Pathogenesis of diabetic cerebral vascular disease complication

Morbimortality and determinants of reperfusion in ischemic stroke

BACKGROUND

Cerebrovascular accident (or stroke) and ischemic heart disease are the the major causes of death in the world. It is estimated that about 85% of strokes are ischemic in origin. Reperfusion therapy in the acute phase of ischemic stroke with a recombinant human tissue plasminogen activator is effective, but some factors influence the success of this treatment.

OBJECTIVE

The aim of this study was to evaluate clinical aspects and possible determinants for reperfusion after venous thrombolysis.

METHODS

This is a retrospective, cross-sectional, observational study based on a review of hospital records of inpatients diagnosed with ischemic stroke treated with intravenous thrombolysis, the main outcome being reperfusion or not.

RESULTS

Data from this study revealed a predominance of females in the group of reperfused patients and males in the non-reperfused group, both maintaining moderate severity on the National Institutes of Health Stroke Scale and admission without statistical significance (p>0.18). In addition, the mean admission severity score was 13.2 for the group of reperfused patients and 14.2 for those not reperfused, and the mean ejection fraction of both groups was within normal functionality, with a mean of 0.50 for reperfused patients and 0.62 for non-reperfused patients.

CONCLUSION

We found an association between successful venous chemical thrombolysis reperfusion and lower mortality in patients with acute stroke.

Primary Prevention of Ischemic Stroke

Ischemic stroke is by far the most common type of cerebrovascular event and remains a major cause of death and disability globally. Despite advancements in acute stroke care, primary prevention is still the most cost-effective approach in reducing the burden of ischemic stroke. The two main strategies for primary stroke prevention include population-wide versus high-risk group interventions. Interventions such as increasing access to primary care, regulation of salt and sugar contents in processed foods, public education, and campaigns to control cerebrovascular risk factors are examples of population-wide interventions. High-risk group interventions, on the other hand, focus on recognition of individuals at risk and aim to modify risk factors in a timely and multifaceted manner. This article provides an overview on conventional modifiable risk factors for ischemic stroke and highlights the emerging risk factors and approaches for high-risk group identification and treatment.

The Brain’s Microvascular Response to High Glycemia and to the Inhibition of Soluble Epoxide Hydrolase Is Sexually Dimorphic

Biological sex and a high glycemic diet (HGD) contribute to dementia, yet little is known about the operative molecular mechanisms. Our goal was to understand the differences between males and females in the multi-genomic response of the hippocampal microvasculature to the HGD, and whether there was vasculoprotection via the inhibition of soluble epoxide hydrolase (sEHI). Adult wild type mice fed high or low glycemic diets for 12 weeks, with or without an sEHI inhibitor (t-AUCB), had hippocampal microvessels isolated by laser-capture microdissection. Differential gene expression was determined by microarray and integrated multi-omic bioinformatic analyses. The HGD induced opposite effects in males and females: the HGD-upregulated genes were involved in neurodegeneration or neuroinflammation in males, whereas in females they downregulated the same pathways, favoring neuroprotection. In males, the HGD was associated with a greater number of clinical diseases than in females, the sEHI downregulated genes involved in neurodegenerative diseases to a greater extent with the HGD and compared to females. In females, the sEHI downregulated genes involved in endothelial cell functions to a greater extent with the LGD and compared to males. Our work has potentially important implications for sex-specific therapeutic targets for vascular dementia and cardiovascular diseases in males and females.

Modulatory effects of vitamin B3 and its derivative on the levels of apoptotic and vascular regulators and cytoskeletal proteins in diabetic rat brain as signs of neuroprotection

BACKGROUND

Beneficial effects of nicotinamide (NAm) and its derivates have been earlier shown in animal models of diabetes mellitus (DM), but the mechanisms of their neuroprotective activities are still largely unknown. The aim of the present study was to investigate if NAm and conjugate of nicotinic acid with gamma-aminobutyric acid (N-GABA) are able to modulate expression levels of apoptosis regulators, angiogenesis-related molecules, and specific cytoskeletal proteins in diabetic rat brain.

