Faculty Bibliography

BACKGROUND:Heterogeneity in response to treatment of pulmonary arterial hypertension (PAH) is a major challenge to improving outcome in this disease. Although vasodilator-responsive PAH (VR-PAH) accounts for a minority of cases, VR-PAH has a pronounced response to calcium channel blockers and better survival than vasodilator-nonresponsive PAH (VN-PAH). We hypothesized that VR-PAH has a different molecular cause from VN-PAH that can be detected in the peripheral blood. METHODS AND RESULTS/RESULTS:Microarrays of cultured lymphocytes from VR-PAH and VN-PAH patients followed at Vanderbilt University were performed with quantitative polymerase chain reaction performed on peripheral blood for the 25 most different genes. We developed a decision tree to identify VR-PAH patients on the basis of the results with validation in a second VR-PAH cohort from the University of Chicago. We found broad differences in gene expression patterns on microarray analysis including cell-cell adhesion factors and cytoskeletal and rho-GTPase genes. Thirteen of 25 genes tested in whole blood were significantly different: EPDR1, DSG2, SCD5, P2RY5, MGAT5, RHOQ, UCHL1, ZNF652, RALGPS2, TPD52, MKNL1, RAPGEF2, and PIAS1. Seven decision trees were built with the use of expression levels of 2 genes as the primary genes: DSG2, a desmosomal cadherin involved in Wnt/β-catenin signaling, and RHOQ, which encodes a cytoskeletal protein involved in insulin-mediated signaling. These trees correctly identified 5 of 5 VR-PAH patients in the validation cohort. CONCLUSIONS:VR-PAH and VN-PAH can be differentiated with the use of RNA expression patterns in peripheral blood. These differences may reflect different molecular causes of the 2 PAH phenotypes. This biomarker methodology may identify PAH patients who have a favorable treatment response.

CONTEXT/BACKGROUND:Interruption of the renin-angiotensin-aldosterone system prevents incident diabetes in high-risk individuals, although the mechanism remains unclear. OBJECTIVE:To test the hypothesis that activation of the endogenous renin-angiotensin-aldosterone system or exogenous aldosterone impairs insulin secretion in humans. DESIGN/METHODS:We conducted a randomized, blinded crossover study of aldosterone vs vehicle and compared the effects of a low-sodium versus a high-sodium diet. SETTING/METHODS:Academic clinical research center. PARTICIPANTS/METHODS:Healthy, nondiabetic, normotensive volunteers. INTERVENTIONS/METHODS:Infusion of exogenous aldosterone (0.7 μg/kg/h for 12.5 h) or vehicle during low or high sodium intake. Low sodium (20 mmol/d; n = 12) vs high sodium (160 mmol/d; n = 17) intake for 5-7 days. MAIN OUTCOME MEASURES/METHODS:Change in acute insulin secretory response assessed during hyperglycemic clamps while in sodium balance during a low-sodium vs high-sodium diet during aldosterone vs vehicle. RESULTS:A low-sodium diet increased endogenous aldosterone and plasma renin activity, and acute glucose-stimulated insulin (-16.0 ± 5.6%; P = .007) and C-peptide responses (-21.8 ± 8.4%; P = .014) were decreased, whereas the insulin sensitivity index was unchanged (-1.0 ± 10.7%; P = .98). Aldosterone infusion did not affect the acute insulin response (+1.8 ± 4.8%; P = .72) or insulin sensitivity index (+2.0 ± 8.8%; P = .78). Systolic blood pressure and serum potassium were similar during low and high sodium intake and during aldosterone infusion. CONCLUSIONS:Low dietary sodium intake reduces insulin secretion in humans, independent of insulin sensitivity.

