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Context: Severe insulin resistance (IR) in the presence of insulin receptor autoantibodies (InsR-aAb) is known as type B insulin resistance (TBIR). Considerable progress in therapy has been achieved, but diagnosis and monitoring of InsR-aAb remains a challenge., Objective: This work aimed to establish a robust in vitro method for InsR-Ab quantification., Methods: Longitudinal serum samples from patients with TBIR at the National Institutes of Health were collected. A bridge-assay for InsR-aAb detection was established using recombinant human insulin receptor as bait and detector. Monoclonal antibodies served as positive controls for validation., Results: The novel assay proved sensitive, robust, and passed quality control. The measured InsR-aAb from TBIR patients was associated with disease severity, decreased on treatment, and inhibited insulin signaling in vitro. Titers of InsR-aAb correlated positively to fasting insulin in patients., Conclusion: Quantification of InsR-aAb from serum samples via the novel in vitro assay enables identification of TBIR and monitoring of successful therapy., (Published by Oxford University Press on behalf of the Endocrine Society 2023.)

Understanding how skeletal muscle fiber proportions are regulated is vital to understanding muscle function. Oxidative and glycolytic skeletal muscle fibers differ in their contractile ability, mitochondrial activity, and metabolic properties. Fiber-type proportions vary in normal physiology and disease states, although the underlying mechanisms are unclear. In human skeletal muscle, we observed that markers of oxidative fibers and mitochondria correlated positively with expression levels of PPARGC1A and CDK4 and negatively with expression levels of CDKN2A, a locus significantly associated with type 2 diabetes. Mice expressing a constitutively active Cdk4 that cannot bind its inhibitor p16INK4a, a product of the CDKN2A locus, were protected from obesity and diabetes. Their muscles exhibited increased oxidative fibers, improved mitochondrial properties, and enhanced glucose uptake. In contrast, loss of Cdk4 or skeletal muscle-specific deletion of Cdk4's target, E2F3, depleted oxidative myofibers, deteriorated mitochondrial function, and reduced exercise capacity, while increasing diabetes susceptibility. E2F3 activated the mitochondrial sensor PPARGC1A in a Cdk4-dependent manner. CDK4, E2F3, and PPARGC1A levels correlated positively with exercise and fitness and negatively with adiposity, insulin resistance, and lipid accumulation in human and rodent muscle. All together, these findings provide mechanistic insight into regulation of skeletal muscle fiber-specification that is of relevance to metabolic and muscular diseases.

Acquired generalized lipodystrophy (AGL) is a rare condition characterized by massive loss of adipose tissue through the body, causing severe metabolic complications. Autoimmune destruction of adipocytes is strongly suspected based on the frequent association of AGL with autoimmune disorders. In 2018, autoantibodies against perilipin 1 (PLIN1) were identified in three patients with autoimmune-associated AGL. However, the pathogenic mechanism and clinical impact of anti-PLIN1 remain unsolved. The prevalence of anti-PLIN1 autoantibodies in an AGL cohort of 40 patients was 50% (20 of 40). Among positive patients, 10 had the autoimmune variety and 10 had panniculitis-associated AGL. The IgG isotype was predominant, although some IgM antibodies were detected. Epitope-mapping studies did not identify a single, major epitope. Instead, autoantibodies typically bound to several different peptides, among which the central (233-405) domain was detected in all antibody-positive patients, for both IgG and IgM autoantibodies. In-depth epitope mapping indicated that anti-PLIN1 autoantibodies predominantly recognize the αβ-hydrolase domain containing 5 (ABHD5) binding site (383-405). Autoantibodies dose-dependently blocked the binding of PLIN1 to ABHD5 and caused a dislocation of ABHD5 toward the cytosol, leading to an increase in lipolysis and lipase activities. Finally, anti-PLIN1 titers significantly correlated with the amount of fat loss, metabolic control impairment, and severity of liver injury. Our data strongly support that anti-PLIN1 autoantibodies are a diagnostic biomarker and a cause of lipodystrophy in patients with AGL., (© 2022 by the American Diabetes Association.)

