Correlations between endothelial function in the systemic and cerebral circulation and insulin resistance in type 2 diabetes mellitus

Association between the triglyceride-glucose index and stroke in middle-aged and older non-diabetic population: A prospective cohort study

BACKGROUND AND AIMS

Data regarding the association between insulin resistance (IR) and stroke among the non-diabetic population is still limited and inconsistent. This study aimed to investigate the association between IR measured by the triglyceride-glucose (TyG) index and the risk of stroke among the middle-aged and elderly Chinese without diabetes.

METHODS AND RESULTS

A total of 17,708 middle-aged and elderly (main respondents≥45 years) individuals without diabetes were enrolled from the China Health and Retirement Longitudinal Study. Participants were divided into 4 categories according to quartiles of the TyG index. During a median follow-up of 7.00 years, a total of 305 (3.93%) incident strokes occurred. With the increase in the TyG index quartiles, stroke incidence increased substantially, compared with the Q1 group, the fully adjusted hazard ratios (HRs) were 1.64 (95% confidence interval [CI], 1.13-2.38), 1.65 (95% CI, 1.10-2.46), and 1.76 (95% CI, 1.21-2.57) for Q2, Q3, and Q4 groups, respectively. The cutoff value we determined for the TyG index was 8.28. Furthermore, the addition of the TyG index to a conventional risk model had an incremental effect on the predictive value for stroke (integrated discrimination improvement 0.17%, P = 0.0025; category-free net reclassification improvement 17.91%, P = 0.0025).

CONCLUSION

TyG index was significantly associated with a higher risk of stroke among the middle-aged and elderly non-diabetic population. Our findings indicated that the TyG index may be a good tool in the prediction of stroke risk for clinical and public health fields.

Endostatin as a Mediator Between Endothelial Function and Cognitive Performance in Those at Risk for Vascular Cognitive Impairment

Background:

Patients with coronary artery disease have an increased risk for developing vascular cognitive impairment. Endothelial function is often diminished and has been associated with lower cognitive performance in these patients. The link between endothelial function and cognition in coronary artery disease is not fully understood. Angiogenesis may play a role in mediating the association between endothelial function and cognition since angiogenic processes rely heavily on the endothelium.

Objective:

The aim of this study was to determine if markers of angiogenesis mediate the relationship between endothelial function and cognition in coronary artery disease patients.

Methods:

In 50 participants with coronary artery disease, endothelial function was assessed using peripheral arterial tonometry. Vascular endothelial growth factor (pro-angiogenic) and endostatin (anti-angiogenic) were measured in peripheral serum samples. Cognition was assessed using the Montreal Cognitive Assessment. A mediation analysis, using a bias corrected inferential bootstrapping method with 10,000 permutations, was used to determine if vascular endothelial growth factor or endostatin mediated an association between peripheral arterial tonometry measures and cognitive performance on the Montreal Cognitive Assessment.

Results:

Endostatin, but not vascular endothelial growth factor, mediated a relationship between endothelial function and cognitive performance when controlling for total years of education, body mass index, coronary artery bypass graft, stent, diabetes, and diuretic use. This analysis was also significant when delayed recall was substituted for the overall score on the Montreal Cognitive Assessment.

Conclusion:

These results suggest that endostatin mediates an association between endothelial function and cognitive performance in coronary artery disease.

Insulin resistance is associated with poor functional outcome after acute ischemic stroke in non-diabetic patients

Insulin resistance is associated with the occurrence of stroke and atherosclerotic disease. However, the relationship between insulin resistance and the prognosis of acute ischemic stroke in non-diabetic patients is unclear. We hypothesized that insulin resistance might affect short-term functional recovery after acute ischemic stroke in non-diabetic patients. Between May 2014 and December 2016, 1377 consecutive patients with acute ischemic stroke were enrolled from a prospectively maintained stroke registry. After excluding patients with transient ischemic attacks (TIA), pre-stroke disabilities, diabetes mellitus, and patients with incomplete evaluations, 517 patients were included in the study. The homeostasis model assessment of insulin resistance (HOMA-IR) score was used to evaluate the degree of insulin resistance. The patients with the highest quartile of log HOMA-IR index scores were younger and had higher fasting blood glucose, total cholesterol, triglycerides, low-density lipoprotein, and HbA1c levels. Multivariable logistic regression analysis revealed that log HOMA-IR scores were independently associated with poor prognosis after adjusting for age and sex and p < 0.1 in univariable analysis. Insulin resistance was associated with the poor functional outcome of non-diabetic stroke patients. This evidence supports treating insulin resistance in acute ischemic stroke patients with blood glucose levels within the normal range.

Effects of adiposity on postural control and cognition in older adults

BACKGROUND

Understanding the impacts of increased adiposity on postural control and cognitive deficits in adults is critical for health practitioners in recommending or prescribing effective weight loss regimens. Despite prior work in this area, the knowledge of increased adiposity impacts on postural control and cognitive deficits in older adults (OAs) is still limited.

