Arterial stiffness in diabetes and hypertension

Helical vasculogenesis driven by cell chirality

The cellular helical structure is well known for its crucial role in development and disease. Nevertheless, the underlying mechanism governing this phenomenon remains largely unexplored, particularly in recapitulating it in well-controlled engineering systems. Leveraging advanced microfluidics, we present compelling evidence of the spontaneous emergence of helical endothelial tubes exhibiting robust right-handedness governed by inherent cell chirality. To strengthen our findings, we identify a consistent bias toward the same chirality in mouse vascular tissues. Manipulating endothelial cell chirality using small-molecule drugs produces a dose-dependent reversal of the handedness in engineered vessels, accompanied by non-monotonic changes in vascular permeability. Moreover, our three-dimensional cell vertex model provides biomechanical insights into the chiral morphogenesis process, highlighting the role of cellular torque and tissue fluidity in its regulation. Our study unravels an intriguing mechanism underlying vascular chiral morphogenesis, shedding light on the broader implications and distinctive perspectives of tubulogenesis within biological systems.

QardioArm Blood Pressure Monitoring in a Population With Type 2 Diabetes: Validation Study

BACKGROUND

Home blood pressure monitoring has many benefits, even more so, in populations prone to high blood pressure, such as persons with diabetes.

OBJECTIVE

The purpose of this research was to validate the QardioArm mobile device in a sample of individuals with noninsulin-dependent type 2 diabetes in accordance with the guidelines of the second International Protocol of the European Society of Hypertension.

METHODS

The sample consisted of 33 patients with type 2 diabetes. To evaluate the validity of QardioArm by comparing its data with that obtained with a digital sphygmomanometer (Omron M3 Intellisense), two nurses collected diastolic blood pressure, systolic blood pressure, and heart rate with both devices.

RESULTS

The analysis indicated that the test device QardioArm met all the validation requirements using a sample population with type 2 diabetes.

CONCLUSIONS

This paper reports the first validation of QardioArm in a population of individuals with noninsulin-dependent type 2 diabetes. QardioArm for home monitoring of blood pressure and heart rate met the requirements of the second International Protocol of the European Society of Hypertension.

Assessment of Arterial Stiffness in Patients With Resistant Hypertension: Additional Insights Into the Pathophysiology of This Condition?

BACKGROUND

Good understanding of the pathophysiological mechanism(s) of resistant hypertension (RH) and the relationship to vascular dysfunction is important for optimal blood pressure control.

METHODS AND RESULTS

The aim of this review article is to summarize the available data on the methods of arterial stiffness assessment, and their usefulness in RH. Several studies that provide information on the noninvasive methods of evaluation of arterial stiffness have been discussed; specifically, pulse wave velocity (PWV) and augmentation index (AIx) tests. Increased arterial stiffness, elevated AIx, and impaired endothelial function all act as indicators and predictors of cardiovascular events in patients with hypertension (HTN).

CONCLUSION

Our review suggests that PWV and AIx are impaired in patients with severe HTN. Early assessment of these characteristics can potentially be of value in patients with RH.

Validation of BP devices QardioArm® in the general population and Omron M6 Comfort® in type II diabetic patients according to the European Society of Hypertension International Protocol (ESH-IP)

BACKGROUND

Following the European Society of Hypertension International Protocol (ESH-IP) Revision 2010, QardioArm® and Omron M6 Comfort IT® oscillometric devices were evaluated in the general population and in patients with type II diabetes, respectively, for self-blood pressure (BP) measurement.

METHODS

Both devices, QardioArm® and Omron M6 Comfort®, measure BP at the brachial level. The ESH-IP Revision 2010 includes a total number of 33 subjects. For each measure, the difference between observer and device BP values was calculated. In all, 99 pairs of BP differences are classified into three categories (≤5, ≤10, and ≤15 mmHg). The protocol procedures were followed precisely.

