Diabetes and stroke: Part one—Risk factors and pathophysiology

Awareness of the Risk Factors for Heart Attack Among the General Public in Pahang, Malaysia: A Cross-Sectional Study

Background

Cardiovascular disease is a leading nationwide cause of morbidity and mortality. Public awareness of risk factors for heart attacks is thought to impact the burden of disease, prevention, and timely management. The objective of this study was to assess the awareness of risk factors for heart attack and to identify the factors associated with the awareness of all modifiable risk factors for heart attack in the general population.

Methods

This is a cross-sectional study conducted among 393 adult individuals in Kuantan, Pahang, Malaysia. Data collection was conducted through face-to-face interviews among the lay public members who were 18–64 years old, excluding healthcare professionals in clinical settings and academic settings. Statistical analysis was performed using chi-square test and logistic regression analysis.

Results

The majority of the individuals identified smoking as a risk factor for heart attack, followed by atrial fibrillation (57.7%), heart disease (54.1%), and obesity (53.8%). However, diabetes (26%) was the risk factor that was least recognized by the participants. A total of 90.6% of participants identified at least one risk factor for heart attack, while 9.8% of the participants did not identify any risk factors for heart attack, whereas 5.6% identified all modifiable heart attack risk factors. Furthermore, participants aged 46–64 years old, married respondents, and Chinese participants, those with higher educational levels, and received prior information demonstrated great awareness of eight modifiable risk factors for heart attack. Multivariable logistic regression presented that participants with aged 55–64, those with family history of heart attack and individuals with dyslipidemia were factors independently related to excellent awareness (p=0.04, OR=6.21, 95% CL= 1.081–35.641), (p=0.049, OR=2.11, 95% CL=0.721–6.230) and (p=0.009, OR= 4.08, 95% CL= 1.427–11.685), respectively.

Conclusion

Awareness of risk factors for heart attack appears to be poor, where most of the respondents recognized only one modifiable risk factor. According to these findings, programs and strategies to raise awareness of modifiable risk factors for HA are urgently needed to protect the lay public from HA.

The REVEAL Study: Ranibizumab Monotherapy or Combined with Laser versus Laser Monotherapy in Asian Patients with Diabetic Macular Edema

OBJECTIVE

The primary study hypothesis was that ranibizumab 0.5 mg monotherapy or combined with laser is superior to laser monotherapy based on mean average change in best-corrected visual acuity (BCVA) over 12 months in Asian patients with visual impairment resulting from diabetic macular edema (DME).

DESIGN

A 12-month, randomized, double-masked, multicenter, laser-controlled, phase III study.

PARTICIPANTS

Three hundred ninety-six patients aged ≥18 years, with type 1 or 2 diabetes mellitus, BCVA of 78-39 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, and visual impairment resulting from DME.

METHODS

Patients were randomized to ranibizumab + sham laser (n = 133), ranibizumab + active laser (n = 132), or sham injection + active laser (n = 131). Ranibizumab/sham injections were administered on day 1 and continued monthly. As of month 3, monthly injections were continued if stable vision was not reached. Treatment was reinitiated if BCVA decreased because of DME progression. Active/sham laser was administered on day 1 and thereafter according to ETDRS guidelines.

MAIN OUTCOME MEASURES

Average change in BCVA from baseline to months 1 through 12, central retinal subfield thickness (CRST), and safety over 12 months.

RESULTS

Ranibizumab monotherapy or combined with laser was superior to laser in improving mean average change in BCVA from baseline to months 1 through 12 (+5.9 and +5.7 vs +1.4 letters). At month 12, greater proportion of patients gained ≥15 letters with ranibizumab and ranibizumab + laser compared with laser (18.8% and 17.8% vs 7.8%). Mean CRST reduced significantly from baseline to month 12 with ranibizumab (-134.6 μm) and ranibizumab + laser (-171.8 μm) versus laser (-57.2 μm). Patients received a mean of 7.8 and 7.0 ranibizumab injections in the ranibizumab and ranibizumab + laser arms, respectively, and 1.5-1.9 active laser across treatment arms over 12 months. Conjunctival hemorrhage was the most common ocular, whereas nasopharyngitis and hypertension were the most common nonocular adverse events. Ranibizumab was not associated with any cases of cerebrovascular hemorrhage and cerebrovascular ischemia. No death related to study treatment was reported.

