Pathophysiological implications of insulin resistance on vascular endothelial function

Association of atherosclerosis indices, serum uric acid to high-density lipoprotein cholesterol ratio and triglycerides-glucose index with hypertension: A gender-disaggregated analysis

This study assessed the association between atherosclerosis indices, serum uric acid to high-density lipoprotein cholesterol ratio (UHR) and triglyceride-glucose (TyG) index and the prevalence of hypertension among MASHAD cohort participants. In this cross-sectional study, the participants were divided into hypertensive and non-hypertensive subjects. The atherosclerosis indices, UHR and TyG index of the two groups were compared. Logistic regression analyses were used to determine the associations of these indices with hypertension in both sex. Receiver operating characteristic (ROC) curve analysis was used to establish the cut-off values for differentiating hypertensive from non-hypertensive subjects. p-values < .05 were considered statistically significant. Data related to 9675 subjects (3035 hypertensive and 6640 non-hypertensive) were analyzed. The mean values of atherosclerosis indices, UHR and TyG index were significantly higher (p < .001) in the hypertensives compared to non-hypertensives. After adjustment for potential confounders, among men, the TyG index (OR = 1.360; 95% CI: 1.210-1.530; p < .001) remained an independent factor for hypertension. Among women, atherogenic index of plasma (OR = 1.005; 95% CI: 1.002-1.007; p < .001), UHR (OR = 1.043; 95% CI: 1.026-1.060; p < .001) and TyG index (OR = 1.519; 95% CI: 1.376-1.677; p < .001) remained independent factors for hypertension. ROC curve analysis revealed that compare to the other indices, TyG index had a better predictive value for hypertension in both sex, especially in women.

The association between the triglyceride-glucose index and the risk of cardiovascular disease in US population aged ≤ 65 years with prediabetes or diabetes: a population-based study

BACKGROUND

The relationship between the triglyceride-glucose (TyG) index and the risk of cardiovascular disease (CVD) in the U.S. population under 65 years of age with diabetes or prediabetes is unknown. The purpose of this study was to investigate the relationship between baseline TyG index and CVD risk in U.S. patients under 65 years of age with diabetes or prediabetes.

METHODS

We used data from the 2003-2018 National Health and Nutrition Examination Survey (NHANES). Multivariate regression analysis models were constructed to explore the relationship between baseline TyG index and CVD risk. Nonlinear correlations were explored using restricted cubic splines. Subgroup analysis and interaction tests were also conducted.

RESULTS

The study enrolled a total of 4340 participants with diabetes or pre-diabetes, with a mean TyG index of 9.02 ± 0.02. The overall average prevalence of CVD was 10.38%. Participants in the higher TyG quartiles showed high rates of CVD (Quartile 1: 7.35%; Quartile 2: 10.04%; Quartile 3: 10.71%; Quartile 4: 13.65%). For CVD, a possible association between the TyG index and the risk of CVD was observed. Our findings suggested a linear association between the TyG index and the risk of CVD. The results revealed a U-shaped relationship between the TyG index and both the risk of CVD (P nonlinear = 0.02583) and CHF (P nonlinear = 0.0208) in individuals with diabetes. Subgroup analysis and the interaction term indicated that there was no significant difference among different stratifications. Our study also revealed a positive association between the TyG index and comorbid MetS in the U.S. population under 65 years of age with prediabetes or diabetes.

CONCLUSIONS

A higher TyG index was linked to an increased likelihood of CVD in the U.S. population aged ≤ 65 years with prediabetes and diabetes. Besides, TyG index assessment will contribute to more convenient and effective screening of high-risk individuals in patients with MetS. Future studies should explore whether interventions targeting the TyG index may improve clinical outcomes in these patients.

Dose-response associations of triglyceride to high-density lipoprotein cholesterol ratio and triglyceride-glucose index with arterial stiffness risk

BACKGROUND

The triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio and triglyceride-glucose (TyG) index are novel indexes for insulin resistance (IR). We aimed to evaluate associations of TG/HDL-C and TyG with arterial stiffness risk.

METHODS

We enrolled 1979 participants from the Rural Chinese Cohort Study, examining arterial stiffness by brachial-ankle pulse wave velocity (baPWV). Logistic and linear regression models were employed to calculate effect estimates. For meta-analysis, we searched relevant articles from PubMed, Embase and Web of Science up to August 26, 2023. The fixed-effects or random-effects models were used to calculate the pooled estimates. We evaluated dose-response associations using restricted cubic splines.

RESULTS

For cross-sectional studies, the adjusted ORs (95%CIs) for arterial stiffness were 1.12 (1.01-1.23) and 1.78 (1.38-2.30) for per 1 unit increment in TG/HDL-C and TyG. In the meta-analysis, the pooled ORs (95% CIs) were 1.26 (1.14-1.39) and 1.57 (1.36-1.82) for per 1 unit increment of TG/HDL-C and TyG. Additionally, both TG/HDL-C and TyG were positively related to PWV, with β of 0.09 (95% CI 0.04-0.14) and 0.57 (95% CI 0.35-0.78) m/s. We also found linear associations of TG/HDL-C and TyG with arterial stiffness risk.

CONCLUSIONS

High TG/HDL-C and TyG were related to increased arterial stiffness risk, indicating TG/HDL-C and TyG may be convincing predictors of arterial stiffness.

Association between healthy dietary patterns and markers of oxidative stress in the Sister Study

PURPOSE

We assessed the cross-sectional association between healthy dietary patterns [alternate Mediterranean diet (aMED), Dietary Approaches to Stop Hypertension (DASH), alternative Healthy Eating Index (aHEI), and Healthy Eating Index 2015 (HEI-2015)] and urinary biomarkers of oxidative stress.

METHODS

Between 2003 and 2009, the Sister Study enrolled 50,884 breast cancer-free US women aged 35 to 74 (non-Hispanic White, 83.7%). Data were analyzed for 844 premenopausal and 454 postmenopausal women who had urine samples analyzed for F2-isoprostanes and non-missing covariate data. Food frequency questionnaire responses were used to calculate dietary pattern scores. Concentrations of 8-iso-prostaglandin F2α (8-iso-PGF2α) and its metabolite (8-iso-PGF2α-M) were measured in urine samples by GC/MS for premenopausal women and LC/MS for postmenopausal women. Multivariable linear regression models were used to estimate associations between aMED, DASH, aHEI, and HEI-2015 and urinary F2-isoprostanes by menopausal status. Effect modification by sociodemographic, lifestyle, and clinical characteristics was also evaluated.

RESULTS

Among premenopausal women, the four dietary indices were inversely associated with 8-iso-PGF2α (aMED βQ4vsQ1: - 0.17, 95% CI - 0.27, - 0.08; DASH βQ4vsQ1: - 0.18, 95% CI - 0.28, - 0.08; aHEI βQ4vsQ1: - 0.20, 95% CI - 0.30, - 0.10; HEI-2015 βQ4vsQ1: - 0.19, 95% CI - 0.29, - 0.10). In contrast, inverse associations with 8-iso-PGF2α-M were found for the continuous aMED, aHEI, and HEI-2015. Associations between dietary indices and 8-iso-PGF2α were generally stronger among younger women, women with lower income, and women with higher BMI. Similar results were observed among postmenopausal women, though only the continuous DASH and aHEI models were statistically significant.

CONCLUSION

Healthy dietary patterns were associated with lower levels of oxidative stress.

Association of the triglyceride-glucose index with all-cause and cardiovascular mortality in patients with cardiometabolic syndrome: a national cohort study

OBJECTIVE

This study aimed to evaluate the association of triglyceride-glucose (TyG) index with all-cause and cardiovascular mortality risk among patients with cardiometabolic syndrome (CMS).

METHODS

We performed a cohort study of 5754 individuals with CMS from the 2001-2018 National Health and Nutrition Examination Survey. The TyG index was calculated as Ln [fasting triglycerides (mg/dL) × fasting glucose (mg/dL)/2]. Multivariate Cox proportional hazards regression models assessed the associations between TyG index and mortality . Non-linear correlations and threshold effects were explored using restricted cubic splines and a two-piecewise Cox proportional hazards model.

RESULTS

Over a median follow-up of 107 months, 1201 all-cause deaths occurred, including 398 cardiovascular disease-related deaths. The multivariate Cox proportional hazards regression model showed a positive association between the TyG index and all-cause and cardiovascular mortality. Each one-unit increase in the TyG index was associated with a 16% risk increase in all-cause mortality (HR: 1.16, 95% CI 1.03, 1.31, P = 0.017) and a 39% risk increase in cardiovascular mortality (HR: 1.39, 95% CI 1.14, 1.71, P = 0.001) after adjusting for confounders. The restricted cubic splines revealed a U-shaped association between the TyG index and all-cause (P for nonlinear < 0.001) and cardiovascular mortality (P for nonlinear = 0.044), identifying threshold values (all-cause mortality: 9.104; cardiovascular mortality: 8.758). A TyG index below these thresholds displayed a negative association with all-cause mortality (HR: 0.58, 95% CI 0.38, 0.90, P = 0.015) but not with cardiovascular mortality (HR: 0.39, 95% CI 0.12, 1.27, P = 0.119). Conversely, a TyG index exceeding these thresholds was positively associated with all-cause and cardiovascular mortality (HR: 1.35, 95% CI 1.17, 1.55, P < 0.001; HR: 1.54, 95% CI 1.25, 1.90, P < 0.001, respectively). Notably, a higher TyG index (≥ threshold values) was significantly associated with increased mortality only among individuals aged under 55 compared to those with a lower TyG index (< threshold values).

