The D84G mutation in STIM1 causes nuclear envelope dysfunction and myopathy in mice.

Stromal interaction molecule 1 (STIM1) is a Ca2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle, where it is best known for its role in store-operated Ca2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focused on a gain-of-function mutation that occurs in humans and mice (STIM1+/D84G mice), in which muscles exhibited constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca2+ transients, SR Ca2+ content, or excitation-contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1+/D84G muscle disrupted nuclear-cytosolic coupling, causing severe derangement in nuclear architecture, DNA damage, and altered lamina A-associated gene expression. Functionally, we found that D84G STIM1 reduced the transfer of Ca2+ from the cytosol to the nucleus in myoblasts, resulting in a reduction of [Ca2+]N. Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca2+ signaling to nuclear stability in skeletal muscle.

Novel Size-Based High-Density Lipoprotein Subspecies and Incident Vascular Events.

Background High-density lipoprotein (HDL) particle concentration likely outperforms HDL cholesterol in predicting atherosclerotic cardiovascular events. Whether size-based HDL subspecies explain the atheroprotective associations of HDL particle concentration remains unknown. Our objective was to assess whether levels of specific size-based HDL subspecies associate with atherosclerotic cardiovascular disease in a multiethnic pooled cohort and improve risk prediction beyond traditional atherosclerotic cardiovascular disease risk factors. Methods and Results Seven HDL size-based subspecies were quantified by nuclear magnetic resonance (LP4 algorithm; H1=smallest; H7=largest) among participants without prior atherosclerotic cardiovascular disease in ARIC (Atherosclerosis Risk in Communities), MESA (Multi-Ethnic Study of Atherosclerosis), PREVEND (Prevention of Renal and Vascular Endstage Disease), and DHS (Dallas Heart Study) cohorts (n=15 371 people). Multivariable Cox proportional hazards models were used to evaluate the association between HDL subspecies and incident myocardial infarction (MI) or ischemic stroke at follow-up (average 8-10 years) adjusting for HDL cholesterol and risk factors. Improvement in risk prediction was assessed via discrimination and reclassification analysis. Within the pooled cohort (median age 57 years; female 54%; Black 22%) higher H1 (small) and H4 (medium) concentrations were inversely associated with incident MI (hazard ratio [HR]/SD, H1 0.88 [95% CI, 0.81-0.94]; H4 0.89 [95% CI, 0.82-0.97]). H4 but not H1 improved risk prediction indices for incident MI. Increasing H2 and H4 were inversely associated with improved risk prediction indices for composite end point of stroke, MI, and cardiovascular death (HR/SD, H2 0.94 [95% CI, 0.88-0.99]; H4 0.91 [95% CI, 0.85-0.98]). Levels of the large subspecies (H6 and H7) were not associated with any vascular end point. Conclusions Two of 7 HDL size-based subspecies modestly improved risk prediction for MI and composite vascular end points in a large multiethnic pooled cohort. These findings support assessment of precise HDL subspecies for future studies regarding clinical utility.

The D84G mutation in STIM1 causes nuclear envelope dysfunction and myopathy in mice.

Stromal interaction molecule 1 (STIM1) is a Ca 2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle where it is best known for its role in store operated Ca 2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focus on a gain of function mutation that occurs in humans and mice (STIM1 +/D84G mice) where muscles exhibit constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca 2+ transients, SR Ca 2+ content or excitation contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1 +/D84G muscle disrupts nuclear-cytosolic coupling causing severe derangement in nuclear architecture, DNA damage, and altered lamina A associated gene expression. Functionally, we found D84G STIM1 reduced the transfer of Ca 2+ from the cytosol to the nucleus in myoblasts resulting in a reduction of [Ca 2+ ] N . Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca 2+ signaling to nuclear stability in skeletal muscle.

Ivabradine toxicity: a case report.