Epoxyeicosatrienoic acids (EETs) protect against the development of insulin resistance in rodents. EETs are hydrolyzed to less biologically active diols by soluble epoxide hydrolase (encoded for by EPHX2). Functional variants of EPHX2 encode for enzymes with increased (Lys55Arg) or decreased (Arg287Gln) hydrolase activity. This study tested the hypothesis that variants of EPHX2 are associated with insulin sensitivity or secretion in humans. Subjects participating in metabolic phenotyping studies were genotyped. Eighty-five subjects underwent hyperglycemic clamps. There was no relationship between the Lys55Arg genotype and insulin sensitivity or secretion. In contrast, the EPHX2 287Gln variant was associated with higher insulin sensitivity index (p=0.019 controlling for body mass index and metabolic syndrome). Also, there was an interactive effect of EPHX2 Arg287Gln genotype and body mass index on insulin sensitivity index (p=0.029). There was no relationship between EPHX2 Arg287Gln genotype and acute or late-phase glucose-stimulated insulin secretion, but disposition index was higher in 287Gln carriers compared with Arg/Arg (p=0.022). Plasma EETs correlated with insulin sensitivity index (r=0.64, p=0.015 for total EETs) and were decreased in the metabolic syndrome. A genetic variant that results in decreased soluble epoxide hydrolase activity is associated with increased insulin sensitivity, as are higher EETs.

BACKGROUND:Dipeptidyl-peptidase 4 (DPP4) inhibitors improve glycemic control in patients with diabetes mellitus by preventing the degradation of glucagon-like peptide-1 (GLP-1). GLP-1 causes vasodilation in animal models but also increases sympathetic activity; the effect of GLP-1 in the human vasculature and how it is altered by DPP4 inhibition is not known. DPP4 also degrades the vasodilator brain natriuretic peptide (BNP) to a less potent metabolite. This study tested the hypothesis that DPP4 inhibition potentiates the vasodilator responses to GLP-1 and BNP in the human forearm. METHOD AND RESULTS/RESULTS:Seventeen healthy subjects participated in this randomized, double-blinded, placebo-controlled crossover study. On each study day, subjects received DPP4 inhibitor (sitagliptin 200 mg by mouth) or placebo. Sitagliptin increased forearm blood flow and decreased forearm vascular resistance without affecting mean arterial pressure and pulse. GLP-1 and BNP were infused in incremental doses via brachial artery. Venous GLP-1 concentrations were significantly higher during sitagliptin use, yet there was no effect of GLP-1 on forearm blood flow in the presence or absence of sitagliptin. BNP caused dose-dependent vasodilation; however, sitagliptin did not affect this response. GLP-1 and BNP had no effect on net norepinephrine release. CONCLUSIONS:These data suggest that GLP-1 does not act as a direct vasodilator in humans and does not contribute to sympathetic activation. Sitagliptin does not regulate vascular function in healthy humans by affecting the degradation of GLP-1 and BNP. CLINICAL TRIAL REGISTRATION URL/BACKGROUND:www.clinicaltrials.gov/ Unique identifier: NCT01413542.

BACKGROUND:Cholelithiasis and cholecystectomy have been proposed as risk factors for liver cancer, but findings have been inconsistent. We assessed this association using data from the Shanghai Women's and Men's Health Studies. METHODS:History of cholelithiasis and cholecystectomy were reported at baseline and follow-up interviews, and liver cancer diagnoses were ascertained from the Shanghai Cancer Registry and Vital Statistics Unit. Adjusted hazard ratios (aHRs) and 95% CIs were calculated after adjustment for potential confounders. RESULTS:A history of cholelithiasis and cholecystectomy was reported by 9.5% and 3.6% of participants at baseline, respectively. After a total of 859,882 person-years of follow-up for women and 391,093 for men, incident liver cancer was detected in 160 women and 252 men. A positive association was observed between a history of cholelithiasis or cholecystectomy and liver cancer in men (aHR 1.46; 95% CI 1.02 to 2.07) and women (aHR 1.55; 95% CI 1.06 to 2.26). Similar results were observed for cholelithiasis only, but cholecystectomy did not reach statistical significance. There was no strong evidence for detection bias of liver cancer due to cholelithiasis or cholecystectomy. CONCLUSIONS:Our study suggests that cholelithiasis and possibly cholecystectomy may increase the risk of liver cancer.