CONCLUSIONS

The TyG index demonstrated a U-shaped correlation with all-cause and cardiovascular mortality in individuals with CMS. The thresholds of 9.104 and 8.758 for all-cause and cardiovascular mortality, respectively, may be used as intervention targets to reduce the risk of premature death and cardiovascular disease.

Modeling diabetic endothelial dysfunction with patient-specific induced pluripotent stem cells

Diabetes is a known risk factor for various cardiovascular complications, mediated by endothelial dysfunction. Despite the high prevalence of this metabolic disorder, there is a lack of in vitro models that recapitulate the complexity of genetic and environmental factors associated with diabetic endothelial dysfunction. Here, we utilized human induced pluripotent stem cell (iPSC)-derived endothelial cells (ECs) to develop in vitro models of diabetic endothelial dysfunction. We found that the diabetic phenotype was recapitulated in diabetic patient-derived iPSC-ECs, even in the absence of a diabetogenic environment. Subsequent exposure to culture conditions that mimic the diabetic clinical chemistry induced a diabetic phenotype in healthy iPSC-ECs but did not affect the already dysfunctional diabetic iPSC-ECs. RNA-seq analysis revealed extensive transcriptome-wide differences between cells derived from healthy individuals and diabetic patients. The in vitro disease models were used as a screening platform which identified angiotensin receptor blockers (ARBs) that improved endothelial function in vitro for each patient. In summary, we present in vitro models of diabetic endothelial dysfunction using iPSC technology, taking into account the complexity of genetic and environmental factors in the metabolic disorder. Our study provides novel insights into the pathophysiology of diabetic endothelial dysfunction and highlights the potential of iPSC-based models for drug discovery and personalized medicine.

Reversing and modulating cellular senescence in beta cells, a new field of opportunities to treat diabetes

Diabetes constitutes a world-wide pandemic that requires searching for new treatments to halt its progression. Cellular senescence of pancreatic beta cells has been described as a major contributor to development and worsening of diabetes. The concept of reversibility of cellular senescence is critical as is the timing to take actions against this "dormant" senescent state. The reversal of cellular senescence can be considered as rejuvenation of the specific cell if it returns to the original "healthy state" and doesn't behave aberrantly as seen in some cancer cells. In rodents, treatment with senolytics and senomorphics blunted or prevented disease progression, however their use carry drawbacks. Modulators of cellular senescence is a new area of research that seeks to reverse the senescence. More research in each of these modalities should lead to new treatments to stop diabetes development and progression.

Cannabinoids Transmogrify Cancer Metabolic Phenotype via Epigenetic Reprogramming and a Novel CBD Biased G Protein-Coupled Receptor Signaling Platform

The concept of epigenetic reprogramming predicts long-term functional health effects. This reprogramming can be activated by exogenous or endogenous insults, leading to altered healthy and different disease states. The exogenous or endogenous changes that involve developing a roadmap of epigenetic networking, such as drug components on epigenetic imprinting and restoring epigenome patterns laid down during embryonic development, are paramount to establishing youthful cell type and health. This epigenetic landscape is considered one of the hallmarks of cancer. The initiation and progression of cancer are considered to involve epigenetic abnormalities and genetic alterations. Cancer epigenetics have shown extensive reprogramming of every component of the epigenetic machinery in cancer development, including DNA methylation, histone modifications, nucleosome positioning, non-coding RNAs, and microRNA expression. Endocannabinoids are natural lipid molecules whose levels are regulated by specific biosynthetic and degradative enzymes. They bind to and activate two primary cannabinoid receptors, type 1 (CB1) and type 2 (CB2), and together with their metabolizing enzymes, form the endocannabinoid system. This review focuses on the role of cannabinoid receptors CB1 and CB2 signaling in activating numerous receptor tyrosine kinases and Toll-like receptors in the induction of epigenetic landscape alterations in cancer cells, which might transmogrify cancer metabolism and epigenetic reprogramming to a metastatic phenotype. Strategies applied from conception could represent an innovative epigenetic target for preventing and treating human cancer. Here, we describe novel cannabinoid-biased G protein-coupled receptor signaling platforms (GPCR), highlighting putative future perspectives in this field.

Potential Role of Oxidative Stress in the Production of Volatile Organic Compounds in Obesity

Obesity is associated with numerous health issues such as sleep disorders, asthma, hepatic dysfunction, cancer, renal dysfunction, diabetes, cardiovascular complications, and infertility. Previous research has shown that the distribution of excess body fat, rather than excess body weight, determines obesity-related risk factors. It is widely accepted that abdominal fat is a serious risk factor for illnesses associated with obesity and the accumulation of visceral fat promotes the release of pro-oxidants, pro-inflammatory, and reactive oxygen species (ROS). The metabolic process in the human body produces several volatile organic compounds (VOCs) via urine, saliva, breath, blood, skin secretions, milk, and feces. Several studies have shown that VOCs are released by the interaction of ROS with underlying cellular components leading to increased protein oxidation, lipid peroxidation, or DNA damage. These VOCs released via oxidative stress in obese individuals may serves as a biomarker for obesity-related metabolic alterations and disease. In this review, we focus on the relationship between oxidative stress and VOCs in obesity.

Antidiabetic effects of Brugmansia aurea leaf extract by modulating the glucose levels, insulin resistance, and oxidative stress mechanism

Background

Ethnopharmacological relevance: Brugmansia, a genus of the Solanaceae family, has historically been utilized in many different parts of the world as an anti-inflammatory for treating skin infections, wounds, and bodily aches and pains. The current study aimed to investigate the potential benefits of a methanolic extract of Brugmansia aurea in the management of diabetes and underlying complications in alloxanized-induced diabetic rats.

Materials and methods

Animals were divided into nine groups (n = 6). Four groups received different standard oral hypoglycemic agents; three groups received 100, 200, and 400 mg/kg of B. aurea leaf extract for six consecutive weeks, and the remaining two were normal and disease control groups. All groups received alloxan (150 mg/kg) except for the normal control. Only those animals whose glucose levels were raised to 200 mg/dl were selected for the study. After a 6-week dosage period, various biochemical parameters, as well as HbA1c, antioxidant profile, oral glucose tolerance test (OGTT), insulin sensitivity, histopathology, and insulin resistance, were measured and compared with the untreated diabetic group.

Results

Brugmansia aurea leaf extract at a dose of 400 mg/kg showed potent antidiabetic activity by reducing blood glucose levels (p < 0.001) after 6 weeks of treatment. OGTT data showed that B. aurea exhibited significant (p < 0.001) glucose tolerance by significantly reducing blood glucose levels in just 2 h post-treatment. Other tests showed that plant extract significantly increased (p < 0.001) insulin sensitivity and decreased (p < 0.001) insulin resistance. The biochemical profile showed reduced triglyceride and cholesterol, while the antioxidant profile showed restoration of antioxidant enzymes in the pancreas, kidney, and liver tissues of treated rats.

Conclusion

The present study indicated that crude extracts of B. aurea increase insulin sensitivity and reduce hyperlipidemia in diabetic rats, which rationalizes the traditional medicinal use of this plant as an antidiabetic agent.

S, Benerji G.V.. 3-Nitrotyrosine (NT) levels in serum and its association with insulin resistance in patients with type 2 diabetes mellitus: Biomarker role of NT in the assessment of oxidative stress mediated impending vascular complications in nephropathy

 Introduction and Aim: 3-Nitrotyrosine (NT) has been recognized as a marker of oxidative stress in diabetes mellitus. NT has also been studied in diverse metabolic conditions. The aim of our study was oriented towards the role of NT as a predictor of oxidative stress mediated impending nephropathy in diabetes mellitus and that with reference to albuminuria. Materials and Methods: A total of 150 type 2 diabetics in the age group   35 - 50 years were enrolled as three groups, comprising 50 each, based on albuminuria. 50 healthy age and gender matched subjects constituted the control group. Serum NT and Insulin were assessed by ELISA. HbA1c was quantitated by immunoturbidimetric method and microalbumin was assessed by turbilatex method. Routine biochemistry was enabled through ERBA EM-200 fully automated analyzer. Stringent quality control was affected.  The study was begun following approval accorded by the competent committees. Results: NT levels were positively correlated with albumin-creatinine ratio and insulin resistance. NT could be used as a predictor of impending vascular complications in diabetic nephropathy.  Conclusion: NT levels could act as a predictor of oxidative stress mediated diabetic nephropathy in the light of albuminuria.  