BACKGROUND: We describe a case of symptomatic bradycardia resulting from ivabradine toxicity by measurement of ivabradine levels, of which there are limited reports in the literature. CASE PRESENTATION: A 43-year-old White female presented with several days of near syncope and dizziness accompanied by a drop in her heart rate to 50 beats per minute. She was taking ivabradine for inappropriate sinus tachycardia. After excluding several other causes of bradycardia, we made the diagnosis of ivabradine toxicity by measurement of serum ivabradine levels, an approach that is currently not clinically available. CONCLUSIONS: Measurement of serum ivabradine levels and knowledge of the pharmacokinetic properties of the drug can be utilized to confirm the diagnosis of ivabradine toxicity.

Soluble Fms-like tyrosine kinase-1 (sFlt-1) is associated with subclinical and clinical atherosclerotic cardiovascular disease: The Dallas Heart Study.

BACKGROUND AND AIMS: Soluble Fms-like tyrosine kinase-1 (sFlt-1) plays a role in angiogenesis, atherogenesis, and preeclampsia. The relationship of sFlt-1 with markers of subclinical atherosclerosis and future atherosclerotic cardiovascular disease (ASCVD) events in a generally healthy population is unknown. METHODS: Participants in the Dallas Heart Study with sFlt-1 measured were included (n = 3292). Abdominal aortic atherosclerosis was measured by MRI and coronary artery calcium (CAC) by CT. The cohort was also followed for subsequent ASCVD events (CV death, MI, stroke, unstable angina, revascularization). Multivariable linear and logistic regression analyses and Cox regression analyses were performed adjusting for demographics and traditional cardiac risk factors. RESULTS: sFlt-1 levels were higher in older individuals, males, and African Americans, and tracked with most traditional risk factors. sFlt-1 was significantly associated with higher prevalence of aortic plaque [OR 1.33 (95% CI 1.02-1.73)], greater abdominal aortic wall thickness (p<0.01) and aortic plaque area (p<0.02) but no difference in coronary artery calcification. There were 322 ASCVD events over 12 years of follow-up. Higher sFlt-1 levels associated with increased ASCVD events in unadjusted (16.1% vs. 8.9%, p<0.001, quartile 4 vs. quartile 1) and adjusted analyses (HR 1.58 [1.14-2.18], p<0.01, quartile 4 vs. quartile 1). Findings were unchanged when analyzing sFlt-1 as a continuous variable or when excluding those with a history of ASCVD. CONCLUSIONS: In a population-based cohort, sFlt-1 is associated with measures of subclinical aortic atherosclerosis and clinical ASCVD events. Future studies are warranted on the therapeutic potential of targeting sFlt-1 for atherosclerotic disease.

Associations Between High-Density Lipoprotein Particles and Ischemic Events by Vascular Domain, Sex, and Ethnicity: A Pooled Cohort Analysis.

BACKGROUND: High-density lipoprotein (HDL) cholesterol concentration (HDL-C) is an established atheroprotective marker, in particular for coronary artery disease; however, HDL particle concentration (HDL-P) may better predict risk. The associations of HDL-C and HDL-P with ischemic stroke and myocardial infarction (MI) among women and Blacks have not been well studied. We hypothesized that HDL-P would consistently be associated with MI and stroke among women and Blacks compared with HDL-C. METHODS: We analyzed individual-level participant data in a pooled cohort of 4 large population studies without baseline atherosclerotic cardiovascular disease: DHS (Dallas Heart Study; n=2535), ARIC (Atherosclerosis Risk in Communities; n=1595), MESA (Multi-Ethnic Study of Atherosclerosis; n=6632), and PREVEND (Prevention of Renal and Vascular Endstage Disease; n=5022). HDL markers were analyzed in adjusted Cox proportional hazard models for MI and ischemic stroke. RESULTS: In the overall population (n=15 784), HDL-P was inversely associated with the combined outcome of MI and ischemic stroke, adjusted for cardiometabolic risk factors (hazard ratio [HR] for quartile 4 [Q4] versus quartile 1 [Q1], 0.64 [95% CI, 0.52-0.78]), as was HDL-C (HR for Q4 versus Q1, 0.76 [95% CI, 0.61-0.94]). Adjustment for HDL-C did not attenuate the inverse relationship between HDL-P and atherosclerotic cardiovascular disease, whereas adjustment for HDL-P attenuated all associations between HDL-C and events. HDL-P was inversely associated with the individual end points of MI and ischemic stroke in the overall population, including in women. HDL-P was inversely associated with MI among White participants but not among Black participants (HR for Q4 versus Q1 for Whites, 0.49 [95% CI, 0.35-0.69]; for Blacks, 1.22 [95% CI, 0.76-1.98]; Pinteraction=0.001). Similarly, HDL-C was inversely associated with MI among White participants (HR for Q4 versus Q1, 0.53 [95% CI, 0.36-0.78]) but had a weak direct association with MI among Black participants (HR for Q4 versus Q1, 1.75 [95% CI, 1.08-2.83]; Pinteraction<0.0001). CONCLUSIONS: Compared with HDL-C, HDL-P was consistently associated with MI and ischemic stroke in the overall population. Differential associations of both HDL-C and HDL-P for MI by Black ethnicity suggest that atherosclerotic cardiovascular disease risk may differ by vascular domain and ethnicity. Future studies should examine individual outcomes separately.