Context: Syndromes of severe insulin resistance (SIR) include insulin receptoropathy, in which all signaling downstream of the insulin receptor is lost, and lipodystrophy, in which some signaling pathways are impaired and others preserved. Women with SIR commonly have ovarian hyperandrogenemia; adrenal-derived 11-oxygenated androgens, produced by CYP11B1, have not been studied., Objective: We aimed to evaluate classic pathway androgens (androstenedione, testosterone) and 11-oxygenated androgens in women with SIR and hyperandrogenemia, and to elucidate the role of insulin receptor signaling for 11-oxygenated androgen production by comparing lipodystrophy and receptoropathy., Methods: Steroid hormones were quantified using LC-MS/MS in a cross-sectional study of 18 women with hyperandrogenemia and SIR (11 lipodystrophy, 7 receptoropathy) and 23 controls. To assess ovarian vs adrenal origin, steroids were compared in receptoropathy patients with (Ovary+) vs without (Ovary-) ovarian function., Results: Compared with controls, classic androgens were elevated in both lipodystrophy and receptoropathy, and 11-oxygenated androgens were increased in lipodystrophy (2.9-fold higher 11β-hydroxyandrostenedione (11OHA4), 2.4-fold higher 11-ketoandrostenedione (11KA4), 3.6-fold higher 11-ketotestosterone (11KT); P < 0.01), but not receptoropathy. Product-to-precursor ratios for CYP11B1 conversion of androstenedione to 11OHA4 were similar in lipodystrophy and controls but decreased in receptoropathy (6.5-fold lower than control; P = 0.001). Classic androgens were elevated in Ovary + but not Ovary- patients., Conclusions: 11-Oxygenated androgens are elevated in lipodystrophy but not receptoropathy. In SIR, insulin receptor signaling is necessary for adrenal hyperandrogenemia but not ovarian hyperandrogenemia; excess classic androgens are derived from the ovaries. Insulin receptor signaling increases adrenal 19-carbon steroid production, which may have implications for more common disorders of mild IR., (Published by Oxford University Press on behalf of the Endocrine Society 2022.)

Context: Cushing syndrome (CS) is associated with impaired health-related quality of life (HRQOL) even after surgical cure., Objective: To characterize patient and provider perspectives on recovery from CS, drivers of decreased HRQOL during recovery, and ways to improve HRQOL., Design: Cross-sectional observational survey., Participants: Patients (n = 341) had undergone surgery for CS and were members of the Cushing's Support and Research Foundation. Physicians (n = 54) were Pituitary Society physician members and academicians who treated patients with CS., Results: Compared with patients, physicians underestimated the time to complete recovery after surgery (12 months vs 18 months, P  = 0.0104). Time to recovery did not differ by CS etiology, but patients with adrenal etiologies of CS reported a longer duration of cortisol replacement medication compared with patients with Cushing disease (12 months vs 6 months, P  = 0.0025). Physicians overestimated the benefits of work (26.9% vs 65.3%, P  < 0.0001), exercise (40.9% vs 77.6%, P  = 0.0001), and activities (44.8% vs 75.5%, P  = 0.0016) as useful coping mechanisms in the postsurgical period. Most patients considered family/friends (83.4%) and rest (74.7%) to be helpful. All physicians endorsed educating patients on recovery, but 32.4% (95% CI, 27.3-38.0) of patients denied receiving sufficient information. Some patients did not feel prepared for the postsurgical experience (32.9%; 95% CI, 27.6-38.6) and considered physicians not familiar enough with CS (16.1%; 95% CI, 12.2-20.8)., Conclusion: Poor communication between physicians and CS patients may contribute to dissatisfaction with the postsurgical experience. Increased information on recovery, including helpful coping mechanisms, and improved provider-physician communication may improve HRQOL during recovery., (Published by Oxford University Press on behalf of the Endocrine Society 2021.)

Context: Lipodystrophy syndromes cause hypertriglyceridemia that improves with leptin treatment using metreleptin. Mechanisms causing hypertriglyceridemia and improvements after metreleptin are incompletely understood., Objective: Determine relationship of circulating lipoprotein lipase (LPL) modulators with hypertriglyceridemia in healthy controls and in patients with lipodystrophy before and after metreleptin., Methods: Cross-sectional comparison of patients with lipodystrophy (generalized lipodystrophy n = 3; partial lipodystrophy n = 11) vs age/sex-matched healthy controls (n = 28), and longitudinal analyses in patients before and after 2 weeks and 6 months of metreleptin. The study was carried out at the National Institutes of Health, Bethesda, Maryland. Outcomes were LPL stimulators apolipoprotein (apo) C-II and apoA-V and inhibitors apoC-III and angiopoietin-like proteins (ANGPTLs) 3, 4, and 8; ex vivo activation of LPL by plasma., Results: Patients with lipodystrophy were hypertriglyceridemic and had higher levels of all LPL stimulators and inhibitors vs controls except for ANGPTL4, with >300-fold higher ANGPTL8, 4-fold higher apoC-III, 3.5-fold higher apoC-II, 1.9-fold higher apoA-V, 1.6-fold higher ANGPTL3 ( P < .05 for all). At baseline, all LPL modulators except ANGPLT4 positively correlated with triglycerides. Metreleptin decreased apoC-II and apoC-III after 2 weeks and 6 months, and decreased ANGPTL8 after 6 months (P < 0.05 for all). Plasma from patients with lipodystrophy caused higher ex vivo LPL activation vs hypertriglyceridemic control plasma ( P < .0001), which did not change after metreleptin., Conclusion: Elevations in LPL inhibitors apoC-III and ANGPTL8 may contribute to hypertriglyceridemia in lipodystrophy, and may mediate reductions in circulating and hepatic triglycerides after metreleptin. These therefore are strong candidates for therapies to lower triglycerides in these patients., (Published by Oxford University Press on behalf of the Endocrine Society 2020.)