An Overview of Glycosylation and its Impact on Cardiovascular Health and Disease

The cardiovascular system is a complex and well-organized system in which glycosylation plays a vital role. The heart and vascular wall cells are constituted by an array of specific receptors; most of them are N- glycosylated and mucin-type O-glycosylated. There are also intracellular signaling pathways regulated by different post-translational modifications, including O-GlcNAcylation, which promote adequate responses to extracellular stimuli and signaling transduction. Herein, we provide an overview of N-glycosylation and O-glycosylation, including O-GlcNAcylation, and their role at different levels such as reception of signal, signal transduction, and exogenous molecules or agonists, which stimulate the heart and vascular wall cells with effects in different conditions, like the physiological status, ischemia/reperfusion, exercise, or during low-grade inflammation in diabetes and aging. Furthermore, mutations of glycosyltransferases and receptors are associated with development of cardiovascular diseases. The knowledge on glycosylation and its effects could be considered biochemical markers and might be useful as a therapeutic tool to control cardiovascular diseases.

The effect of grape seed extract supplementation on oxidative stress and inflammation: A systematic review and meta-analysis of controlled trials

BACKGROUND

Grape seed extract (GSE) seems to have antioxidant and anti-inflammatory properties due to its high polyphenolic content. Nevertheless, the scientific literature in this field is controversial and inconclusive. Therefore, we aimed to conduct a systematic review and meta-analysis of controlled trials to evaluate the effect of supplementation with GSE on biomarkers of oxidative stress and inflammation.

METHODS

Medline, Scopus, Cochrane Library, Google Scholar and Web of Science databases were searched up to 10 September 2020 using appropriate keywords without restrictions. In the systematic review phase, all biomarkers of oxidative stress and inflammation were considered as outcomes. In the meta-analysis phase, six biomarkers were selected as outcomes, and weighted mean difference (WMD) or standardised mean difference (SMD) with 95% confidence interval (CI) was calculated for them using a random-effects model.

RESULTS

Twenty-three studies were included in the systematic review, and 19 studies were included in the meta-analysis. GSE supplementation caused a significant decrease in malondialdehyde (SMD: -1.04, 95% CI: -1.65, -0.42), oxidised low-density lipoprotein (SMD: -0.44, 95% CI: -0.75, -0.13) and high-sensitivity C-reactive protein (WMD: -0.48 mg/L, 95% CI: -0.94, -0.03) and a marginally significant increase in total antioxidant capacity (SMD: 0.49, 95% CI: -0.05, 1.04) but did not significantly influence C-reactive protein (WMD: -0.36 mg/L, 95% CI: -1.02, 0.30) and white blood cell count (WMD: 0.12 × 10⁹ /L, 95% CI: -0.25, 0.48).

CONCLUSION

It appears that GSE supplementation can remarkably modulate the body's redox system, particularly through the inhibition of lipid peroxidation, but has neutral or mildly beneficial effects on inflammatory responses.

Substance-P Inhibits Cardiac Microvascular Endothelial Dysfunction Caused by High Glucose-Induced Oxidative Stress

Diabetes is characterized by high glucose (HG) levels in the blood circulation, leading to exposure of the vascular endothelium to HG conditions. Hyperglycemia causes oxidative stress via excessive reactive oxygen species (ROS) production in the endothelium, which leads to cellular dysfunction and the development of diabetic vascular diseases. Substance-P (SP) is an endogenous peptide involved in cell proliferation and migration by activating survival-related signaling pathways. In this study, we evaluated the role of SP in cardiac microvascular endothelial cells (CMECs) in HG-induced oxidative stress. CMECs were treated with diverse concentrations of glucose, and then the optimal dose was determined. Treatment of CMECs with HG reduced their viability and induced excessive ROS secretion, inactivation of PI3/Akt signaling, and loss of vasculature-forming ability in vitro. Notably, HG treatment altered the cytokine profile of CMECs. However, SP treatment inhibited the HG-mediated aggravation of CMECs by restoring viability, free radical balance, and paracrine potential. SP-treated CMECs retained the capacity to form compact and long stretching-tube structures. Collectively, our data provide evidence that SP treatment can block endothelial dysfunction in hyperglycemia and suggest the possibility of using SP for treating diabetic complications as an antioxidant.

Hypoxia-Inducible Factor Regulates Endothelial Metabolism in Cardiovascular Disease

Endothelial cells (ECs) form a physical barrier between the lumens and vascular walls of arteries, veins, capillaries, and lymph vessels; thus, they regulate the extravasation of nutrients and oxygen from the circulation into the perivascular space and participate in mechanisms that maintain cardiovascular homeostasis and promote tissue growth and repair. Notably, their role in tissue repair is facilitated, at least in part, by their dependence on glycolysis for energy production, which enables them to resist hypoxic damage and promote angiogenesis in ischemic regions. ECs are also equipped with a network of oxygen-sensitive molecules that collectively activate the response to hypoxic injury, and the master regulators of the hypoxia response pathway are hypoxia-inducible factors (HIFs). HIFs reinforce the glycolytic dependence of ECs under hypoxic conditions, but whether HIF activity attenuates or exacerbates the progression and severity of cardiovascular dysfunction varies depending on the disease setting. This review summarizes how HIF regulates the metabolic and angiogenic activity of ECs under both normal and hypoxic conditions and in a variety of diseases that are associated with cardiovascular complications.

MicroRNA-532-5p-programmed cell death protein 4 (PDCD4) axis regulates angiotensin II-induced human umbilical vein endothelial cell apoptosis and proliferation

BACKGROUND

This study was carried out to investigate the effect of microRNA miR-532-5p on the proliferation of hypertension endothelial cells.

METHODS

Angiotensin II (Ang II)-treated human umbilical vein endothelial cells (HUVECs) and primary human aortic endothelial cells (HAECs) were used as cell models to imitate the pathological changes in endothelial cells under hypertensive conditions. The expression levels of miR-532-5p and programmed cell death protein 4 (PDCD4) were detected by Quantitative Real-time PCR (qRT-PCR). The effects of miR-532-5p and PDCD4 on the proliferation of HUVECs and HAECs treated with Ang II were detected by Methyl Thiazolyl Tetrazolium (MTT) assay. The effects of miR-532-5p and PDCD4 on the apoptosis and cell cycle of HUVECs and HAECs treated with Ang II were detected by flow cytometry. Western blot was used to detect the expression levels of PDCD4, apoptosis-related proteins and cycle-related proteins in HUVECs and HAECs treated with Ang II. Bioinformatics analysis and Luciferase gene reporter assay were used to assess the relationship between miR-532-5p and PDCD4.

RESULTS

The expression levels of miR-532-5p were reduced, while the expression levels of PDCD4 were raised in Ang II-treated HUVECs and HAECs. MiR-532-5p mimic and si-PDCD4 restrained the apoptosis, promoted the proliferation of Ang II-treated HUVECs and HAECs and caused S-phase arrest of cells. PDCD4 was identified as a potential target for miR-532-5p. Knockdown of PDCD4 significantly affected apoptosis and proliferation of Ang II-treated HUVECs. MiR-532-5p regulates apoptosis and proliferation of Ang II-induced HUVECs and HAECs. In addition, overexpression of PDCD4 attenuated the effect of miR-532-5p on the proliferation of Ang II-treated HUVECs and HAECs.

CONCLUSION

MiR-532-5p inhibited the expression of PDCD4, thereby inhibiting apoptosis and promoting proliferation of Ang II-treated HUVECs and HAECs.

Association Between Triglyceride-Glucose Index and Hypertension: A Meta-Analysis

Background: Triglyceride-glucose (TyG) index is a recently proposed surrogate indicator of insulin resistance. Previous studies evaluating the association between TyG index and hypertension risk in general adult population showed inconsistent results. We performed a meta-analysis to systematically evaluate this association. Methods: Observational studies, which evaluated the independent association between TyG index and hypertension in the general adult population, were identified by systematic search of PubMed, Embase, Web of Science, Wanfang data, and Chinese National Knowledge Infrastructure databases. A random-effect model, which incorporated the potential intra-study heterogeneity, was used for the meta-analysis. Results: Eight observational studies including 200,044 participants were included. Results showed that compared with those with the lowest category of TyG index, subjects with the highest category of TyG index were associated with higher odds of hypertension [adjusted risk ratio (RR): 1.53, 95% confidence interval (CI): 1.26-1.85, I ² = 54%, P < 0.001]. Sensitivity analysis by excluding one dataset at a time showed consistent result (adjusted RR: 1.44-1.62, P all < 0.001). Results of univariate meta-regression analysis showed that differences in sample size, mean age, male proportion, mean body mass index, and study quality score among the included studies did not have significant influence on the association between TyG index and hypertension (P values all > 0.10), suggesting that differences in these characteristics may not be the major source of heterogeneity. Subgroup analyses showed that study characteristics such as study design, participant ethnicity, age, or sex of the participants did not significantly affect the association (P for subgroup difference all >0.05). Conclusions: Higher TyG index may be associated with higher odds of hypertension in general adult population. Large-scale prospective cohort studies are needed to validate these findings, and further studies are needed to elucidate the potential pathophysiological mechanisms underlying the association between TyG index and hypertension.

