Laura A. Scrimgeour

Distinguishing Persistent Insulin Autoantibodies With Differential Risk: Nonradioactive Bivalent Proinsulin/Insulin Autoantibody Assay

A subset of children develops persistent insulin autoantibodies (IAA; almost always as the only islet autoantibody) without evidence of progression to diabetes. The aim of the current study was the development and characterization of the performance of a nonradioactive fluid phase IAA assay in relation to standard IAA radioassay. We developed a nonradioactive IAA assay where bivalent IAA cross-link two insulin moieties in a fluid phase. The serum samples positive for anti-islet autoantibodies from 150 newly diagnosed patients with diabetes (Barbara Davis Center plus Diabetes Autoantibody Standardization Program [DASP] workshop) and 70 prediabetic subjects who were followed to diabetes were studied. In addition, sequential samples from 64 nondiabetic subjects who were persistently IAA+ were analyzed. With 99th percentile of specificity, the new assay with the technology from Meso Scale Discovery Company (MSD-IAA) detects as positive 61% (61 of 100) of new-onset patients and 80% (56 of 70) of prediabetic patients compared with our current fluid phase micro-IAA radioassay (mIAA; 44 and 74%, respectively). In addition, MSD-IAA demonstrated better sensitivity than our mIAA from blinded DASP workshop (68 vs. 56% with the same 99% specificity). Of 64 IAA+ nondiabetic subjects, 25% (8 of 32) who had only IAA and thus the low risk for progression to diabetes were positive with MSD-IAA assay. In contrast, 100% (32 of 32) high-risk children (IAA plus other islet autoantibodies) were positive with MSD-IAA. The IAA detectable by radioassay, but not MSD-IAA, were usually of lower affinity compared with the IAA of the high-risk children. These data suggest that a subset of IAA with current radioassay (not MSD-IAA) represents biologic false positives in terms of autoimmunity leading to diabetes. We hypothesize that factors related to the mechanism of loss of tolerance leading to diabetes determine high affinity and MSD-IAA reactivity.

Use of CoZmonitor® in youth with type 1 diabetes*

Background:  The purpose of this study was to evaluate the effectiveness of directly integrating self‐monitoring blood glucose (BG) information with insulin pump therapy on overall glycemic control.

Glycogen synthase kinase 3β inhibition reduces mitochondrial oxidative stress in chronic myocardial ischemia

Objectives: Glycogen synthase kinase 3&bgr; (GSK‐3&bgr;) inhibition has been reported to increase microvascular density and improve myocardial blood flow in a porcine model of chronic myocardial ischemia and metabolic syndrome. Inhibition of GSK‐3&bgr; can also be cardioprotective by modulating fibrosis signaling and mitochondrial‐induced apoptosis. We hypothesized GSK‐3&bgr; inhibition would have a beneficial effect on myocardial fibrosis and oxidative stress in a porcine model of chronic myocardial ischemia and metabolic syndrome. Methods: Pigs were fed a high fat diet for 4 weeks followed by placement of an ameroid constrictor to the left circumflex coronary artery. Three weeks later animals received either no drug or a GSK‐3&bgr; inhibitor. The diets and placebo/GSK‐3&bgr; inhibition were continued for an additional 5 weeks, the pigs were then euthanized, and the myocardial tissue was harvested. Collagen expression was analyzed via Picrosirius staining. Oxidative stress was analyzed via Oxyblot analysis. Protein expression was analyzed via Western blot. Results: GSK‐3&bgr; inhibition was associated with decreased collagen expression and oxidative stress in the ischemic and nonischemic myocardial tissue compared with control. There was a decrease in profibrotic proteins transforming growth factor‐&bgr;, p‐SMAD2/3, and matrix metalloproteinase‐9, and in proapoptotic and oxidative stress proteins, apoptosis inducing factor, the cleaved caspase 3/caspase 3 protein ratio and phosphorylated myeloid cell leukemia sequence‐1 in the GSK‐3&bgr; inhibited group compared with the control. Conclusions: In the setting of metabolic syndrome and chronic myocardial ischemia, inhibition of GSK‐3&bgr; decreases collagen formation and oxidative stress in myocardial tissue. GSK‐3&bgr; inhibition might be having this beneficial effect by downregulating transforming growth factor‐&bgr;/SMAD2/3 signaling and decreasing mitochondrial induced cellular stress.

Extracellular Vesicle Injection Improves Myocardial Function and Increases Angiogenesis in a Swine Model of Chronic Ischemia