METHODS

After six weeks of streptozotocin induced type 1 DM, rats were daily administered either by NAm (100 mg/kg) or N-GABA (55 mg/kg) intraperitoneally for two weeks. Protein levels were assessed by western blot and immunohistochemistry.

RESULTS

Both NAm and N-GABA down-regulated NF-κB and Bax levels in diabetic rat brain, suggesting their anti-apoptotic activities. Tested compounds normalized VEGF and nNOS contents improving pro-angiogenic signaling reduced by hyperglycemia. Western blot showed marked up-regulation of astroglial marker GFAP and lowering neurofilament protein levels in DM group, confirmed immunohistochemically, indicating the development of reactive astrogliosis as a major response to diabetes-induced neurodegeneration. NAm had no effects on GFAP and Nf-L levels in the diabetic brain, while N-GABA increased their expression. Inversely, NAm and N-GABA dramatically reduced enhanced levels of GFAP and Nf-L found in the blood serum of diabetic rats, providing for the first time strong evidence for preserving blood-brain barrier integrity by studied compounds.

CONCLUSION

Thus, NAm and N-GABA may exert neuroprotective effects by decreasing pro-apoptotic regulators levels and improving expression of angiogenic and cytoskeletal proteins impaired by hyperglycemia in rat brain.

Cerebral arterial architectonics and CFD simulation in mice with type 1 diabetes mellitus of different duration

Type 1 diabetes is a chronic autoimmune disease that affects tens of millions of people. Diabetes mellitus is one of the strongest factors in the development of cerebrovascular diseases. In this study we used NOD.CB17 Prkdcscid mice and the pharmacological model of type 1 diabetes mellitus of different duration to study changes in the cerebral vasculature. We used two combined approaches using magnetic resonance angiography both steady and transient CFD blood flow modeling. We identified the influence of type 1 diabetes on the architectonics and hemodynamics of the large blood vessels of the brain as the disease progresses. For the first time, we detected a statistically significant change in angioarchitectonics (the angles between the vessels of the circle of Willis, cross-sections areas of vessels) and hemodynamic (maximum blood flow rate, hydraulic resistance) in animals with diabetes duration of 2 months, that is manifested by the development of asymmetry of cerebral blood flow. The result shows the negative effect of diabetes on cerebral circulation as well as the practicability of CFD modeling. This may be of extensive interest, in pharmacological and preclinical studies.

Obesity and diabetes: similar respiratory mechanical but different gas exchange defects

Diabetes mellitus increases smooth muscle tone and causes tissue remodeling, affecting elastin and collagen. Although the lung is dominated by these elements, diabetes is expected to modify the airway function and respiratory tissue mechanics. Therefore, we characterized the respiratory function in patients with diabetes with and without associated obesity. Mechanically ventilated patients with normal body shapes were divided into the control nondiabetic (n = 73) and diabetic (n = 31) groups. The other two groups included obese patients without diabetes (n = 43) or with diabetes (n = 30). The mechanical properties of the respiratory system were determined by forced oscillation technique. Airway resistance (Raw), tissue damping (G), and tissue elastance (H) were assessed by forced oscillation. Capnography was applied to determine phase 3 slopes and dead space indices. The intrapulmonary shunt fraction (Qs/Qt) and the lung oxygenation index (Pa_O2/FI_O2) were estimated from arterial and central venous blood samples. Compared with the corresponding control groups, diabetes alone increased the Raw (7.6 ± 6 cmH₂O.s/l vs. 3.1 ± 1.9 cmH₂O.s/l), G (11.7 ± 5.5 cmH₂O/l vs. 6.5 ± 2.8 cmH₂O/l), and H (31.5 ± 11.8 cmH₂O/l vs. 24.2 ± 7.2 cmH₂O/l (P < 0.001 for all). Diabetes increased the capnographic phase 3 slope, whereas Pa_O2/FI_O2 or Qs/Qt was not affected. Obesity alone caused similar detrimental changes in respiratory mechanics and alveolar heterogeneity, but these alterations also compromised gas exchange. We conclude that diabetes-induced intrinsic mechanical abnormalities are counterbalanced by hypoxic pulmonary vasoconstriction, which maintained intrapulmonary shunt fraction and oxygenation ability of the lungs.