TP63 Is Significantly Upregulated in Diabetic Kidney

The role of tumor protein 63 (TP63) in regulating insulin receptor substrate 1 (IRS-1) and other downstream signal proteins in diabetes has not been characterized. RNAs extracted from kidneys of diabetic mice (db/db) were sequenced to identify genes that are involved in kidney complications. RNA sequence analysis showed more than 4- to 6-fold increases in TP63 expression in the diabetic mice’s kidneys, compared to wild-type mice at age 10 and 12 months old. In addition, the kidneys from diabetic mice showed significant increases in TP63 mRNA and protein expression compared to WT mice. Mouse proximal tubular cells exposed to high glucose (HG) for 48 h showed significant decreases in IRS-1 expression and increases in TP63, compared to cells grown in normal glucose (NG). When TP63 was downregulated by siRNA, significant increases in IRS-1 and activation of AMP-activated protein kinase (AMPK (p-AMPK-Th¹⁷²)) occurred under NG and HG conditions. Moreover, activation of AMPK by pretreating the cells with AICAR resulted in significant downregulation of TP63 and increased IRS-1 expression. Ad-cDNA-mediated over-expression of tuberin resulted in significantly decreased TP63 levels and upregulation of IRS-1 expression. Furthermore, TP63 knockdown resulted in increased glucose uptake, whereas IRS-1 knockdown resulted in a decrease in the glucose uptake. Altogether, animal and cell culture data showed a potential role of TP63 as a new candidate gene involved in regulating IRS-1 that may be used as a new therapeutic target to prevent kidney complications in diabetes.

Triglyceride-glucose index and the incidence of atherosclerotic cardiovascular diseases: a meta-analysis of cohort studies

Background

Insulin resistance has been demonstrated to be involved in the pathogenesis of atherosclerotic cardiovascular diseases (ASCVDs). This study evaluated the association between the triglyceride–glucose (TyG) index, a novel surrogate indicator of insulin resistance, and the incidence of ASCVDs in people without ASCVDs at baseline by performing a meta-analysis.

Methods

Cohort studies reporting the multivariate-adjusted association between the TyG index and the incidence of ASCVDs were obtained by searching the PubMed and Embase databases. A random-effects model incorporating intra-study heterogeneity was applied to combine the results.

Results

Eight cohort studies comprising 5,731,294 participants were included in this meta-analysis. The results showed that compared to those with the lowest TyG index category, participants with the highest TyG index category were independently associated with a higher risk of ASCVDs [hazard ratio (HR): 1.61, 95% confidence interval (CI) 1.29–2.01, I² = 80%, P < 0.001]. This finding was consistent with the meta-analysis results with the TyG index analyzed as a continuous variable (HR per 1-unit increment of the TyG index: 1.39, 95% CI 1.18–1.64, I² = 89%, P < 0.001). Subgroup analyses suggested that the age, sex, and diabetic status did not significantly affect the association (for subgroup analyses, all P > 0.05). Moreover, participants with the highest TyG index category were independently associated with a higher risk of coronary artery disease [(CAD), HR: 1.95, 95% CI 1.47–2.58, I² = 92%, P < 0.001] and stroke (HR: 1.26, 95% CI 1.23–1.29, I² = 0%, P < 0.001).

Conclusions

A higher TyG index may be independently associated with a higher incidence of ASCVDs, CAD, and stroke in people without ASCVDs at baseline.

Assessment of Early Markers of Cardiovascular Risk in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a heterogeneous syndrome, with long-term sequelae from birth to senescence. The long-term effects of PCOS are attributed to several metabolic aberrations ensuing the syndrome. In a systematic review of literature regarding the cardiovascular risk factors that accompany PCOS, we found that macrovascular function has been assessed by flow-mediated dilatation (FMD), microvascular function by venous occlusion plethysmography (VOP), and arterial structure by ultrasonographic assessment of intima-media thickness (IMT) usually of the carotid artery. Contradictory results have been reported; however, in most studies, endothelial dysfunction, an early marker of atherosclerosis assessed either by haemodynamic methods such as FMD or by biochemical methods such as endothelin-1 levels, was found to be impaired. VOP is a less-studied method, with few indices altered. IMT was found to be altered in most of the included studies, but the population was more heterogeneous. Inflammatory markers, including C-reactive protein, were also found to be altered in most studies. On the other hand, a number of interventions have been shown beneficial for the markers of cardiovascular risk, in the context of insulin-sensitizers. However, other interventions such as oral contraceptive pills or statins did not consistently show a similar beneficial effect. In summary, the early identification and eventual treatment of cardiovascular clinical and biochemical risk factors may be used in clinical practice to prevent potential 'silent' triggers of cardiovascular disease.

Assessment of Early Markers of Cardiovascular Risk in Polycystic Ovary Syndrome

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Acute Effects of Metformin and Vildagliptin after a Lipid-Rich Meal on Postprandial Microvascular Reactivity in Patients with Type 2 Diabetes and Obesity: A Randomized Trial

Background: Type 2 diabetes mellitus and obesity are both related to endothelial dysfunction. Postprandial lipemia is a cardiovascular risk. Notably, it is known that a high-fat diet may elicit microvascular dysfunction, even in healthy subjects. Since anti-diabetic drugs have different mechanisms of action and also distinct vascular benefits, we aimed to compare the results of two anti-diabetic drugs after the intake of a lipid-rich meal on microcirculation in patients with type 2 diabetes and obesity. In parallel, we also investigated the metabolic profile, oxidative stress, inflammation, plasma viscosity, and some gastrointestinal peptides. Subjects/Methods: We included 38 drug-naïve patients, all women aged between 19 and 50 years, with BMI ≥ 30 kg/m². We performed endothelial measurements and collected samples before (fasting) and after the intake of a lipid-rich meal at 30, 60, 120, and 180 min. Patients were randomized to metformin or vildagliptin, given orally just before the meal. Endothelial function was assessed by videocapillaroscopy and laser-Doppler flowmetry to investigate microvascular reactivity. Besides, we also investigated plasma viscosity, inflammatory and oxidative stress biomarkers, gastrointestinal peptides, and metabolic profile in all time points. Results: No differences at baseline were noted between groups. Vildagliptin increased glucagon-like peptide-1 compared to metformin. Paired comparisons showed that, during the postprandial period, vildagliptin significantly changed levels of insulin and glucagon-like peptide-1, and also the dipeptidyl peptidase-4 activity, while metformin had effects on plasma glucose solely. Metformin use during the test meal promoted an increase in functional capillary density, while vildagliptin kept non-nutritive microvascular blood flow and vasomotion unchanged. Conclusions: After the intake of a lipid-rich meal, the use of vildagliptin preserved postprandial non-nutritive microflow and vasomotion, while metformin increased capillary recruitment, suggesting protective and different mechanisms of action on microcirculation.

Molecular process of glucose uptake and glycogen storage due to hamamelitannin via insulin signalling cascade in glucose metabolism

Understanding the mechanism by which the exogenous biomolecule modulates the GLUT-4 signalling cascade along with the information on glucose metabolism is essential for finding solutions to increasing cases of diabetes and metabolic disease. This study aimed at investigating the effect of hamamelitannin on glycogen synthesis in an insulin resistance model using L6 myotubes. Glucose uptake was determined using 2-deoxy-D-[1-³H] glucose and glycogen synthesis were also estimated in L6 myotubes. The expression levels of key genes and proteins involved in the insulin-signaling pathway were determined using real-time PCR and western blot techniques. The cells treated with various concentrations of hamamelitannin (20 µM to 100 µM) for 24 h showed that, the exposure of hamamelitannin was not cytotoxic to L6 myotubes. Further the 2-deoxy-D-[1-³H] glucose uptake assay was carried out in the presence of wortmannin and Genistein inhibitor for studying the GLUT-4 dependent cell surface recruitment. Hamamelitannin exhibited anti-diabetic activity by displaying a significant increase in glucose uptake (125.1%) and glycogen storage (8.7 mM) in a dose-dependent manner. The optimum concentration evincing maximum activity was found to be 100 µm. In addition, the expression of key genes and proteins involved in the insulin signaling pathway was studied to be upregulated by hamamelitannin treatment. Western blot analysis confirmed the translocation of GLUT-4 protein from an intracellular pool to the plasma membrane. Therefore, it can be conceived that hamamelitannin exhibited an insulinomimetic effect by enhancing the glucose uptake and its further conversion into glycogen by regulating glucose metabolism.

Cellular Fibronectin Containing Extra Domain A Causes Insulin Resistance via Toll-like Receptor 4

We determined the role of cellular fibronectin (CFN) containing the alternatively spliced extra domain A (FN-EDA) in causing insulin resistance (IR) through toll-like receptor 4 (TLR4). Circulating FN-EDA level was evaluated in mouse and rat IR models. Specific anti-FN-EDA antibody and TLR4 inhibitor were used to study its role in IR in mice. CFN protein was injected to evaluate TLR4 dependent effect of FN-EDA in IR. Furthermore, FN-EDA was estimated in blood plasma and correlated with demographic and clinical characteristics in healthy human participants (n = 38). High-fat diet feeding significantly increased circulating FN-EDA in both mouse (P = 0.03) and rat (P = 0.02) IR models. Antibody against FN-EDA protected mice from IR by increasing glucose disposal rate following glucose (P = 0.02) and insulin (P = 0.01) tolerance tests. CFN protein injection caused IR, however, TLR4 inhibitor protected the mice from CFN induced IR. Multivariate regression analysis predicted an independent positive correlation between circulating FN-EDA and fasting plasma glucose (P = 0.003) in healthy human participants. In conclusion, FN-EDA may cause IR through TLR4 by decreasing glucose disposal rate following glucose and insulin load. Targeting FN-EDA thus can be considered as a possible therapeutic strategy to delay prediabetes progression to diabetes.