Importance: Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis affecting multiple organs and commonly caused by somatic pathogenic variants in BRAF V600E and mitogen-activated protein kinase genes. Clinical features of ECD result from histiocytic involvement of various tissues; while endocrine involvement in ECD occurs frequently, the prevalence of central or primary hypothyroidism has not been thoroughly investigated., Objective: To assess hypothalamus-pituitary-thyroid (HPT) dysfunction in patients with ECD., Design, Setting, and Participants: This cross-sectional study included 61 patients with ECD who were enrolled in a natural history study at a tertiary care center between January 2011 and December 2018. ECD was diagnosed on the basis of clinical, genetic, and histopathological features. Data were analyzed in March 2020., Exposure: Diagnosis of ECD., Main Outcomes and Measures: Main outcome was the prevalence of thyroid dysfunction in adults with ECD compared with community estimates. Patients underwent baseline evaluation with a thyroid function test, including thyrotropin, free thyroxine (fT4), and total thyroxine (T4), and sellar imaging with magnetic resonance imaging or computed tomography scan. The association of HPT dysfunction was assessed for differences in age, sex, body mass index, BRAF V600E status, high sensitivity C-reactive protein level, sellar imaging, and pituitary hormonal dysfunction., Results: A total of 61 patients with ECD (46 [75%] men; mean [SD] age, 54.3 [10.9] years) were evaluated. Seventeen patients (28%) had hypothyroidism requiring levothyroxine therapy. The prevalence of both central and primary hypothyroidism were higher than community estimates (central hypothyroidism: 9.8% vs 0.1%; odds ratio, 109.0; 95% CI, 37.4-260.6; P < .001; primary hypothyroidism: 18.0% vs 4.7%; OR, 4.4; 95% CI, 2.1-8.7; P < .001). Patients with hypothyroidism (both primary and central), compared with patients with euthyroidism, had higher body mass index (median [interquartile range] 31.4 [28.3-38.3] vs 26.7 [24.4-31.9]; P = .004) and a higher prevalence of panhypopituitarism (7 [47%] vs 3 [7%]; P < .001). Among patients with hypothyroidism, those with central hypothyroidism, compared with patients with primary hypothyroidism, had a lower mean (SD) body mass index (28.3 [2.6] vs 36.3 [5.9]; P = .007) and higher frequencies of abnormal sellar imaging (5 [83%] vs 3 [27%]; P = .050) and panhypopituitarism (5 [83%] vs 3 [27%]; P = .050)., Conclusions and Relevance: In this cohort study, a higher prevalence of central and primary hypothyroidism was identified in patients with ECD compared with the community. There should be a low threshold for testing for hypothyroidism in patients with ECD, and treatment should follow standard guidelines.

Background: African Americans (AAs) are at a higher risk for developing type 2 diabetes compared with non-Hispanic whites (NHWs). The causal role of β-cell glucose sensitivity (β-GS) and insulin clearance in hyperinsulinemia in AA adults is unclear., Objective: Using a cross-sectional study design, we compared β-cell function and insulin clearance in nondiabetic AAs (n = 36) and NHWs (n = 47) after a mixed meal test (MMT)., Methods: Insulin secretion rate, glucose sensitivity, rate sensitivity, and insulin sensitivity during MMT were derived from a mathematical model. Levels of insulin-degrading enzyme (IDE) and carcinoembryonic antigen-related cell adhesion molecule-1 (CEACAM1), key players in insulin clearance, were measured (by enzyme-linked immunosorbent assay) in hepatic cytosolic fractions from age-, sex-, and body mass index-matched AA and NHW cadaveric donors (n = 10)., Results: Fasting and mean postprandial plasma glucose levels were similar in both ethnic groups. AAs had significantly higher fasting and mean postprandial plasma insulin levels. However, fasting ISR, total insulin output, and insulin sensitivity during MMT were not different between the groups. β-GS and rate sensitivity were higher in AAs. Fasting and meal plasma insulin clearance were lower in AAs. Hepatic levels of IDE and CEACAM-1 were similar in AAs and NHWs. Hepatic IDE activity was significantly lower in AAs., Conclusions: In this study, lower insulin clearance contributes to higher plasma insulin levels in AAs. Reduced insulin clearance may be explained by lower IDE activity levels in AAs. Further confirmatory studies are needed to investigate diminished insulin clearance in AAs as a result of lower IDE activity levels., (Published by Oxford University Press on behalf of the Endocrine Society 2020.)