Examining the Relationship between Semiquantitative Methods Analysing Concentration-Time and Enhancement-Time Curves from Dynamic-Contrast Enhanced Magnetic Resonance Imaging and Cerebrovascular Dysfunction in Small Vessel Disease

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can be used to examine the distribution of an intravenous contrast agent within the brain. Computational methods have been devised to analyse the contrast uptake/washout over time as reflections of cerebrovascular dysfunction. However, there have been few direct comparisons of their relative strengths and weaknesses. In this paper, we compare five semiquantitative methods comprising the slope and area under the enhancement-time curve, the slope and area under the concentration-time curve ( S l o p e C o n and A U C C o n ), and changes in the power spectrum over time. We studied them in cerebrospinal fluid, normal tissues, stroke lesions, and white matter hyperintensities (WMH) using DCE-MRI scans from a cohort of patients with small vessel disease (SVD) who presented mild stroke. The total SVD score was associated with A U C C o n in WMH ( p < 0.05 ), but not with the other four methods. In WMH, we found higher A U C C o n was associated with younger age ( p < 0.001 ) and fewer WMH ( p < 0.001 ), whereas S l o p e C o n increased with younger age ( p > 0.05 ) and WMH burden ( p > 0.05 ). Our results show the potential of different measures extracted from concentration-time curves extracted from the same DCE examination to demonstrate cerebrovascular dysfunction better than those extracted from enhancement-time curves.

THE RISK OF MULTIPLE INTRACRANIAL ANEURYSM FORMATION IN PATIENTS WITH MALIGNANT DISEASE UNDERGOING RADIATION THERAPY: A CASE REPORT AND LITERATURE REVIEW

Neoplastic etiology of intracranial cerebral aneurysm is rare. Yet, the risk of its development is higher in malignant tumor patients receiving radiation therapy. Due to the possible negative effects of irradiation on intracranial vessel walls, the risk of aneurysm formation after radiation therapy, which is crucial for some types of breast cancer patients, continues to be a matter of debate. The aim of this study was to evaluate the hazard of multiple intracranial aneurysm development in patients with malignant disease undergoing radiation therapy. It is based on literature review and case report of a 77-year-old female patient who underwent surgery for multifocal invasive hormone-receptor positive ductal breast carcinoma of no special type, followed by chemotherapy, adjuvant radiation and hormone therapy. Her comorbidity included arterial hypertension and type 2 diabetes. Six unruptured intracranial aneurysms of different bilateral locations were diagnosed incidentally by multi-slice computed tomography angiography and digital subtraction angiography of cerebral vessels. Due to the bilateral aneurysm multiplicity, tumor characteristics and prognosis, comorbidity and relatively advanced age, the patient was not selected for active endovascular or microsurgical aneurysm treatment but only periodical clinical, oncologic and radiological follow-up was advised. In conclusion, the risk of multiple intracranial aneurysm formation in patients with breast cancer undergoing radiation therapy is low, but still possible. Long-term follow-up and regular cerebral angiographic check-up studies are necessary in selected malignant patients to decrease such a risk and to evade the worst outcome associated with aneurysm rupture.

Farnesyl Pyrophosphate Synthase Blocker Ibandronate Reduces Thoracic Aortic Fibrosis in Diabetic Rats

BACKGROUND

This study assessed the effect of ibandronate (IBN), a farnesyl pyrophosphate synthase (FPPS) inhibitor, on vascular remodeling in diabetic rats.

METHODS

A rat model of diabetes was induced by a high-fat and high-sugar diet combined with a small dose of streptozotocin. The diabetic rats received 5 µg/kg of ibandronate solution or normal saline subcutaneously every morning for 16 weeks. The morphology of the thoracic aorta was assessed by hematoxylin and eosin and Masson's trichrome staining techniques. Gene expression levels of connective tissue growth factor (CTGF) and FPPS were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) analysis. CTGF and FPPS protein levels were determined by Western blotting analysis.