Screening of the active fractions from the Coreopsis tinctoria Nutt. Flower on diabetic endothelial protection and determination of the underlying mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

The Coreopsis tinctoria Nutt. flower (CTF) has been used traditionally in China for treating hypertension and diabetes as well as reducing body weight and blood fat. However, the vascular protection effect of the CTF has not been studied to date.

AIM OF THE STUDY

This study aimed to screen and identify bioactive fractions from the CTF with a diabetic endothelial protection effect and to clarify the underlying mechanism.

MATERIALS AND METHODS

The vascular protection effect of Fraction A was studied in high-fat diet and streptozocin-induced diabetic models. The endothelial protection effect of Fraction A-2 was further studied in an in vitro vascular endothelial dysfunction model induced by high glucose. In a high glucose-induced human umbilical vein endothelial cell (HUVEC) model, Fractions A-2-2 and A-2-3 were screened, and their detailed mechanisms of endothelial protection were studied. Liquid chromatography mass spectrometry (LC-MS) was used to identify the main components in Fractions A-2-2 and A-2-3.

RESULTS

Fraction A treatment significantly improved the endothelium-dependent vasodilation of the mesenteric artery induced by acetylcholine in diabetic rats. The maximum relaxation was 79.82 ± 2.45% in the control group, 64.36 ± 9.81% in the model group, and 91.87 ± 7.38% in the Fraction A treatment group (P < 0.01). Fraction A treatment also decreased rat tail pressure compared with the model group at the 12th week. The systolic blood pressure was 152.7 5 ± 16.99 mmHg in the control group, 188.50 ± 5.94 mmHg in the model group, and 172.60 ± 14.31 mmHg in the Fraction A treatment group (P < 0.05). The mean blood pressure was 128.50 ± 13.79 mmHg in the control group, 157.00 ± 6.06 mmHg in the model group, and 144.80 ± 11.97 mmHg in the Fraction A treatment group (P < 0.05). In an in vitro vascular endothelium-dependent vasodilation dysfunction model induced by high glucose, Fraction A-2 improved the vasodilation of the mesenteric artery. The maximum relaxation was 82.15 ± 16.24% in the control group, 73.29 ± 14.25% in the model group, and 79.62 ± 13.89% in the Fraction A-2 treatment group (P < 0.05). In a high glucose-induced HUVEC model, Fraction A-2-2 and Fraction A-2-3 upregulated the expression of IRS-1, Akt, and eNOS and increased the levels of p-IRS-1^Ser307, p-Akt ^Ser473, and p-eNOS^Ser1177 and also decreased the expression of NOX4, TNF-α, IL-6, sVCAM, sICAM, and NF-κB (P < 0.01). With the intervention of AG490 and LY294002, the above effects of Fraction A-2-2 and Fraction A-2-3 were inhibited (P < 0.01). LC-MS data showed that in Fraction A-2-2 and Fraction A-2-3, there were 10 main components: flavanocorepsin; polyphenolic; flavanomarein; isochlorogenic acid A; dicaffeoylquinic acid; coreopsin; marein; coreopsin; luteolin-7-O-glucoside; and 3',5,5',7-tetrahydroxyflavanone-O-hexoside.

CONCLUSION

The protective effect of the CTF on diabetic endothelial dysfunction may be due to its effect on the JAK2/IRS-1/PI3K/Akt/eNOS pathway and the related oxidative stress and inflammation. The results strongly suggested that Fraction A-2-2 and Fraction A-2-3 were the active fractions from the CTF, and the CTF might be a potential option for the prevention of vascular complications in diabetes.

Chronic inhibition of phosphodiesterase 5 with tadalafil affords cardioprotection in a mouse model of metabolic syndrome: role of nitric oxide

Patients with metabolic syndrome (MetS) often exhibit generalized endothelial and cardiac dysfunction with decreased nitric oxide (NO) production and/or bioavailability. Since phosphodiesterase 5 (PDE5) inhibitors restore NO signaling, we hypothesized that chronic treatment with long-acting PDE5 inhibitor tadalafil may enhance plasma NO levels and reduce cardiac dysfunction following ischemia/reperfusion (I/R) injury in C57BL/6NCrl-Leprdb-lb/Crl mice with MetS phenotypes. Adult male MetS mice were randomized to receive vehicle solvent or tadalafil (1 mg/kg,i.p.) daily for 28 days and C57BL/6NCrl mice served as healthy wild-type controls. After 28 days, cardiac function was assessed by echocardiography and hearts from a subset of mice were isolated and subjected to 30 min of global ischemia followed by 60 min of reperfusion (I/R) in ex vivo Langendorff mode. Body weight, blood lipids, and glucose levels were elevated in MetS mice as compared with wild-type controls. The dyslipidemia in MetS was ameliorated following tadalafil treatment. Although left ventricular (LV) systolic function was minimally altered in the MetS mice, there was a significant diastolic dysfunction as indicated by reduction in the ratio of peak velocity of early to late filling of the mitral inflow, which was significantly improved by tadalafil treatment. Post-ischemic cardiac function, heart rate, and coronary flow decreased significantly in MetS mice compared to wild-type controls, but preserved by tadalafil treatment. Myocardial infarct size was significantly smaller following I/R, which was associated with higher plasma levels of nitrate and nitrite in the tadalafil-treated MetS mice. In conclusion, tadalafil induces significant cardioprotective effects as shown by improvement of LV diastolic function, lipid profile, and reduced infarct size following I/R. Tadalafil treatment enhanced NO production, which may have contributed to the cardioprotective effects.

Modulation of Small Artery Function by Insulin in Young Women: Role of Adiposity

OBJECTIVES

Vascular dysfunction is common in obesity. Insulin can directly modulate arterial function, but its role is unclear in obesity. We examined the influence of adiposity on direct effects of insulin on human artery responses.

METHODS

22 healthy women were stratified by median BMI into lower (LA) (n=11) and higher adiposity (HA) (n=11). Small arteries from gluteal biopsies were tested for contractile responses to Noradrenaline (NA), the endothelium-dependent dilator Carbachol and the endothelium-independent dilator sodium nitroprusside were examined before and after incubation with 100 mU/ml human insulin.

RESULTS

Contractile responses were similar in the two groups. Insulin reduced NA-induced contraction in HA [3.5 (2.4-4.6) vs. 2.4 (1.4-3.4) mN/mm: p=0.004] but not those from LA [4.1 (2.8-5.3) vs. 3.7 (2.5-5.0) mN/mm: p=0.33]. Endothelium-dependent dilation (EDD) was significantly reduced in arteries from women in the HA (34.7 (18.8-50.6%)) compared to those from women in the LA (62.3 (46.2- 78.4); p=0.013). Insulin improved EDD (change in maximal dilation before/after insulin (%)) in arteries from the HA (37.7 (18.0 to 57.3) but not the LA (6.3 (-6.5 to 19.1), p=0.007.

CONCLUSION

Reduced EDD evident in arteries from HA subjects improve by incubating in insulin. Hyperinsulinaemia may be necessary in maintaining endothelial function in obesity.

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.

Regulatory Effects of O-GlcNAcylation in Vascular Smooth Muscle Cells on Diabetic Vasculopathy

Vascular complications from uncontrolled hyperglycemia are the leading cause of death in patients with diabetes mellitus. Previous reports have shown a strong correlation between hyperglycemia and vascular calcification, which increases mortality and morbidity in individuals with diabetes. However, the precise underlying molecular mechanisms of hyperglycemia-induced vascular calcification remain largely unknown. Transdifferentiation of vascular smooth muscle cells (VSMC) into osteoblast-like cells is a known culprit underlying the development of vascular calcification in the diabetic vasculature. Pathological conditions such as high glucose levels and oxidative stress are linked to enhanced osteogenic differentiation of VSMC both in vivo and in vitro. It has been demonstrated that increased expression of runt-related transcription factor 2 (Runx2), a bone-related transcription factor, in VSMC is necessary and sufficient for the induction of VSMC calcification. Addition of a single O-linked β-N-acetylglucosamine (O-GlcNAc) moiety to the serine/threonine residues of target proteins (O-GlcNAcylation) has been observed in the arteries of diabetic patients, as well as in animal models in association with the enhanced expression of Runx2 and aggravated vascular calcification. O-GlcNAcylation is a dynamic and tightly regulated process, that is mediated by 2 enzymes, O-GlcNAc transferase and O-GlcNAcase. Glucose is metabolized into UDP-β-D-N-acetylglucosamine, an active sugar donor of O-GlcNAcylation via the hexosamine biosynthetic pathway. Overall increases in the O-GlcNAcylation of cellular proteins have been closely associated with cardiovascular complications of diabetes. In this review, the authors provide molecular insights into cardiovascular complications, including diabetic vasculopathy, that feature increased O-GlcNAcylation in people with diabetes.

