Eleni Boutati

Glucose transporter expression on the plasma membrane of resting and activated white blood cells

Background  In white blood cells (WBC), the increase in glucose utilization is a prominent feature during immune response and this depends on the function of specific glucose transporter (GLUT) isoforms. The objective was to examine the effects of activation by Phorbol 12‐myristate 13‐acetate (PMA) or lipopolysaccharide (LPS) and insulin on the expression of GLUT isoforms in all subpopulations of WBC.

Evaluation of glucose transport and its regulation by Insulin in human Monocytes using flow cytometry

We investigated the effects of insulin on glucose transport in human monocytes using flow cytometry, a method with several advantages over previously used techniques. We hypothesized that monocytes could be used as tools to study insulin action at the cellular level and facilitate the investigation of mechanisms that lead to insulin resistance.

Adiponectin levels and expression of adiponectin receptors in isolated monocytes from overweight patients with coronary artery disease

BackgroundAdiponectin has insulin-sensitizing and anti-atherosclerotic effects, partly mediated through its action on monocytes. We aimed to determine adiponectin levels and expression of its receptors (AdipoR1 and AdipoR2) in peripheral monocytes from overweight and obese patients with coronary artery disease (CAD).MethodsFifty-five overweight/obese patients, suspected for CAD, underwent coronary angiography: 31 were classified as CAD patients (stenosis ≥ 50% in at least one main vessel) and 24 as nonCAD. Quantitative RT-PCR and flow cytometry were used for determining mRNA and protein surface expression of adiponectin receptors in peripheral monocytes. A high sensitivity multiplex assay (xMAP technology) was used for the determination of plasma adiponectin and interleukin-10 (IL-10) secreted levels.ResultsPlasma adiponectin levels were decreased in CAD compared to nonCAD patients (10.9 ± 3.1 vs. 13.8 ± 5.8 μg/ml respectively, p = 0.033). In multivariable analysis, Matsuda index was the sole independent determinant of adiponectin levels. AdipoR1 and AdipoR2 protein levels were decreased in monocytes from CAD compared to nonCAD patients (59.5 ± 24.9 vs. 80 ± 46 and 70.7 ± 39 vs. 95.6 ± 47.8 Mean Fluorescence Intensity Arbitrary Units respectively, p < 0.05). No significant differences were observed concerning the mRNA levels of the adiponectin receptors between CAD and nonCAD patients. AdipoR2 protein levels were positively correlated with plasma adiponectin and Matsuda index (r = 0.36 and 0.31 respectively, p < 0.05 for both). Furthermore, basal as well as adiponectin-induced IL-10 release was reduced in monocyte-derived macrophages from CAD compared to nonCAD subjects.ConclusionsOverweight patients with CAD compared to those without CAD, had decreased plasma adiponectin levels, as well as decreased surface expression of adiponectin receptors in peripheral monocytes. This fact together with the reduced adiponectin-induced IL-10 secretion from CAD macrophages could explain to a certain extent, an impaired atheroprotective action of adiponectin.

Low Ankle-Brachial Index predicts early risk of recurrent stroke in patients with acute cerebral ischemia

OBJECTIVE Low ankle-brachial blood pressure index (ABI) identifies patients with symptomatic and asymptomatic peripheral arterial disease (PAD). We sought to investigate the association of low ABI with early risk of stroke recurrence in patients with acute cerebral ischemia (ACI) and without history of symptomatic PAD. METHODS Consecutive patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA) and no previous history of PAD were prospectively evaluated with ABI measurements. Demographic characteristics, vascular risk factors and secondary prevention therapies were documented. An ABI ≤0.90 in either leg was considered as evidence of asymptomatic PAD, and an ABI >0.90 was considered as normal. Patients with elevated ABI (>1.30) were excluded. The outcome of interest was recurrent stroke during 30-day follow-up. RESULTS A total of 176 patients with acute cerebral ischemia (mean age 64±14 years, 59.1% men, 76.7% AIS) were evaluated. Asymptomatic PAD was detected in 14.8% (95%CI: 10.2-20.8%) of the studied population. The following factors were independently associated with low ABI on multivariate logistic regression models, after adjustment for potential confounders: coronary artery disease (p=0.008), diabetes mellitus (p=0.017) and increasing age (p=0.042). The cumulative 30-day recurrence rate was higher in patients with low ABI (19.2%; 95%CI: 4.1-34.3) compared to the rest (3.3%; 95%CI: 0.4-6.2%; p=0.001). Atherothrombotic stroke (ASCO grade I; p<0.001), increasing age (p=0.002) and low ABI (p=0.004) were independent predictors of stroke recurrence on multivariate Cox regression models adjusting for confounders. CONCLUSIONS Low ABI appears to be associated with a higher risk of early recurrent stroke in patients with ACI and no history of symptomatic PAD.

