Tenomodulin promotes human adipocyte differentiation and beneficial visceral adipose tissue expansion.

Proper regulation of energy storage in adipose tissue is crucial for maintaining insulin sensitivity and molecules contributing to this process have not been fully revealed. Here we show that type II transmembrane protein tenomodulin (TNMD) is upregulated in adipose tissue of insulin-resistant versus insulin-sensitive individuals, who were matched for body mass index (BMI). TNMD expression increases in human preadipocytes during differentiation, whereas silencing TNMD blocks adipogenesis. Upon high-fat diet feeding, transgenic mice overexpressing Tnmd develop increased epididymal white adipose tissue (eWAT) mass, and preadipocytes derived from Tnmd transgenic mice display greater proliferation, consistent with elevated adipogenesis. In Tnmd transgenic mice, lipogenic genes are upregulated in eWAT, as is Ucp1 in brown fat, while liver triglyceride accumulation is attenuated. Despite expanded eWAT, transgenic animals display improved systemic insulin sensitivity, decreased collagen deposition and inflammation in eWAT, and increased insulin stimulation of Akt phosphorylation. Our data suggest that TNMD acts as a protective factor in visceral adipose tissue to alleviate insulin resistance in obesity.

Parental mastery of continuous subcutaneous insulin infusion skills and glycemic control in youth with type 1 diabetes.

OBJECTIVE: The purpose of this study is to determine whether parental knowledge of the continuous subcutaneous insulin infusion (CSII) device affects glycemic control as measured by hemoglobin A1c (A1C) level. SUBJECTS AND METHODS: Parents of children with type 1 diabetes mellitus (T1DM) using CSII completed a 14-item questionnaire. Questions 1-10 were knowledge-based questions that required the parent to extract specific information from their child's CSII device. Questions 11-14 asked parents to provide a self-assessment of their CSII knowledge. RESULTS: Twenty-two parents of youth with T1DM participated in the study. Ten of the youth were in the Low-A1C group (A1C<8%), and the other 12 were in the High-A1C group (A1C≥8%). Parents of youth in the Low-A1C group scored statistically better on the 10-item performance survey than parents of youth in the High-A1C group. Most of the parents of children in the Low-A1C group responded that they knew their child's insulin pump "very well" and that their pump knowledge had "increased" since their child started on the insulin pump. CONCLUSIONS: Our findings reveal that youth with T1DM whose parents are more knowledgeable about pump functions have optimal glycemic control as evidenced by A1C. These findings underscore the importance of ongoing pump training for both pediatric patients and their parents.

Effects of a multicomponent wellness intervention on dyslipidemia among overweight adolescents.

Behavioral changes are the first line of treatment for dyslipidemia in adolescents, but outcome data on the effectiveness of this approach are inconsistent. This study aims to assess the effect of a 13-week multicomponent wellness intervention program, which included weekly nutrition classes and structured cardiovascular, flexibility, and strength training on dyslipidemia in nine overweight/obese [body mass index (BMI) > or = 85th percentile] and nine lean (BMI <85th percentile) adolescents. Clinical measurements and lipid profile assessment were performed before and after the intervention. At the completion of the study, the overweight/obese adolescents demonstrated a 15% increase in high-density lipoprotein cholesterol (HDL-C) levels (mean, 47 +/- 8 vs. 54 +/- 5 mg/dL), whereas there was no improvement in BMI or other measurements. The participants in the lean group showed no change in their anthropometric and serum parameters. A multicomponent wellness intervention resulted in a significant increase of cardioprotective HDL-C levels, which have been associated with coronary health in adulthood.

What causes the insulin resistance underlying obesity?

PURPOSE OF REVIEW: The association between obesity and insulin resistance is an area of much interest and enormous public health impact, with hundreds of articles being published in the last year focused on the possible mechanisms that underlie this association. The purpose to this review is to highlight some of the key recent literature with emphasis on emerging concepts. RECENT FINDINGS: The specific link between visceral adipose tissue accumulation and insulin resistance continues to be discerned. Visceral adiposity is correlated with accumulation of excess lipid in liver, and results in cell autonomous impairment in insulin signaling. Visceral adipose tissue is also prone to inflammation and inflammatory cytokine production, which also contribute to impairment in insulin signaling. The expansion of visceral adipose tissue and excess lipid accumulation in liver and muscle may result from limited expandability of subcutaneous adipose tissue, due to the properties of its extracellular matrix and capacity for capillary growth. SUMMARY: Recent studies underscore the need to better understand the mechanisms linking visceral adiposity with liver fat accumulation, the mechanisms by which ectopic fat accumulation cause insulin resistance, and the mechanisms by which the size of adipose tissue depots is determined.

Body mass index-independent inflammation in omental adipose tissue associated with insulin resistance in morbid obesity.

