Stroke presentation in Type 2 diabetes and the metabolic syndrome

Diabetic aggravation of stroke and animal models

Cerebral ischemia in diabetics results in severe brain damage. Different animal models of cerebral ischemia have been used to study the aggravation of ischemic brain damage in the diabetic condition. Since different disease conditions such as diabetes differently affect outcome following cerebral ischemia, the Stroke Therapy Academic Industry Roundtable (STAIR) guidelines recommends use of diseased animals for evaluating neuroprotective therapies targeted to reduce cerebral ischemic damage. The goal of this review is to discuss the technicalities and pros/cons of various animal models of cerebral ischemia currently being employed to study diabetes-related ischemic brain damage. The rational use of such animal systems in studying the disease condition may better help evaluate novel therapeutic approaches for diabetes related exacerbation of ischemic brain damage.

Cerebrovascular complications of diabetes: focus on cognitive dysfunction

The incidence of diabetes has more than doubled in the United States in the last 30 years and the global disease rate is projected to double by 2030. Cognitive impairment has been associated with diabetes, worsening quality of life in patients. The structural and functional interaction of neurons with the surrounding vasculature is critical for proper function of the central nervous system including domains involved in learning and memory. Thus, in this review we explore cognitive impairment in patients and experimental models, focusing on links to vascular dysfunction and structural changes. Lastly, we propose a role for the innate immunity-mediated inflammation in neurovascular changes in diabetes.

Paradoxical Elevation of High Density Lipoprotein Cholesterol in Association with Lacunar-Type Cerebral Infarction

Background

The aim of this study was to evaluate the association between high-density lipoprotein cholesterol (HDLC) levels and the risk of lacunar infarction (LI) in a retrospective cohort study in China.

Material/Methods

We recruited 229 patients with obsolete brain infarctions single side (SOBI), 218 with obsolete brain infarctions bilateral sides (BOBI), 193 with both acute stroke and obsolete lacunar infarctions single side (AI&SOBI), 113 with both acute stroke and obsolete lacunar infarctions bilateral sides (AI&BOBI), and 203 without any infarctions (Control).

Results

1) The plasma levels of HDLC in group BOBI, AI&SOBI, and AI&BOBI were higher than in the control group, and lower in group SOBI than in the control group (p<0.01). 2) The plasma levels of HDLC in group AI&SOBI were significantly higher than in group SOBI (p<0.01). 3) The plasma levels of HLDL were similar between group AI&SOBI and AI&BOBI. 4) There were significant relationships between HDLC and acute lacunar stroke, even after adjusting for these factors such as age, sex, triglyceride, total cholesterol, low-density lipoprotein cholesterol, and history of diabetes (p=0.001). 4) Compared with the controls, the calculation of odds ratios indicated relative risk estimates of higher HDLC for acute lacunar stroke with obsolete lacunar infarction.

Conclusions

Elevated HDLC may be an independent predictor of recurrent stroke with obsolete lacunar infarctions single side in Chinese people, justifying clinical trials for secondary prevention of stroke by generally increasing HLDL level. According to the difference between single and bilateral side multiple silent lacunar infarcts, it is inferred that HDLC may increase the risk of atherothrombotic infarction but reduce the risk of cardioembolic infarction in the general Chinese population.

β-Cell adaptation in a mouse model of glucocorticoid-induced metabolic syndrome

Glucocorticoids (GCs) are stress hormones primarily responsible for mobilizing glucose to the circulation. Due to this effect, insulin resistance and glucose intolerance are concerns in patients with endogenous overproduction of GCs and in patients prescribed GC-based therapy. In addition, hypercortisolemic conditions share many characteristics with the metabolic syndrome. This study reports on a thorough characterization, in terms of glucose control and lipid handling, of a mouse model where corticosterone is given via the drinking water. C57BL/6J mice were treated with corticosterone (100 or 25 μg/ml) or vehicle in their drinking water for 5 weeks after which they were subjected to insulin or glucose tolerance tests. GC-treated mice displayed increased food intake, body weight gain, and central fat deposit accumulations. In addition, the GC treatment led to dyslipidemia as well as accumulation of ectopic fat in the liver and skeletal muscle, having a substantial negative effect on insulin sensitivity. Also glucose intolerance and hypertension, both part of the metabolic syndrome, were evident in the GC-treated mice. However, the observed effects of corticosterone were reversed after drug removal. Furthermore, this study reveals insights into β-cell adaptation to the GC-induced insulin resistance. Increased pancreatic islet volume due to cell proliferation, increased insulin secretion capacity, and increased islet chaperone expression were found in GC-treated animals. This model mimics the human metabolic syndrome. It could be a valuable model for studying the complex mechanisms behind the development of the metabolic syndrome and type 2 diabetes, as well as the multifaceted relations between GC excess and disease.

