus IL-1β/TNF-α-induced dye uptake was abrogated by connexin 43 (Cx43) but not pannexin1 knockdown. Furthermore, Cx43 hemichannel activity was associated with enhanced ATP release and activation of p38 MAPK, inducible NO synthase, COX₂, PGE₂ receptor EP₁, and P2X₇/P2Y₁ receptors. Inhibition of the above pathways prevented completely the increase in Cx43 hemichannel activity of cells treated high glucose and IL-1β/TNF-α. Both synthetic and endogenous cannabinoids (CBs) also prevented the increment in Cx43 hemichannel opening, as well as the subsequent generation and release of ATP and NO induced by pro-inflammatory conditions. The counteracting action of CBs also was extended to other endothelial alterations evoked by IL-1β/TNF-α and high glucose, including increased ATP-dependent Ca²⁺ dynamics and insulin-induced NO production. Finally, inhibition of Cx43 hemichannels also prevented the ATP release from endothelial cells treated with IL-1β/TNF-α and high glucose. Therefore, we propose that reduction of hemichannel activity could represent a strategy against the activation of deleterious pathways that lead to endothelial dysfunction and possibly cell damage evoked by high glucose and pro-inflammatory conditions during cardiovascular diseases.

Physiological and pathophysiological role of reactive oxygen species and reactive nitrogen species in the kidney

End‐stage renal disease is a leading cause of morbidity and mortality worldwide. The prevalence of the disease and the number of patients who receive renal replacement therapy are expected to increase in the next decade. Accumulating evidence suggests that chronic hypoxia in the tubulointerstitium represents the final common pathway to end‐stage renal failure, and that reactive oxygen species (ROS) and reactive nitrogen species (RNS) are the key players in kidney injury. However, ROS and RNS that exceed the physiological levels associated with the pathophysiology of most kidney diseases. The molecules that comprise ROS and RNS play an important role in regulating solute and water reabsorption in the kidney, which is vital for maintaining electrolyte homeostasis and the volume of extracellular fluid. This article reviews the physiological and pathophysiological role of ROS and RNS in normal kidney function and in various kidney diseases.

l-Citrulline Supplementation: Impact on Cardiometabolic Health

Diminished bioavailability of nitric oxide (NO), the gaseous signaling molecule involved in the regulation of numerous vital biological functions, contributes to the development and progression of multiple age- and lifestyle-related diseases. While l-arginine is the precursor for the synthesis of NO by endothelial-nitric oxide synthase (eNOS), oral l-arginine supplementation is largely ineffective at increasing NO synthesis and/or bioavailability for a variety of reasons. l-citrulline, found in high concentrations in watermelon, is a neutral alpha-amino acid formed by enzymes in the mitochondria that also serves as a substrate for recycling l-arginine. Unlike l-arginine, l-citrulline is not quantitatively extracted from the gastrointestinal tract (i.e., enterocytes) or liver and its supplementation is therefore more effective at increasing l-arginine levels and NO synthesis. Supplementation with l-citrulline has shown promise as a blood pressure lowering intervention (both resting and stress-induced) in adults with pre-/hypertension, with pre-clinical (animal) evidence for atherogenic-endothelial protection. Preliminary evidence is also available for l-citrulline-induced benefits to muscle and metabolic health (via vascular and non-vascular pathways) in susceptible/older populations. In this review, we examine the impact of supplementing this important urea cycle intermediate on cardiovascular and metabolic health outcomes and identify future directions for investigating its therapeutic impact on cardiometabolic health.