Predicting trait-environment relationships for venation networks along an Andes-Amazon elevation gradient.

Understanding functional trait-environment relationships (TERs) may improve predictions of community assembly. However, many empirical TERs have been weak or lacking conceptual foundation. TERs based on leaf venation networks may better link individuals and communities via hydraulic constraints. We report measurements of vein density, vein radius, and leaf thickness for more than 100 dominant species occurring in ten forest communities spanning a 3,300 m Andes-Amazon elevation gradient in Peru. We use these data to measure the strength of TERs at community scale and to determine whether observed TERs are similar to those predicted by physiological theory. We found strong support for TERs between all traits and temperature, as well weaker support for a predicted TER between maximum abundance-weighted leaf transpiration rate and maximum potential evapotranspiration. These results provide one approach for developing a more mechanistic trait-based community assembly theory.

Comparison of genetic variation between rare and common congeners of Dipodomys with estimates of contemporary and historical effective population size.

Species with low effective population sizes are at greater risk of extinction because of reduced genetic diversity. Such species are more vulnerable to chance events that decrease population sizes (e.g. demographic stochasticity). Dipodomys elator, (Texas kangaroo rat) is a kangaroo rat that is classified as threatened in Texas and field surveys from the past 50 years indicate that the distribution of this species has decreased. This suggests geographic range reductions that could have caused population fluctuations, potentially impacting effective population size. Conversely, the more common and widespread D. ordii (Ord's kangaroo rat) is thought to exhibit relative geographic and demographic stability. We assessed the genetic variation of D. elator and D. ordii samples using 3RAD, a modified restriction site associated sequencing approach. We hypothesized that D. elator would show lower levels of nucleotide diversity, observed heterozygosity, and effective population size when compared to D. ordii. We were also interested in identifying population structure within contemporary samples of D. elator and detecting genetic variation between temporal samples to understand demographic dynamics. We analyzed up to 61,000 single nucleotide polymorphisms. We found that genetic variability and effective population size in contemporary D. elator populations is lower than that of D. ordii. There is slight, if any, population structure within contemporary D. elator samples, and we found low genetic differentiation between spatial or temporal historical samples. This indicates little change in nuclear genetic diversity over 30 years. Results suggest that genetic diversity of D. elator has remained stable despite reduced population size and/or abundance, which may indicate a metapopulation-like system, whose fluctuations might counteract species extinction.

If You Build it Will They Come? Patients, Providers and Blockchains in Health Technology Assessment.

It is an open question as to whether blockchains can become an integral part of health care management in the US. On the one hand, there are the advocates of blockchains who see them as empowering patients to capture property rights to their medical records in a secure, encrypted, and portable form. On the other hand, there are blockchain critics that see the opportunities offered in health care as little different from those offered in other industries, viewing a blockchain structure as one that may reduce administrative and transaction costs, with little thought given to the potential of blockchain platforms to support a range of health technology assessment activities. While previous commentaries have pointed to this potential, the obstacles offered by the absence of clearly defined property rights and the absence of a market for DNA profiles have not been explored. The case put forward here is that any expectation that a blockchain as a 'one-stop-shop' for the interrogation of personal health records alone is unlikely to succeed. Apart from property rights effectively blocking this business model the blockchain vendor should consider targeted value added activities. At best, only a subset of records has the possibility of being transferred, with ongoing concerns regarding their quality and scope. This does not mean that the blockchain software model should be rejected. Far from it. The blockchain as a health technology assessment platform has the potential to support added value activities which not only improve the process of care and reduce costs and improve efficiencies, but also provide an ideal framework for property rights assignment. This opens the door to incentives and the monetization of value added health data by patients and providers, capturing rents that are at the moment expropriated by third parties. Critical issues are not only property rights and creation of a market place, but the ability to link and incentivize patients and their providers to support active blockchains to generate value added.

Blockchains, Formulary Evaluations and Health Technology Assessment.