Nitric Oxide Resistance, Induced in the Myocardium by Diabetes, Is Circumvented by the Nitric Oxide Redox Sibling, Nitroxyl

Aim: Impairment of tissue responsiveness to exogenous and endogenous nitric oxide (NO^•), known as NO^• resistance, occurs in many cardiovascular disease states, prominently in diabetes and especially in the presence of marked hyperglycemia. In this study, we sought to determine in moderate and severe diabetes (i) whether NO^• resistance also occurs in the myocardium, and (ii) whether the NO^• redox sibling nitroxyl (HNO) circumvents this. Results: The spectrum of acute NO^• effects (induced by diethylamine-NONOate), including vasodilation, and enhanced myocardial contraction and relaxation were impaired by moderately diabetic rats ([blood glucose] ∼20 mM). In contrast, acute HNO effects (induced by isopropylamine-NONOate) were preserved even in more severe diabetes ([blood glucose] >28 mM). Intriguingly, the positive inotropic effects of HNO were significantly enhanced in diabetic rat hearts. Further, progressive attenuation of soluble guanylyl cyclase (sGC) contribution to myocardial NO^• responses occurred with increasing severity of diabetes. Nevertheless, activation of sGC by HNO remained intact in the myocardium. Innovation: Diabetes is associated with marked attenuation of vascular and myocardial effects of NO and NO donors, and this NO^• resistance is circumvented by HNO, suggesting potential therapeutic utility for HNO donors in cardiovascular emergencies in diabetics. Conclusion: These results provide the first evidence that NO^• resistance occurs in diabetic hearts, and that HNO largely circumvents this problem. Further, the positive inotropic and lusitropic effects of HNO are enhanced in a severely diabetic myocardium, a finding that warrants further mechanistic interrogation. The results support a potential role for therapeutic HNO administration in acute treatment of ischemia and/or heart failure in diabetics.

Impact of Alpha-Lipoic Acid Chronic Discontinuous Treatment in Cardiometabolic Disorders and Oxidative Stress Induced by Fructose Intake in Rats

Insulin resistance (IR) and cardiometabolic disorders are the main consequences of today’s alimentary behavior. This study evaluates the effects of a chronic-discontinuous treatment with alpha-lipoic acid (AL), an antioxidant substance that improves glycemic control associated with diabetes mellitus, on metabolic disorders and plasma oxidative stress induced by fructose intake, in rats. Sprague-Dawley rats (48 animals) were randomized into two series (n = 24): rats fed with standard chow or with standard chow supplemented with 60% fructose. In each of the two series, for 2 weeks/month over 12 weeks, a group of rats (n = 12) was intraperitoneally injected with NaCl 0.9%, and a second group (n = 12) received AL 50 mg/kg/day. Body weight, glycemia, and systolic blood pressure were monitored throughout the study. After 12 weeks, IR, plasma lipoproteins, uric acid, transaminase activities, and oxidative stress markers were assessed. The high fructose-enriched diet induced cardiometabolic disorders (hypertension, hyperglycemia, IR and dyslipidemia), an increase in uric acid concentration, transaminase activities and C-reactive protein level. This diet also enhanced plasma products of lipid and protein oxidation, homocysteine level, and decreased GSH/GSSG ratio. In this field, there is evidence to indicate that oxidative stress plays an important role in the etiology of diabetic complications. AL discontinuous treatment prevents the metabolic disorders induced by fructose intake, reduced plasma lipid and protein oxidation-products, and restored the GHS/GSSG ratio. Our study proves a promising potential of the chronic-discontinuous treatment of AL and highlights the pleiotropic effects of this antioxidant substance in metabolic disorders such as diabetes.

Impaired Endothelium-Dependent Hyperpolarization Underlies Endothelial Dysfunction during Early Metabolic Challenge: Increased ROS Generation and Possible Interference with NO Function

Endothelial dysfunction is a hallmark of diabetic vasculopathies. Although hyperglycemia is believed to be the culprit causing endothelial damage, the mechanism underlying early endothelial insult in prediabetes remains obscure. We used a nonobese high-calorie (HC)-fed rat model with hyperinsulinemia, hypercholesterolemia, and delayed development of hyperglycemia to unravel this mechanism. Compared with aortic rings from control rats, HC-fed rat rings displayed attenuated acetylcholine-mediated relaxation. While sensitive to nitric oxide synthase (NOS) inhibition, aortic relaxation in HC-rat tissues was not affected by blocking the inward-rectifier potassium (Kir) channels using BaCl₂ Although Kir channel expression was reduced in HC-rat aorta, Kir expression, endothelium-dependent relaxation, and the BaCl₂-sensitive component improved in HC rats treated with atorvastatin to reduce serum cholesterol. Remarkably, HC tissues demonstrated increased reactive species (ROS) in smooth muscle cells, which was reversed in rats receiving atorvastatin. In vitro ROS reduction, with superoxide dismutase, improved endothelium-dependent relaxation in HC-rat tissues. Significantly, connexin-43 expression increased in HC aortic tissues, possibly allowing ROS movement into the endothelium and reduction of eNOS activity. In this context, gap junction blockade with 18-β-glycyrrhetinic acid reduced vascular tone in HC rat tissues but not in controls. This reduction was sensitive to NOS inhibition and SOD treatment, possibly as an outcome of reduced ROS influence, and emerged in BaCl₂-treated control tissues. In conclusion, our results suggest that early metabolic challenge leads to reduced Kir-mediated endothelium-dependent hyperpolarization, increased vascular ROS potentially impairing NO synthesis and highlight these channels as a possible target for early intervention with vascular dysfunction in metabolic disease. SIGNIFICANCE STATEMENT: The present study examines early endothelial dysfunction in metabolic disease. Our results suggest that reduced inward-rectifier potassium channel function underlies a defective endothelium-mediated relaxation possibly through alteration of nitric oxide synthase activity. This study provides a possible mechanism for the augmentation of relatively small changes in one endothelium-mediated relaxation pathway to affect overall endothelial response and highlights the potential role of inward-rectifier potassium channel function as a therapeutic target to treat vascular dysfunction early in the course of metabolic disease.

Increased coronary arteriolar contraction to serotonin in juvenile pigs with metabolic syndrome

Metabolic syndrome (MetS) is associated with alterations in coronary vascular smooth muscle and endothelial function. The current study examined the contractile response of the isolated coronary arterioles to serotonin in pigs with and without MetS and investigated the signaling pathways responsible for serotonin-induced vasomotor tone. The MetS pigs (8-weeks old) were fed with a hyper-caloric, fat/cholesterol diet and the control animals (lean) were fed with a regular diet for 12 weeks (n = 6/group). The coronary arterioles (90–180 μm in diameter) were dissected from the harvested pig myocardial tissues and the in vitro coronary arteriolar response to serotonin was measured in the presence of pharmacological inhibitors. The protein expressions of phospholipase A2 (PLA₂), TXA₂ synthase, and the thromboxane-prostanoid (TP) receptor in the pigs’ left ventricular tissue samples were measured using Western blotting. Serotonin (10⁻⁹–10⁻⁵ M) induced dose-dependent contractions of coronary-resistant arterioles in both non-MetS control (lean) and MetS pigs. This effect was more pronounced in the MetS vessels compared with those of non-MetS controls (lean, P < 0.05]. Serotonin-induced contraction of the MetS vessels was significantly inhibited in the presence of the selective PLA₂ inhibitor quinacrine (10⁻⁶ M), the COX inhibitor indomethacin (10⁻⁵ M), and the TP receptor antagonist SQ29548 (10⁻⁶ M), respectively (P < 0.05). MetS exhibited significant increases in tissue levels of TXA₂ synthase and TP receptors (P < 0.05 vs. lean), respectively. MetS is associated with increased contractile response of porcine coronary arterioles to serotonin, which is in part via upregulation/activation of PLA₂, COX, and subsequent TXA₂, suggesting that alteration of vasomotor function may occur at an early stage of MetS and juvenile obesity.

Impaired insulin sensitivity is associated with worsening cognition in HIV-infected patients

OBJECTIVE

To determine the association of insulin sensitivity and metabolic status with declining cognition in HIV-infected individuals.

METHODS

We conducted targeted clinical and metabolic measures in longitudinal plasma samples obtained from HIV-infected patients enrolled in the Central Nervous System HIV Anti-Retroviral Therapy Effects Research Study (CHARTER). Findings were validated with plasma samples from the Multicenter AIDS Cohort Study (MACS). Patients were grouped according to longitudinally and serially assessed cognitive performance as having stably normal or declining cognition.

RESULTS

Patients with declining cognition exhibited baseline hyperinsulinemia and elevated plasma c-peptide levels with normal c-peptide/insulin ratios, suggesting that insulin production was increased, but insulin clearance was normal. The association of hyperinsulinemia with worsening cognition was further supported by low high-density lipoprotein (HDL), high low-density lipoprotein/HDL ratio, and elevated cholesterol/HDL ratio compared to patients with stably normal cognition.

CONCLUSIONS

These findings suggest that hyperinsulinemia and impaired insulin sensitivity are associated with cognitive decline in antiretroviral therapy-treated HIV-infected patients.

Nigella sativa L. seed regulated eNOS, VCAM-1 and LOX-1 genes expression and improved vasoreactivity in aorta of diabetic rat

ETHNOPHARMACOLOGICAL RELEVANCE

Nigella sativa L. seed has been widely used in traditional medicine for the treatment of diabetes. The major reason for vascular complications in diabetic patients is endothelial dysfunction. However, the impact of N. sativa seed on endothelial dysfunction in diabetes remains unclear.

