The Effects of Carboxyl-group Specific Modification and Triiodo-L-thyronine on Cardiac Sodium Channels

The patch clamp method was used to evaluate the effects of 3,5,3\u27-triiodo-L-thyronine (T3) and carboxyl modification on adult rabbit ventricular Na+ channels. In contrast to TTX-sensitive Na+ channels, Ca2+ block of cardiac Na+ channels was not prevented by selective carboxyl modification by trimethyloxonium (TMO) or water soluble carbodiimide (WSC). In 2 mM Ca2+, TMO-treated patches exhibited 3 discrete conductance (γNa) levels. An abbreviation of mean open time (MOT) accompanied each decrease in γNa. The effects on channel gating of elevating external Ca2+ differed from those of TMO pretreatment. Ensemble averages after TMO showed a shortening of the time to peak current and an acceleration of the rate of current decay. WSC caused a decrease in γNa and an abbreviation of MOT at all potentials tested. We conclude that alteration of the surface potential by a single carboxyl modification is inadequate to explain the effects of TMO and WSC. Physiological concentrations of T3 increased bursting as measured by the ratio of long events (LE) to the total number of events. In the cell-attached patch configuration, addition of 5 nM T3 to the pipette increased the %LE at all potentials examined. The increase had a biphasic voltage-dependence and peaked at -50 mV. A similar increase in the %LE occurred with 50 nM T3 suggesting saturation at ≤5 nM. LEs sometimes were grouped into runs, but the more usual pattern suggested that modal shifts occurred in ~1 s. Addition of T3 to the bath but not the pipette in cell-attached patches failed to alter the MOT, unitary current, or %LE. Na+ channel gating also was unaffected by patch excision or by addition of T3 to the cytoplasmic face of inside-out patches. Nevertheless, with T3 in the pipette, patch excision to the inside-out configuration caused a dramatic increase in the %LE, especially near the threshold potential, and an increase in the MOT. These results suggested that T3 was not membrane permeable during the time scale of the experiments and that T3\u27s action required close proximity to the extracellular face of the Na+ channel

Statins Decrease Oxidative Stress and ICD Therapies

Recent studies demonstrate that statins decrease ventricular arrhythmias in internal cardioverter defibrillator (ICD) patients. The mechanism is unknown, but evidence links increased inflammatory and oxidative states with increased arrhythmias. We hypothesized that statin use decreases oxidation. Methods. 304 subjects with ICDs were surveyed for ventricular arrhythmia. Blood was analyzed for derivatives of reactive oxygen species (DROMs) and interleukin-6 (IL-6). Results. Subjects included 252 (83%) men, 58% on statins, 20% had ventricular arrhythmias. Average age was 63 years and ejection fraction (EF) 20%. ICD implant duration was 29 ± 27 months. Use of statins correlated with lower ICD events (r = 0.12, P = .02). Subjects on statins had lower hsCRP (5.2 versus 6.3; P = .05) and DROM levels (373 versus 397; P = .03). Other factors, including IL-6 and EF did not differ between statin and nonstatin use, nor did beta-blocker or antiarrhythmic use. Multivariate cross-correlation analysis demonstrated that DROMs, statins, IL-6 and EF were strongly associated with ICD events. Multivariate regression shows DROMs to be the dominant predictor. Conclusion. ICD event rate correlates with DROMs, a measure of lipid peroxides. Use of statins is associated with reduced DROMs and fewer ICD events, suggesting that statins exert their effect through reducing oxidation

Automated external cardioversion defibrillation monitoring in cardiac arrest: a randomized trial