β-Arrestins are major regulators of G protein-coupled receptor-mediated signaling processes. Their potential roles in regulating adipocyte function in vivo remain unexplored. Here we report the novel finding that mice lacking β-arrestin-2 (barr2) selectively in adipocytes show significantly reduced adiposity and striking metabolic improvements when consuming excess calories. We demonstrate that these beneficial metabolic effects are due to enhanced signaling through adipocyte β3-adrenergic receptors (β3-ARs), indicating that barr2 represents a potent negative regulator of adipocyte β3-AR activity in vivo. Interestingly, essentially all beneficial metabolic effects caused by adipocyte barr2 deficiency are absent in adipocyte barr2-PRDM16 double KO mice, indicating that the metabolic improvements caused by the lack of barr2 in adipocytes are mediated by the browning/beiging of white adipose tissue. Our data support the novel concept that 'G protein-biased' β3-AR agonists that do not promote β3-AR/barr2 interactions may prove useful for the treatment of obesity and related metabolic disorders.

Context: Surrogate indices of muscle and hepatic insulin sensitivity derived from an oral glucose tolerance test (OGTT) are frequently used in clinical studies. However, the predictive accuracy of these indices has not been validated., Design: In this cross-sectional study, hyperinsulinemic-euglycemic glucose clamp with tritiated glucose infusion and a 75-g OGTT were performed in individuals (n = 659, aged 18 to 49 years, body mass index of 16 to 64 kg/m 2 ) with varying degrees of glucose tolerance. A calibration model was used to assess the ability of OGTT-derived, tissue-specific surrogate indices [hepatic insulin resistance index (HIRI) and muscle insulin sensitivity index (MISI)] to predict insulin sensitivity/resistance indices derived from the reference glucose clamp [Hepatic-IR basal , a product of fasting plasma insulin and hepatic glucose production (HGP), Hepatic-IR clamp , reciprocal of the percent suppression of HGP during the insulin clamp corrected for plasma insulin concentration, and Muscle-IS clamp , a measure of peripheral glucose disposal]. Predictive accuracy was assessed by root mean squared error of prediction and leave-one-out, cross-validation-type square root of the mean squared error of prediction., Results: HIRI and MISI were correlated with their respective clamp-derived indices. HIRI was negatively related to Muscle-IS clamp ( r = -0.62, P < 0.0001) and MISI correlated with Hepatic-IR derived from the clamp (Hepatic-IR basal : r = -0.48, P < 0.0001 and Hepatic-IR clamp : r = -0.41, P < 0.0001). However, the accuracy of HIRI and MISI to predict Hepatic-IR (basal or during clamp) was not significantly different. Likewise, the ability of HIRI and MISI to predict Muscle-IS clamp was also similar., Conclusion: Our findings indicate that the surrogate indices derived from an OGTT are accurate in predicting insulin sensitivity but are not tissue specific.

The known interactions between the somatotropic and hypothalamic-pituitary-gonadal (HPG) axes have not been well delineated in older individuals. Aging-associated decline in insulin like growth factor-1 (IGF-1) levels has been proposed to play a role in reproductive senescence in animals. However, the effects of GH on LH secretion are unknown in older individuals. Our objective was to determine whether GH modulates LH secretion or levels of sex steroids (SS) in healthy older (ages 65-88 years) men ( n  = 24) and women ( n  = 24) with low-normal plasma IGF-1 levels. In a double-masked, placebo-controlled ( n  = 24), randomized study, we evaluated the effects of GH ( n  = 24, 20  μ g/kg sc 3×/week) for 26 weeks on nocturnal LH secretory dynamics [(8 pm to 8 am, Q20) min sampling and analyzed by multiparameter deconvolution algorithm]. Indices of LH secretion [frequency, mass per burst, pulsatile production rate, and approximate entropy (ApEn)] and fasting serum IGF-1, SHBG, and SS (TT, fT, or E2) were measured. At baseline, all indices of LH secretion (frequency, mass per burst, pulsatile production rate) were inversely ( P  < 0.05) related to IGF-1, but not to mean nocturnal serum GH concentrations. GH administration for 26 weeks increased serum IGF-1, but exerted no significant effects on LH secretory dynamics, or concentrations of SSs (TT, fT, or E2) or SHBG in older women or men. These data suggest that GH-mediated increases in IGF-1 do not modulate the HPG axis in older individuals., (Published 2017. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)