BACKGROUND: Obesity is a strong risk factor for resistance to insulin-mediated glucose disposal, a precursor of type 2 diabetes and other disorders. However, not all obese individuals are insulin resistant. We sought to identify the molecular pathways that might cause obesity-associated insulin resistance in humans by studying the morbidly obese who were insulin sensitive versus insulin resistant, thereby eliminating obesity as a variable. METHODS: Combining gene expression profiling with computational approaches, we determined the global gene expression signatures of omental and subcutaneous adipose tissue samples obtained from similarly obese patients undergoing gastric bypass surgery. RESULTS: Gene sets related to chemokine activity and chemokine receptor binding were identified as most highly expressed in the omental tissue from insulin-resistant compared with insulin-sensitive subjects, independent of the body mass index. These upregulated genes included chemokines (C-C motif) ligand 2, 3, 4, and 18 and interleukin-8/(CC-X motif) ligand 8 and were not differentially expressed in the subcutaneous adipose tissues between the 2 groups of subjects. Insulin resistance, but not the body mass index, was associated with increased macrophage infiltration in the omental adipose tissue, as was adipocyte size, in these morbidly obese subjects. CONCLUSION: Our findings have demonstrated that inflammation of the omental adipose tissue is strongly associated with insulin resistance in human obesity even in subjects with similar body mass index values.

Body mass index, treatment practices, and mortality in patients with acute heart failure.

OBJECTIVES: Obesity is associated with an increased risk of heart failure (HF). Among patients presenting with acute HF, however, differences in clinical characteristics, treatment regimens, and short-term prognosis of varying weights are largely unknown, particularly from a broader population-based perspective. METHODS: A total of 3722 patients admitted with acute HF to 11 greater Worcester (Massachusetts, USA) hospitals during 1995 and 2000 were categorized as being lean (n = 216), normal weight (n = 1465), overweight (n = 1007), or obese (n = 1034) at the time of hospitalization. RESULTS: Obese patients with decompensated HF were significantly younger (mean age = 71 years) compared with patients of normal weight (mean age = 79 years). Obese patients were more likely to have a history of diabetes and have previously undergone a percutaneous coronary intervention than patients of normal body weight. Lean patients (body mass index<18.5 kg/m2) were less likely to be treated with effective cardiac therapies than normal weight patients, whereas obese patients were more likely to be treated with diuretics. Obese patients experienced a significantly lower in-hospital (4.3 vs. 7.2%) and 30-day (7.3 vs. 14.5%) death rate than normal weight patients, whereas lean patients experienced the highest in-hospital (10.2%) and 30-day (19.9%) death rates. CONCLUSION: The results of this study in residents of a large central New England metropolitan area suggest that obesity is associated with increased survival in patients with acute HF. Further assessment of the 'obesity paradox', and careful attention to patients with a low body mass index, in patients with decompensated HF is warranted.

Accuracy of [18F]fluorodopa positron emission tomography for diagnosing and localizing focal congenital hyperinsulinism.

OBJECTIVES: Focal lesions in infants with congenital hyperinsulinism (HI) represent areas of adenomatosis that express a paternally derived ATP-sensitive potassium channel mutation due to embryonic loss of heterozygosity for the maternal 11p region. This study evaluated the accuracy of 18F-fluoro-l-dihydroxyphenylalanine ([18F]DOPA) positron emission tomography (PET) scans in diagnosing focal vs. diffuse disease and identifying the location of focal lesions. DESIGN: A total of 50 infants with HI unresponsive to medical therapy were studied. Patients were injected iv with [18F]DOPA, and PET scans were obtained for 50-60 min. Images were coregistered with abdominal computed tomography scans. PET scan interpretations were compared with histological diagnoses. RESULTS: The diagnosis of focal or diffuse HI was correct in 44 of the 50 cases (88%). [18F]DOPA PET identified focal areas of high uptake of radiopharmaceutical in 18 of 24 patients with focal disease. The locations of these lesions matched the areas of increased [18F]DOPA uptake on the PET scans in all of the cases. PET scan correctly located five lesions that could not be visualized at surgery. The positive predictive value of [18F]DOPA in diagnosing focal adenomatosis was 100%, and the negative predictive value was 81%. CONCLUSIONS: [18F]DOPA PET scans correctly diagnosed 75% of focal cases and were 100% accurate in identifying the location of the lesion. These results suggest that [18F]DOPA PET imaging provides a useful guide to surgical resection of focal adenomatosis and should be considered as a guide to surgery in all infants with congenital HI who have medically uncontrollable disease.

Congenital hyperinsulinism - a review of the disorder and a discussion of the anesthesia management.

Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in infants and children. In most affected infants, CHI is caused by a specific genetic defect that results in the altered expression of pancreatic beta cells causing unregulated oversecretion of insulin. Infants with CHI may have either focal or diffuse abnormalities of the pancreatic beta-cells. Both forms of CHI manifest as hypoglycemia, usually in the early newborn period. Focal disease can be treated effectively with surgical resection of the affected area, resulting in a total cure or rendering the patient amenable to medical management. Most children with diffuse disease are unresponsive to medical therapy, and require near-total pancreatectomy. At The Children's Hospital of Philadelphia, we have developed a multidisciplinary program for diagnosis and treatment of CHI. Anesthesiologists have played an integral role in the perioperative care of these infants, which includes diagnostic procedures, partial or near-total pancreatectomy, and postoperative pain management. In this review, we describe the clinical features, diagnostic methods and anesthetic concerns in children with CHI.

