The Conductor of the Autonomic Orchestra

Bad bedfellows – autonomic dysfunction, inflammation, and diabetes! Are they related? How? Evidence suggests the activation of inflammatory cytokines like IL-6 and TNFα in newly diagnosed type 2 diabetes and that the inflammatory change correlates with abnormalities in sympathovagal balance. Dysfunction of the autonomic system predicts cardiovascular risk and sudden death in patients with type 2 diabetes. It occurs in prediabetes, providing opportunities for early intervention. The importance of recognizing autonomic dysfunction as a predictor of morbidity and mortality with intensification of treatment suggests that all patients with type 2 diabetes at onset, and those with type 1 diabetes after 5 years should be screened for autonomic imbalance. These tests can be performed at the bedside with real time output of information – within the scope of the practicing physician – facilitates diagnosis and allows the application of sound strategies for management. The window of opportunity for aggressive control of all the traditional risk factors for cardiovascular events or sudden death with intensification of therapy is with short duration diabetes, the absence of cardiovascular disease, and a history of severe hypoglycemic events. To this list we can now add autonomic dysfunction and neuropathy, which have become the most powerful predictors of risk for mortality. It seems prudent that practitioners should be encouraged to become familiar with this information and apply risk stratification in clinical practice. After all, how difficult is it to ask patients “do you have numb feet?” and to determine their heart rate variability – it could be lifesaving. Ultimately methods to reset the hypothalamus and the inflammatory cascade are needed if we are to impact the care of patients with this compendium of conditions

Nerve Growth Factor and Diabetic Neuropathy

Neuropathy is one of the most debilitating complications of both type 1 and type 2 diabetes, with estimates of prevalence between 50–90% depending on the means of detection. Diabetic neuropathies are heterogeneous and there is variable involvement of large myelinated fibers and small, thinly myelinated fibers. Many of the neuronal abnormalities in diabetes can be duplicated by experimental depletion of specific neurotrophic factors, their receptors or their binding proteins. In experimental models of diabetes there is a reduction in the availability of these growth factors, which may be a consequence of metabolic abnormalities, or may be independent of glycemic control. These neurotrophic factors are required for the maintenance of the neurons, the ability to resist apoptosis and regenerative capacity. The best studied of the neurotrophic factors is nerve growth factor (NGF) and the related members of the neurotrophin family of peptides. There is increasing evidence that there is a deficiency of NGF in diabetes, as well as the dependent neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) that may also contribute to the clinical symptoms resulting from small fiber dysfunction. Similarly, NT3 appears to be important for large fiber and IGFs for autonomic neuropathy. Whether the observed growth factor deficiencies are due to decreased synthesis, or functional, e.g. an inability to bind to their receptor, and/or abnormalities in nerve transport and processing, remains to be established. Although early studies in humans on the role of neurotrophic factors as a therapy for diabetic neuropathy have been unsuccessful, newer agents and the possibilities uncovered by further studies should fuel clinical trials for several generations. It seems reasonable to anticipate that neurotrophic factor therapy, specifically targeted at different nerve fiber populations, might enter the therapeutic armamentarium

A 70-year-old male with peripheral neuropathy, ataxia and antigliadin antibodies shows improvement in neuropathy, but not ataxia, after intravenous immunoglobulin and gluten-free diet

This is a case of a 70-year-old man with severe peripheral neuropathy, type 2 diabetes and progressively worsening cerebellar ataxia. He was found to have circulating antigliadin and antireticulin antibodies compatible with celiac disease in the absence of intestinal pathology. The peripheral neuropathy improved with a gluten-free diet, antioxidants and intravenous immunoglobulin, whereas the ataxia did not. This case illustrates the need to test for celiac disease in patients with idiopathic ataxia and peripheral neuropathy and the need for alternative therapies for ataxia

Use of Heart Rate Reserve and Rating of Perceived Exertion to Prescribe Exercise Intensity in Diabetic Autonomic Neueropathy