Pancreatic β -cell dysfunction because of reduced β -cell mass and function is a primary determinant in the progression of diabetes. Increase in β -cell mass and compensatory hyperinsulinaemia is frequently associated with insulin-resistant states. Although the humoral factors mediating this compensatory response are unknown, serpinB1, a protease inhibitor, has recently been proposed to be one such factor. In this study, we examine the relationships between plasma serpinB1, insulin sensitivity, and pancreatic β -cell function in non-diabetic individuals. 117 subjects (women, n  = 50, men, n  = 67; age= 37.6 ± 10.8; BMI=31.1 ± 7.7 kg/m 2 ) underwent an insulin-modified frequently sampled intravenous glucose tolerance test (FSIVGTT) at the NIH Clinical Research Center. Acute insulin response (AIR) and insulin sensitivity index (SI) were obtained from the FSIVGTT with MINMOD analysis. The Quantitative Insulin Sensitivity Check Index (QUICKI) was calculated from fasting insulin and glucose values. Plasma serpinB1 levels were measured using an ELISA assay. Simple linear correlation analyses were performed to evaluate the relationship between serpinB1 and measures of insulin sensitivity and β -cell function. Circulating serpinB1 levels were unrelated to age, sex, race, BMI, or percent body fat. SI but not AIR significantly correlated with circulating serpinB1 levels ( r  = 0.23, P  < 0.05). QUICKI tended to positively correlate with serpinB1 ( r  = 0.16, P  = 0.09). Circulating serpinB1 is directly associated with insulin sensitivity but not β -cell function in non-diabetic adults. Whether this modest association plays a role in insulin sensitivity in humans remains to be clarified., (Published [2017]. This article is a U.S. Government work and is in the public domain in the USA.)

Context: The TSH receptor (TSHR) is considered the main target of stimulatory autoantibodies in the pathogenesis of Graves' ophthalmopathy (GO); however, it has been suggested that stimulatory IGF-1 receptor (IGF-1R) autoantibodies also play a role., Objective: We previously demonstrated that a monoclonal stimulatory TSHR antibody, M22, activates TSHR/IGF-1R cross talk in orbital fibroblasts/preadipocytes obtained from patients with GO (GO fibroblasts [GOFs]). We show that cross talk between TSHR and IGF-1R, not direct IGF-1R activation, is involved in the mediation of GO pathogenesis stimulated by Graves' autoantibodies., Design/setting/participants: Immunoglobulins were purified from the sera of 57 GO patients (GO-Igs) and tested for their ability to activate TSHR and/or IGF-1R directly and TSHR/IGF-1R cross talk in primary cultures of GOFs. Cells were treated with M22 or GO-Igs with or without IGF-1R inhibitory antibodies or linsitinib, an IGF-1R kinase inhibitor., Main Outcome Measures: Hyaluronan (hyaluronic acid [HA]) secretion was measured as a major biological response for GOF stimulation. IGF-1R autophosphorylation was used as a measure of direct IGF-1R activation. TSHR activation was determined through cAMP production., Results: A total of 42 out of 57 GO-Ig samples stimulated HA secretion. None of the GO-Ig samples exhibited evidence for IGF-1R autophosphorylation. Both anti-IGF-1R antibodies completely inhibited IGF-1 stimulation of HA secretion. By contrast, only 1 IGF-1R antibody partially blocked HA secretion stimulated by M22 or GO-Igs in a manner similar to linsitinib, whereas the other IGF-1R antibody had no effect on M22 or GO-Ig stimulation. These findings show that the IGF-1R is involved in GO-Igs stimulation of HA secretion without direct activation of IGF-1R., Conclusions: IGF-1R activation by GO-Igs occurs via TSHR/IGF-1R cross talk rather than direct binding to IGF-1R, and this cross talk is important in the pathogenesis of GO.