Impaired HDL Metabolism Links GlycA, A Novel Inflammatory Marker, with Incident Cardiovascular Events.

High-density lipoproteins (HDL) exert anti-atherosclerotic effects via reverse cholesterol transport, yet this salutary property is impaired in the setting of inflammation. GlycA, a novel integrated glycosylation marker of five acute phase reactants, is linked to cardiovascular (CV) events. We assessed the hypothesis that GlycA is associated with measures of impaired HDL function and that dysfunctional HDL may contribute to the association between GlycA and incident CV events. Baseline measurements of HDL cholesterol (HDL-C), HDL particle concentration (HDL-P), apoliprotein A1 (Apo A1), cholesterol efflux capacity, GlycA and high-sensitivity C-reactive protein (hs-CRP) were obtained from the Dallas Heart Study, a multi-ethnic cohort of 2643 adults (median 43 years old; 56% women, 50% black) without cardiovascular disease (CVD). GlycA was derived from nuclear magnetic resonance imaging. Participants were followed for first nonfatal MI, nonfatal stroke, coronary revascularization, or CV death over a median of 12.4 years (n = 197). The correlation between GlycA and hs-CRP was 0.58 (p < 0.0001). In multivariate models with HDL-C, GlycA was directly associated with HDL-P and Apo A1 and inversely associated with cholesterol efflux (standardized beta estimates: 0.08, 0.29, -0.06, respectively; all p ≤ 0.0004) GlycA was directly associated with incident CV events (adjusted hazard ratio (HR) for Q4 vs. Q1: 3.33, 95% confidence interval (CI) 1.99, 5.57). Adjustment for cholesterol efflux mildly attenuated this association (HR for Q4 vs. Q1: 3.00, 95% CI 1.75 to 5.13). In a multi-ethnic cohort, worsening inflammation, as reflected by higher GlycA levels, is associated with higher HDL-P and lower cholesterol efflux. Impaired cholesterol efflux likely explains some of the association between GlycA and incident CV events. Further studies are warranted to investigate the impact of inflammation on HDL function and CV disease.

Effects of Delivering SLCO1B1 Pharmacogenetic Information in Randomized Trial and Observational Settings.

