Tuberin levels during cellular differentiation in brain development.

Tuberin is a member of a large protein complex, Tuberous Sclerosis Complex (TSC), and acts as a sensor for nutrient status regulating protein synthesis and cell cycle progression. Mutations in the Tuberin gene, TSC2, permits the formation of tumors that can lead to developmental defects in many organ systems, including the central nervous system. Tuberin is expressed in the brain throughout development and levels of Tuberin have been found to decrease during neuronal differentiation in cell lines in vitro. Our current work investigates the levels of Tuberin at two stages of embryonic development in vivo, and we study the mRNA and protein levels during a time course using immortalized cell lines in vitro. Our results show that total Tuberin levels are tightly regulated through developmental stages in the embryonic brain. At a cell biology level, we show that Tuberin levels are higher when cells are cultured as neurospheres, and knockdown of Tuberin results in a reduction in the number of neurospheres. This functional data supports the hypothesis that Tuberin is an important regulator of stemness and the reduction of Tuberin levels might support functional differentiation in the central nervous system. Understanding how Tuberin expression is regulated throughout neural development is essential to fully comprehend the role of this protein in several developmental and neural pathologies.

High-throughput allele-specific expression across 250 environmental conditions.

Gene-by-environment (GxE) interactions determine common disease risk factors and biomedically relevant complex traits. However, quantifying how the environment modulates genetic effects on human quantitative phenotypes presents unique challenges. Environmental covariates are complex and difficult to measure and control at the organismal level, as found in GWAS and epidemiological studies. An alternative approach focuses on the cellular environment using in vitro treatments as a proxy for the organismal environment. These cellular environments simplify the organism-level environmental exposures to provide a tractable influence on subcellular phenotypes, such as gene expression. Expression quantitative trait loci (eQTL) mapping studies identified GxE interactions in response to drug treatment and pathogen exposure. However, eQTL mapping approaches are infeasible for large-scale analysis of multiple cellular environments. Recently, allele-specific expression (ASE) analysis emerged as a powerful tool to identify GxE interactions in gene expression patterns by exploiting naturally occurring environmental exposures. Here we characterized genetic effects on the transcriptional response to 50 treatments in five cell types. We discovered 1455 genes with ASE (FDR < 10%) and 215 genes with GxE interactions. We demonstrated a major role for GxE interactions in complex traits. Genes with a transcriptional response to environmental perturbations showed sevenfold higher odds of being found in GWAS. Additionally, 105 genes that indicated GxE interactions (49%) were identified by GWAS as associated with complex traits. Examples include GIPR-caffeine interaction and obesity and include LAMP3-selenium interaction and Parkinson disease. Our results demonstrate that comprehensive catalogs of GxE interactions are indispensable to thoroughly annotate genes and bridge epidemiological and genome-wide association studies.

A genotype-directed comparative effectiveness trial of Bucindolol and metoprolol succinate for prevention of symptomatic atrial fibrillation/atrial flutter in patients with heart failure: Rationale and design of the GENETIC-AF trial.

BACKGROUND: Few therapies are available for the safe and effective treatment of atrial fibrillation (AF) in patients with heart failure. Bucindolol is a non-selective beta-blocker with mild vasodilator activity previously found to have accentuated antiarrhythmic effects and increased efficacy for preventing heart failure events in patients homozygous for the major allele of the ADRB1 Arg389Gly polymorphism (ADRB1 Arg389Arg genotype). The safety and efficacy of bucindolol for the prevention of AF or atrial flutter (AFL) in these patients has not been proven in randomized trials. METHODS/DESIGN: The Genotype-Directed Comparative Effectiveness Trial of Bucindolol and Metoprolol Succinate for Prevention of Symptomatic Atrial Fibrillation/Atrial Flutter in Patients with Heart Failure (GENETIC-AF) trial is a multicenter, randomized, double-blinded "seamless" phase 2B/3 trial of bucindolol hydrochloride versus metoprolol succinate, for the prevention of symptomatic AF/AFL in patients with reduced ejection fraction heart failure (HFrEF). Patients with pre-existing HFrEF and recent history of symptomatic AF are eligible for enrollment and genotype screening, and if they are ADRB1 Arg389Arg, eligible for randomization. A total of approximately 200 patients will comprise the phase 2B component and if pre-trial assumptions are met, 620 patients will be randomized at approximately 135 sites to form the Phase 3 population. The primary endpoint is the time to recurrence of symptomatic AF/AFL or mortality over a 24-week follow-up period, and the trial will continue until 330 primary endpoints have occurred. CONCLUSIONS: GENETIC-AF is the first randomized trial of pharmacogenetic guided rhythm control, and will test the safety and efficacy of bucindolol compared with metoprolol succinate for the prevention of recurrent symptomatic AF/AFL in patients with HFrEF and an ADRB1 Arg389Arg genotype. (ClinicalTrials.govNCT01970501).