<p>Abstract</p> <p>Background</p> <p>In-hospital cardiac arrest has a poor prognosis despite active electrocardiography monitoring. The initial rhythm of approximately 25% of in-hospital cardiopulmonary resuscitation (CPR) events is pulseless ventricular tachycardia/ventricular fibrillation (VT/VF). Early defibrillation is an independent predictor of survival in CPR events caused by VT/VF. The automated external cardioverter defibrillator (AECD) is a device attached by pads to the chest wall that monitors, detects, and within seconds, automatically delivers electric countershock to an appropriate tachyarrhythmia.</p> <p>Study Objectives</p> <p>• To evaluate safety of AECD monitoring in hospitalized patients.</p> <p>• To evaluate whether AECDs provide earlier defibrillation than hospital code teams.</p> <p>Methods</p> <p>The study is a prospective trial randomizing patients admitted to the telemetry ward to standard CPR (code team) or standard CPR plus AECD monitoring (PowerHeart CRM). The AECD is programmed to deliver one 150 J biphasic shock to patients in sustained VT/VF. Data is collected using the Utstein criteria for cardiac arrest. The primary endpoint is time-to-defibrillation; secondary outcomes include neurological status and survival to discharge, with 3-year follow-up.</p> <p>Results</p> <p>To date, 192 patients have been recruited in the time period between 10/10/2006 to 7/20/2007. A total of 3,655 hours of telemetry data have been analyzed in the AECD arm. The AECD has monitored ambulatory telemetry patients in sinus rhythm, sinus tachycardia, supraventricular tachycardia, atrial flutter or fibrillation, with premature ventricular complexes and non-sustained VT without delivery of inappropriate shocks. One patient experienced sustained VT during AECD monitoring, who was successfully defibrillated (17 seconds after meeting programmed criteria). There are no events to report in the control arm. The patient survived the event without neurological complications. During the same time period, mean time to shock for VT/VF cardiac arrest occurring outside the telemetry ward was 230 ± 50 seconds.</p> <p>Conclusion</p> <p>AECD monitoring is safe and likely results in earlier defibrillation than standard telemetry monitoring.</p> <p>Trial Registration</p> <p>National Institutes of Health registration ID: NCT00382928</p

Effect of α7 nicotinic acetylcholine receptor activation on cardiac fibroblasts: A mechanism underlying RV fibrosis associated with cigarette smoke exposure

INTRODUCTION: Right ventricular dysfunction is associated with numerous smoking-related illnesses including chronic obstructive pulmonary disease (COPD) where it is present even in absence of pulmonary hypertension. It is unknown if exposure to cigarette smoke has direct effects on RV function and cardiac fibroblast proliferation or collagen synthesis. In this study, we evaluated cardiac function and fibrosis in mice exposed to cigarette smoke (CS) and determined mechanisms of smoke-induced changes in cardiac fibroblast signaling and fibrosis. METHODS: AKR mice were exposed to cigarette smoke for six weeks followed by echocardiography and evaluation of cardiac hypertrophy, collagen content, and pulmonary muscularization. Proliferation and collagen content were evaluated in primary isolated rat cardiac fibroblasts (CF) exposed to cigarette smoke extract (CSE) or nicotine. Markers of cell proliferation, fibrosis, and proliferative signaling were determined by immunoblot or Sircol collagen assay. RESULTS: Mice exposed to CS had significantly decreased RV function as determined by TAPSE. There were no changes in LV parameters. RV collagen content was significantly elevated but there was no change in RV hypertrophy or pulmonary vascular muscularization. CSE directly increased cardiac fibroblast proliferation and collagen content in CF. Nicotine alone reproduced these effects. CSE and nicotine-induced fibroblast proliferation and collagen content were mediated through α7 nicotinic acetylcholine receptors and were dependent on PKC-α, PKC-δ, and reduced p38-MAPK phosphorylation. CONCLUSION: CS and nicotine have direct effects on cardiac fibroblasts to induce proliferation and fibrosis which may negatively affect right heart function

CD8+ T cell concentration determines their efficiency in killing cognate antigen–expressing syngeneic mammalian cells in vitro and in mouse tissues