RESULTS

Rats with diabetes mellitus showed moderate hyperglycemia, insulin resistance, hyperlipidemia and thoracic aortic fibrosis. FPPS was significantly upregulated in the thoracic aorta from diabetic animals. Interestingly, IBN treatment for 16 weeks alleviated the diabetes-induced histopathologic changes in the thoracic aortic wall and reduced CTGF protein and mRNA levels.

CONCLUSIONS

These findings provided evidence that FPPS is involved in thoracic aortic fibrosis in diabetic rats. Meanwhile, IBN could alleviate vascular remodeling in diabetic animals.

Disrupted topological organization of human brain connectome in diabetic retinopathy patients

OBJECTIVE

There is increasing neuroimaging evidence that type 2 diabetes patients with retinal microvascular complications show abnormal brain functional and structural architecture and are at an increased risk of cognitive decline and dementia. However, changes in the topological properties of the functional brain connectome in diabetic retinopathy (DR) patients remain unknown. The aim of this study was to explore the topological organization of the brain connectome in DR patients using graph theory approaches.

METHODS

Thirty-five DR patients (18 males and 17 females) and 38 healthy controls (HCs) (18 males and 20 females), matched for age, sex, and education, underwent resting-state magnetic resonance imaging scans. Graph theory analysis was performed to investigate the topological properties of brain functional connectome at both global and nodal levels.

RESULTS

Both DR and HC groups showed high-efficiency small-world network in their brain functional networks. Notably, the DR group showed reduction in the clustering coefficient (P=0.0572) and local efficiency (P=0.0151). Furthermore, the DR group showed reduced nodal centralities in the default-mode network (DMN) and increased nodal centralities in the visual network (VN) (P<0.01, Bonferroni-corrected). The DR group also showed abnormal functional connections among the VN, DMN, salience network (SN), and sensorimotor network (SMN). Altered network metrics and nodal centralities were significantly correlated with visual acuity and fasting blood glucose level in DR patients.

CONCLUSION

DR patients showed abnormal topological organization of the human brain connectome. Specifically, the DR group showed reduction in the clustering coefficient and local efficiency, relative to HC group. Abnormal nodal centralities and functional disconnections were mainly located in the DMN, VN, SN, and SMN in DR patients. Furthermore, the disrupted topological attributes showed correlations with clinical variables. These findings offer important insight into the neural mechanism of visual loss and cognitive deficits in DR patients.

Blunted cerebral oxygenation during exercise in women with gestational diabetes mellitus: associations with macrovascular function and cardiovascular risk factors

AIM/HYPOTHESIS

This cross-sectional, observational, controlled study examined cerebral oxygenation during exercise, an index of cerebrovascular function and cortical activation, in pregnancies complicated by gestational diabetes mellitus (GDM) and unaffected pregnancies. The association of cerebral oxygenation with macrovascular and cardiovascular function indices was also evaluated.

MATERIAL AND METHODS

Vascular function and structure [aortic pulse-wave-velocity (PWV), augmentation index (AI), carotid intima-media thickness], as well as 24-hour ambulatory blood pressure (BP) were assessed in women with GDM (n = 21) and uncomplicated pregnancies (n = 16), at 26-32 gestational weeks. Changes in cerebral oxygenation [oxy- (O₂Hb), deoxy- (HHb) and total- (tHb) hemoglobin] were continuously recorded by near-infrared spectroscopy (NIRS) during intermittent handgrip exercise. Beat-by-beat BP and systemic vascular resistance (SVR) were assessed (Finapres).

RESULTS

Women with GDM had higher AI than controls. During exercise, women with GDM maintained a smaller force (p < 0.05), despite similar ratings of perceived exertion. Despite similar increases in BP during exercise, the GDM group exhibited a lower average and total (AUC) increase in cerebral-O₂Hb than controls (p < 0.05). In addition, GDM exhibited a slower rate of cerebral-O₂Hb decay during recovery (p < 0.05). SVR was lower in GDM compared to controls throughout the protocol (p < 0.01). Cerebral oxygenation indices were correlated with PWV and AI (p < 0.05).