RESEARCH QUESTION

The purposes of the current study were: (a) to assess the relationship between postural measures and adiposity measures by using regression model analyses and, (b) to examine the impacts of increased adiposity and age on cognitive performance.

METHODS

A total of thirty (30) individuals aged 60+ years participated in the study. Participants were classified into three groups based upon their BMI scores at the onset of the study. The normal weight (NW) (BMI: 18.5-24.9 kg/m²), the overweight (OW) (BMI: 25-29.9 kg/m²), and the obese (OB) groups (BMI: 30-40 kg/m²) each had five females and five males. Participants were required to perform two test sessions: (1) anthropometry assessment and body composition scanning; and (2) evaluation of plantar tactile function, postural control, and cognitive function.

RESULTS

Overall, our findings indicate that increased adiposity in OAs is associated with declines in both cognitive function and postural control.

SIGNIFICANCE

Our data also indicate that measures such as BMI and abdominal fat mass amounts/ratios offer the best insight to the impact of adiposity on cognitive function and postural control measures. However, further work is still needed to clarify the mechanistic links between adiposity and cognitive-postural deficits.

Plant polyphenols Morin and Quercetin rescue nitric oxide production in diabetic mouse aorta through distinct pathways

Diabetic vascular complications are associated with endothelial dysfunction. Various plant-derived polyphenols benefit cardiovascular function by protecting endothelial nitric oxide (NO) production through as yet unclear mechanisms. This study compared the effects of two structurally similar polyphenols, Morin (MO) and Quercetin (QU), on endothelial function in isolated aorta from control and streptozotocin (STZ)-induced diabetic mice. Vascular function under treatment with MO, QU, and various signaling pathway modulators was measured by isometric tension in an organ bath system, NO production by chemical assay and HPLC, and changes in protein signaling factor expression or activity by western blotting (WB). Both polyphenols acted as potent vasodilators and this effect was associated with increased phosphorylation of Akt and endothelial NO synthase (eNOS). An Akt inhibitor blocked MO- and QU-induced vasorelaxation as well as Akt phosphorylation. However, inhibitors of phosphoinositide 3-kinase (PI3K) and AMP-activated protein kinase (AMPK) suppressed only QU-induced vasorelaxation, NO production, and AMPK phosphorylation. These results suggested that plant polyphenols MO and QU both promote eNOS-mediated NO production and vasodilation in diabetic aorta, MO via Akt pathway activation and QU via PI3K/Akt and AMPK pathway activation. Elucidation of these pathways may define effective therapeutic targets for diabetic vascular dysfunction.

Value of triglyceride-glucose index for the estimation of ischemic stroke risk: Insights from a general population

BACKGROUND AND AIMS

Recent studies have recognized triglyceride-glucose index (TyG) as a practical surrogate of insulin resistance. Previous studies have demonstrated that insulin resistance contributes to ischemic stroke via multiple mechanisms. Our study aimed to investigate the association between TyG and prevalent ischemic stroke, exploring the value of TyG to optimize the risk stratification of ischemic stroke.

METHODS AND RESULTS

This cross-sectional study included 10,900 subjects (mean age: 59.95 years, 59.8% females) from rural areas of northeast China between September 2017 to May 2018. TyG was calculated as ln[fasting triglyceride (mg/dl) × fasting plasma glucose (mg/dl)/2]. The prevalence of ischemic stroke was 5.49%. After adjusting for all covariates, each SD increment of TyG caused 22.8% additional risk for ischemic stroke. When dividing TyG into quartiles, the top quartile had a 1.776 times risk for ischemic stroke against the bottom category. Furthermore, smoothing curve fitting demonstrated this association was linear in the whole range of TyG. Finally, AUC revealed an improvement when introducing TyG into clinical risk factors (0.746 vs 0.751, p = 0.029). Consistently, category-free net reclassification index (0.195, 95% CI: 0.112-0.277, P < 0.001) and integrated discrimination index (0.003, 95% CI: 0.001-0.004, P < 0.001) confirmed the improvement by TyG to stratify ischemic stroke risk.

CONCLUSION

The prevent ischemic stroke correlated proportionally with the increment of TyG, implicating the linearity of TyG as an indicator of ischemic stroke. Our findings suggest the potential value of TyG to optimize the risk stratification of ischemic stroke in a general population.