Insulin resistance and metabolic syndrome in patients with nonfunctioning adrenal incidentalomas: a cause-effect relationship?

The objective of the study was to assess insulin resistance (IR) and metabolic syndrome (MS) in patients with nonfunctioning adrenal incidentalomas (NFAIs). Among a total cohort of 46 patients with adrenal incidentalomas, we studied 29 patients with NFAIs (mean age, 54 ± 9 years; body mass index, 29 ± 3 kg/m(2)) and 37 age-, sex-, and body mass index-matched healthy controls. Besides the endocrine workup, IR was evaluated using fasting glucose and insulin concentrations, homeostasis model assessment of IR, and quantitative insulin sensitivity check index. In a subgroup of patients undergoing an oral glucose tolerance test, Matsuda index and total area under the curve for glucose and insulin were also evaluated. Total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, and other biochemical parameters were measured with standard techniques. Body composition was determined with dual-energy x-ray absorptiometry. Patients with NFAIs exhibited higher fasting glucose, insulin, and homeostasis model assessment of IR values; decreased quantitative insulin sensitivity check index and Matsuda index; and an increased-although not statistically significant-area under the curve for glucose and insulin compared with controls (P < .05). In addition, they exhibited higher systolic and diastolic blood pressure, triglycerides, and γ-glutamyltransferase and lower high-density lipoprotein cholesterol levels compared with controls (P < .05). Patients with NFAIs were all obese with a central type of fat accumulation and increased appendicular lean mass. Indices of IR showed a positive correlation with indices of MS (P < .05), but no correlation with markers of hormonal activity. Nonfunctioning adrenal incidentalomas are characterized by IR, hypertension, dyslipidemia, and fatty liver disease, all of them being components of MS. Thus, patients with NFAIs should be screened for MS during their initial workup to identify those at cardiometabolic risk and implement the appropriate interventions.

Restoration of early insulin secretion after a meal in type 2 diabetes: effects on lipid and glucose metabolism.

Background  In type 2 diabetes (T2D) insulin secretion after a meal is delayed; this may have an impact on the development of hyperglycaemia and hyperlipidaemia.

Multiple endocrine neoplasia type 2A in two families with the familial medullary thyroid carcinoma associated G533C mutation of the RET proto-oncogene

INTRODUCTION Multiple endocrine neoplasia type 2A (MEN2A) is an autosomal dominant hereditary disorder, associated with a cluster of germline gain-of-function mutations of the RET proto-oncogene (RET), mainly in exons 10-15. The G533C mutation in exon 8 of the RET is rare and has been mainly related to the familial medullary thyroid carcinoma. PATIENTS-METHODS We describe the RET G533C mutation in exon 8 of the RET in two unrelated female index patients, with MEN2A phenotype, consisting of pheochromocytoma which was the presenting feature and medullary thyroid carcinoma. In addition, 12 family members were also studied. DNA extraction, PCR, and sequencing of RET was performed in exons 7-19 and 21, following standard procedures. RESULTS The mutation was found in both index patients and in 6 out of 12 family members (50%). Three of them were biochemically affected with histologically proven medullary thyroid carcinoma in two of them while there are no certain clues regarding the other three members as they declined further evaluation. CONCLUSION Patients with MEN2A should be also searched in exon 8 while positive carriers of this mutation should be screened annually for pheochromocytoma or other components of the syndrome.