CONCLUSIONS

This study provided novel evidence for blunted cerebral oxygenation during exercise in women with GDM compared to uncomplicated pregnancies, suggesting a link between reduced cerebrovascular function with exercise intolerance in GDM. Cerebral oxygenation during physical stress was correlated with macrovascular function and cardiovascular risk factors. More studies are needed to examine whether this impaired cerebral oxygenation reflects early cerebrovascular disease.

Rhodiola crenulata Attenuates High Glucose Induced Endothelial Dysfunction in Human Umbilical Vein Endothelial Cells

Rhodiola crenulata root extract (RCE), a traditional Chinese medicine, has been shown to regulate glucose and lipid metabolism via the AMPK pathway in high glucose (HG) conditions. However, the effect of RCE on HG-induced endothelial dysfunction remains unclear. The present study was designed to examine the effects and mechanisms of RCE against hyperglycemic insult in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were pretreated with or without RCE and then exposed to 33[Formula: see text]mM HG medium. The cell viability, nitrite production, oxidative stress markers, and vasoactive factors, as well as the mechanisms underlying RCE action, were then investigated. We found that RCE significantly improved cell death, nitric oxide (NO) defects, and oxidative stress in HG conditions. In addition, RCE significantly decreased the HG-induced vasoactive markers, including endothelin-1 (ET-1), fibronectin, and vascular endothelial growth factor (VEGF). However, the RCE-restored AMPK-Akt-eNOS-NO axis and cell viability were abolished by the presence of an AMPK inhibitor. These findings suggested that the protective effects of RCE were associated with the AMPK-Akt-eNOS-NO signaling pathway. In conclusion, we showed that RCE protected endothelial cells from hyperglycemic insult and demonstrated its potential for use as a treatment for endothelial dysfunction in diabetes mellitus.

Effect of Cinnamaldehyde on Glucose Metabolism and Vessel Function

Background

Material/Methods

Results

Conclusions

MicroRNA-126 suppresses inflammation in endothelial cells under hyperglycemic condition by targeting HMGB1

MicroRNA-126(miR-126) targets involved in inflammation need to be identified. In this study, we aim to investigate whether high-mobility group box 1(HMGB1), an inflammation-related gene, is the target of miR-126 in diabetic vascular endothelium. The diabetic apoE^-/- mice model, a classical diabetic atherosclerosis model, was established. The aorta of diabetic apoE^-/- mice showed decrease of miR-126 and elevation of HMGB1 and inflammation. Next, we employed several in vitro experiments to address the role of miRNA-126 on the regulation of HMGB1 in endothelial cells under hyperglycemic and inflammatory conditions. Manipulation of miRNA levels in human umbilical vein endothelial cells (HUVECs) was achieved by transfecting cells with miR-126 mimic and antagomir. Overexpression of miR-126 could decrease the expression of downstream components of HMGB1 including TNF-α, ROS, and NADPH oxidase activity in HUVECs under hyperglycemic condition. Nevertheless, such phenomenon was completely reversed by miR-126 antagomir. The expression of HMGB1 protein rather than HMGB1 mRNA was down-regulated after transfection with miR-126 mimic, which indicated the modulation of HMGB1 mediated by miR-126 was at the posttranslational level. Luciferase reporter assay confirmed the 3'-UTR of HMGB1 gene was a direct target of miR-126. Western blot analysis also indicated that overexpression of miR-126 contributed to the elevation of p-eNOS, eNOS and p-AKT expressions, respectively. In summary, our findings suggest that miR-126 may suppress inflammation and ROS production in endothelial cells treated by high glucose through modulating the expression of HMGB1. Our study provides a novel pathogenic link between dysregulated miRNA expression and inflammation in diabetic vascular endothelium.