Blockchains have the potential, if appropriately implemented and managed, of contributing to a fundamental change in the application of techniques of health technology assessment in formulary decision making. Rather than continuing to rely on claims made by manufacturers that are non-evaluable, the introduction of blockchains as adjunct to the electronic medical record, meet an unmet medical need in enabling a platform for the real time assessment of claims. Rather than focusing the case for their product on lifetime cost-per-QALY models, which have no chance of ever being validated, the blockchain platform offers a low cost opportunity for claims evaluation. Manufacturers would be required to abandon the construction of imaginary cost-per-QALY worlds to support claims for pricing and formulary trier position, in favor of claims that can be evaluated and reported back to formulary committees in a short yet meaningful time horizon. Manufacturers would present a claims assessment protocol as part of the formulary submission package. If agreed with the formulary committee, the protocol would be implemented and managed through the patient blockchain membership. Claims would be monitored and evaluated in real time with a final report to the formulary committee in a matter of months. Lifetime imaginary claims for cost-per-QALY, set alongside willingness-to-pay thresholds, would be a thing of the past. Pricing decisions and formulary placement would reflect a robust evidence base and not just extrapolations from pivotal clinical trials.

Blockchains, Property Rights and Health Technology Assessment in the Pharmaceutical and Device (s) Industries.

Ongoing concerns with the security of health information, both from the perspective of the individual patient as well as health systems has led to increased attention being given to the potential role of blockchain technology in the secure storage of health information through encryption, the integration of diverse health record systems and the vesting of property and access rights to health data in the patient. While the security offered by blockchain technology has long been recognized in the finance sector with the emergence of a range of cryptocurrencies as a medium of exchange and store of value, demonstrating the value of blockchain technology in health management and health technology assessment has yet to be achieved. In this commentary, a number of questions are raised as to the potential value offered by blockchain technology as a complement to existing electronic medical record systems. Chief among these are: (i) the allocation of property rights as a necessary precondition for blockchain uptake; (ii) access and incentives for active as opposed to passive blockchain membership; (iii) monetization of blockchain access; (iv) capturing data from within the blockchain and the possibility of value added data; (v) the potential for blockchain platforms in formulary evaluations; (vi) the blockchain as a managed market for health data; and (vii) the role of intermediation in blockchain management.

Effect of statins and white blood cell count on mortality in patients with ischemic left ventricular dysfunction undergoing percutaneous coronary intervention.

BACKGROUND: While morbidity and mortality were shown to be increased in the setting of an elevated white blood cell (WBC) count for patients with acute coronary syndrome, the impact of statin therapy on mortality for patients with an elevated WBC count is unknown in high-risk patients with coronary artery disease. HYPOTHESIS: The goal of this study was to determine whether statin therapy improved survival in patients with elevated WBC count undergoing percutaneous coronary intervention (PCI) with preexisting left ventricular (LV) dysfunction, a population at high risk for adverse outcomes. METHODS: We retrospectively evaluated consecutive patient procedures performed at our institution from 1996 through 1999. Patients had a technically adequate angiographic left ventriculogram with a calculated ejection fraction (EF) < or = 50%. Patients with prior coronary artery bypass graft were excluded. Mortality data were retrieved using the U.S. Social Security Death Index. Follow-up ranged from 3.5 to 6.5 years. Means are provided with +/- standard deviation, and p values < 0.05 were considered significant. RESULTS: Of the study population of 238 patients (average EF 39 +/- 9.8%, mean age 57.5 +/- 12 years, 68% men) 61% underwent PCI for a recent myocardial infarction, 68% received stents, and 65% were discharged on statins. Mean WBC count was 9,000 +/- 3,100 cells/mm3, with 28% of patients having a WBC > or = 10,000 cells/mm3. During follow-up, 27% of our population died. Patients with a WBC > or = 10,000 had worse survival than patients with WBC < 10,000 (1-year survival: 86 vs. 96%, p < 0.05; 3-year survival: 79 vs. 89%, p < 0.05). Survival was significantly improved in patients on statin therapy regardless of WBC count, but the greatest benefit tended to be in patients with WBC > or = 10,000 (WBC > or = 10,000; odds ratio [OR] 5.14, 95% confidence interval [CI] 1.44-19.0, WBC < 10,000; OR 2.79,95% CI 1.13-7.1). Proportional hazard regression analysis demonstrated that both statin therapy and WBC count predicted mortality. CONCLUSION: Patients undergoing PCI with LV dysfunction discharged on statins had improved survival regardless of WBC count, with a trend for greater improvement in patients with elevated WBC counts. In addition, WBC count predicts mortality in this high-risk population with LV dysfunction undergoing PCI.