QuASAR: quantitative allele-specific analysis of reads.

MOTIVATION: Expression quantitative trait loci (eQTL) studies have discovered thousands of genetic variants that regulate gene expression, enabling a better understanding of the functional role of non-coding sequences. However, eQTL studies are costly, requiring large sample sizes and genome-wide genotyping of each sample. In contrast, analysis of allele-specific expression (ASE) is becoming a popular approach to detect the effect of genetic variation on gene expression, even within a single individual. This is typically achieved by counting the number of RNA-seq reads matching each allele at heterozygous sites and testing the null hypothesis of a 1:1 allelic ratio. In principle, when genotype information is not readily available, it could be inferred from the RNA-seq reads directly. However, there are currently no existing methods that jointly infer genotypes and conduct ASE inference, while considering uncertainty in the genotype calls. RESULTS: We present QuASAR, quantitative allele-specific analysis of reads, a novel statistical learning method for jointly detecting heterozygous genotypes and inferring ASE. The proposed ASE inference step takes into consideration the uncertainty in the genotype calls, while including parameters that model base-call errors in sequencing and allelic over-dispersion. We validated our method with experimental data for which high-quality genotypes are available. Results for an additional dataset with multiple replicates at different sequencing depths demonstrate that QuASAR is a powerful tool for ASE analysis when genotypes are not available. AVAILABILITY AND IMPLEMENTATION: http://github.com/piquelab/QuASAR. CONTACT: fluca@wayne.edu or rpique@wayne.edu SUPPLEMENTARY INFORMATION: Supplementary Material is available at Bioinformatics online.

Recovery after orthopedic surgery: techniques to increase duration of pain control.

PURPOSE OF REVIEW: Ambulatory surgery continues to expand in scope and volume. Part of this development is supported by improvements in anesthesia care, especially in the realm of postoperative analgesia, which is often outlasted by the pain. The purpose of this review is to outline methods of increasing the duration of postoperative pain control. RECENT FINDINGS: There have been recent advances in the use of perineural catheters for the performance of continuous nerve blocks, the use of adjuvants to extend the duration of single dose blocks, methods to improve the technical performance of blocks, systemic multimodal analgesia, and novel or experimental agents. SUMMARY: The ideas and findings described in this review are taken from the most recent literature and show promise of aiding in the continued improvement of patient care through their dissemination and refinement by further research. Of the modalities reviewed in current use, the continuous perineural catheter combined with systemic multimodal analgesics represents the best combination of safety and efficacy to provide prolonged postoperative analgesia.

Parturition after vestibulectomy.

INTRODUCTION: Provoked vestibulodynia is the most common cause of sexual pain in premenopausal women. Vulvar vestibulectomy has been shown to be an effective treatment. AIM: To determine the optimum route of parturition in women who become pregnant after vulvar vestibulectomy. METHODS: All women who underwent a complete vulvar vestibulectomy by one of four surgeons were contacted between 12 and 72 months after surgery. For all women who had a term pregnancy and subsequent delivery, the research assistant abstracted data from the charts. Descriptive statistics were applied. MAIN OUTCOME MEASURES: The number of women who underwent a delivery after a vestibulectomy, mode of delivery, and rate of perineal lacerations. RESULTS: Of 109 women, 44 (40%) had undergone at least one term pregnancy and delivery; 23 (52%) were vaginal, and 21 (48%) were cesarean deliveries. Of the vaginal deliveries, 11 (48%) were over an intact perineum. Three (13%) women had a midline episiotomy, none of which extended into third or fourth degree lacerations and one woman (4.4%) sustained a spontaneous fourth degree perineal laceration. CONCLUSIONS: Vaginal delivery after vulvar vestibulectomy appears to be a safe option, with no increased perineal morbidity above the general population. Furthermore, it is not an indication for a cesarean delivery.