CONCLUSIONS

Ranibizumab monotherapy or combined with laser showed superior BCVA improvements over laser treatment alone in Asian patients with visual impairment resulting from DME. No new ocular or nonocular safety findings were observed and treatment was well tolerated over 12 months.

Correlations between peroxisome proliferator activator receptor γ, Cystatin C, or advanced oxidation protein product, and atherosclerosis in diabetes patients

We aimed to explore the relationship between peroxisome proliferator activator receptor γ (PPAR γ), Cystatin C or advanced oxidation protein product (AOPP) and atherosclerosis (AS), and identify their diagnostic values for AS. Eighty AS patients above the age of 75 with type 2 diabetes were screened by brachial-ankle pulse wave velocity (baPWV) and ankle brachial index (ABI). The baseline level of patients was firstly analyzed, and then the expression of PPAR γ was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Meanwhile, a double-antibody sandwich enzyme-linked immunosorbent assay was performed to analyze the concentration of AOPP, and immunonephelometry was carried out to detect the concentration of Cystatin C. The baseline level of patients was basically consistent. The expression of PPAR γ was significantly higher in severe AS than mild AS patients (P < 0.05), while no differences were found in serum Cystatin C and AOPP between severe AS and mild AS patients (P > 0.05). Thus, PPAR γ exhibited a high diagnostic value for severe AS (AUC = 0.850), but not Cystatin C and AOPP (AUC = 0.553, AUC = 0.4780). Moreover, the combination of PPAR γ, Cystatin C and AOPP exhibited a quite high diagnostic value in AS (AUC = 0.961, Sen = 0.9, Spe = 0.975), which was also higher than PPAR γ alone. In conclusion, the contents of PPAR γ, Cystatin C and AOPP were closely related to AS in diabetes, indicating a potential clinical diagnostic value of PPAR γ, Cystatin C and AOPP in diabetes with AS.

HCdc14A is involved in cell cycle regulation of human brain vascular endothelial cells following injury induced by high glucose, free fatty acids and hypoxia

Cell cycle processes play a vital role in vascular endothelial proliferation and dysfunction. Cell division cycle protein 14 (Cdc14) is an important cell cycle regulatory phosphatase. Previous studies in budding yeast demonstrated that Cdc14 could trigger the inactivation of mitotic cyclin-dependent kinases (Cdks), which are required for mitotic exit and cytokinesis. However, the exact function of human Cdc14 (hCdc14) in cell cycle regulation during vascular diseases is yet to be elucidated. There are two HCdc14 homologs: hCdc14A and hCdc14B. In the current study, we investigated the potential role of hCdc14A in high glucose-, free fatty acids (FFAs)-, and hypoxia-induced injury in cultured human brain vascular endothelial cells (HBVECs). Data revealed that high glucose, FFA, and hypoxia down-regulated hCdc14A expression remarkably, and also affected the expression of other cell cycle-related proteins such as cyclin B, cyclin D, cyclin E, and p53. Furthermore, the combined addition of the three stimuli largely blocked cell cycle progression, decreased cell proliferation, and increased apoptosis. We also determined that hCdc14A was localized mainly to centrosomes during interphase and spindles during mitosis using confocal microscopy, and that it could affect the expression of other cycle-related proteins. More importantly, the overexpression of hCdc14A accelerated cell cycle progression, enhanced cell proliferation, and promoted neoplastic transformation, whereas the knockdown of hCdc14A using small interfering RNA produced the opposite effects. Therefore, these findings provide novel evidence that hCdc14A might be involved in cell cycle regulation in cultured HBVECs during high glucose-, FFA-, and hypoxia-induced injury.