Improvement of vascular dysfunction by argirein through inhibiting endothelial cell apoptosis associated with ET-1/Nox4 signal pathway in diabetic rats

Endothelial cell apoptosis plays an important role in the pathophysiological mechanism of vascular complications in type 2 diabetes mellitus (T2DM). Argirein, a new synthetic compound was demonstrated to inactivate NADPH oxidase to alleviate cardiac dysfunction in T2DM. Here, we investigated whether argirein medication attenuated the vascular dysfunction in T2DM by inhibiting endothelial cell apoptosis which was associated with NADPH oxidase. The rat aortic endothelial cells (RAECs) were incubated with glucose (30 mM) for 48 hour in vitro. It was shown that high glucose significantly increased the protein expression of BAX (Bcl-2 Associated X protein) and Caspase-3 and decreased Bcl2 (B-Cell Leukemia/Lymphoma 2) protein level in RAECs, which was normalized by argirein medication. The annexin V-FITC bound cell percentage and DNA fragments in agarose electrophoresis were markedly suppressed by argirein to confirm the anti-apoptotic property of argirein in RAECs. Furthermore, we found that argirein blocked the endothelin (ET)-1/Nox4 signal-dependent superoxide (O₂^−.) generation, which regulated endothelial cell apoptosis in RAECs. In vivo, argirein intervention relieved the vasodilatory response to acetylcholine and restored the expressions of Nox4 and BAX in the aorta endothelium of high-fat diet (HFD)-fed rats following streptozocin (STZ) injection. For the first time, we demonstrated that argirein could inhibit vascular endothelial cell apoptosis, which was attributed to blocking ET-1/Nox4 signal-dependent O₂⁻ generation in RAECs. This current study revealed the therapeutic effects of argirein to prevent the vascular complication in T2DM through inhibiting endothelial cell apoptosis which was associated with the anti-oxidative property of argirein.

Visualization of skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing method

To realize visualization of the skin microvascular dysfunction of type 1 diabetic mice, we combined laser speckle contrast imaging and hyperspectral imaging to simultaneously monitor the noradrenaline (NE)-induced responses of vascular blood flow and blood oxygen with the development of diabetes through optical clearing skin window. The main results showed that venous and arterious blood flow decreased without recovery after injection of NE; furthermore, the decrease of arterious blood oxygen induced by NE greatly weakened, especially for 2- and 4-week diabetic mice. This change in vasoconstricting effect of NE was related to the expression of α1-adrenergic receptor. This study demonstrated that skin microvascular function was a potential research biomarker for early warning in the occurrence and development of diabetes. The in vivo skin optical clearing method provides a feasible solution to realize visualization of cutaneous microvessels for monitoring microvascular reactivity under pathological conditions. In addition, visual monitoring of skin microvascular function response has guiding significance for early diagnosis of diabetes and clinical research.

Visualization of skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing method

To realize visualization of the skin microvascular dysfunction of type 1 diabetic mice, we combined laser speckle contrast imaging and hyperspectral imaging to simultaneously monitor the noradrenaline (NE)-induced responses of vascular blood flow and blood oxygen with the development of diabetes through optical clearing skin window. The main results showed that venous and arterious blood flow decreased without recovery after injection of NE; furthermore, the decrease of arterious blood oxygen induced by NE greatly weakened, especially for 2- and 4-week diabetic mice. This change in vasoconstricting effect of NE was related to the expression of α1-adrenergic receptor. This study demonstrated that skin microvascular function was a potential research biomarker for early warning in the occurrence and development of diabetes. The in vivo skin optical clearing method provides a feasible solution to realize visualization of cutaneous microvessels for monitoring microvascular reactivity under pathological conditions. In addition, visual monitoring of skin microvascular function response has guiding significance for early diagnosis of diabetes and clinical research.

Insulin resistance in ischemic stroke

Insulin resistance often refers to a pathological condition in which cells fail to respond to the normal actions of insulin. Increasing literature has noted a critical role of insulin resistance in the pathogenesis of ischemic stroke. Insulin resistance plays an important role in the pathogenesis of ischemic stroke via enhancing advanced changes of atherosclerosis. A variety of literature indicates that insulin resistance enhances platelet adhesion, activation and aggregation which are conducive to the occurrence of ischemic stroke. Insulin resistance also induces hemodynamic disturbances and contributes to the onset of ischemic stroke. In addition, insulin resistance may augment the role of the modifiable risk factors in ischemic stroke and induce the occurrence of ischemic stroke. Preclinical and clinical studies have supported that improving insulin resistance may be an effective measure to prevent or delay ischemic stroke.

Cerebrovascular Disease: Consequences of Obesity-Induced Endothelial Dysfunction

Despite the well-known global impact of overweight and obesity in the incidence of cerebrovascular disease, many aspects of this association are still inconsistently defined. In this chapter we aim to present a critical review on the links between obesity and both ischemic and hemorrhagic stroke and discuss its influence on functional outcomes, survival, and current treatments to acute and chronic stroke. The role of cerebrovascular endothelial function and respective modulation is also described as well as its laboratory and clinical assessment. In this context, the major contributing mechanisms underlying obesity-induced cerebral endothelial function (adipokine secretion, insulin resistance, inflammation, and hypertension) are discussed. A special emphasis is given to the participation of adipokines in the pathophysiology of stroke, namely adiponectin, leptin, resistin, apelin, and visfatin.