Determination of hospitalization type by investigator case report form or adjudication committee in a large heart failure clinical trial (ß-Blocker Evaluation of Survival Trial [BEST]).

BACKGROUND: End point committees are routinely used to adjudicate efficacy and safety end points in clinical trials. The 2,708-patient ß-Blocker Evaluation of Survival Trial (BEST) originally determined hospitalization type via investigator case report forms (CRFs), which captured whether a hospitalization was due to worsening heart failure (HF). Recently, the BEST End Points Committee (EPC) completed a blinded adjudication of all hospitalizations, allowing a comparison of the CRF method to the EPC method of determining hospitalization type. We sought to compare the investigator-determined mode of hospitalizations with the adjudicated events, to quantify the degree of agreement, and to compare the clinical trial results by method of event classification. METHODS: The BEST EPC reviewed all 5,086 hospitalizations that occurred in BEST. Events were identified using investigator-reported hospitalizations, as well as those documented by FDA Form 3500 (MedWatch) reports. RESULTS: The investigators identified more HF hospitalization events than adjudication (2,466 vs 1,729, P < .0001, paired analysis). Eight hundred thirty-four (34%) HF hospitalizations identified in CRFs were not confirmed by adjudication. Ninety-seven (6%) adjudicated events were not identified by the investigator reported method. One thousand six hundred thirty-two events were similarly identified by both methods. CONCLUSIONS: The EPC adjudication identified fewer HF hospitalizations than did the investigator reported method with no change in the hazard ratio for this end point. Our findings suggest that independent end point committees may improve reliability through reduced variance, thus providing similar outcome results with fewer events and no increase in CIs.

Suspected systemic calcinosis and calciphylaxis in 5 horses.

Five horses were presented with signs of myopathy along with systemic malaise, hyperfibrinogenemia, hyperphosphatemia, and an elevated calcium phosphorus product (Ca*P). Postmortem findings were consistent with systemic calcinosis, a syndrome of calcium deposition in the tissue of organs including lungs, kidneys, muscle, and heart that has not been previously described in horses.

Interpreting Coronary Artery Disease Risk Through Gene-Environment Interactions in Gene Regulation.

GWAS and eQTL studies identified thousands of genetic variants associated with complex traits and gene expression. Despite the important role of environmental exposures in complex traits, only a limited number of environmental factors were measured in these studies. Measuring molecular phenotypes in tightly controlled cellular environments provides a more tractable setting to study gene-environment interactions in the absence of other confounding variables. We performed RNA-seq and ATAC-seq in endothelial cells exposed to retinoic acid, dexamethasone, caffeine, and selenium to model genetic and environmental effects on gene regulation in the vascular endothelium-a common site of pathology in cardiovascular disease. We found that genes near regions of differentially accessible chromatin were more likely to be differentially expressed [OR = (3.41, 6.52), [Formula: see text]]. Furthermore, we confirmed that environment-specific changes in transcription factor binding are a key mechanism for cellular response to environmental stimuli. Single nucleotide polymorphisms (SNPs) in these transcription response factor footprints for dexamethasone, caffeine, and retinoic acid were enriched in GTEx eQTLs from artery tissues, indicating that these environmental conditions are latently present in GTEx samples. Additionally, SNPs in footprints for response factors in caffeine are enriched in colocalized eQTLs for coronary artery disease (CAD), suggesting a role for caffeine in CAD risk. By combining GWAS, eQTLs, and response genes, we annotated environmental components that can increase or decrease disease risk through changes in gene expression in 43 genes. Interestingly, each treatment may amplify or buffer genetic risk for CAD, depending on the particular SNP or gene considered.

Bucindolol for the Maintenance of Sinus Rhythm in a Genotype-Defined HF Population: The GENETIC-AF Trial.

