Single-fiber conduction velocity test allows earlier detection of abnormalities in diabetes

Rivista: Muscle Nerve

Autori: Padua L, Stålberg E, Caliandro P, Muscogiuri G, Pazzaglia C, Sorice GP, Granata G, Salomone E, Pontecorvi A, Giaccari A

 

Abstract

Introduction

The purpose of this study was to determine whether single-fiber conduction velocity (SF-CV) of a small number of axons increases sensitivity for identification of motor nerve conduction alterations in patients with diabetes.

Methods

Twenty-one consecutive diabetic patients in good metabolic control were studied. For each patient, conventional (C-CV) and SF-CV results were correlated with the presence of neuropathic symptoms.

Results

Nine of 21 patients reported symptoms suggestive of mild nerve impairment. Three patients had abnormal sural nerve CV, 1 of whom also had abnormal motor nerve conduction. Eighteen patients had normal findings on conventional tests, 3 of whom had slowing of SF-CV.

Conclusions

SF-CV is able to detect mild myelin damage with higher sensitivity than conventional tests. The use of SF-CV may be a helpful tool in the early identification of diabetic polyneuropathy, and it may be useful for tailoring an approach to diabetic polyneuropathy. Muscle Nerve, 2011

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Removal of Duodenum Elicits GLP-1 Secretion

Rivista: Diabetes Care

Autori: Muscogiuri G, Mezza T, Prioletta A, Sorice GP, Clemente G, Sarno G, Nuzzo G, Pontecorvi A, Holst JJ, Giaccari A.

OBJECTIVE To evaluate the effect of removal of the duodenum on the complex interplay between incretins, insulin, and glucagon in nondiabetic subjects.

RESEARCH DESIGN AND METHODS For evaluation of hormonal secretion and insulin sensitivity, 10 overweight patients without type 2 diabetes (age 61 ± 19.3 years and BMI 27.9 ± 5.3 kg/m2) underwent a mixed-meal test and a hyperinsulinemic-euglycemic clamp before and after pylorus-preserving pancreatoduodenectomy for ampulloma.

RESULTS All patients experienced a reduction in insulin (P = 0.002), C-peptide (P = 0.0002), and gastric inhibitory peptide (GIP) secretion (P = 0.0004), while both fasting and postprandial glucose levels increased (P = 0.0001); GLP-1 and glucagon responses to the mixed meal increased significantly after surgery (P = 0.02 and 0.031). While changes in GIP levels did not correlate with insulin, glucagon, and glucose levels, the increase in GLP-1 secretion was inversely related to the postsurgery decrease in insulin secretion (R2 = 0.56; P = 0.012) but not to the increased glucagon secretion, which correlated inversely with the reduction of insulin (R2= 0.46; P = 0.03) and C-peptide (R2 = 0.37; P = 0.04). Given that the remaining pancreas presumably has preserved intraislet anatomy, insulin secretory capacity, and α- and β-cell interplay, our data suggest that the increased glucagon secretion is related to decreased systemic insulin.

CONCLUSIONS Pylorus-preserving pancreatoduodenectomy was associated with a decrease in GIP and a remarkable increase in GLP-1 levels, which was not translated into increased insulin secretion. Rather, the hypoinsulinemia may have caused an increase in glucagon secretion.

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Predictive models of insulin resistance derived from simple morphometric and biochemical indices related to obesity and the metabolic syndrome in baboons

Rivista: Cardiovascular Diabetology

Autori: Alberto O Chavez, Amalia Gastaldelli, Rodolfo Guardado-Mendoza, Juan C Lopez-Alvarenga, M Michelle Leland, M Elizabeth Tejero, GianPio Sorice, Francesca Casiraghi, Alberto Davalli, Raúl A Bastarrachea, Anthony G Comuzzie, Ralph A DeFronzo, Franco Folli

Background

Non-human primates are valuable models for the study of insulin resistance and human obesity. In baboons, insulin sensitivity levels can be evaluated directly with the euglycemic clamp and is highly predicted by adiposity, metabolic markers of obesity and impaired glucose metabolism (i.e. percent body fat by DXA and HbA1c). However, a simple method to screen and identify obese insulin resistant baboons for inclusion in interventional studies is not available.