BACKGROUND: Outcomes of tailoring statin-type based on solute carrier organic anion transporterfamily member 1B1 ( SLCO1B1)pharmacogenetic toxicity information on patient, provider, and pharmacological outcomes are unknown. METHODS: The trial randomized 159 patients not taking statins because of prior statin myalgia 1:1 to receiving SLCO1B1 GIST (Genotype Informed Statin Therapy) versus usual care (UC) and followed for up to 8 months. The UC arm received their SLCO1B1 results post-trial. The primary outcome was statin adherence using the Morisky Medication Adherence Scale, which was assessed in those patients who reinitiated statins. Secondary outcomes assessed in all participants included statin reinitiation and LDLc (low-density lipoprotein cholesterol), within and post-trial. Using commercial laboratory data, serial LDLc were compared between 1907 patients receiving SLCO1B1 testing and propensity-matched, untested controls. RESULTS: Trial participants were 25% SLCO1B1*5 carriers. Statin adherence was similar between arms (Morisky Medication Adherence Scale in GIST versus UC, 6.8±1.5 versus 6.9±1.6, P=0.96). GIST led to more new statin prescriptions (55.4% versus 38.0%, P=0.04) and lower LDLc at 3 months (131.9±42.0 versus 144.4±43.0 mg/dL; P=0.048) with similar magnitude at 8 months (128.6±37.9 versus 141.0±44.4; P=0.12). SLCO1B1*5 carriers exhibited a greater drop in LDLc with GIST versus UC (interaction P=0.048). Post-trial, LDLc decreased in UC participants who crossed over to GIST compared with those allocated to GIST (-14.9±37.8 versus +9.0±37.3 mg/dL, P=0.03). Patients tested for SLCO1B1 though a commercial laboratory had a greater LDLc decrease ( P=0.04) compared with controls. CONCLUSIONS: Delivery of SLCO1B1 pharmacogenetic testing that addresses statin myalgia improved statin reinitiation and LDLc but did not improve self-reported statin adherence. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01894230.

Single vs. dual chamber implantable cardioverter-defibrillators or programming of implantable cardioverter-defibrillators in patients without a bradycardia pacing indication: systematic review and meta-analysis.

Aims: Implantable cardioverter-defibrillators (ICDs) are key in the prevention of sudden cardiac death, but outcomes may vary by type of device or programming [single chamber (SC) vs. dual chamber (DC)] in patients without a bradycardia pacing indication. We sought to meta-analyse patient outcomes of randomized trials of SC vs. DC devices or programming. Methods and results: We searched PubMed, Embase, Scopus, Web of Science, and Cochrane trials databases for relevant studies excluding those published before 2000, involving children, or not available in English. Endpoints included mortality, inappropriate ICD therapies, and implant complications. Endpoints with at least three reporting studies were meta-analysed. We identified eight studies meeting inclusion criteria representing 2087 patients with 16.1 months mean follow-up. Mean age was 62.7 years (SD 1.92); in six studies reporting sex, most patients were male (85%). Comparing patients with a SC or DC ICD or programming, we found similar rates of mortality [odds ratio (OR) 0.95, 95% confidence interval (CI) 0.54-1.68; P = 0.86] and inappropriate therapies (OR 1.46, 95% CI 0.97-2.19; P = 0.07) in five and six studies, respectively. In three studies of SC vs. DC ICDs (but not programming) rates of pneumothorax and lead dislodgement were not different (OR 2.12, 95% CI 0.18-24.72; P = 0.55 and OR 0.87, 95% CI 0.32-2.47; P = 0.83, respectively). Conclusion: In this meta-analysis of randomized controlled trials comparing SC vs. DC ICD device or programming, there was no significant difference in inappropriate therapies, mortality, pneumothorax, or lead dislodgement. Future studies should compare these devices over longer follow-up and in specific patient populations.

Elucidation of the molecular interaction between cisplatin and flavonol(s) and their effect on DNA binding.

Combination therapy of cisplatin with flavonols is a promising treatment for increasing the efficacy of cisplatin when combating cancer. However, little is known about the molecular interactions between cisplatin and flavonols. The data herein helps to elucidate this interaction. Spectrophotometric data in the UV-visible range indicates that hydroxyl groups on the B-ring of flavonols are essential for reactivity with cisplatin. The use of a quartz crystal microbalance with dissipation monitoring approach clearly supports the critical role played by B-ring hydroxyls in their interactions with a cisplatin-bound double-stranded DNA surface; an increase in the number of hydroxyl groups on the B-ring of flavonols parallels the increase in their reaction rates with cisplatin and correlates well with their reported effects on leukemia cell apoptosis efficacy. This study underscores the importance of B-ring hydroxyls in cisplatin's toxicity and may be used to better understand and improve combination therapies of flavonols with cisplatin.