OBJECTIVES: The purpose of this study was to compare the effectiveness of bucindolol with that of metoprolol succinate for the maintenance of sinus rhythm in a genetically defined heart failure (HF) population with atrial fibrillation (AF). BACKGROUND: Bucindolol is a beta-blocker whose unique pharmacologic properties provide greater benefit in HF patients with reduced ejection fraction (HFrEF) who have the beta1-adrenergic receptor (ADRB1) Arg389Arg genotype. METHODS: A total of 267 HFrEF patients with a left ventricular ejection fraction (LVEF) <0.50, symptomatic AF, and the ADRB1 Arg389Arg genotype were randomized 1:1 to receive bucindolol or metoprolol therapy and were up-titrated to target doses. The primary endpoint of AF or atrial flutter (AFL) or all-cause mortality (ACM) was evaluated by electrocardiogram (ECG) during a 24-week period. RESULTS: The hazard ratio (HR) for the primary endpoint was 1.01 (95% confidence interval [CI]: 0.71 to 1.42), but trends for bucindolol benefit were observed in several subgroups. Precision therapeutic phenotyping revealed that a differential response to bucindolol was associated with the interval of time from the initial diagnoses of AF and HF to randomization and with the onset of AF relative to that of the initial HF diagnosis. In a cohort whose first AF and HF diagnoses were <12 years prior to randomization, in which AF onset did not precede HF by more than 2 years (n = 196), the HR was 0.54 (95% CI: 0.33 to 0.87; p = 0.011). CONCLUSIONS: Pharmacogenetically guided bucindolol therapy did not reduce the recurrence of AF/AFL or ACM compared to that of metoprolol therapy in HFrEF patients, but populations were identified who merited further investigation in future phase 3 trials.

Dose Response of ß-Blockers in Adrenergic Receptor Polymorphism Genotypes.

Background In heart failure (HF) with reduced ejection fraction, 2 clinical trials, the BEST (ß-Blocker Evaluation of Survival Trial) and HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training), have reported an effectiveness interaction between the ADRB1 (ß-1 adrenergic receptor) Arg389Gly polymorphism and ß-blockers (BBs). HF-ACTION additionally reported a dose-related interaction of unclear origin. If confirmed and pharmacogenetically resolved, these findings may have important implications for HF with reduced ejection fraction precision therapy. We used uniform methodology to investigate BB dose-ADRB1 Arg389Gly polymorphism interaction with major clinical end points in BEST/bucindolol and HF-ACTION/other BB databases. Methods This was a retrospective analysis of prospectively designed DNA substudies from BEST (N=1040) and HF-ACTION (N=957). Subjects were genotyped for ADRB1 Arg389Gly and ADRA2C (α2C adrenergic receptor) Ins322-325Del. BB dose was defined as either no/low dose or high dose, according to total daily dose of either bucindolol (BEST subjects) or other BB (HF-ACTION subjects) standardized to carvedilol equivalents. The main outcome of interest was all-cause mortality, and CV mortality/HF hospitalization was a secondary outcome. Results Subjects in each trial had less all-cause mortality with high- versus no/low-dose BB if they had ADRB1 Arg389Arg (BEST: hazard ratio [HR]=0.40, P=0.002; HF-ACTION: HR=0.45, P=0.005) but not Arg389Gly genotype (both P>0.2). Among gene-dose groups, there was a differential favorable treatment effect of 46% for high-dose bucindolol with ADRB1 Arg389Arg versus Gly carrier genotype (HR, 0.54; P=0.018), but not for no/low-dose bucindolol. In contrast, HF-ACTION Arg389Arg genotype subjects taking no/low-dose BB had greater all-cause mortality compared with 389Gly carriers (HR, 1.83; P=0.015), whereas all-cause mortality did not vary by genotype among subjects taking high-dose BB (HR, 0.84; P=0.55). Conclusions The enhanced HF with reduced ejection fraction efficacy of bucindolol in the ADRB1 Arg389Arg versus 389Gly carrier genotypes occurs at high dose. Other BBs taken at low dose have reduced efficacy for Arg389Arg genotype subjects compared with 389Gly carriers, suggesting a greater relative treatment effect at high dose. These data support guideline recommendations to use high, clinical trial target doses of all BBs to treat HF with reduced ejection fraction.