AIM OF THE STUDY

This study was conducted to evaluate the effect of the hydroalcoholic extract of N. sativa seed on eNOS, VCAM-1, and LOX-1 genes expression and the vasoreactivity of aortic rings to acetylcholine (Ach) in streptozotocin (STZ)-induced diabetic rat.

MATERIALS AND METHODS

Treated rats received N. sativa seed extract (100, 200, and 400 mg/kg) daily by gavage for 6 weeks. The fasting blood glucose and lipids were measured and atherogenic index of plasma (AIP) was calculated. The endothelium-dependent vasoreactivity responses of isolated aortic rings were evaluated in the presence of cumulative concentrations of Ach (10^-8-10^-5 M). eNOS, VCAM-1, and LOX-1 genes expression in aortic tissue was assessed by using real time polymerase chain reaction (PCR).

RESULTS

Male diabetic Wistar rats treated with N. sativa seed extract for six weeks reduced serum glucose and lipids and improved AIP. The vasorelaxant responses of aortic rings to Ach were markedly improved. N. sativa seed significantly increased eNOS in mRNA expression level and function, while it decreased VCAM-1 and LOX-1 expressions in vascular cells of aortic tissue which assessed only in mRNA level.

CONCLUSIONS

The results of this study showed that N. sativa seed more likely, has antidiabetic and antihyperlipidemic properties and improved vasoreactivity, endothelial dysfunction, and vascular inflammation in diabetic rats' aorta.

Metabolic Syndrome Is an Independent Risk Factor for Acquired Premature Ejaculation

Purpose

To determine the role of metabolic syndrome (MetS) as a risk factor for acquired premature ejaculation (PE) after considering the various risk factors, such as lower urinary tract symptoms, erectile dysfunction, hypogonadism, and prostatitis.

Materials and Methods

From January 2012 to January 2017, records of 1,029 men were analyzed. We performed multivariate analysis to identify risk factors for PE, including the covariate of age, marital status, International Prostate Symptom Score, International Index of Erectile Function (IIEF) score, National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI) score, serum testosterone levels, and all components of MetS. Acquired PE was defined as self-reported intravaginal ejaculation latency time ≤3 minutes, and MetS was diagnosed using the modified National Cholesterol Education Program Adult Treatment Panel III criteria.

Results

Of 1,029 men, 74 subjects (7.2%) had acquired PE and 111 (10.8%) had MetS. Multivariate analysis showed that the IIEF overall satisfaction score (odds ratio [OR]=0.67, p<0.001), NIH-CPSI pain score (OR=1.07, p=0.035), NIH-CPSI voiding score (OR=1.17, p=0.032), and presence of MetS (OR=2.20, p=0.022) were significantly correlated with the prevalence of acquired PE. In addition, the Male Sexual Health Questionnaire for Ejaculatory Dysfunction scores and ejaculation anxiety scores progressively decreased as the number of components of MetS increased.

Conclusions

MetS may be an independent predisposing factor for the development of acquired PE. Effective prevention and treatment of MetS could also be important for the prevention and treatment of acquired PE.

LncRNA SRA deregulation contributes to the development of atherosclerosis by causing dysfunction of endothelial cells through repressing the expression of adipose triglyceride lipase

It has been well established that long non‑coding RNAs (lncRNAs) are crucial mediators in a diverse range of diseases, including atherosclerosis. The present study aimed to examine the molecular mechanisms underlying the association between steroid receptor RNA activator (SRA) and atherosclerosis. Reverse transcription‑quantitative polymerase chain reaction analysis, western blot analysis and luciferase assays were performed to examine interactions among SRA, adipose triglyceride lipase (ATGL) and peroxisome proliferator‑activated receptor (PPARγ), and the effect of resveratrol (RSV) on the levels of SRA, ATGL and PPARγ. ELISA was performed to determine the effects of SRA and RSV on the production of inflammatory‑associated cytokines. The results showed that knockdown of the expression of SRA by transfecting HUVECs with short hairpin RNA‑SRA inhibited the production of ATGL and PPARγ. A plasmid coding SRA RNA, but not the SRAP protein, attenuated the luciferase activity of the ATGL promoter. PPARγ had no effect on the luciferase activity driven by the ATGL promoter in the absence of rosiglitazone, whereas the luciferase activity of the ATGL promoter was elevated in the presence of rosiglitazone. This effect was eliminated by SRA. SRA enhanced the production of inflammatory‑associated cytokines, including tumor necrosis factor‑α, interleukin‑6, monocyte chemotactic protein‑1 and intercellular adhesion molecule‑1; however, the promoting effect of SRA was eliminated by RSV. RSV increased the expression of ATGL and PPARγ, but not that of SRA. RSV distinctly and concentration‑dependently upregulated the luciferase activity of ATGL, compared with that in the cells without RSV treatment, whereas treating with rosiglitazone inhibited the effect of RSV on the luciferase activity of ATGL. The present study examined the roles of SRA in atherosclerosis, and the effects of changes in SRA and ATGL on inflammatory cytokines and HUVEC dysfunction.

Hypoglycemic Properties of the Aqueous Extract from the Stem Bark of Ceiba pentandra in Dexamethasone-Induced Insulin Resistant Rats

Parts of Ceiba pentandra are wildly used in Africa to treat diabetes and previous works have demonstrated their in vivo antidiabetic effects on type 1 diabetes models. In addition, it has been recently shown that the decoction and the methanol extract from the stem bark of C. pentandra potentiate in vitro, the peripheral glucose consumption by the liver and skeletal muscle slices. But nothing is known about its effect on type II diabetes, especially on insulin resistance condition. We investigated herein the antihyperglycemic, insulin-sensitizing potential, and cardioprotective effects of the dried decoction from the stem bark of Ceiba pentandra (DCP) in dexamethasone-induced insulin resistant rats. DCP phytochemical analysis using LC-MS showed the presence of many compounds, including 8-formyl-7-hydroxy-5-isopropyl-2-methoxy-3-methyl-1,4-naphthaquinone, 2,4,6-trimethoxyphenol, and vavain. Wistar rats were given intramuscularly (i.m.) dexamethasone (1 mg/kg/day) alone or concomitantly with oral doses of DCP (75 or 150 mg/kg/day) or metformin (40 mg/kg/day) for 9 days. Parameters such as body weight, glycemia, oral glucose tolerance, plasma triglycerides and cholesterol, blood pressure, and heart rate were evaluated. Moreover, cardiac, hepatic and aortic antioxidants (reduced glutathione, catalase, and superoxide dismutase), malondialdehyde level, and nitric oxide content were determined. DCP decreased glycemia by up to 34% and corrected the impairment of glucose tolerance induced by dexamethasone but has no significant effect on blood pressure and heart rate. DCP reduced the total plasma cholesterol and triglycerides as compared to animals treated only with dexamethasone. DCP also increased catalase, glutathione, and NO levels impaired by dexamethasone, without any effect on SOD and malondialdehyde. In conclusion, the decoction of the stem bark of Ceiba pentandra has insulin sensitive effects as demonstrated by the improvement of glucose tolerance, oxidative status, and plasma lipid profile. This extract may therefore be a good candidate for the treatment of type II diabetes.

The Relationship between the Triglyceride to High-Density Lipoprotein Cholesterol Ratio and Metabolic Syndrome

BACKGROUND

Metabolic syndrome is associated with cardiovascular diseases and is characterized by insulin resistance. Recent studies suggest that the triglyceride/high-density lipoprotein cholesterol (TG/HDLC) ratio predicts insulin resistance better than individual lipid levels, including TG, total cholesterol, low-density lipoprotein cholesterol (LDLC), or HDLC. We aimed to elucidate the relationship between the TG/HDLC ratio and metabolic syndrome in the general Korean population.

METHODS

We evaluated the data of adults ≥20 years old who were enrolled in the Korean National Health and Nutrition Examination Survey in 2013 and 2014. Subjects with angina pectoris, myocardial infarction, stroke, or cancer were excluded. Metabolic syndrome was defined by the harmonized definition. We examined the odds ratios (ORs) of metabolic syndrome according to TG/HDLC ratio quartiles using logistic regression analysis (SAS ver. 9.4; SAS Institute Inc., Cary, NC, USA). Weighted complex sample analysis was also conducted.

RESULTS

We found a significant association between the TG/HDLC ratio and metabolic syndrome. The cutoff value of the TG/HDLC ratio for the fourth quartile was ≥3.52. After adjustment, the OR for metabolic syndrome in the fourth quartile compared with that of the first quartile was 29.65 in men and 20.60 in women (P<0.001).

CONCLUSION

The TG/HDLC ratio is significantly associated with metabolic syndrome.