Optical coherence tomography for blood glucose monitoring in vitro through spatial and temporal approaches

As diabetes causes millions of deaths worldwide every year, new methods for blood glucose monitoring are in demand. Noninvasive approaches may increase patient adherence to treatment while reducing costs, and optical coherence tomography (OCT) may be a feasible alternative to current invasive diagnostics. This study presents two methods for blood sugar monitoring with OCT in vitro. The first, based on spatial statistics, exploits changes in the light total attenuation coefficient caused by different concentrations of glucose in the sample using a 930-nm commercial OCT system. The second, based on temporal analysis, calculates differences in the decorrelation time of the speckle pattern in the OCT signal due to blood viscosity variations with the addition of glucose with data acquired by a custom built Swept Source 1325-nm OCT system. Samples consisted of heparinized mouse blood, phosphate buffer saline, and glucose. Additionally, further samples were prepared by diluting mouse blood with isotonic saline solution to verify the effect of higher multiple scattering components on the ability of the methods to differentiate glucose levels. Our results suggest a direct relationship between glucose concentration and both decorrelation rate and attenuation coefficient, with our systems being able to detect changes of 65  mg/dL in glucose concentration.

Role of ultrasonography in the evaluation of correlation between strain and elasticity of common carotid artery in patients with diabetic nephropathy

OBJECTIVE

This study aimed to investigate the correlation between strain and elasticity of the common carotid artery (CCA) by ultrasonography and evaluate its clinical significance in patients with diabetic nephropathy (DN).

METHODS

A total of 68 DN patients and 54 healthy subjects were randomly recruited from the Ultrasound Department from April 2014 to March 2015. The maximum of circumferential strain (CSmax), maximum of circumferential strain rate (CSRmax), compliance coefficient (CC) and stiffness index (β) of the CCA were determined by ultrasonography in all the patients, and correlation analysis was performed.

RESULTS

The CC, CSmax and CSRmax in DN group were significantly lower than in healthy controls (P<0.05), but β was markedly higher than in control group (P<0.05). There was a significantly positive correlation of CSmax and CSRmax with CC and a negative correlation with β in both control group and DN group.

CONCLUSION

There is significant correlation between strain and elastic of the CCA. CSmax and CSRmax may be used to reflect the mechanical characteristics of CCA.

Circulating interleukin-1β promotes endoplasmic reticulum stress-induced myocytes apoptosis in diabetic cardiomyopathy via interleukin-1 receptor-associated kinase-2

Aim

IL-1β was considered as an important inflammatory cytokine in diabetic cardiovascular complications. DCM is one of the major manifestations of diabetic cardiovascular complications whose specific mechanisms are still unclear. In this study, we investigated the role of IL-1β in myocytes apoptosis in DCM.

Methods

In the in vitro study, high- glucose medium and/or IL-1β were used to incubate the isolated primary myocytes. siRNA was used to knockdown the irak2 gene expression. Apoptosis was evaluated by Hoechst and TUNEL staining. In the in vivo study, DCM in rats was induced by STZ injection and confirmed by cardiac hemodynamic determinations. The IL-1 receptor antagonist, IL-1Ra was also used to treat DCM rats. Myocardial apoptosis was assessed by TUNEL assay. In both in vitro and in vivo studies, expression levels of GRP-78, IRAK-2 and CHOP were analyzed by Western Blotting. ELISA was employed to exam the IL-1β content in serum and cell supernatants.

Results

Myocytes were not identified as the source of IL-1β secretion under high- glucose incubation. High glucose incubation and/or IL-1β incubation elevated ER- stress mediated myocytes apoptosis which was attenuated by irak2 silencing. Dramatically increased circulating and myocardial IL-1β levels were found in DCM rats which stimulated activation of ER stress and lead to elevated myocytes apoptosis. The administration of IL-1Ra, however, attenuated IRAK2/CHOP induced apoptosis without affecting fasting blood glucose concentration.

Conclusions

Elevated circulating IL-1β contributed to promote ER stress- induced myocytes apoptosis by affecting IRAK-2/CHOP pathway in DCM.