Context: Apolipoprotein CIII (apoCIII), an inhibitor of lipoprotein lipase, plays an important role in triglyceride metabolism. However, the role of apoCIII in hypertriglyceridemia in lipodystrophy and the effects of leptin replacement on apoCIII levels are unknown., Objective: The objective of the study was to test the hypotheses that apoCIII is elevated in hypertriglyceridemic patients with lipodystrophy and that leptin replacement in these patients lowers circulating apoCIII., Design, Setting, Study Participants, Intervention, and Outcome Measures: Using a post hoc cross-sectional case-control design, we compared serum apoCIII levels from patients with lipodystrophy not associated with HIV (n = 60) and age-, gender-, race-, and ethnicity-matched controls (n = 54) participating in ongoing studies at the National Institutes of Health. In a prospective, open-label, ongoing study, we studied the effects of 6–12 months of leptin replacement on apoCIII in lipodystrophy patients as an exploratory outcome., Results: ApoCIII was higher in lipodystrophy patients (geometric mean [25th and 75th percentiles]) (23.9 mg/dL [14.6, 40.3]) compared with controls (14.9 mg/dL [12.3, 17.7]) (P < .0001). ApoCIII and triglyceride levels were positively correlated in patients with lipodystrophy (R = 0.72, P < .0001) and healthy controls (R = 0.6, P < .0001). Leptin replacement (6–12 mo) did not significantly alter apoCIII (before leptin: 23.4 mg/dL [14.5, 40.1]; after leptin: 21.4 mg/dL [16.7, 28.3]; P = .34)., Conclusions: Leptin replacement in lipodystrophy did not alter serum apoCIII levels. Elevated apoCIII may play a role in the hypertriglyceridemia of lipodystrophy independent of leptin deficiency and replacement.

Context: Serum free cortisol (SFF) responses to cosyntropin simulation test (CST) may more accurately assess adrenal function than total cortisol (TF)., Objective: The objective of the study was to evaluate the diagnostic utility of SFF responses during a 250-μg CST., Design: We recruited healthy volunteers (HV; n = 27), patients with primary and secondary adrenal insufficiency (n = 19 and n = 24, respectively), and subjects with Child-Pugh class A cirrhosis (CH; n = 15). Each received 250 μg cosyntropin with measurement of ACTH and corticosteroid binding globulin (CBG) at time 0 and TF and SFF at 0, 30, and 60 minutes. Salivary cortisol was measured at all time points in CH subjects., Results: Peak SFF and TF were significantly higher in HVs vs both AI groups (P < .05). Peak SFF and TF (6.8 μg/dL vs 2.2 μg/dL; [188 nmol/L vs 62 nmol/L]; P < .01) were significantly higher in the secondary adrenal insufficiency vs primary adrenal insufficiency patients. The optimal peak SFF criterion to identify adrenal insufficiency patients vs HV was 0.9 μg/dL (25 nmol/L) (sensitivity of 95%, specificity of 100%). Mean CBG and albumin levels were similar among all four groups. CH patients had a higher peak SFF than HV (2.4 vs 2.0 μg/dL; P = .02. In the CH patients, peak salivary cortisol levels correlated well with peak SFF (rs = 0.84, P = .005). CBG levels were similar among the groups., Conclusion: We provide normative data for SFF values in HV and AI during the CST. Normal CBG levels in mild cirrhosis did not affect the interpretation of the CST.

Background: Myocardial steatosis, an independent predictor of diastolic dysfunction, is frequently present in type 2 diabetes mellitus. High free fatty acid flux, hyperglycemia, and hyperinsulinemia may play a role in myocardial steatosis. There are no prior studies examining the relationship between insulin sensitivity (antilipolytic and glucose disposal actions of insulin) and cardiac steatosis., Objective: Using a cross-sectional study design of individuals with and without metabolic syndrome (MetSyn), we examined the relationships between cardiac steatosis and the sensitivity of the antilipolytic and glucose disposal actions of insulin., Methods: Pericardial fat (PF) volume, intramyocardial and hepatic fat (MF and HF) content, visceral fat (VF) and sc fat content were assessed by magnetic resonance imaging in 77 subjects (49 without MetSyn and 28 with MetSyn). In a subset of the larger cohort (n = 52), peripheral insulin sensitivity index (SI) and adipocyte insulin sensitivity (Adipo-SI) were determined from an insulin-modified frequently sampled iv glucose tolerance test. The Quantitative Insulin Sensitivity Check Index was used as a surrogate for hepatic insulin sensitivity., Results: Individuals with the MetSyn had significantly higher body mass index, total body fat, and MF, PF, HF, and VF content. HF and VF, but not MF, were negatively correlated with the Quantitative Insulin Sensitivity Check Index, Adipo-SI, and SI. Stepwise regression revealed that waist circumference and serum triglyceride levels independently predicted MF and PF, respectively. Adipo-SI and serum triglyceride levels independently predict HF., Conclusion: Myocardial steatosis is unrelated to hepatic, adipocyte, or peripheral insulin sensitivity. Although it is frequently observed in insulin-resistant subjects, further studies are necessary to identify and delineate pathogenic mechanisms that differentially affect cardiac and hepatic steatosis.