Changes in Left Ventricular Ejection Fraction Predict Survival and Hospitalization in Heart Failure With Reduced Ejection Fraction.

BACKGROUND: Left ventricular remodeling, as commonly measured by left ventricular ejection fraction (LVEF), is associated with clinical outcomes. Although change in LVEF over time should reflect response to therapy and clinical course, serial measurement of LVEF is inconsistently performed in observational settings, and the incremental prognostic value of change in LVEF has not been well characterized. METHODS AND RESULTS: The ß-Blocker Evaluation of Survival Trial measured LVEF by radionuclide ventriculography at baseline and at 3 and 12 months after randomization. We built a series of multivariable models with 16 clinical parameters plus change in LVEF for predicting 4 major clinical end points, including the trial's primary end point of all-cause mortality. Among 2484 patients with at least 1 follow-up LVEF, change in LVEF was the second most significant predictor (behind baseline creatinine) of all-cause mortality (adjusted hazard ratio for improvement in LVEF by ≥5 U responder versus nonresponder [95% confidence intervals] for all-cause mortality=0.62 [0.52-0.73]). Other end points, including heart failure hospitalization or the composite of all-cause mortality and heart failure hospitalization, yielded similar results. LVEF change ≥5 U was associated with a modest increase in discrimination when added to traditional predictors and was predictive of outcomes in both the bucindolol and placebo treatment groups. LVEF change as a predictor of outcomes was affected by sex and race, with evidence that LVEF improvement is associated with less survival benefit in African Americans and women. CONCLUSIONS: Serial evaluation for LVEF change predicts both survival and heart failure hospitalization and provides a dynamic/real-time measure of prognosis in heart failure with reduced LVEF. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000560.

New-onset atrial fibrillation predicts heart failure progression.

BACKGROUND: Atrial fibrillation and heart failure with reduced left ventricular ejection fraction have interrelated pathophysiologies. New-onset atrial fibrillation in heart failure patients has been associated with increased mortality, but has not been definitively related to clinical heart failure progression. METHODS: To test the hypothesis that new-onset atrial fibrillation is related to clinical heart failure progression, in 2392 patients without atrial fibrillation at randomization in the Beta-blocker Evaluation of Survival Trial we measured clinical endpoints in patients who did (Group 1, n = 190) or did not (Group 2, n = 2202) develop new-onset atrial fibrillation. Results were also compared with the 303 patients who entered the trial in atrial fibrillation (Baseline/chronic group), and in Group 1/2 patients we conducted a multivariate analysis of covariates potentially related to time to first heart failure hospitalization. RESULTS: Compared with Group 2, Group 1 patients post atrial fibrillation onset had a ∼2-fold increase in mortality (P < .0001) and a ∼4.5-fold increase in all-cause or heart failure hospitalization days/patient (hospitalization burden, both P < .0001). In Group 1, both types of hospitalization burden were 2.9-fold greater than in the Baseline/chronic group (P < .001), and hospitalization burden increased ∼6-fold (P < .0001) compared with the pre-event period. On multivariate analysis, new-onset atrial fibrillation was a highly significant (P < .00001) predictor of heart failure hospitalization. CONCLUSIONS: In addition to being a discrete electrophysiologic event, in heart failure patients, new-onset atrial fibrillation is a predictor of and trigger for clinical heart failure progression.

Race, common genetic variation, and therapeutic response disparities in heart failure.

Because of its comparatively recent evolution, Homo sapiens exhibit relatively little within-species genomic diversity. However, because of genome size, a proportionately small amount of variation creates ample opportunities for both rare mutations that may cause disease as well as more common genetic variations that may be important in disease modification or pharmacogenetics. Primarily because of the East African origin of modern humans, individuals of African ancestry (AA) exhibit greater degrees of genetic diversity than more recently established populations, such as those of European ancestry (EA) or Asian ancestry. Those population effects extend to differences in frequency of common gene variants that may be important in heart failure natural history or therapy. For cell-signaling mechanisms important in heart failure, we review and present new data for genetic variation between AA and EA populations. Data indicate that: 1) neurohormonal signaling mechanisms frequently (16 of the 19 investigated polymorphisms) exhibit racial differences in the allele frequencies of variants comprising key constituents; 2) some of these differences in allele frequency may differentially affect the natural history of heart failure in AA compared with EA individuals; and 3) in many cases, these differences likely play a role in observed racial differences in drug or device response.