Objective- Individuals with diabetic autonomic neuropathy (DAN) exhibit an increased resting heart rate but depressed maximal heart rate. Thus, the purpose of this study was to examine the validity of using either percent of heart rate reserve (HRR) or a rating of perceived exertion (RPE) scale to prescribe exercise intensity in diabetic individuals both with and without DAN. Research Design and Methods-The subjects consisted of 23 individuals with type 2 diabetes, ages 45-75 years, with (DAN; n=13) or without (No DAN; n=10) clinical signs of DAN, as assessed by heart rate variability using the expiration-to-inspiration ratio of the R-R interval. Peak aerobic capacity was determined using a graded protocol on a cycle ergometer, with RPE, heart rate, and Vo2 values recorded at each Stage. Results-The subjects were similar with the exception of depressed autonomic function in DAN subjects. Peak respiratory exchange ratio values were significantly higher (P\u3c0.05) in the DAN group (1.08 +/- 0.02 vs. 1.02 +/- 0.01 in No DAN subjects), although DAN subjects exhibited a significantly lower (P\u3c0.05) peak exercise heart rate. A similarly highly linear relationship between %HRR and percent Vo2 reserve (Vo2R) existed for both groups (r=0.98). A similar slightly weaker relationship (r=0.94) was found between RPE and %Vo2R. Conclusions-in conclusion, in diabetic individuals, %HRR provides an accurate prediction of %VO2R and can be used to prescribe and monitor exercise intensity, regardless of the presence of DAN. The RPE scale is, also a valid, albeit slightly less accurate, method to monitor exercise intensity in diabetic individuals

Cardiac Autonomic Imbalance in Newly Diagnosed and Established Diabetes Is Associated with Markers of Adipose Tissue Inflammation

Introduction. Diabetics die from cardiovascular disease at a much greater rate than nondiabetics. Cardiac autonomic imbalance predicts increased cardiovascular risk and mortality. We studied the relationship between cardiac autonomic imbalance and adipose tissue-derived inflammation in newly diagnosed and established type 2 diabetes. Materials and Methods. Non-diabetics, newly diagnosed diabetics, and established diabetics were included. Anthropomorphic and biochemical measurements were obtained, and insulin resistance was approximated. Cardiac autonomic function was assessed using conventional measures and with power spectral analysis of heart rate. Results and Discussion. Heart rate variability was reduced in all diabetics. Interleukin-6 was higher in diabetics, as was the high molecular weight adiponectin-to-leptin ratio. Interleukin-6 correlated negatively with measures of autonomic balance. Ratios of adiponectin to leptin correlated positively with measures of autonomic balance. Cardiac autonomic imbalance and inflammation occur early in diabetes and are interrelated. Conclusions. Cardiac autonomic imbalance correlates with the adipose tissue-derived inflammation seen early in type 2 diabetes

Use of somatostatin analog in management of carcinoid syndrome

Carcinoid tumors are the most frequent gut neuroendocrine tumors accounting for more than 50% of all tumors of the gastroenteropancreatic (GEP) axis. These tumors appear to derive from a stem cell line capable of differentiating into a variety of malignant cells that secrete many different peptides and amines. The symptoms of carcinoid tumors are often non-specific, vague abdominal pain that may precede the diagnosis by a median of 9 years. Carcinoid syndrome occurs in <10% of patients. We evaluated the effects of SMS 201-995 in 14 such patients, 12 with diarrhea, 8 with flushing, 3 with wheezing, one with tricuspid valve incompetence, 6 with facial teleangiectasia, 3 with a pellagra type dermatosis and one with myopathy. Diarrhea was abolished or significantly reduced in 83%, flushing in 100%, wheezing in 100%, and myopathy improved in the one patient. Blood serotonin was resistant to change, urine 5HIAA fell in 75%, and most gut neuropeptide hormones apart from somatostatin were suppressed. Tumor growth appeared to be slowed in 2/3 of cases treated for up to 4 years. The analog of somatostatin appears to be a useful addition to the therapeutic armamentarium for carcinoid tumors and the symptom complex .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44412/1/10620_2005_Article_BF01536042.pd

A patient-reported outcomes analysis of lanreotide in the treatment of NETs patients with carcinoid syndrome : evidence from the ELECT trial