RESULTS

QardioArm® and Omron M6 Comfort® fulfilled the requirements of the ESH-IP and passed the validation process successfully. For QardioArm®, a total of 69 out of 99 comparisons for systolic blood pressure (SBP) showed an absolute difference within 5 mmHg and 82 out of 99 for diastolic blood pressure (DBP). As for Omron M6 Comfort®, a total of 83 out of 99 comparisons for SBP showed an absolute difference within 5 mmHg and 77 out of 99 for DBP. The mean differences between the device and mercury readings were 0.7±5.9 mmHg for SBP and 0.3±4.1 mmHg for DBP for QardioArm® and -1.4±4.7 mmHg for SBP and -2.1±4.3 mmHg for DBP for Omron M6 Comfort®. With regard to part 2 of ESH-IP 2010, 27 out of 33 subjects had a minimum of two out of three measurements within 5 mmHg difference for SBP and 31 out of 33 subjects for DBP for the QardioArm®, and 29 out of 33 patients had a minimum of two out of three measurements within 5 mmHg difference for SBP and 26 out of 33 patients for DBP for Omron M6 Comfort®.

CONCLUSION

QardioArm® and Omron M6 Comfort® readings differing from the mercury standard by <5, 10, and 15 mmHg fulfill the ESH-IP Revision 2010 requirements. Consequently, these two devices are suitable for use in the general population and non-insulin-dependent type II diabetic patients, respectively.

Two weeks taurine supplementation reverses endothelial dysfunction in young male type 1 diabetics

Type 1 diabetics have a well-recognised risk of accelerated cardiovascular disease. Even in the absence of clinical signs there are detectable abnormalities of conduit vessel function. Our group has previously reported reversal of endothelial dysfunction in diabetics with pravastatin. In young asymptomatic smokers, taurine supplementation has a beneficial impact on macrovascular function, assessed by FMD, and shows an up-regulation of nitric oxide from monocyte-endothelial cell interactions. We hypothesise that taurine supplementation reverses early endothelial abnormalities in young male type 1 diabetics, as assessed by applanation tonometry, brachial artery ultrasound and laser Doppler fluximetry. Asymptomatic, male diabetics (n=9) were scanned prior to treatment and then randomised in a double-blind cross-over fashion to receive either 2 weeks placebo or taurine. Control patients (n=10) underwent a baseline scan. Assessed diabetics had detectable, statistically significant abnormalities when compared with controls, in both arterial stiffness (augmentation index) and brachial artery reactivity (FMD). Both of these parameters were returned to control levels with 2 weeks taurine supplementation. In conclusion, 2 weeks taurine supplementation reverses early, detectable conduit vessel abnormalities in young male diabetics. This may have important implications in the long-term treatment of diabetic patients and their subsequent progression towards atherosclerotic disease.

Early manifestation of macrovasculopathy in newly diagnosed never treated type II diabetic patients with no traditional CVD risk factors

Type II diabetes patients have increased risk of macrovascular complications compared with the general population. Arterial stiffness is considered as an independent predictor of macrovascular events. This study investigated arterial stiffness in newly diagnosed never treated diabetes and impaired glucose tolerance (IGT) patients without any traditional cardiovascular diseases (CVD) risk factors. After preliminary screening of 1620 individuals, 30 diabetic and 30 IGT patients were recruited and compared with age- and sex-matched 30 normoglycaemic subjects. The subjects were newly diagnosed, never treated, normotensive, non-obese, non-hyperlipidaemic and non-smoker. Haemodynamic variables, pulse wave velocity (PWV) and augmentation index (AI) were measured. The PWV was significantly higher in diabetic patients (10.37+/-2.64m/s vs. 8.70+/-1.29m/s; p=0.035) and was of borderline significant in IGT subjects (9.54+/-1.56m/s vs.8.70+/-1.29m/s, p=0.078) compared to normoglycaemic individuals. Augmentation index was higher of borderline significant in diabetic (134.53+/-17.32% vs. 129.17+/-11.18%, p=0.055) and IGT patients (132.02+/-16.11% vs. 129.17+/-11.18%, p=0.059) compared to normoglycaemic individuals. The study demonstrated that newly diagnosed never treated diabetic patients without any CV complications had early manifestation of macrovascular diseases as evident by increased arterial stiffness. The findings also revealed early manifestations of preclinical vasculopathy and potentially increased risk for development of macrovascular diseases at an early age in diabetic patients.