Prevention of atrial fibrillation by bucindolol is dependent on the beta1389 Arg/Gly adrenergic receptor polymorphism.

OBJECTIVES: This study assessed the impact of bucindolol, a beta-blocker/sympatholytic agent, on the development of atrial fibrillation (AF) in advanced chronic heart failure with reduced left ventricular ejection fraction (HFREF) patients enrolled in the BEST (Beta-Blocker Evaluation of Survival Trial). BACKGROUND: ß-blockers have modest efficacy for AF prevention in HFREF patients. Bucindolol's effects on HF and ventricular arrhythmic endpoints are genetically modulated by ß1- and α(2c)-adrenergic receptor (AR) polymorphisms that can be used to subdivide HFREF populations into those with bucindolol effectiveness levels that are enhanced, unchanged, or lost. METHODS: BEST enrolled 2,708 New York Heart Association (NYHA) class III to IV HFREF patients. A substudy in which 1,040 patients' DNA was genotyped for the ß1-AR position 389 Arg/Gly and the α(2c)322-325 wild type (Wt)/deletion (Del) polymorphisms, and new-onset AF was assessed from adverse event case report forms or electrocardiograms at baseline and at 3 and 12 months. RESULTS: In the entire cohort, bucindolol reduced the rate of new-onset AF compared to placebo by 41% (hazard ratio [HR]: 0.59 [95% confidence interval (CI): 0.44 to 0.79], p = 0.0004). In the 493 ß1389 arginine homozygotes (Arg/Arg) in the DNA substudy, bucindolol reduced new-onset AF by 74% (HR: 0.26 [95% CI: 0.12 to 0.57]), with no effect in ß1389 Gly carriers (HR: 1.01 [95% CI: 0.56 to 1.84], interaction test = 0.008). When ß1389 Gly carriers were subdivided by α(2c) Wt homozygotes (n = 413, HR: 0.94 [95% CI: 0.48 to 1.82], p = 0.84) or Del variant carriers (n = 134, HR: 1.33 [95% CI: 0.32 to 5.64], p = 0.70), there was a positive interaction test (p = 0.016) when analyzed with ß1389 Arg homozygotes. CONCLUSIONS: Bucindolol prevented new-onset AF; ß1 and α(2c) polymorphisms predicted therapeutic response; and the 47% of patients who were ß1389 Arg homozygotes had an enhanced effect size of 74%. (Beta-Blocker Evaluation in Survival Trial [BEST]; NCT00000560)

Effect of bucindolol on heart failure outcomes and heart rate response in patients with reduced ejection fraction heart failure and atrial fibrillation.

AIMS: There is little evidence of beta-blocker treatment benefit in patients with heart failure and reduced left ventricular ejection fraction (HFREF) and atrial fibrillation (AF). We investigated the effects of bucindolol in HFREF patients with AF enrolled in the Beta-blocker Evaluation of Survival Trial (BEST). METHODS AND RESULTS: A post-hoc analysis of patients in BEST with and without AF was performed to estimate the effect of bucindolol on mortality and hospitalization. Patients were also evaluated for treatment effects on heart rate and the influence of beta1-adrenergic receptor position 389 (ß(1)389) arginine (Arg) vs. glycine (Gly) genotypes. In the 303/2708 patients in AF, patients receiving bucindolol were more likely to achieve a resting heart rate ≤ 80 b.p.m. at 3 months (P < 0.005) in the absence of treatment-limiting bradycardia. In AF patients and sinus rhythm (SR) patients who achieved a resting heart rate ≤ 80 b.p.m., there were beneficial treatment effects on cardiovascular mortality/cardiovascular hospitalization [hazard ratio (HR) 0.61, P = 0.025, and 0.79, P = 0.002]. Without achieving a resting heart rate ≤ 80 b.p.m., there were no treatment effects on events in either group. ß(1)389-Arg/Arg AF patients had nominally significant reductions in all-cause mortality/HF hospitalization and cardiovascular mortality/hospitalization with bucindolol (HR 0.23, P = 0.037 and 0.28, P = 0.039), whereas Gly carriers did not. There was no evidence of diminished heart rate response in ß(1)389-Arg homozygotes. CONCLUSION: In HFREF patients with AF, bucindolol was associated with reductions in composite HF endpoints in those who achieved a resting heart rate ≤ 80 b.p.m. and nominally in those with the ß(1)389-Arg homozygous genotype.