Methods

We studied a population of twenty baboons with the euglycemic clamp technique to characterize a population of obese nondiabetic, insulin resistant baboons, and used a multivariate linear regression analysis (adjusted for gender) to test different predictive models of insulin sensitivity (insulin-stimulated glucose uptake = Rd) using abdominal circumference and fasting plasma insulin. Alternatively, we tested in a separate baboon population (n = 159), a simpler model based on body weight and fasting plasma glucose to predict the whole-body insulin sensitivity (Rd/SSPI) derived from the clamp.

Results

In the first model, abdominal circumference explained 59% of total insulin mediated glucose uptake (Rd). A second model, which included fasting plasma insulin (log transformed) and abdominal circumference, explained 64% of Rd. Finally, the model using body weight and fasting plasma glucose explained 51% of Rd/SSPI. Interestingly, we found that percent body fat was directly correlated with the adipocyte insulin resistance index (r = 0.755, p < 0.0001).

Conclusion

In baboons, simple morphometric measurements of adiposity/obesity, (i.e. abdominal circumference), plus baseline markers of glucose/lipid metabolism, (i.e. fasting plasma glucose and insulin) provide a feasible method to screen and identify overweight/obese insulin resistant baboons for inclusion in interventional studies aimed to study human obesity, insulin resistance and type 2 diabetes mellitus.

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Metabolic Syndrome in Transplant Patients: An Academic or a Health Burden?

Rivista: Transplantation Proceedings

Autori: G.P. Sorice, G. Muscogiuri, T. Mezza, A. Prioletta, A. Giaccari

Metabolic syndrome is a cluster of risk factors that predispose to major cardiovascular diseases, liver steatosis and fibrosis, as well as reduced renal function. Metabolic syndrome and its early hepatic manifestation, non-alcoholic fatty liver disease, are prevalent both among the general population and in pre- and posttransplantation settings. Because indications for solid-organ transplantation are gradually increasing, attention should focus on the incidence of metabolic syndrome among transplanted patients, defined as posttransplant metabolic syndrome (PTMS). Subjects with worse metabolic profiles with two or more criteria of the syndrome show lower survival rates and greater co-morbidities.

However, it is still unclear whether the pathophysiology of posttransplantation metabolic syndrome differ from that of the general population and may be determined by the primary disease affecting the liver or kidney, or amplified or altered by the immunosuppressive treatment, as it has already been established that corticosteroids and calcineurin inhibitors cause metabolic disarrangements. Although there is controversy regarding the definition and the impact of PTMS on overall survival rates following transplantation, these patients are at increased risk for cardiovascular morbidity and mortality. Early recognition, prevention, and treatment of these conditions may impact long-term survival after transplantation. Thus, even if metabolic syndrome in transplant patients remains an unclear definition, an insulin resistance is present in these patients. The treatment of this condition represents a health problem that requires intervention by clinicians before and after transplantation.

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Metabolic syndrome in transplant patients: an updating point of view

Rivista: Minerva Endocrinol

Autori: G. P. Sorice, L. Di Pizio, V. A. Sun, T. Schirò, G. Muscogiuri, T. Mezza, C. M. A. Cefalo, A. Prioletta, A. Pontecorvi, A. Giaccari

Metabolic syndrome (MS) is a cluster of risk factors that predispose to major cardiovascular diseases and its complications, determining liver and kidney impairment. In the last decade, the indications to transplantation are increasing, with a linear incidence of the complications of the procedure. MS represents one of the commonest, being in turn may the consequence of the underlying disease that required the transplantation, or the result of the medical treatment, as well as one of the most important factor influencing the morbidity and mortality of the transplanted patients. Due to the growing incidence of the MS in these patients, it is crucial to focus and clarify the leading causes determining the onset of the metabolic disarrangement, its outcome and the hypothetical mechanism through which the clinicians could reduce the impact of the disease. In fact, prevention, early recognition, and treatment of the factor that could predict the onset or progression of the MS after the transplantation may impact long term survival of patients, that is again the scope of the same transplant. This review will update the different mechanisMS of the pathogenesis of MS in this population, the clinical effects of the presence of the MS, observing the risk factors to be treated before and after the transplantation and suggesting the management of the follow-up.