Improvement of glycaemic control by nateglinide decreases systolic blood pressure in drug-naive patients with type 2 diabetes

BACKGROUND

It has been speculated that oral hypoglycaemic agents that block K-ATP channels could potentially increase blood pressure by blocking such channels in vascular myocytes. No information about this issue exists regarding nateglinide.

DESIGN

A multicentre, double-blind, placebo-controlled, randomized trial was conducted in 109 drug-naive 30- to 75-year-old patients with type 2 diabetes and < 5 years of diabetes diagnosis, who are not taking antihypertensive drugs. These patients were assigned to receive placebo or fixed doses of nateglinide (120 mg before each main meal: breakfast, lunch and dinner) and evaluated at weeks 0 and 12 for (i) body mass index and blood pressure; (ii) standard laboratory tests, including haemoglobin A1c (HbA1c) and fasting plasma glucose; and (iii) incremental area under the curve for glucose and C-peptide after a standardized liquid breakfast challenge, homeostasis model assessment (HOMA)-B% (as surrogate of beta-cell activity) and HOMA-S% (as surrogate of insulin sensitivity).

RESULTS

At the end of the follow-up period, patients in the nateglinide group (n = 55), compared to patients in the placebo group (n = 54), showed lower values of HbA1c (6.7 +/- 0.6 vs. 7.2 +/- 0.7%, respectively; P < 0.001), fasting plasma glucose (7.9 +/- 2.1 vs. 8.5 +/- 2.0 mmol L(-1); P = 0.023) and systolic blood pressure (125.3 +/- 15.4 vs. 129.3 +/- 18.7 mmHg; P = 0.015), and higher values of HOMA-B%[75.7 (51.8-99.4) vs. 57.7 (42.2-83.4); P = 0.033]. A positive correlation was found between changes in HbA1c and systolic blood pressure in the nateglinide group (r = 0.355, P = 0.011).

CONCLUSIONS

In drug-naive patients with type 2 diabetes, the improvement in glycaemic control with nateglinide is associated with a decrease in systolic blood pressure.

Changes in Aortic Function After Interposition of a Tubular Graft in the Descending Porcine Thoracic Aorta

The objective of the study was to investigate the alterations of aortic function after interposition of a tubular graft in the descending porcine thoracic aorta. Eight healthy Landrace pigs were subjected to thoracotomy under sterile conditions. A 5-cm-long segment of descending thoracic aorta was replaced with a Dacron graft. Pulse wave velocity (PWV) was measured using simultaneous recordings of electrocardiogram and Doppler pressure waveforms, which were received from right carotid and femoral arteries. Then, the recordings were fed to a computer for analytical estimation of PWV in several occasions: right after the interposition (D0), and after 15 (D15) and 30 (D30) days time. Euthanasia was performed after the D30-recordings and the aortic graft area was removed. "Before graft" (BG) as well as "after graft" (AG) aortic regions were examined under light microscopy in order to determine the aortic thickness (T) and number of lamellar units (LU). Eight sham-operated pigs were used as controls. The results showed that PWV decreased as soon as the graft interposition took place and was maintained, until the end of experiment (P < 0.05). Aortic wall thickness was increased both at pregraft and postgraft areas (P < 0.05), and LUs were also increased at the same regions. It is concluded that the interposition of a tubular graft in the descending thoracic aorta resulted in a decrease in PWV, which may improve left ventricular performance and enhance myocardial perfusion, due to a delay in the arrival of the reflecting diastolic wave.

Pioglitazone prevents corporal veno-occlusive dysfunction in a rat model of type 2 diabetes mellitus

OBJECTIVE

To determine whether corporal veno-occlusive dysfunction (CVOD), corporal smooth muscle (SM) loss, fibrosis and oxidative stress occur in a rat model of type 2 diabetes, and whether these are counteracted by pioglitazone, as pioglitazone is vasculoprotective, and corporal SM is an extension of arterial SM.

MATERIALS AND METHODS

Male obese Zucker fa/fa rats were fed chow containing 0%, 0.001% or 0.02% pioglitazone for 2 or 5 months, using untreated lean Zucker and Fischer 344 rats as controls. Functional changes were determined by dynamic-infusion cavernosometry. Histological changes were assessed by histochemistry and immunohistochemistry followed by quantitative image analysis and/or quantitative Western blot.