Combinatorial pharmacogenetic interactions of bucindolol and ß1, α2C adrenergic receptor polymorphisms.

BACKGROUND: Pharmacogenetics involves complex interactions of gene products affecting pharmacodynamics and pharmacokinetics, but there is little information on the interaction of multiple genetic modifiers of drug response. Bucindolol is a ß-blocker/sympatholytic agent whose efficacy is modulated by polymorphisms in the primary target (ß(1) adrenergic receptor [AR] Arg389 Gly on cardiac myocytes) and a secondary target modifier (α(2C) AR Ins [wild-type (Wt)] 322-325 deletion [Del] on cardiac adrenergic neurons). The major allele homozygotes and minor allele carriers of each polymorphism are respectively associated with efficacy enhancement and loss, creating the possibility for genotype combination interactions that can be measured by clinical trial methodology. METHODOLOGY: In a 1,040 patient substudy of a bucindolol vs. placebo heart failure clinical trial, we tested the hypothesis that combinations of ß(1)389 and α(2C)322-325 polymorphisms are additive for both efficacy enhancement and loss. Additionally, norepinephrine (NE) affinity for ß(1)389 AR variants was measured in human explanted left ventricles. PRINCIPAL FINDINGS: The combination of ß(1)389 Arg+α(2C)322-325 Wt major allele homozygotes (47% of the trial population) was non-additive for efficacy enhancement across six clinical endpoints, with an average efficacy increase of 1.70-fold vs. 2.32-fold in ß(1)389 Arg homozygotes+α(2C)322-325 Del minor allele carriers. In contrast, the minor allele carrier combination (13% subset) exhibited additive efficacy loss. These disparate effects are likely due to the higher proportion (42% vs. 8.7%, P = 0.009) of high-affinity NE binding sites in ß(1)389 Arg vs. Gly ARs, which converts α(2C)Del minor allele-associated NE lowering from a therapeutic liability to a benefit. CONCLUSIONS: On combination, the two sets of AR polymorphisms 1) influenced bucindolol efficacy seemingly unpredictably but consistent with their pharmacologic interactions, and 2) identified subpopulations with enhanced (ß(1)389 Arg homozygotes), intermediate (ß(1)389 Gly carriers+α(2C)322-325 Wt homozygotes), and no (ß(1)389 Gly carriers+α(2C)322-325 Del carriers) efficacy.

Influence of global region on outcomes in heart failure ß-blocker trials.

OBJECTIVES: We sought to describe the United States and the rest of the world (ROW) outcomes from the major ß-blocker heart failure (HF) trials. BACKGROUND: HF trials have demonstrated differences in outcomes by geographic region. METHODS: Randomized, double-blind, placebo-controlled studies that evaluated ß-blockers in HF patients, had a primary endpoint of mortality, and enrolled U.S. patients were included. Relative risk (RR) was calculated for patients enrolled in the United States and ROW. Meta-analysis of the combined mortality rates was performed using the Cochran-Mantel-Haenszel statistic, stratified by study. RESULTS: A total of 8,988 patients were enrolled in the MERIT-HF (Metoprolol Controlled-Release Randomized Intervention Trial in Heart Failure), COPERNICUS (Carvedilol Prospective Randomized Cumulative Survival trial), and BEST (ß-Blocker Evaluation of Survival Trial) combined; 4,198 (46.7%) were from the United States. In the U.S. cohort, the RR reduction for each ß-blocker was of smaller magnitude than in the overall cohort and no longer significant, whereas in the ROW subgroup, the mortality benefit for ß-blockade persisted. In the pooled analysis (n = 11,635), the RR of death was reduced by 23% (p < 0.001) with ß-blockade compared with placebo. In contrast, the mortality reduction associated with ß-blockade in the U.S. cohort was small and not statistically significant (RR: 0.92, 95% confidence interval [CI]: 0.82 to 1.02, p = 0.11). The survival benefit persisted in the ROW cohort (RR: 0.64, 95% CI: 0.56 to 0.72, p < 0.001). CONCLUSIONS: Among patients enrolled in the United States, ß-blockade was associated with a lower magnitude of survival benefit, whereas the ROW response was similar to the total study population. This geographic difference in treatment response may be a reflection of population differences, genetics, cultural or social differences in disease management, or low power and statistical chance.