Expansion of adult beta-cell mass in response to increased metabolic demand is dependent on HNF-4alpha.

The failure to expand functional pancreatic beta-cell mass in response to increased metabolic demand is a hallmark of type 2 diabetes. Lineage tracing studies indicate that replication of existing beta-cells is the principle mechanism for beta-cell expansion in adult mice. Here we demonstrate that the proliferative response of beta-cells is dependent on the orphan nuclear receptor hepatocyte nuclear factor-4alpha (HNF-4alpha), the gene that is mutated in Maturity-Onset Diabetes of the Young 1 (MODY1). Computational analysis of microarray expression profiles from isolated islets of mice lacking HNF-4alpha in pancreatic beta-cells reveals that HNF-4alpha regulates selected genes in the beta-cell, many of which are involved in proliferation. Using a physiological model of beta-cell expansion, we show that HNF-4alpha is required for beta-cell replication and the activation of the Ras/ERK signaling cascade in islets. This phenotype correlates with the down-regulation of suppression of tumorigenicity 5 (ST5) in HNF-4alpha mutants, which we identify as a novel regulator of ERK phosphorylation in beta-cells and a direct transcriptional target of HNF-4alpha in vivo. Together, these results indicate that HNF-4alpha is essential for the physiological expansion of adult beta-cell mass in response to increased metabolic demand.

Diagnosis and localization of focal congenital hyperinsulinism by 18F-fluorodopa PET scan.

OBJECTIVES: To assess the accuracy of 18F-fluoro-L-dihydroxyphenylalanine ([18F]-DOPA) PET scans to diagnose focal versus diffuse disease and to localize focal lesions in infants with congenital hyperinsulinism. STUDY DESIGN: Twenty-four infants with hyperinsulinism unresponsive to medical therapy were studied. Patients were injected intravenously with [18F]-DOPA, and PET scans were obtained for 1 hour. Images were coregistered with abdominal CT scans. RESULTS: The diagnosis of focal or diffuse hyperinsulinism was correct in 23 of the 24 cases (96%) and equivocal in 1 case. [18F]-DOPA PET identified focal areas of high uptake of radiopharmaceutical in 11 patients. Pathology results confirmed that all 11 had focal adenomatosis, and the locations of these lesions matched the areas of increased [18F]-DOPA uptake on the PET scans in all of the cases. CONCLUSIONS: [18F]-DOPA PET scans were 96% accurate in diagnosing focal or diffuse disease and 100% accurate in localizing the focal lesion. These results suggest that [18F]-DOPA PET imaging should be considered in all infants with congenital hyperinsulinism who need to have pancreatectomy.

Functional genomics of the beta-cell: short-chain 3-hydroxyacyl-coenzyme A dehydrogenase regulates insulin secretion independent of K+ currents.

Recent advances in functional genomics afford the opportunity to interrogate the expression profiles of thousands of genes simultaneously and examine the function of these genes in a high-throughput manner. In this study, we describe a rational and efficient approach to identifying novel regulators of insulin secretion by the pancreatic beta-cell. Computational analysis of expression profiles of several mouse and cellular models of impaired insulin secretion identified 373 candidate genes involved in regulation of insulin secretion. Using RNA interference, we assessed the requirements of 10 of these candidates and identified four genes (40%) as being essential for normal insulin secretion. Among the genes identified was Hadhsc, which encodes short-chain 3-hydroxyacyl-coenzyme A dehydrogenase (SCHAD), an enzyme of mitochondrial beta-oxidation of fatty acids whose mutation results in congenital hyperinsulinism. RNA interference-mediated gene suppression of Hadhsc in insulinoma cells and primary rodent islets revealed enhanced basal but normal glucose-stimulated insulin secretion. This increase in basal insulin secretion was not attenuated by the opening of the KATP channel with diazoxide, suggesting that SCHAD regulates insulin secretion through a KATP channel-independent mechanism. Our results suggest a molecular explanation for the hyperinsulinemia hypoglycemic seen in patients with SCHAD deficiency.

PTU-associated vasculitis in a girl with Turner Syndrome and Graves' disease.

Palpable purpura is a concerning clinical finding in pediatric patients and can have many causes, including infectious and autoimmune processes. A rare cause, drug-induced vasculitis, may result from the production of antineutrophil cytoplasmic antibodies (ANCAs) in response to a medication. We report a girl with Turner syndrome and Graves' disease who presented with palpable purpuric lesions. The diagnosis of propylthiouracil (PTU)-associated vasculitis was made by observation of consistent clinical features, the detection of elevated ANA and ANCA in the blood, and the observed clinical resolution of symptoms following withdrawal of PTU. Subsequent treatment of persistent hyperthyroidism with radioablation did not result in an exacerbation of the vasculitis, a complication described in prior case reports.