Purpose: The purpose of this analysis of patient-reported outcomes from the ELECT (Evaluation of Lanreotide Depot/Autogel Efficacy and Safety as a Carcinoid Syndrome Treatment) trial (NCT00774930) was to explore the effect of lanreotide on symptoms of carcinoid syndrome. Specifically, this post hoc analysis was designed to identify the most important patient-reported outcomes for patients in ELECT. Methods: The post hoc analysis of ELECT, a placebo-controlled study of lanreotide in patients with neuroendocrine tumors, evaluated patient-reported outcomes during the double-blind phase of the trial, specifically daily diarrhea and flushing symptoms, octreotide rescue use, and the EORTC QLQ-C30 and QLQ-GINET21 questionnaires at baseline and week 12. Principal component (PC) analysis was applied on baseline data to identify independent variable clusters and clinically meaningful summary measures that highly correlated to these PCs. From those, the minimum clinical important differences were derived so to perform a responder analysis. Results: The three largest PCs captured 42.9% of the variation among baseline variables. The C30 summary score (C30-SS), diarrhea burden, and flushing burden were highly correlated with PC1, PC2, and PC3, respectively. Lanreotide patients were more likely to experience an improvement on the C30-SS (risk ratio [RR] 2.42; P=0.023), diarrhea burden (RR 2.85; P=0.005), and flushing burden (RR 1.39; P=0.31) compared to placebo patients. Lanreotide-treated patients have a higher probability of being a responder on at least one of the three domains of C30-SS, diarrhea burden, or flushing burden compared to placebo patients (RR 1.48; P=0.06). Conclusion: The higher response rates in the diarrhea burden are consistent with the previously reported effects of lanreotide on octreotide rescue medication use, while the findings of a greater efficacy of lanreotide vs placebo in the quality-of-life domains represent a novel aspect in the benefits of lanreotide

Effect of Bromocriptine-QR (a Quick-Release Formulation of Bromocriptine Mesylate) on Major Adverse Cardiovascular Events in Type 2 Diabetes Subjects

Background: Bromocriptine-QR (a quick-release formulation of bromocriptine mesylate), a dopamine D2 receptor agonist, is a US Food and Drug Administrration–approved treatment for type 2 diabetes mellitus (T2DM). A 3070-subject randomized trial demonstrated a significant, 40% reduction in relative risk among bromocriptine-QR-treated subjects in a prespecified composite cardiovascular (CV) end point that included ischemic-related (myocardial infarction and stroke) and nonischemic-related (hospitalization for unstable angina, congestive heart failure [CHF], or revascularization surgery) end points, but did not include cardiovascular death as a component of this composite. The present investigation was undertaken to more critically evaluate the impact of bromocriptine-QR on cardiovascular outcomes in this study subject population by (1) including CV death in the above-described original composite analysis and then stratifying this new analysis on the basis of multiple demographic subgroups and (2) analyzing the influence of this intervention on only the “hard” CV end points of myocardial infarction, stroke, and CV death (major adverse cardiovascular events [MACEs]). Methods and Results: Three thousand seventy T2DM subjects on stable doses of ≤2 antidiabetes medications (including insulin) with HbA1c ≤10.0 (average baseline HbA1c=7.0) were randomized 2:1 to bromocriptine-QR (1.6 to 4.8 mg/day) or placebo for a 52-week treatment period. Subjects with heart failure (New York Heart Classes I and II) and precedent myocardial infarction or revascularization surgery were allowed to participate in the trial. Study outcomes included time to first event for each of the 2 CV composite end points described above. The relative risk comparing bromocriptine-QR with the control for the cardiovascular outcomes was estimated as a hazard ratio with 95% confidence interval on the basis of Cox proportional hazards regression. The statistical significance of any between-group difference in the cumulative percentage of CV events over time (derived from a Kaplan–Meier curve) was determined by a log-rank test on the intention-to-treat population. Study subjects were in reasonable metabolic control, with an average baseline HbA1c of 7.0±1.1, blood pressure of 128/76±14/9, and total and LDL cholesterol of 179±42 and 98±32, respectively, with 88%, 77%, and 69% of subjects being treated with antidiabetic, antihypertensive, and antihyperlipidemic agents, respectively. Ninety-one percent of the expected person-year outcome ascertainment was obtained in this study. Respecting the CV-inclusive composite cardiovascular end point, there were 39 events (1.9%) among 2054 bromocriptine-QR-treated subjects versus 33 events (3.2%) among 1016 placebo subjects, yielding a significant, 39% reduction in relative risk in this end point with bromocriptine-QR exposure (P=0.0346; log-rank test) that was not influenced by age, sex, race, body mass index, duration of diabetes, or preexisting cardiovascular disease. In addition, regarding the MACE end point, there were 14 events (0.7%) among 2054 bromocriptine-QR-treated subjects and 15 events (1.5%) among 1016 placebo-treated subjects, yielding a significant, 52% reduction in relative risk in this end point with bromocriptine-QR exposure (P<0.05; log-rank test). Conclusions: These findings reaffirm and extend the original observation of relative risk reduction in cardiovascular adverse events among type 2 diabetes subjects treated with bromocriptine-QR and suggest that further investigation into this impact of bromocriptine-QR is warranted