We describe a quantitative model for assessing the cytolytic activity of antigen-specific CD8+ T cells in vitro and in vivo in which the concentration of antigen-specific CD8+ T cells determines the efficiency with which these cells kill cognate antigen–expressing melanoma cells in packed cell pellets, in three-dimensional collagen-fibrin gels in vitro, and in established melanomas in vivo. In combination with a clonogenic assay for melanoma cells, collagen-fibrin gels are 4,500–5,500-fold more sensitive than the packed cell pellet–type assays generally used to measure CD8+ T cell cytolytic activity. An equation previously used to describe neutrophil bactericidal activity in vitro and in vivo also describes antigen-specific CD8+ T cell–mediated cytolysis of cognate antigen-expressing melanoma cells in collagen-fibrin gels in vitro and in transplanted tumors in vivo. We have used this equation to calculate the critical concentration of antigen-specific CD8+ T cells, which is the concentration of these cells required to hold constant the concentration of a growing population of cognate antigen-expressing melanoma cells. It is ∼3.5 × 105/ml collagen-fibrin gel in vitro and ∼3 × 106/ml or /g melanoma for previously published studies of ex vivo–activated adoptively transferred tumor antigen–specific CD8+ T cell killing of cognate antigen–expressing melanoma cells in established tumors in vivo. The antigen-specific CD8+ T cell concentration required to kill 100% of 2 × 107/ml cognate antigen-expressing melanoma cells in collagen fibrin gels is ≥107/ml of gel

Pollen sterols are associated with phylogenetics and environment but not with pollinators

Phytosterols are primary plant metabolites that have fundamental structural and regulatory functions. They are also essential nutrients for phytophagous insects, including pollinators, that cannot synthesize sterols. Despite the well-described composition and diversity in vegetative plant tissues, few studies have examined phytosterol diversity in pollen. We quantified 25 pollen phytosterols in 122 plant species (105 genera, 51 families) to determine their composition and diversity across plant taxa. We searched literature and databases for plant phylogeny, environmental conditions, and pollinator guilds of the species to examine the relationships with pollen sterols. 24-methylenecholesterol, sitosterol and isofucosterol were the most common and abundant pollen sterols. We found phylogenetic clustering of twelve individual sterols, total sterol content and sterol diversity, and of sterol groupings that reflect their underlying biosynthesis pathway (24 carbon alkylation, ring B desaturation). Plants originating in tropical-like climates (higher mean annual temperature, lower temperature seasonality, higher precipitation in wettest quarter) were more likely to record higher pollen sterol content. However, pollen sterol composition and content showed no clear relationship with pollinator guilds. Our study is the first to show that pollen sterol diversity is phylogenetically clustered and that pollen sterol content may adapt to environmental conditions

Early efficacy of CABG care delivery in a low procedure-volume community hospital: operative and midterm results

BACKGROUND: The Leapfrog Group recommended that coronary artery bypass grafting (CABG) surgery should be done at high volume hospitals (>450 per year) without corresponding surgeon-volume criteria. The latter confounds procedure-volume effects substantially, and it is suggested that high surgeon-volume (>125 per year) rather than hospital-volume may be a more appropriate indicator of CABG quality. METHODS: We assessed 3-year isolated CABG morbidity and mortality outcomes at a low-volume hospital (LVH: 504 cases) and compared them to the corresponding Society of Thoracic Surgeons (STS) national data over the same period (2001–2003). All CABGs were performed by 5 high-volume surgeons (161–285 per year). "Best practice" care at LVH – including effective practice guidelines, protocols, data acquisition capabilities, case review process, dedicated facilities and support personnel – were closely modeled after a high-volume hospital served by the same surgeon-team. RESULTS: Operative mortality was similar for LVH and STS (OM: 2.38% vs. 2.53%), and the corresponding LVH observed-to-expected mortality (O/E = 0.81) indicated good quality relative to the STS risk model (O/E<1). Also, these results were consistent irrespective of risk category: O/E was 0, 0.9 and 1.03 for very-low risk (<1%), low risk (1–3%) and moderate-to-high risk category (>3%), respectively. Postoperative leg wound infections, ventilator hours, renal dysfunction (no dialysis), and atrial fibrillation were higher for LVH, but hospital stay was not. The unadjusted Kaplan-Meier survival for the LVH cohort was 96%, 94%, and 92% at one, two, and three years, respectively. CONCLUSION: Our results demonstrated that high quality CABG care can be achieved at LVH programs if 1) served by high volume surgeons and 2) patient care procedures similar to those of large programs are implemented. This approach may prove a useful paradigm to ensure high quality CABG care and early efficacy at low volume institutions that wish to comply with the Leapfrog standards