UNLABELLED:Dipeptidyl peptidase-4 inhibitors prevent the degradation of incretin hormones and reduce postprandial hyperglycemia in patients with type 2 diabetes mellitus. Dipeptidyl peptidase-4 degrades other peptides with a penultimate proline or alanine, including bradykinin and substance P, which are also substrates of angiotensin-converting enzyme (ACE). During ACE inhibition, substance P is inactivated primarily by dipeptidyl peptidase-4, whereas bradykinin is first inactivated by aminopeptidase P. This study tested the hypothesis that dipeptidyl peptidase-4 inhibition potentiates vasodilator and fibrinolytic responses to substance P when ACE is inhibited. Twelve healthy subjects participated in this randomized, double-blinded, placebo-controlled crossover study. On each study day, subjects received sitagliptin 200 mg by mouth or placebo. Substance P and bradykinin were infused via brachial artery before and during intra-arterial enalaprilat. Sitagliptin and enalaprilat each reduced forearm vascular resistance and increased forearm blood flow without affecting mean arterial pressure, but there was no interactive effect of the inhibitors. Enalaprilat increased bradykinin-stimulated vasodilation and tissue plasminogen activator release; sitagliptin did not affect these responses to bradykinin. The vasodilator response to substance P was unaffected by sitagliptin and enalaprilat; however, substance P increased heart rate and vascular release of norepinephrine during combined ACE and dipeptidyl peptidase-4 inhibition. In women, sitagliptin diminished tissue plasminogen activator release in response to substance P both alone and during enalaprilat. Substance P increases sympathetic activity during combined ACE and dipeptidyl peptidase-4 inhibition. CLINICAL TRIAL REGISTRATION/BACKGROUND:- URL: http://www.clinicaltrials.gov. Unique identifier: NCT01413542.

OBJECTIVES/OBJECTIVE:To test the hypothesis that low bispectral index scores and low sedative requirements during therapeutic hypothermia predict poor neurologic outcome. DESIGN/METHODS:Observational study of a prospectively collected cohort. SETTING/METHODS:Cardiovascular ICU. PATIENTS/METHODS:One hundred sixty consecutive cardiac arrest patients treated with therapeutic hypothermia. INTERVENTIONS/METHODS:None. MEASUREMENTS AND RESULTS/RESULTS:Eighty-four of the 141 subjects (60%) who survived hypothermia induction were discharged from the ICU with poor neurologic outcome, defined as a cerebral performance category score of 3, 4, or 5. These subjects had lower bispectral index (p < 0.001) and sedative requirements (p < 0.001) during hypothermia compared with the 57 subjects discharged with good outcome. Early prediction of neurologic recovery was best 7 hours after ICU admission, and median bispectral index scores at that time were 31 points lower in subjects discharged with poor outcome (11 [interquartile range, 4-29] vs 42 [37-49], p < 0.001). Median sedation requirements decreased by 17% (interquartile range, -50 to 0%) 7 hours after ICU admission in subjects with poor outcome but increased by 50% (interquartile range, 0-142%) in subjects with good outcome (p < 0.001). Each 10-point decrease in bispectral index was independently associated with a 59% increase in the odds of poor outcome (95% CI, 32-76%; p < 0.001). The model including bispectral index and sedative requirement correctly reclassified 15% of subjects from good to poor outcome and 1% of subjects from poor to good outcome. The model incorrectly reclassified 1% of subjects from poor to good outcome but did not incorrectly reclassify any from good to poor outcome. CONCLUSIONS:Bispectral index scores and sedative requirements early in the course of therapeutic hypothermia improve the identification of patients who will not recover from brain anoxia. The ability to accurately predict nonrecovery after cardiac arrest could facilitate discussions with families, reduce patient suffering, and limit use of ICU resources in futile cases.