Context: Activation of the melanocortin-4 receptor (MC4R) with the synthetic agonist RM-493 decreases body weight and increases energy expenditure (EE) in nonhuman primates. The effects of MC4R agonists on EE in humans have not been examined to date., Objective, Design, and Setting: In a randomized, double-blind, placebo-controlled, crossover study, we examined the effects of the MC4R agonist RM-493 on resting energy expenditure (REE) in obese subjects in an inpatient setting., Study Participants and Methods: Twelve healthy adults (6 men and 6 women) with body mass index of 35.7 ± 2.9 kg/m(2) (mean ± SD) received RM-493 (1 mg/24 h) or placebo by continuous subcutaneous infusion over 72 hours, followed immediately by crossover to the alternate treatment. All subjects received a weight-maintenance diet (50% carbohydrate, 30% fat, and 20% protein) and performed 30 minutes of standardized exercise daily. Continuous EE was measured on the third treatment day in a room calorimeter, and REE in the fasting state was defined as the mean of 2 30-minute resting periods., Results: RM-493 increased REE vs placebo by 6.4% (95% confidence interval, 0.68-13.02%), on average by 111 kcal/24 h (95% confidence interval, 15-207 kcal, P = .03). Total daily EE trended higher, whereas the thermic effect of a test meal and exercise EE did not differ significantly. The 23-hour nonexercise respiratory quotient was lower during RM-493 treatment (0.833 ± 0.021 vs 0.848 ± 0.022, P = .02). No adverse effect on heart rate or blood pressure was observed., Conclusions: Short-term administration of the MC4R agonist RM-493 increases REE and shifts substrate oxidation to fat in obese individuals.

Background: Observational studies show that glucocorticoid therapy and the endogenous hypercortisolism of Cushing's syndrome (CS) are associated with increased rates of cardiovascular morbidity and mortality. However, the causes of these findings remain largely unknown., Objective: To determine whether CS patients have increased coronary atherosclerosis., Design: A prospective case-control study was performed., Setting: Subjects were evaulated in a clinical research center., Subjects: Fifteen consecutive patients with ACTH-dependent CS, 14 due to an ectopic source and 1 due to pituitary Cushing's disease were recruited. Eleven patients were studied when hypercortisolemic; 4 patients were eucortisolemic due to medication (3) or cyclic hypercortisolism (1). Fifteen control subjects with at least one risk factor for cardiac disease were matched 1:1 for age, sex, and body mass index., Primary Outcome Variables: Agatston score a measure of calcified plaque and non-calcified coronary plaque volume were quantified using a multidetector CT (MDCT) coronary angiogram scan. Additional variables included fasting lipids, blood pressure, history of hypertension or diabetes, and 24-hour urine free cortisol excretion., Results: CS patients had significantly greater noncalcified plaque volume and Agatston score (noncalcified plaque volume [mm(3)] median [interquartile ranges]: CS 49.5 [31.4, 102.5], controls 17.9 [2.6, 25.3], P < .001; Agatston score: CS 70.6 [0, 253.1], controls 0 [0, 7.6]; P < .05). CS patients had higher systolic and diastolic blood pressures than controls (systolic: CS 143 mm Hg [135, 173]; controls, 134 [123, 136], P < .02; diastolic CS: 86 [80, 99], controls, 76 [72, 84], P < .05)., Conclusions: Increased coronary calcifications and noncalcified coronary plaque volumes are present in patients with active or previous hypercortisolism. Increased atherosclerosis may contribute to the increased rates of cardiovascular morbidity and mortality in patients with glucocorticoid excess.

Context: Isolated hypogonadotropic hypogonadism (IHH) is caused by defective GnRH secretion or action resulting in absent or incomplete pubertal development and infertility. Most women with IHH ovulate with physiological GnRH replacement, implicating GnRH deficiency as the etiology. However, a subset does not respond normally, suggesting the presence of defects at the pituitary or ovary., Objectives: The objective of the study was to unmask pituitary or ovarian defects in IHH women using a physiological regimen of GnRH replacement, relating these responses to genes known to cause IHH., Design, Setting, and Subjects: This study is a retrospective analysis of 37 IHH women treated with iv pulsatile GnRH (75 ng/kg per bolus)., Main Outcome Measures: Serum gonadotropin and sex steroid levels were measured, and 14 genes implicated in IHH were sequenced., Results: During their first cycle of GnRH replacement, normal cycles were recreated in 60% (22 of 37) of IHH women. Thirty percent of women (12 of 37) demonstrated an attenuated gonadotropin response, indicating pituitary resistance, and 10% (3 of 37) exhibited an exaggerated FSH response, consistent with ovarian resistance. Mutations in CHD7, FGFR1, KAL1, TAC3, and TACR3 were documented in IHH women with normal cycles, whereas mutations were identified in GNRHR, PROKR2, and FGFR1 in those with pituitary resistance. Women with ovarian resistance were mutation negative., Conclusions: Although physiological replacement with GnRH recreates normal menstrual cycle dynamics in most IHH women, hypogonadotropic responses in the first week of treatment identify a subset of women with pituitary dysfunction, only some of whom have mutations in GNRHR. IHH women with hypergonadotropic responses to GnRH replacement, consistent with an additional ovarian defect, did not have mutations in genes known to cause IHH, similar to our findings in a subset of IHH men with evidence of an additional testicular defect.