Background Mesenchymal stem cell–derived extracellular vesicles (EVs) are believed to be cardioprotective in myocardial infarct. The objective of this study was to examine the effects of human mesenchymal cell–derived EV injection on cardiac function, myocardial blood flow, and vessel density in the setting of chronic myocardial ischemia. Methods and Results Twenty‐three Yorkshire swine underwent placement of an ameroid constrictor on their left circumflex artery. Two weeks later, the animals were split into 2 groups: the control group (CON; n=7) and the EV myocardial injection group (MVM; n=10). The MVM group underwent myocardial injection of 50 μg of EVs in 2 mL 0.9% saline into the ischemic myocardium. Five weeks later, the pigs underwent a harvest procedure, and the left ventricular myocardium was analyzed. Absolute blood flow and the ischemic/nonischemic myocardial perfusion ratio were increased in the ischemic myocardium in the MVM group compared with the CON group. Pigs in the MVM group had increased capillary and arteriolar density in the ischemic myocardial tissue compared with CON pigs. There was an increase in expression of the phospho–mitogen‐activated protein kinase/mitogen‐activated protein kinase ratio, the phospho–endothelial nitric oxide synthase/endothelial nitric oxide synthase ratio, and total protein kinase B in the MVM group compared with CON. There was an increase in cardiac output and stroke volume in the MVM group compared with CON. Conclusions In the setting of chronic myocardial ischemia, myocardial injection of human mesenchymal cell–derived EVs increases blood flow to ischemic myocardial tissue by induction of capillary and arteriolar growth via activation of the protein kinase B/endothelial nitric oxide synthase and mitogen‐activated protein kinase signaling pathways resulting in increased cardiac output and stroke volume.

Lessons Learned From an Untreated “Benign” Thoracic Tumor

We describe a patient with Doege-Potter syndrome (solitary fibrous tumor of the pleura presenting with hypoglycemia) and illustrate several important lessons learned from the case. Seven years after the initial diagnosis, the tumor showed significant growth and developed a high-grade undifferentiated component. Solitary fibrous tumors do grow and cannot be deemed benign. Resection should be considered in all patients who are candidates for operation upon diagnosis. Our case also serves as a reminder of this rare syndrome, inasmuch as early recognition of the association of hypoglycemia with these tumors may have allowed for earlier diagnosis and avoidance of extensive tests in our patient.

Decreased contractile response of peripheral arterioles to serotonin after CPB in patients with diabetes

Background: Regulation of coronary vasomotor tone by serotonin is significantly changed after cardioplegic arrest and reperfusion. The current study investigates whether cardiopulmonary bypass may also affect peripheral arteriolar response to serotonin in patients with or without diabetes. Methods: Human peripheral microvessels (90–180 &mgr;m diameter) were dissected from harvested skeletal muscle tissues from diabetic and non‐diabetic patients before and after cardiopulmonary bypass and cardiac surgery (n=8/group). In vitro contractile response to serotonin was assessed by videomicroscopy in the presence or absence of serotonin alone (10−9‐10−5M) or combined with the selective serotonin 1B receptor (5‐HT1B) antagonist, SB224289 (10−6M). 5‐HT1A/1B protein expression in the skeletal muscle was measured by Western‐blot and immunohistochemistry. Results: There were no significant differences in contractile response of peripheral arterioles to serotonin (10−5M) pre‐cardiopulmonary bypass between diabetic and non‐diabetic patients. After cardiopulmonary bypass, contractile response to serotonin was significantly impaired in both diabetic and non‐diabetic patients compared to their pre‐cardiopulmonary bypass counterparts (P < .05). This effect was more pronounced in diabetic patients than non‐diabetic patients (P < .05 versus non‐diabetic). The contractile response to serotonin was significantly inhibited by the 5‐HT1B antagonist in both diabetic and non‐diabetic vessels (P < .05 versus serotonin alone). There were no significant differences in the expression/distribution of 5‐HT1A/1B between non‐diabetic and diabetic groups or between pre‐ versus post‐ cardiopulmonary bypass vessels. Conclusions: Cardiopulmonary bypass is associated with decreased contractile response of peripheral arterioles to serotonin and this effect was exaggerated in the presence of diabetes. Serotonin‐induced contractile response of the peripheral arterioles was via 5‐HT1B in both diabetic and non‐diabetic patients.

Alcohol attenuates myocardial ischemic injury

Background: Moderate alcohol consumption is cardioprotective but the mechanism of action remains unclear. Nuclear factor &kgr;‐B regulates the expression of genes involved in inflammation, stress, and apoptosis. We used a swine model of diet‐induced metabolic syndrome to investigate the effects of red wine and vodka on nuclear factor &kgr;‐B signaling and cytokine activity in chronically ischemic myocardium. Methods: Yorkshire swine were given a high‐fat diet for 4 weeks; an ameroid constrictor was then placed on the left circumflex artery. The high‐fat diet was continued and the swine were divided into 3 groups for 7 weeks: hypercholesterolemic diet alone (control, n = 8), hypercholesterolemic diet with vodka (vodka, n = 8), and hypercholesterolemic diet with wine (wine, n = 8). Ischemic myocardium was analyzed by Western blot and cytokine array. Results: Administration of alcohol was associated with decreased expression of inhibitor of &kgr;‐B kinase complex &agr;, inhibitor of &kgr;‐B kinase complex &bgr;, and phosphorylated inhibitor of &kgr;‐B &bgr; in the ischemic myocardium compared with the control group. Alcohol administration demonstrated an increase in nuclear factor &kgr;‐B in the ischemic myocardium. Both wine and vodka demonstrated a significant decrease in leptin, interleukin‐1&agr;, IL‐13, IL‐15, and interferon‐&ggr;. Vodka demonstrated a significant decrease in phosphorylated BCL‐2 and caspase‐9. Conclusion: In ischemic myocardium, alcohol modulates the nuclear factor &kgr;‐B pathway, which may contribute to the adaptive response of tissues to the stress of ischemia. Furthermore, both wine and vodka decreased multiple proinflammatory cytokines. This study provides a mechanism by which alcohol may be cardioprotective in ischemic myocardium.