BACKGROUND:Intraoperative hemolysis and inflammation are associated with acute kidney injury (AKI) following cardiac surgery. Plasma-free hemoglobin induces heme oxygenase-1 (HO-1) expression. HO-1 degrades heme but increases in experimental models of AKI. This study tested the hypothesis that plasma HO-1 concentrations are associated with intraoperative hemolysis and are increased in patients that develop AKI following cardiac surgery. METHODS:We measured plasma HO-1, free hemoglobin, and inflammatory markers in 74 patients undergoing cardiopulmonary bypass (CPB). AKI was defined as an increase in serum creatinine concentration of 50% or 0.3 mg/dl within 72 h of surgery. RESULTS:Twenty-eight percent of patients developed AKI. HO-1 concentrations increased from 4.2 ± 0.2 ng/ml at baseline to 6.6 ± 0.5 ng/ml on postoperative day (POD) 1 (p < 0.001). POD1 HO-1 concentrations were 3.1 ng/ml higher (95% CI 1.1-5.1) in AKI patients, as was the change in HO-1 from baseline to POD1 (4.4 ± 1.3 ng/ml in AKI patients vs. 1.5 ± 0.3 ng/ml in no-AKI patients, p = 0.006). HO-1 concentrations remained elevated in AKI patients even after controlling for AKI risk factors and preoperative drug therapy. Peak-free hemoglobin concentrations correlated with peak HO-1 concentrations on POD1 in patients that developed AKI (p = 0.02). Duration of CPB and post-CPB IL-6 and IL-10 concentrations were also associated with increased HO-1 on POD1. CONCLUSION/CONCLUSIONS:Plasma HO-1 is increased in patients that develop AKI, and CPB duration, hemolysis, and inflammation are associated with increased HO-1 concentrations following cardiac surgery. Strategies that alter hemolysis and HO-1 expression during cardiac surgery may affect risk for AKI.

BACKGROUND:Sarcoidosis is an idiopathic, granulomatous disease for which molecular and immunologic studies have shown an association between it and mycobacterial antigens. Microbial antigens can reduce expression of the tyrosine kinase Lck, which has been associated with sarcoidosis severity. Here we investigate the efficacy of Concomitant Levofloxacin, Ethambutol, Azithromycin, and Rifampin (the CLEAR regimen) for treatment of chronic, pulmonary sarcoidosis. METHODS:Fifteen chronic, pulmonary sarcoidosis patients with forced vital capacities (FVC) between 45-80% of predicted were enrolled in this open-label trial. The primary efficacy endpoint was change in absolute FVC from baseline to completion of therapy. Secondary endpoints were change in functional capacity measured by Six Minute Walk Distance (6MWD) and quality of life assessment measured by St. George's Respiratory Questionnaire (SGRQ). RESULTS:Of 15 patients enrolled, 11 completed 4 weeks of therapy, and 8 completed 8 weeks of therapy. The CLEAR regimen was associated with an increase in FVC of 0.23 liters at 4 weeks and 0.42 liters at 8 weeks (P=0.0098 and 0.016, respectively). The 6MWD increased by 87 meters from baseline to 8 weeks (p=0.0078). The mean score of the validated SGRQ was improved at 8 weeks over baseline (p=0.023). Normalized expression of Lck and NF-κB was observed in those with clinical improvement. CONCLUSIONS:The CLEAR regimen is associated with improved absolute FVC, as well as increased functional capacity and quality-of-life in selected chronic pulmonary sarcoidosis patients. Larger, randomized, controlled trials are needed to confirm these findings and to identify patients most likely to benefit from therapy. ClinicalTrials.gov number NCT01169038.

Cardiovascular drugs are the most commonly prescribed medications. Some prior assays successfully detect cardiovascular drugs among multiple classes using a single sample. Here, we develop an assay to detect a broad range of cardiovascular drug classes to include commonly used cardiovascular drugs and evaluate the assay's analytical and statistical properties in a clinical setting. We describe a protocol for drug detection that encompasses 34 commonly prescribed cardiovascular drugs or drug metabolites with a single LC-MS/MS method using 100μL of serum or plasma. Drug classes monitored by this assay include: anticoagulants, angiotensin converting enzyme inhibitors (ACEI), angiotensin II receptor blockers (ARB), beta blockers, calcium channel blockers, diuretics, statins, and vasodilators, as well as digoxin, fenofibrate, and niacin. Analytical accuracy and precision for each drug were evaluated by repeating the assay on spiked samples at low, medium, and high concentrations. In 294 clinical samples obtained from hospitalized patients for whom medication administration was recorded, we evaluated the assay's statistical sensitivity, specificity, and accuracy. For the 34 drugs or drug metabolites, the assay was statistically sensitive (>0.90) for all drugs except captopril (0.25), isosorbide (0.81), and niacin (0.89). The assay was statistically specific for all drugs, with a minimum specificity of 0.94 (aspirin). To our knowledge, this method is the first method of simultaneous analysis of 34 cardiovascular drugs or drug metabolites from nine drug classes evaluated using clinical samples from hospitalized patients.