Context: ACTH-producing neuroendocrine tumor (NET) of the thymus is a rare cause of Cushing's syndrome (CS). The literature consists mainly of isolated case reports., Patients: We studied 12 cases (eight males and four females) diagnosed between 1986 and 2010 with CS and thymic NET who underwent surgical resection., Main Outcome Measures: We measured time from onset of CS to diagnosis of thymic NET, tumor size, histological grade, time to recurrence, and survival and performed a meta-analysis of other published cases of CS associated with thymic NET., Results: Eleven of 12 patients presented with classic features of CS at a median age of 21 yr (range, 7-51). Four were children. The 24-h urine free cortisol was greater than 16-fold of normal, and biochemical testing was consistent with ectopic ACTH production in all 11. Another patient presenting with pulmonary embolus had a thymic mass and was later diagnosed with CS. All patients underwent thymectomy, and nine of 10 tumors exhibited positive ACTH immunochemistry. Median tumor diameter was 5 cm (range, 1-11.5). Six patients recurred 20-28 months after surgery with metastases to mediastinal lymph nodes (n = 5), bone (n = 5), liver (n = 1), parotid gland (n = 1), and breast (n = 1). Four of five patients treated with radiation therapy also received chemotherapy. All recurrent patients received ketoconazole; four later underwent bilateral adrenalectomy. Six recurrent patients died 22-90 months (median, 57) after thymectomy. At last review, six patients were alive 14-90 months (median, 49) after thymectomy. These data are similar to those from the meta-analysis., Conclusions: Thymic ACTH-producing NET is an aggressive disease that should be considered in CS with ectopic ACTH secretion, particularly in younger patients.

GLUCOCORTICOIDS are steroid hormones that strongly influence intermediary carbohydrate metabolism by increasing the transcription rate of glucose-6-phosphatase (G6Pase), a key enzyme of gluconeogenesis, and suppress the immune system through the glucocorticoid receptor (GR). The liver X receptors (LXRs), on the other hand, bind to cholesterol metabolites, heterodimerize with the retinoid X receptor (RXR), and regulate the cholesterol turnover, the hepatic glucose metabolism by decreasing the expression of G6Pase, and repress a set of inflammatory genes in immune cells. Since the actions of these receptors overlap with each other, we evaluated the crosstalk between the GR- and LXR-mediated signaling systems. Transient transfection-based reporter assays and gene silencing methods using siRNAs for LXRs showed that overexpression/ligand (GW3965) activation of LXRs/RXRs repressed GR-stimulated transactivation of certain glucocorticoid response element (GRE)-driven promoters in a gene-specific fashion. Activation of LXRs by GW3965 attenuated dexamethasone-stimulated elevation of circulating glucose in rats. It also suppressed dexamethasone-induced mRNA expression of hepatic glucose-6-phosphatase (G6Pase) in rats, mice and human hepatoma HepG2 cells, whereas endogenous, unliganded LXRs were required for dexamethasone-induced mRNA expression of phosphoenolpyruvate carboxylase. In microarray transcriptomic analysis of rat liver, GW3965 differentially regulated glucocorticoid-induced transcriptional activity of about 15% of endogenous glucocorticoid-responsive genes. To examine the mechanism through which activated LXRs attenuated GR transcriptional activity, we examined LXRα/RXRα binding to GREs. Endogenous LXRα/RXRα bound GREs and inhibited GR binding to these DNA sequences both in in vitro and in vivo chromatin immunoprecipitation assays, while their recombinant proteins did so on classic or G6Pase GREs in gel mobility shift assays. We propose that administration of LXR agonists may be beneficial in glucocorticoid treatment- or stress-associated dysmetabolic states by directly and gene-specifically attenuating the transcriptional activity of the GR on glucose and/or lipid metabolism.