Microglia are selectively activated in endocrine and cardiovascular control centres in streptozotocin-induced diabetic rats

Type 1 and 2 diabetes are associated with dysfunction in multiple hormone systems, as well as increased sympathetic nerve activity, which may contribute to the development of diabetic complications. In other pathologies, such as myocardial infarction, increased sympathetic drive is associated with neuroinflammation and microglial activation in the hypothalamic paraventricular nucleus (PVN), a brain region that regulates sympathetic drive and multiple endocrine responses. In the present study, we used immunohistochemistry to study microglial and neuronal activation in the PVN and related brain regions in streptozotocin (STZ)-induced diabetic rats. As expected, STZ treatment was associated with elevated blood glucose within 1 week. STZ injections also caused neuronal activation in the PVN and superoptic nucleus (SON) but not in the nucleus tractus solitarius (NTS), which was evident by 6 weeks. STZ-treated rats showed increased plasma osmolarity, which would be expected to activate PVN and SON neurones. There was no apparent increase in histochemical markers of microglial activation, including phospho-p38, phospho-extracellular signal regulated kinase, P2X4 receptor or interleukin 1-β even at 10 weeks after STZ-treatment. However, we did see a significant increase in the percentage of microglia with an activated morphology in the PVN, SON and NTS, although not in surrounding hypothalamic, brainstem or cortical regions. These morphological changes included a significant reduction in microglial process length and were evident by 8 weeks but not 6 weeks. The delayed onset of microglial changes compared to neuronal activation in the PVN and SON suggests the over-excitation of neurones as a mechanism of microglial activation. This delayed microglial activation may, in turn, contribute to the endocrine dysregulation and the elevated sympathetic nerve activity reported in STZ-treated rats.

Comparison of carotid and cerebrovascular stenosis between diabetic and nondiabetic patients using digital subtraction angiography

BACKGROUND

The aim of our study was to evaluate the differences of prevalence and manifestation of extracranial and intracranial artery stenosis between patients with and without type 2 diabetes using digital subtraction angiography.

METHODS

A retrospective study was conducted by analyzing clinical and lifestyle data collected from 1137 patients enrolled in the Nanjing Stroke Registry Program between June 2004 and March 2011. Vascular risk factors were analyzed, and carotid and cerebrovascular artery stenoses were measured in 383 patients with type 2 diabetes mellitus and 754 nondiabetic patients by digital subtraction angiography.

RESULTS

In all, 1069 stenoses were found among 383 diabetic patients and 1990 among 754 nondiabetic patients. No statistical differences were observed for the distribution of stenosis in intracranial-extracranial vessels between diabetic and nondiabetic patients (P=.210). There was no difference in the distribution of stenosis in the anterior and posterior circulation vessels between these 2 groups (P=.628). Among diabetic patients with stenosis, a single stenosis was found in 116 (30.29%) and multiple stenoses were found in 267 (69.71%). In their nondiabetic counterparts, a single stenosis was found in 249 (33.02%) and multiple stenoses were found in 505 (66.98%). Compared with nondiabetic patients, the diabetic patients have a tendency of a higher incidence of multiple stenosis. Nonobstructive stenosis occurs more often in diabetic than in nondiabetic patients (P=.002).

CONCLUSIONS

This retrospective study suggests that diabetes be associated with higher incidence of nonobstructive stenosis and that there be no significant difference observed in the extent and distribution of the extra- and intracranial artery stenoses between diabetic and nondiabetic patients.

Evaluation of IScore validity in a Greek cohort of patients with type 2 diabetes

Background

Diabetes constitutes a risk factor for stroke that also aggravates stroke prognosis. Several prognostic models have been developed for the evaluation of neurologic status, severity, short-term functional outcome and mortality of stroke patients. IScore is a novel tool recently developed in order to predict mortality rates within 30 days and 1 year after ischemic stroke and diabetes is not included in the scoring scale of IScore. The aim of the present study was to evaluate and compare IScore validity in ischemic stroke patients with and without diabetes.