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Metabolic consequences of the occlusion of the main pancreatic duct with acrylic glue after pancreaticoduodenectomy

Rivista: The American Journal of Surgery

Autori: Teresa Mezza, Gennaro Clemente, Gian Pio Sorice, Caterina Conte, Agostino Maria De Rose, Vincin Alice Sun, Chiara Maria Assunta Cefalo, Alfredo Pontecorvi, Gennaro Nuzzo, Andrea Giaccari

Background
Pancreaticoduodenectomy represents the major treatment for pancreatic and periampullary neoplasms. Complications related to pancreaticojejunostomy are still the leading cause of morbidity and mortality. A solution proposed by some surgeons is the occlusion of main pancreatic duct by acrylic glue, avoiding pancreaticojejunostomy. Nevertheless, the consequences of this procedure on glucose metabolism are not well-defined.

Methods
We retrospectively analyzed a cohort of 50 patients who underwent pancreaticoduodenectomy and had metabolic assessments available. The metabolic evaluation included the following: body composition and clinical evaluation, an oral glucose tolerance test, and an hyperinsulinemic euglycemic clamp procedure.

Results
Twenty-three patients underwent pancreatic duct occlusion and were compared with 27 patients, well-matched controls, who underwent pancreaticojejunostomy. Pancreatic duct occlusion leads to a greater impairment in insulin secretion compared with classic pancreaticojeunostomy.

Conclusion
Pancreatic duct occlusion is associated with a greater reduction in insulin secretion but does not lead to meaningful differences in the management of patients with diabetes.

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Medical Therapy of Aortic Aneurysms: A Pathophysiology-Based Approach

Rivista: Current Vascular Pharmacology

Autori: Giovanna Muscogiuri, Gian Pio Sorice, Devjit Tripathy, Alberto O. Chavez, Alberto Davalli, Richard A. Lange, Franco Folli

One of the critical points in the pathogenesis of aortic aneurysms (AAs) is the disruption of the balance between vascular extracellular matrix (ECM) deposition and degradation. AAs are common features in some genetically determined diseases of the connective tissue, such as Marfan and Ehlers-Danlos. Acquired factors determining an enhanced inflammatory state of the arterial wall also play a key role. Previous studies have determined the role of tumor growth factor β (TGF-β); as a principal mediator of the pathogenesis of the alterations of the arterial wall homeostasis in AAs. The medical management of any AA is mainly focused on the use of pharmacological agents that reduce hemodynamic stress of the aortic wall, since hypertension is the major risk factor for the enlargement and rupture of the AAs. However, this is far from being a comprehensive pathophysiology-based therapeutic approach. Drugs potentially able to reduce the release of TGF-β may play a role in the pathogenesis of the AAs. They work by improving matrix repair, decreasing the proteolytic pattern and inhibition of angiotensin-converting enzyme (ACE) as well as preventing angiotensin II-induced angiotensin type-1 receptor (AT1R) activation. A new pathophysiology-based therapeutic approach, involving the mechanisms leading to the rupture of the AAs, could represent an additional tool in combination with the current established antihypertensive therapy.

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Insulin Resistance Alters Islet Morphology in Nondiabetic Humans

Rivista: Diabetes

Autori: Teresa Mezza, Giovanna Muscogiuri, Gian Pio Sorice, Gennaro Clemente, Jiang Hu, Alfredo Pontecorvi, Jens J. Holst, Andrea Giaccari, Rohit N. Kulkarni

Type 2 diabetes is characterized by poor glucose uptake in metabolic tissues and manifests when insulin secretion fails to cope with worsening insulin resistance. In addition to its effects on skeletal muscle, liver, and adipose tissue metabolism, it is evident that insulin resistance also affects pancreatic β-cells. To directly examine the alterations that occur in islet morphology as part of an adaptive mechanism to insulin resistance, we evaluated pancreas samples obtained during pancreatoduodenectomy from nondiabetic subjects who were insulin-resistant or insulin-sensitive. We also compared insulin sensitivity, insulin secretion, and incretin levels between the two groups. We report an increased islet size and an elevated number of β- and α-cells that resulted in an altered β-cell–to–α-cell area in the insulin- resistant group. Our data in this series of studies suggest that neogenesis from duct cells and transdifferentiation of α-cells are potential contributors to the β-cell compensatory response to insulin resistance in the absence of overt diabetes.