Age and the metabolic syndrome as risk factors for ischemic stroke: improving preclinical models of ischemic stroke

Ischemic stroke represents a leading cause of morbidity and mortality in the developed world. This disabling and sometimes fatal event puts an ever increasing burden on the family members and medical professionals who care for stroke victims. Preclinical ischemic stroke research has predominantly utilized young adult, healthy animals, a clear discrepancy when considering the clinical population affected by stroke. A broad spectrum of risk factors such as age, obesity, diabetes, and hypertension has been associated with an increased stroke risk. The effect of these comorbidities on both stroke pathophysiology and outcome has not been emphasized and has been recognized as a shortcoming of preclinical studies. By addressing these conditions in experimental models of ischemic stroke, it may be possible to more accurately represent the clinical scenario and improve therapeutic translation from bench-to-bedside. In this work, we review many of the risk factors associated with increased stroke risk, particularly as each risk factor relates to inflammation. Additionally, we explore potential animal models that could be utilized in identifying the contribution of these risk factors to stroke outcome. By investigating the risk factors for stroke and how these may alter stroke pathophysiology, the present discrepancies between preclinical studies and the clinical reality can be reconciled in an effort to improve therapeutic development and translation from bench-to-bedside.

Metabolic syndrome and its components in individuals undergoing rehabilitation after stroke

BACKGROUND AND PURPOSE

: Individuals participating in stroke rehabilitation are in jeopardy of future vascular events, including a second stroke. Nevertheless, vascular risk assessment is often overlooked in this population. Metabolic syndrome (MetS) may be a useful construct for risk assessment because of its predictive ability in distinguishing patients who are at high risk of future morbidity. This study documented the prevalence of MetS and its components in stroke rehabilitation patients. In addition, clinical characteristics of subgroups with and without MetS were compared.

METHODS

: Health records of 200 adult patients who had participated in inpatient stroke rehabilitation were reviewed. The prevalence and extent of clustering of the five components of MetS-obesity, hypertension, hypertriglyceridemia, low high-density lipoprotein cholesterol, and insulin resistance-were examined.

RESULTS

: Of the total sample, 61% had MetS and 97% had at least one MetS component, with hypertension and low high-density lipoprotein cholesterol being the most prevalent. The number of comorbidities, number of prescription drugs, and history of coronary heart disease were positively related to the presence of MetS. The components were predicted by a single underlying factor, providing support for the validity of using the MetS construct to assess vascular risk in this population.

DISCUSSION AND CONCLUSIONS

: Awareness of the high prevalence of MetS in individuals undergoing stroke rehabilitation should motivate physical therapists and other rehabilitation clinicians to intervene to prevent the recurrence of vascular events. Early screening for this high-risk condition and implementation of targeted interventions to reduce future vascular morbidity should become priorities in stroke rehabilitation.

High glucose attenuates VEGF expression in rat multipotent adult progenitor cells in association with inhibition of JAK2/STAT3 signalling

This study was to investigate the effect of high glucose (HG) on vascular endothelial growth factor (VEGF) expression in bone marrow stem cells and JAK2/STAT-3 signalling. Adult rat bone marrow multipotent progenitor cells (rMAPCs) were cultured to evaluate VEGF expression (both mRNA and protein) with or without exposure to HG for up to 48 hrs using RT-PCR and ELISA. JAK2 and STAT3 phosphorylation in rMAPCs was analysed by Western blotting. With cells in normal media, VEGF mRNA level after 24 hrs of culture was significantly increased by 15 times over baseline (day 0) with detectable level of VEGF protein intracellularly using immunofluorescence staining. Although there was no measurable VEGF in the media after 24 hrs of culture, a significant amount of VEGF was detected in the media after 48 hrs of incubation. VEGF expression was associated with constitutive activation of JAK2 and STAT3 in rMAPCs. However, VEGF mRNA level was significantly reduced without detectable VEGF in the media when rMAPCs exposed to HG for 48 hrs. Tyrosine-phosphorylation of JAK2 and STAT3 and nuclear translocation of phosphorylated STAT3 were significantly decreased in the cells exposed to HG for 48 hrs. When JAK2 and STAT3 phosphorylation was blocked by the selective inhibitor AG490, VEGF mRNA level was significantly decreased in rMAPCs in normal media by 80% with no detectable VEGF in the media. VEGF expression was significantly suppressed in rMAPCs cultured in HG media that was further reduced by AG490. VEGF expression in rMAPCs is impaired by HG possibly through inhibition of JAK2/STAT3 signalling.

Metabolic syndrome and stroke

The metabolic syndrome is highly prevalent worldwide, and its cardiovascular toll is expected to rise with the growing obesity epidemic. Mounting evidence points to an association between metabolic syndrome and first or recurrent stroke. This article discusses the emerging data supporting a link between stroke and the metabolic syndrome and underscores the need to better understand the syndrome's pathophysiology, with a goal to appropriately and intensively limit the burden of this multiple risk factor entity.