Methods

This prospective study included 312 consecutive Caucasian patients with type 2 diabetes and 222 Caucasian patients without diabetes admitted for ischemic stroke in a tertiary Greek hospital. Thirty-day and 1-year IScores were individually calculated for each patient and actual mortality was monitored at the same time intervals. IScore’s predictive ability and calibration was evaluated and compared for ischemic stroke patients with and without diabetes. The performance of IScore for predicting 30 and 1-year mortality between patients with and without diabetes was assessed by determining the calibration and discrimination of the score. The area under the receiver operating characteristic curve was used to evaluate the discriminative ability of IScore for patients with and without diabetes, whereas the calibration of IScore was assessed by the Hosmer–Lemeshow goodness-of fit statistic.

Results

Baseline population characteristics and mortality rates did not differ significantly for both cohorts. IScore values were significantly higher for patients with diabetes at 30 days and 1 year after ischemic stroke and patients with diabetes presented more frequently with lacunar strokes. Based on ROC curves analysis IScore’s predictive ability for 30 day mortality was excellent, without statistically significant difference, for both cohorts. Predictive ability for 1 year mortality was also excellent for both groups with significantly better ability for patients with diabetes especially at high score values. Calibration of the model was good for both groups of patients.

Conclusions

IScore accurately predicts mortality in acute ischemic stroke Caucasian patients with and without diabetes with higher efficacy in predicting 1 year mortality in patients with diabetes especially with high scores.

Comparison of selective versus dual endothelin receptor antagonism on cerebrovascular dysfunction in diabetes

OBJECTIVES

Cerebrovascular tone plays a key role in controlling cerebral blood flow. Our studies have demonstrated that the endothelin system is upregulated in type 2 diabetes leading to increased sensitivity to endothelin-1 and decreased relaxation in basilar artery. While chronic endothelin A receptor blockade restored relaxation, selective endothelin B receptor blockade caused paradoxical constriction in diabetes. Whether this effect was due to activation of endothelin A receptors in the presence of endothelin B receptor blockade or due to the loss of vasculoprotective effects of endothelin B receptors remained unknown. The current study hypothesizes that due to the antagonism of the vasculoprotective endothelin receptor B, dual blockade will not be as effective as selective endothelin receptor A antagonism in improving cerebrovascular dysfunction in type 2 diabetes.

METHODS

These studies were done in non-obese, type 2 diabetic Goto-Kakizaki rats administered either vehicle, selective endothelin receptor A antagonist Atrasentan (5 mg/kg) or dual endothelin antagonist Bosentan (100 mg/kg) for 4 weeks. At termination, basilar arteries were collected and mounted on a wire myograph and cumulative dose-response curves to endothelin-1 (1-500 nM) and acetylcholine (1 nM-5 μm) were studied.

RESULTS

Basilar artery was highly sensitive to endothelin-1-mediated constriction in diabetic animals. While neither Atrasentan nor Bosentan affected endothelium-dependent vascular relaxation in control animals, both treatments improved the maximum dilatation in diabetes and Atrasentan also improved sensitivity to acetylcholine.

CONCLUSION

In light of our previous data which showed that endothelin B receptors are vasculoprotective and blockade of this receptor worsens relaxation, current findings suggest that when blocked simultaneously with the endothelin receptor A, the endothelin receptor B antagonism is protective by reducing the hyperreactivity and improving cerebrovascular function in diabetes.

Electrochemical glucose biosensor of platinum nanospheres connected by carbon nanotubes

BACKGROUND

Glucose biosensors comprised of nanomaterials such as carbon nanotubes (CNTs) and metallic nanoparticles offer enhanced electrochemical performance that produces highly sensitive glucose sensing. This article presents a facile biosensor fabrication and biofunctionalization procedure that utilizes CNTs electrochemically decorated with platinum (Pt) nanospheres to sense glucose amperometrically with high sensitivity.