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IL-21 Is a Major Negative Regulator of IRF4-Dependent Lipolysis Affecting Tregs in Adipose Tissue and Systemic Insulin Sensitivity

Rivista: Diabetes

Autori: Marta Fabrizi, Valentina Marchetti, Maria Mavilio, Arianna Marino, Viviana Casagrande, Michele Cavalera, Josè Maria Moreno-Navarrete, Teresa Mezza, Gian Pio Sorice, Loredana Fiorentino, Rossella Menghini, Renato Lauro, Giovanni Monteleone, Andrea Giaccari, José Manuel Fernandez Real, Massimo Federici

Obesity elicits immune cell infiltration of adipose tissue provoking chronic low-grade inflammation. Regulatory T cells (Tregs) are specifically reduced in adipose tissue of obese animals. Since interleukin (IL)-21 plays an important role in inducing and maintaining immune-mediated chronic inflammatory processes and negatively regulates Treg differentiation/activity, we hypothesized that it could play a role in obesity-induced insulin resistance. We found IL-21 and IL-21R mRNA expression upregulated in adipose tissue of high-fat diet (HFD) wild-type (WT) mice and in stromal vascular fraction from human obese subjects in parallel to macrophage and inflammatory markers. Interestingly, a larger infiltration of Treg cells was seen in the adipose tissue of IL-21 knockout (KO) mice compared with WT animals fed both normal diet and HFD. In a context of diet-induced obesity, IL-21 KO mice, compared with WT animals, exhibited lower body weight, improved insulin sensitivity, and decreased adipose and hepatic inflammation. This metabolic phenotype is accompanied by a higher induction of interferon regulatory factor 4 (IRF4), a transcriptional regulator of fasting lipolysis in adipose tissue. Our data suggest that IL-21 exerts negative regulation on IRF4 and Treg activity, developing and maintaining adipose tissue inflammation in the obesity state.

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High-normal tsh values in obesity: Is it insulin resistance or adipose tissue’s guilt?

Rivista: Obesity

Autori: Giovanna Muscogiuri, Gian P. Sorice, Teresa Mezza, Annamaria Prioletta, Anna P. Lassandro, Tommaso Pirronti, Silvia Della Casa, Alfredo Pontecorvi, Andrea Giaccari

Objective:

Clinical evidences reported subclinical alterations of thyroid function in obesity, although the relationship between thyroid status and obesity remains unclear. We cross-sectionally investigated the influence of metabolic features on hypothalamic–pituitary–thyroid axis in obesity.

Design and Methods:

We enrolled 60 euthyroid subjects with no history of type 2 diabetes mellitus and assessed the relationship of thyroid function with insulin resistance, measured using euglycemic clamp, and abdominal fat volume, quantified by computed tomography scan (CT scan). Thyroid stimulating hormone (TSH) correlated with BMI (r = 0.46; P = 0.02), both visceral (r = 0.58; P = 0.02) and subcutaneous adipose tissue volumes (r = 0.43; P = 0.03) and insulin resistance (inverse relationship with insulin sensitivity–glucose uptake: r = −0.40; P = 0.04).

Results:

After performing multivariate regression, visceral adipose tissue volume was found to be the most powerful predictor of TSH (β = 3.05; P = 0.01), whereas glucose uptake, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, subcutaneous adipose tissue volume, and triglycerides were not. To further confirm the hypothesis that high-normal TSH values could be dependent on adipose tissue, and not on insulin resistance, we restricted our analyses to moderately obese subjects’ BMI ranging 30-35 kg/m2. This subgroup was then divided as insulin resistant and insulin sensitive according to the glucose uptake (≤ or >5 mg·kg−1·min−1, respectively). We did not find any statistical difference in TSH (insulin resistant: 1.62 ± 0.65 µU/ml vs. insulin sensitive: 1.46 ± 0.48; P = not significant) and BMI (insulin resistant: 32.2 ± 1.6 kg/m2 vs. insulin sensitive: 32.4 ± 1.4; P = not significant), thus confirming absence of correlation between thyroid function and insulin sensitivity per se.

Conclusion:

Our study suggests that the increase in visceral adipose tissue is the best predictor of TSH concentration in obesity, independently from the eventual concurrent presence of insulin resistance.

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