Insulin-Stimulated Rates of Glucose Uptake in Muscle in Hyperthyroidism: The Importance of Blood Flow

BACKGROUND In hyperthyroidism, although hepatic insulin resistance is well established, information on the effects of insulin on glucose uptake in skeletal muscle is variable. METHODS To investigate this, a meal was given to nine hyperthyroid (HR) and seven euthyroid (EU) subjects. Blood was withdrawn for 360 min from a forearm deep vein and the radial artery for measurements of insulin and glucose. Forearm blood flow (BF) was measured with strain-gauge plethysmography. Glucose flux was calculated as arteriovenous difference multiplied by BF and fractional glucose extraction as arteriovenous difference divided by arterial glucose concentrations. RESULTS Both groups displayed comparable postprandial glucose levels, with the HR having higher insulin levels than the EU. In the forearm of HR vs. EU: 1) glucose flux was similar [area under the curve (AUC)(0-360) 673 +/- 143 vs. 826 +/- 157 micromol per 100 ml tissue]; 2) BF was increased (AUC(0-360) 3076 +/- 338 vs. 1745 +/- 145 ml per 100 ml tissue, P = 0.005); and 3) fractional glucose extraction was decreased (AUC(0-360) 14.5 +/- 3 vs. 32 +/- 5%min, P = 0.03). CONCLUSIONS These results suggest that, in hyperthyroidism, insulin-stimulated glucose uptake in muscle is impaired; this defect is corrected, at least in part, by the increases in BF.

Prevalence of Symptomatic Intracranial Atherosclerosis in Caucasians: A Prospective, Multicenter, Transcranial Doppler Study

There are limited data available regarding symptomatic intracranial atherosclerosis (SIA) prevalence in Caucasians. We sought to investigate SIA prevalence among Caucasian patients hospitalized with acute cerebral ischemia (ACI) in a prospective, multicenter Transcranial Doppler sonography (TCD) study.

Rates of Glucose Uptake in Adipose Tissue and Muscle in Vivo after a Mixed Meal in Women with Morbid Obesity

BACKGROUND AND AIMS Although whole-body insulin resistance in obesity is established, information on insulin action in peripheral tissues, especially adipose tissue (AD), is limited. This study was undertaken in morbid obesity to investigate insulin action on glucose disposal in AD and muscle (M). SUBJECTS AND METHODS A meal was given to 30 obese (age 34 +/- 1 yr, body mass index 47 +/- 1 kg/m(2)) and 10 nonobese women (age 39 +/- 4 yr, body mass index 23 +/- 1 kg/m(2)). Samples for glucose and insulin were taken for 360 min from veins draining the abdominal subcutaneous AD and forearm muscles and from the radial artery. Blood flow (BF) was measured in AD ((133)Xe) and M (plethysmography). RESULTS The area under the curve divided by time (AUC(0-360 min)/360 min) in obese vs. nonobese was as follows: 1) arterial glucose was similar 6.04 +/- 0.2 vs. 5.67 +/- 0.1 mm), but insulin was increased (65.5 +/- 6.6 vs. 28.7 +/- 1.7 mU/liter, P = 0.0004); 2) BF was decreased (3 +/- 0.2 vs. 4.4 +/- 0.3 ml/min per 100 ml tissue in M, P = 0.002 and 1.8 +/- 0.1 vs. 3.7 +/- 0.3 ml/min per 100 ml tissue in AD, P < 0.0001); 3) glucose uptake was decreased (0.9 +/- 0.1 vs. 2.3 +/- 0.4 micromol/min per 100 ml tissue in M, P = 0.002 and 0.45 +/- 0.1 vs. 1.1 +/- 0.17 micromol/min per 100 ml tissue in AD, P = 0.01); 4) fractional glucose extraction was decreased in M (5 +/- 1 vs. 9 +/- 1%, P = 0.03), but was similar in AD (3 +/- 1 vs. 3.6 +/- 1.4%); 5) glucose uptake (per total fat mass) was increased (0.275 +/- 0.04 vs. 0.12 +/- 0.02 mmol/min, P = 0.027). CONCLUSION In morbid obesity, the sensitivity of glucose metabolism to insulin is impaired in M, due to defects in insulin-stimulated glucose use and decreased BF, and in AD, at least in part, due to decreased BF. However, increased total fat mass provides a sink for the excess of glucose and compensates for insulin resistance.