METHOD

Carbon nanotubes are grown in situ by microwave plasma chemical vapor deposition (MPCVD) and electro-chemically decorated with Pt nanospheres to form a CNT/Pt nanosphere composite biosensor. Carbon nanotube electrodes are immobilized with fluorescently labeled bovine serum albumin (BSA) and analyzed with fluorescence microscopy to demonstrate their biocompatibility. The enzyme glucose oxidase (GO(X)) is immobilized onto the CNT/Pt nanosphere biosensor by a simple drop-coat method for amperometric glucose sensing.

RESULTS

Fluorescence microscopy demonstrates the biofunctionalization capability of the sensor by portraying adsorption of fluorescently labeled BSA unto MPCVD-grown CNT electrodes. The subsequent GO(X)-CNT/Pt nanosphere biosensor demonstrates a high sensitivity toward H(2)O(2) (7.4 microA/mM/cm(2)) and glucose (70 microA/mM/cm(2)), with a glucose detection limit and response time of 380 nM (signal-to-noise ratio = 3) and 8 s (t(90%)), respectively. The apparent Michaelis-Menten constant (0.64 mM) of the biosensor also reflects the improved sensitivity of the immobilized GO(X)/nanomaterial complexes.

CONCLUSIONS

The GO(X)-CNT/Pt nanosphere biosensor outperforms similar CNT, metallic nanoparticle, and more conventional carbon-based biosensors in terms of glucose sensitivity and detection limit. The biosensor fabrication and biofunctionalization scheme can easily be scaled and adapted for microsensors for physiological research applications that require highly sensitive glucose sensing.

Diabetes mellitus and cerebrovascular disease: which are the actual data?

Cerebrovascular disease (CeVD) represents a major cause of morbidity and mortality worldwide. Diabetes mellitus (DM) represents an independent risk factor for CeVD. The aim of the present review is to describe the epidemiology of CeVD in patients with DM and to explain how DM and diabetic autonomic neuropathy can increase the risk of CeVD. The prevention and management of CeVD in the diabetic population are also analyzed.

New strategies for the prevention of stroke

1. Stroke is a major cause of disability and death worldwide. It is preferable to prevent stroke rather than to treat it and, for the prevention of stroke, all risk factors relating to stroke need to be understood. The present paper reviews potential new strategies for the prevention of stroke based on findings of new risk factors, as well as classical risk factors. 2. Recently, new risk factors related to stroke were reported, including dysfunction of the arterial baroreflex, pro-inflammatory cytokines, vitamins and hormone deficiency. Correspondingly, therapies targeting these risk factors where shown to significantly reduce the incidence and/or severity of stroke. 3. Because the genesis of stroke is multifactorial, the prevention of stroke should not target one risk factor only. Combination therapies with drugs acting on different risk factors may be more effective in the prevention of stroke.

Effect of chronic and selective endothelin receptor antagonism on microvascular function in type 2 diabetes

Vascular dysfunction, which presents either as an increased response to vasoconstrictors or an impaired relaxation to dilator agents, results in worsened cardiovascular outcomes in diabetes. We have established that the mesenteric circulation in Type 2 diabetes is hyperreactive to the potent vasoconstrictor endothelin-1 (ET-1) and displays increased nitric oxide-dependent vasodilation. The current study examined the individual and/or the relative roles of the ET receptors governing vascular function in the Goto-Kakizaki rat, a mildly hyperglycemic, normotensive, and nonobese model of Type 2 diabetes. Diabetic and control rats received an antagonist to either the ET type A (ETA; atrasentan; 5 mg x kg(-1) x day(-1)) or type B (ET(B); A-192621; 15 or 30 mg x kg(-1) x day(-1)) receptors for 4 wk. Third-order mesenteric arteries were isolated, and vascular function was assessed with a wire myograph. Maximum response to ET-1 was increased in diabetes and attenuated by ETA antagonism. ETB blockade with 15 mg/kg A-192621 augmented vasoconstriction in controls, whereas it had no further effect on ET-1 hyperreactivity in diabetes. The higher dose of A-192621 showed an ETA-like effect and decreased vasoconstriction in diabetes. Maximum relaxation to acetylcholine (ACh) was similar across groups and treatments. ETB antagonism at either dose had no effect on vasorelaxation in control rats, whereas in diabetes the dose-response curve to ACh was shifted to the right, indicating a decreased relaxation at 15 mg/kg A-192621. These results suggest that ETA receptor blockade attenuates vascular dysfunction and that ETB receptor antagonism exhibits differential effects depending on the dose of the antagonists and the disease state.