An alpha2C-adrenergic receptor polymorphism alters the norepinephrine-lowering effects and therapeutic response of the beta-blocker bucindolol in chronic heart failure.

BACKGROUND: Adrenergic activation is an important determinant of outcomes in chronic heart failure. Adrenergic activity is regulated in part by prejunctional alpha(2C)-adrenergic receptors (ARs), which exhibit genetic variation in humans. Bucindolol is a novel beta-AR blocking agent that also lowers systemic norepinephrine and thus is also a sympatholytic agent. This study investigated whether alpha(2C)-AR polymorphisms affect sympatholytic effects of bucindolol in patients with heart failure. METHODS AND RESULTS: In the beta-Blocker Evaluation of Survival Trial, adrenergic activation was estimated by systemic venous norepinephrine measured at baseline, 3 months, and 12 months posttreatment in patients treated with placebo or bucindolol. In the beta-Blocker Evaluation of Survival Trial AR polymorphism substudy, DNA was collected from 1040 of the 2708 randomized patients, and alpha(2C)-AR gene polymorphisms (alpha(2C) Del322-325 or the wild-type counterpart) were measured by polymerase chain reaction and gel electrophoresis. Patients who were alpha(2C) Del carriers (heterozygotes or homozygotes) exhibited a much greater sympatholytic response to bucindolol (decrease in norepinephrine at 3 months of 153+/-57 pg/mL, P=0.012 compared with placebo versus decrease of 50+/-13 pg/mL in alpha(2C) wild type, P=0.0005 versus placebo; P=0.010 by interaction test). alpha(2C) Del carriers had no evidence of a favorable survival benefit from bucindolol (mortality compared with placebo hazard ratio, 1.09; 95% CI, 0.57 to 2.08; P=0.80), whereas bucindolol-treated subjects who were wild type for the alpha(2C)-AR had a 30% reduction in mortality (hazard ratio, 0.70; 95% CI, 0.51 to 0.96; P=0.025). CONCLUSIONS: In the beta-Blocker Evaluation of Survival Trial AR polymorphism substudy, the norepinephrine lowering and clinical therapeutic responses to bucindolol were strongly influenced by alpha(2C) receptor genotype.

Home study course: winter 2008.

OBJECTIVE: The Home Study Course is intended for the practicing colposcopist or practitioner who is seeking to develop or enhance his/her colposcopic skills. The goal of the course is to present colposcopic cases that are unusual or instructive in terms of appearance, presentation, or management or that demonstrate new and important knowledge in the area of colposcopy or pathology. Participants may benefit from reading and studying the material or from testing their knowledge by answering the questions. ACCME ACCREDITATION: The American Society for Colposcopy and Cervical Pathology (ASCCP) is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians. The ASCCP designates this education activity for a maximum of 1 AMA PRA Category I Credittrade mark. Physicians should only claim credit commensurate with the extent of their participation in the activity. The ASCCP also designates their educational activity for 1 Category 1 credit hour of the ASCCP's Program for Continuing Professional Development. Credit is available for those who choose to apply. The Home Study Course is planned and produced in accordance with the ACCME's Essential Areas and Elements. DISCLOSURE: The clinical history and images in the Home Study Course may represent an actual case, but not always. To improve educational quality, some gross, cytological, or histological images may come from photographic libraries. Good teaching cases are often difficult to obtain, and we encourage our readers to submit cases with high-quality images to the Home Study Course editor or executive editor to consider for publication. Lastly, faculty must disclose any significant financial interest or relationship with proprietary entities that may have a direct relationship to the subject matter. For this course, the authors had the following relationships to report: Gordon D. Davis, MD, FACOG: No such relationship to report Joseph A.D. Brooks, MD: No such relationship to report.