Laser angioplasty and laser-induced thrombolysis in revascularization of anomalous coronary arteries.

Acute coronary syndromes such as unstable angina and myocardial infarction are attributed to a pathophysiologic process that involves rupture of atherosclerotic plaque and subsequent thrombosis. Percutaneous intervention of anomalous coronary arteries in patients who present with acute coronary syndromes impose unique technical challenges related to the specific anatomic course and morphology of these vessels. Selection of appropriate guiding catheter configuration, choice of supportive guidewire, and proper delivery and activation of debulking devices and stents are important steps toward achieving adequate results. Excimer laser angioplasty is a debulking technology for removal of atherosclerotic plaque and associated thrombi. To date, application of laser angioplasty in anomalous coronary arteries is unreported. We herein present clinical data and discuss technical aspects related to performance of excimer laser angioplasty in three symptomatic patients with acute coronary syndrome, two having an anomalous right coronary artery and one with an anomalous circumflex artery. The delivery of laser energy in these cases resulted in rapid thrombolysis of an occlusive thrombus, successful debulking of the underlying atherosclerotic plaque, facilitation of adjunct balloon angioplasty and stenting, and ultimately, improved clinical condition.

Improved survival for stenting vs. balloon angioplasty for the treatment of coronary artery disease in patients with ischemic left ventricular dysfunction.

While earlier studies of balloon angioplasty (BA) in patients with left ventricular (LV) dysfunction suggested high late mortality, a study directly comparing coronary stenting and BA has not been performed. Since stenting provides a more durable revascularization, we sought to compare long-term survival in patients undergoing stenting vs BA in patients with decreased left ventricular ejection fractions (LVEF). We evaluated consecutive patient procedures performed in our institution from 1996 through 1999. Patients were considered part of the stent group if they received at least one stent. To be included, patients had to have a technically adequate angiographic LV gram with a calculated LVEF

Phased-array intracardiac echocardiography during pulmonary vein isolation and linear ablation for atrial fibrillation.

INTRODUCTION: Fluoroscopic imaging provides limited anatomic guidance for left atrial structures. The aim of this study was to determine the utility of real-time, phased-array intracardiac echocardiography during radiofrequency ablation for atrial fibrillation. METHODS AND RESULTS: In 29 patients undergoing pulmonary vein isolation (n = 16) or linear (n = 13) left atrial radiofrequency ablation for atrial fibrillation, intracardiac phased-array echocardiography was used to visualize left atrial anatomy and the pulmonary veins, as well as ablation and mapping catheters during ablation procedures. In the 16 pulmonary vein isolation patients, the mean pulmonary vein ostial diameters measured by venography and intracardiac echocardiography were similar for all veins positions, except that left common pulmonary vein diameters were larger as measured by echocardiography (2.50 +/- 0.29 cm) than by venography (1.79 +/- 0.50 cm, P = 0.001). The ostial diameters measured by echocardiography and venography were not correlated, however (r = 0.23, P = 0.19). As directed by echocardiography, only 1 of 25 circular mapping catheters (4%) used in 16 patients was replaced due to inappropriate sizing of the pulmonary veins. Mean pulmonary vein Doppler flow velocities increased after ablation for left-sided veins but ostial diameters were unchanged. In the linear ablation patients, the entire extent of the linear electrode array could be visualized in only 3 of 52 of catheter positions (6%) in the 13 patients. A portion of the catheter could be seen in only 50% of all target catheter positions. CONCLUSION: Phased-array intracardiac echocardiography (1) allows sizing and positioning of pulmonary vein mapping catheters, (2) provides measures of pulmonary vein ostial diameters, (3) continuously monitors pulmonary vein Doppler flow velocities, and (4) has limited use in positioning linear ablation catheters in the left atrium.