Effect of chronic endothelin receptor antagonism on cerebrovascular function in type 2 diabetes

Diabetes increases the risk of stroke and contributes to poor clinical outcomes in this patient population. Myogenic tone of the cerebral vasculature, including basilar arteries, plays a key role in controlling cerebral blood flow. Increased myogenic tone is ameliorated with ET receptor antagonism in Type 1 diabetes. However, the role of endothelin-1 (ET-1) and its receptors in cerebrovascular dysfunction in Type 2 diabetes, a common comorbidity in stroke patients, remains poorly elucidated. Therefore, we hypothesized that 1) cerebrovascular dysfunction occurs in the Goto-Kakizaki (GK) model of Type 2 diabetes, and 2) pharmacological antagonism of ETA receptors ameliorates, while ETB receptor blockade augments vascular dysfunction. GK or control rats were treated with antagonists to either ETA (atrasentan, 5 mg.kg(-1).day(-1)) or ETB (A-192621, 15 or 30 mg.kg(-1).day(-1)) receptors for 4 wk and vascular function of basilar arteries was assessed using a wire myograph. GK rats exhibited increased sensitivity to ET-1. ET(A) receptor antagonism caused a rightward shift, indicating decreased sensitivity in diabetes, while it increased sensitivity to ET-1 in control rats. Endothelium-dependent relaxation was impaired in diabetes. ETA receptor blockade restored relaxation to control values in the GK animals with no significant effect in Wistar rats and ETB blockade with 30 mg.kg(-1).day(-1) A-192621 caused paradoxical constriction in diabetes. These studies demonstrate that cerebrovascular dysfunction occurs and may contribute to altered regulation of myogenic tone and cerebral blood flow in diabetes. While ETA receptors mediate vascular dysfunction, ETB receptors display differential effects. These results underscore the importance of ETA/ETB receptor balance and interactions in cerebrovascular dysfunction in diabetes.

Glucose neurotoxicity

Neurons have a constantly high glucose demand, and unlike muscle cells they cannot accommodate episodic glucose uptake under the influence of insulin. Neuronal glucose uptake depends on the extracellular concentration of glucose, and cellular damage can ensue after persistent episodes of hyperglycaemia--a phenomenon referred to as glucose neurotoxicity. This article reviews the pathophysiological manifestation of raised glucose in neurons and how this can explain the major components of diabetic neuropathy.

A Comparison of Ghrelin, Glucose, Alpha-amylase and Protein Levels in Saliva from Diabetics

During the past decade, many salivary parameters have been used to characterize disease states. Ghrelin (GAH) is recently-discovered peptide hormone secreted mainly from the stomach but also produced in a number of other tissues including salivary glands. The aim of this work was to examine the relationship between active (aGAH) and inactive (dGAH) ghrelin in the saliva and other salivary parameters in type II diabetic patients and healthy controls. Salivary parameters were assessed in a single measurement of unstimulated whole saliva from 20 obese and 20 non-obese type II diabetes patients, and in 22 healthy controls. Total protein and alpha-amylase were determined by colorimetric methods, and glucose by the glucose-oxidase method. Saliva aGAH and dGAH levels were measured using a commercial radioimmunoassay (RIA) kit. Salivary concentrations of aGAH and dGAH ghrelin were more markedly decreased in obese diabetic subjects than in the two other groups. Glucose and alpha-amylase levels were higher in diabetic subjects than in controls. Furthermore, there were correlations between GAH levels and BMI, and between GAH and blood pressure. However, there was no marked variability in saliva flow rates among the groups. These results indicate that measurement of salivary GAH and its relationship to other salivary parameters might help to provide insight into the role of ghrelin in diabetes.