RESULTS

CVOD was detected at 4.5 months of diabetes, accompanied by a lower corporal SM/collagen ratio, and increases in collagen, collagen III/I ratio, apoptotic index, and systemic and tissue oxidative stress. In the short-term treatment, high-dose pioglitazone normalized glycaemia and ameliorated fibrosis and oxidative stress, but induced CVOD, whereas the effects with the low dose were not significant. However, low-dose pioglitazone for 5 months corrected all alterations.

CONCLUSION

Type 2 diabetes in Zucker fa/fa rats was associated with penile corporal fibrosis, oxidative stress, and CVOD, which were ameliorated by long-term low-dose pioglitazone, suggesting that this drug might protect the SM, independently from its antidiabetic effect.

Mechanisms, Significance and Treatment of Vascular Dysfunction in Type 2 Diabetes Mellitus

Endothelial dysfunction and increased arterial stiffness occur early in the pathogenesis of diabetic vasculopathy. They are both powerful independent predictors of cardiovascular risk. Advances in non-invasive methodologies have led to widespread clinical investigation of these abnormalities in diabetes mellitus, generating a wealth of new knowledge concerning the mechanisms of vascular dysfunction, risk factor associations and potential treatment targets. Endothelial dysfunction primarily reflects decreased availability of nitric oxide (NO), a critical endothelium-derived vasoactive factor with vasodilatory and anti-atherosclerotic properties. Techniques for assessing endothelial dysfunction include ultrasonographic measurement of flow-mediated vasodilatation of the brachial artery and plethysmography measurement of forearm blood flow responses to vasoactive agents. Arterial stiffness may be assessed using pulse wave analysis to generate measures of pulse wave velocity, arterial compliance and wave reflection. The pathogenesis of endothelial dysfunction in type 2 diabetes is multifactorial, with principal contributors being oxidative stress, dyslipidaemia and hyperglycaemia. Elevated blood glucose levels drive production of reactive oxidant species (ROS) via multiple pathways, resulting in uncoupling of mitochondrial oxidative phosphorylation and endothelial NO synthase (eNOS) activity, reducing NO availability and generating further ROS. Hyperglycaemia also contributes to accelerated arterial stiffening by increasing formation of advanced glycation end-products (AGEs), which alter vessel wall structure and function. Diabetic dyslipidaemia is characterised by accumulation of triglyceride-rich lipoproteins, small dense low-density lipoprotein (LDL) particles, reduced high-density lipoprotein (HDL)-cholesterol and increased postprandial free fatty acid flux. These lipid abnormalities contribute to increasing oxidative stress and may directly inhibit eNOS activity. Although lipid-regulating agents such as HMG-CoA reductase inhibitors (statins), fibric acid derivatives (fibrates) and fish oils are used to treat diabetic dyslipidaemia, their impact on vascular function is less clear. Studies in type 2 diabetes have yielded inconsistent results, but this may reflect sampling variation and the potential over-riding influence of oxidative stress, dysglycaemia and insulin resistance on endothelial dysfunction. Results of positive intervention trials suggest that improvement in vascular function is mediated by both lipid and non-lipid mechanisms, including anti-inflammatory, anti-oxidative and direct effects on the arterial wall. Other treatments, such as renin-angiotensin-aldosterone system antagonists, insulin sensitisers and lifestyle-based interventions, have shown beneficial effects on vascular function in type 2 diabetes. Novel approaches, targeting eNOS and AGEs, are under development, as are new lipid-regulating therapies that more effectively lower LDL-cholesterol and raise HDL-cholesterol. Combination therapy may potentially increase therapeutic efficacy and permit use of lower doses, thereby reducing the risk of adverse drug effects and interactions. Concomitant treatments that specifically target oxidative stress may also improve endothelial dysfunction in diabetes. Vascular function studies can be used to explore the therapeutic potential and mechanisms of action of new and established interventions, and provide useful surrogate measures for cardiovascular endpoints in clinical trials.