Endothelial microparticles prevent lipid-induced endothelial damage via Akt/eNOS signaling and reduced oxidative stress

Endothelial microparticles (EMPs) are endothelium-derived submicron vesicles that are released in response to diverse stimuli and are elevated in cardiovascular disease, which is correlated with risk factors. This study investigates the effect of EMPs on endothelial cell function and dysfunction in a model of free fatty acid (FFA) palmitate-induced oxidative stress. EMPs were generated from TNF-α-stimulated HUVECs and quantified by using flow cytometry. HUVECs were treated with and without palmitate in the presence or absence of EMPs. EMPs were found to carry functional eNOS and to protect against oxidative stress by positively regulating eNOS/Akt signaling, which restored NO production, increased superoxide dismutase and catalase, and suppressed NADPH oxidase and reactive oxygen species (ROS) production, with the involvement of NF-erythroid 2-related factor 2 and heme oxygenase-1. Conversely, under normal conditions, EMPs reduced NO release and increased ROS and redox-sensitive marker expression. In addition, functional assays using EMP-treated mouse aortic rings that were performed under homeostatic conditions demonstrated a decline in endothelium-dependent vasodilatation, but restored the functional response under lipid-induced oxidative stress. These data indicate that EMPs harbor functional eNOS and potentially play a role in the feedback loop of damage and repair during homeostasis, but are also effective in protecting against FFA-induced oxidative stress; thus, EMP function is reflected by the microenvironment.-Mahmoud, A. M., Wilkinson, F. L., McCarthy, E. M., Moreno-Martinez, D., Langford-Smith, A., Romero, M., Duarte, J., Alexander, M. Y. Endothelial microparticles prevent lipid-induced endothelial damage via Akt/eNOS signaling and reduced oxidative stress.

Serum Insulin-Like Growth Factor 1 and the Risk of Ischemic Stroke: The Framingham Study

BACKGROUND AND PURPOSE

Low insulin-like growth factor 1 (IGF-1) has been associated with increased risk of atherosclerosis and atrial fibrillation in cross-sectional studies. Yet, prospective data linking IGF-1 levels to the development of ischemic stroke remain inconclusive. We examined prospectively the association between serum IGF-1 levels and incident ischemic stroke.

METHODS

We measured serum IGF-1 levels in 757 elderly individuals (mean age 79±5, 62% women), free of prevalent stroke, from the Framingham original cohort participants at the 22nd examination cycle (1990-1994) and were followed up for the development of ischemic stroke. Cox models were used to relate IGF-1 levels to the risk for incident ischemic stroke, adjusted for potential confounders.

RESULTS

During a mean follow-up of 10.2 years, 99 individuals developed ischemic stroke. After adjustment for age, sex, and potential confounders, higher IGF-1 levels were associated with a lower risk of incident ischemic stroke, with subjects in the lowest quintile of IGF-1 levels having a 2.3-fold higher risk of incident ischemic stroke (95% confidence interval, 1.09-5.06; P=0.03) as compared with those in the top quintile. We observed an effect modification by diabetes mellitus and waist-hip ratio for the association between IGF-1 and ischemic stroke (P<0.1). In subgroup analyses, the effects were restricted to subjects with diabetics and those in top waist-hip ratio quartile, in whom each standard deviation increase in IGF-1 was associated with a 61% (hazard ratio, 0.39; 95% confidence interval, 0.20-0.78; P=0.007) and 41% (hazard ratio, 0.59; 95% confidence interval, 0.37-0.95; P=0.031) lower risk of incident ischemic stroke, respectively.

CONCLUSIONS

IGF-1 levels were inversely associated with ischemic stroke, especially among persons with insulin resistance.

Effect of Dark Chocolate Extracts on Phorbol 12-Myristate 13-Acetate-Induced Oxidative Burst in Leukocytes Isolated by Normo-Weight and Overweight/Obese Subjects

Oxidative and inflammatory stress represents a major risk factor for cardiovascular disease (CVD) in overweight and obese subjects. Between the different plant foods, chocolate has been shown to decrease CVD risk due to its antioxidant and anti-inflammatory properties. However, as we recently showed in epidemiological studies, meta-analyses, and human trials, dietary antioxidants resulted more effective in subjects characterized by an ongoing oxidative stress, than in healthy people. Aim of this work was to investigate the effect of different concentrations of chocolate phenolic extract (CPE) on in vitro free radical production, stimulated by phorbol 12-myristate 13-acetate (PMA), in leukocytes extracted from blood of normo-weight and overweight/obese subjects. Neutrophils from overweight/obese group had a significantly higher free radical production compared to the normo-weight group. In neutrophils, the lowest CPE concentration significantly reduced free radical production in overweight/obese group only, and higher CPE concentrations were effective in both groups. In monocytes, the CPE concentration that was significantly effective in reducing free radical production was lower in overweight/obese subjects than in normo-weight subjects. Chocolate polyphenol extracts inhibit oxidative burst in human neutrophils and monocytes with a higher efficiency in subjects characterized by an unphysiological oxidative/inflammatory stress, such as overweight and obese. Results of this study provide further evidence about a differential role of dietary antioxidant strictly related to the “stress” condition of the subjects.

Antihypertensive effects of Tartary buckwheat flavonoids by improvement of vascular insulin sensitivity in spontaneously hypertensive rats

Tartary buckwheat flavonoids alleviate hypertension through attenuating vascular insulin resistance and oxidative stress.

Physical activity and metabolic health in chronic kidney disease: a cross-sectional study

Background

Patients with chronic kidney disease (CKD) are at high risk of progression to end stage renal disease and cardiovascular events. Physical activity may reduce these risks by improving metabolic health. We tested associations of physical activity with central components of metabolic health among people with moderate-severe non-diabetic CKD.

Methods

We performed a cross-sectional study of 47 people with CKD (estimated GFR <60 ml/min/1.73 m²) and 29 healthy control subjects. Accelerometry was used to measured physical activity over 7 days, the hyperinsulinemic-euglycemic clamp was used to measure insulin sensitivity, and DXA was used to measured fat mass. We tested associations of physical activity with insulin sensitivity, fat mass, blood pressure, serum lipid concentrations, and serum high sensitivity C-reactive protein concentration using multivariable linear regression, adjusting for possible confounding factors.

Results

Participants with CKD were less active than participants without CKD (mean (SD) 468.1 (233.1) versus 662.3 (292.5) counts per minute) and had lower insulin sensitivity (4.1 (2.1) versus 5.2 (2.0 (mg/min)/(μU/mL)), higher fat mass (32.0 (11.4) versus 29.4 (14.8) kg), and higher triglyceride concentrations (153.2 (91.6) versus 99.6 (66.8) mg/dL). With adjustment for demographics, comorbidity, medications, and estimated GFR, each two-fold higher level of physical activity was associated with a 0.9 (mg/min)/(μU/mL) higher insulin sensitivity (95% CI 0.2, 1.5, p = 0.006), an 8.0 kg lower fat mass (−12.9, −3.1, p = 0.001), and a 37.9 mg/dL lower triglyceride concentration (−71.9, −3.9, p = 0.03). Associations of physical activity with insulin sensitivity and triglycerides did not differ significantly by CKD status (p-values for interaction >0.3).

Conclusions

Greater physical activity is associated with multiple manifestations of metabolic health among people with moderate-severe CKD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0400-x) contains supplementary material, which is available to authorized users.

Obesity, Oxidative Stress, Adipose Tissue Dysfunction, and the Associated Health Risks: Causes and Therapeutic Strategies

Obesity is gaining acceptance as a serious primary health burden that impairs the quality of life because of its associated complications, including diabetes, cardiovascular diseases, cancer, asthma, sleep disorders, hepatic dysfunction, renal dysfunction, and infertility. It is a complex metabolic disorder with a multifactorial origin. Growing evidence suggests that oxidative stress plays a role as the critical factor linking obesity with its associated complications. Obesity per se can induce systemic oxidative stress through various biochemical mechanisms, such as superoxide generation from NADPH oxidases, oxidative phosphorylation, glyceraldehyde auto-oxidation, protein kinase C activation, and polyol and hexosamine pathways. Other factors that also contribute to oxidative stress in obesity include hyperleptinemia, low antioxidant defense, chronic inflammation, and postprandial reactive oxygen species generation. In addition, recent studies suggest that adipose tissue plays a critical role in regulating the pathophysiological mechanisms of obesity and its related co-morbidities. To establish an adequate platform for the prevention of obesity and its associated health risks, understanding the factors that contribute to the cause of obesity is necessary. The most current list of obesity determinants includes genetic factors, dietary intake, physical activity, environmental and socioeconomic factors, eating disorders, and societal influences. On the basis of the currently identified predominant determinants of obesity, a broad range of strategies have been recommended to reduce the prevalence of obesity, such as regular physical activity, ad libitum food intake limiting to certain micronutrients, increased dietary intake of fruits and vegetables, and meal replacements. This review aims to highlight recent findings regarding the role of oxidative stress in the pathogenesis of obesity and its associated risk factors, the role of dysfunctional adipose tissue in development of these risk factors, and potential strategies to regulate body weight loss/gain for better health benefits.

Animal models of insulin resistance: A review

Insulin resistance can be seen as a molecular and genetic mystery, with a role in the pathophysiology of type 2 diabetes mellitus. It is a basis for a number of chronic diseases like hypertension, dyslipidemia, glucose intolerance, coronary heart disease, cerebral vascular disease along with T2DM, thus the key is to cure and prevent insulin resistance. Critical perspicacity into the etiology of insulin resistance have been gained by the use of animal models where insulin action has been modulated by various transgenic and non-transgenic models which is not possible in human studies. The following review comprises the pathophysiology involved in insulin resistance, various factors causing insulin resistance, their screening and various genetic and non-genetic animal models highlighting the pathological and metabolic characteristics of each.