CloVR: A virtual machine for automated and portable sequence analysis from the desktop using cloud computing

Next-generation sequencing technologies have decentralized sequence acquisition, increasing the demand for new bioinformatics tools that are easy to use, portable across multiple platforms, and scalable for high-throughput applications. Cloud computing platforms provide on-demand access to computing infrastructure over the Internet and can be used in combination with custom built virtual machines to distribute pre-packaged with pre-configured software. We describe the Cloud Virtual Resource, CloVR, a new desktop application for push-button automated sequence analysis that can utilize cloud computing resources. CloVR is implemented as a single portable virtual machine (VM) that provides several automated analysis pipelines for microbial genomics, including 16S, whole genome and metagenome sequence analysis. The CloVR VM runs on a personal computer, utilizes local computer resources and requires minimal installation, addressing key challenges in deploying bioinformatics workflows. In addition CloVR supports use of remote cloud computing resources to improve performance for large-scale sequence processing. In a case study, we demonstrate the use of CloVR to automatically process next-generation sequencing data on multiple cloud computing platforms. The CloVR VM and associated architecture lowers the barrier of entry for utilizing complex analysis protocols on both local single- and multi-core computers and cloud systems for high throughput data processing.https://doi.org/10.1186/1471-2105-12-35

The role of routine post-natal abdominal ultrasound for newborns in a resource-poor setting: a longitudinal study

<p>Abstract</p> <p>Background-</p> <p>Neonatal abdominal ultrasound is usually performed in Nigeria to investigate neonatal symptoms rather than as a follow up to evaluate fetal abnormalities which were detected on prenatal ultrasound. The role of routine obstetric ultrasonography in the monitoring of pregnancy and identification of fetal malformations has partly contributed to lowering of fetal mortality rates. In Nigeria which has a high maternal and fetal mortality rate, many pregnant women do not have ante-natal care and not infrequently, women also deliver their babies at home and only bring the newborns to the clinics for immunization. Even when performed, most routine obstetric scans are not targeted towards the detection of fetal abnormalities.</p> <p>The aim of the present study is to evaluate the benefit of routinely performing abdominal scans on newborns with a view to detecting possible abnormalities which may have been missed ante-natally.</p> <p>Methods-</p> <p>This was a longitudinal study of 202 consecutive, apparently normal newborns. Routine clinical examination and abdominal ultrasound scans were performed on the babies by their mother's bedside, before discharge. Neonates with abnormal initial scans had follow-up scans.</p> <p>Results-</p> <p>There were 108 males and 94 females. There were 12 (5.9%) abnormal scans seen in five male and seven female neonates. Eleven of the twelve abnormalities were in the kidneys, six on the left and five on the right. Three of the four major renal anomalies- absent kidney, ectopic/pelvic kidney and two cases of severe hydronephrosis were however on the left side. There was one suprarenal abnormality on the right suspected to be a possible infected adrenal haemorrage. Nine of the abnormal cases reported for follow- up and of these, two cases had persistent severe abnormalities.</p> <p>Conclusions-</p> <p>This study demonstrated a 5.9% incidence of genito urinary anomalies on routine neonatal abdominal ultrasound in this small population. Routine obstetric USS is very useful but inadequate availability of skilled personnel and cost implications create great challenges in poor resource settings like Nigeria. However, awareness should be created so that parents who can afford such investigations can make informed decisions.</p