bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutrients obtained from leaf litter can improve the growth of dipterocarp seedlings
Authors: Brearley Francis Q. , Press Malcolm C. , Scholes Julie D. 
Published: September 2003

Summary• In tropical rain forests the rate of litterfall is high, and is the most important nutrient cycling pathway in these ecosystems. We tested two hypotheses using seedlings of dipterocarp species: (1) addition of leaf litter improves growth; (2) and litter addition affects both ectomycorrhizal (ECM) colonization and community structure.• Three dipterocarp species with contrasting ecologies (Parashorea tomentella, Hopea nervosa and Dryobalanops lanceolata) were grown in a nursery in forest soil with or without the addition of litter.• Litter addition improved the growth of all three species. There was no effect of litter addition on total percentage ECM colonization but ECM diversity and percentage colonization by Cenococcum geophilum were lower with litter addition. Foliar δ15N was lower in two of the three species grown in the presence of litter, reflecting the lower δ15N of the litter compared with the soil. There was a negative correlation between δ15N and percentage ECM, suggesting a role for ECMs in accessing litter‐derived N sources.• This study shows that litter addition improved the growth of dipterocarp seedlings and that the ECM associations of dipterocarps facilitated access to this organic nutrient source. This has implications for the successful regeneration of seedlings in the rain forest understorey.
Biochemical traits of lichens differing in relative desiccation tolerance
Authors: Kranner Ilse , Zorn Margret , Turk Boris , Wornik Sabine , Beckett Richard P. , Batič Franc 
Published: September 2003

Summary• Oxidative stress arises when desiccation restricts photosynthesis and light energy is transferred from photo‐excited pigments onto ground state oxygen. We tested whether a highly desiccation tolerant lichen, Pseudevernia furfuracea, displays better protection against oxidative stress than more sensitive species, Lobaria pulmonaria and Peltigera polydactyla.• We rehydrated lichens after desiccation periods of 2, 7 and 9 weeks and assessed their viability by measuring CO2 exchange using IRGA. During desiccation and rehydration, photosynthetic pigments and the antioxidant α‐tocopherol were analysed by HPLC, and peroxidases by spectrophotometry.•  Pseudevernia furfuracea contained considerably lower chlorophyll, α‐tocopherol and β‐carotene concentrations and peroxidase activity than the two other lichens. However, it recovered photosynthesis rapidly, even after remaining in the desiccated state for 2 months while there was a significant delay in the onset of photosynthesis in L. pulmonaria and P. polydactyla.• We conclude that high antioxidant concentrations do not necessarily indicate better adaptation to desiccation. Rather, the ability to rapidly re‐establish the species‐specific normal antioxidant concentrations during rehydration, even after longer desiccation times, is a characteristic of well‐adapted species.
Extreme events as shaping physiology, ecology, and evolution of plants: toward a unified definition and evaluation of their consequences
Authors: Gutschick Vincent P. , BassiriRad Hormoz 
Published: September 2003

SummaryHere we consider how extreme events, particularly climatic and biotic, affect the physiology, development, ecology and evolution of organisms, focusing on plants. The marked effects on organisms are of increasing interest for ecological prediction, given the natural and anthropogenic changes in spectra of extreme events being induced by global change. Yet there is currently a paucity of knowledge or even a common world‐view of how extreme events shape individuals, communities and ecosystems. We propose that extreme events need be defined in terms of organismal responses of acclimation and of de‐acclimation or hysteresis. From this definition we proceed to develop a number of hypotheses, including that fitness effects of extreme events occur primarily during recovery. We review evidence that, on the evolutionary time scale, selection is virtually absent except during extreme events; these drive strong directional selection, even to trait fixation and speciation. We describe a number of new tools, both conceptual and technological, that are now at hand or that merit rapid development.

Contents

I.
Introduction
22

II.
Moving to an organismally based definition of extreme events
22

III.
Features to discern in extreme events
26

IV.
Additional challenges in the study of extreme events
27

V.
Evolutionary dimensions
29

VI.
The mandate for new conceptual tools for ecological and evolutionary prediction
34

VII.
Tools in hand, and tools needed, to study extreme events
35

VIII.
Conclusions
37

Acknowledgements
37

References
38
Editorials: Sodium Balance in Hemodialysis Therapy
Authors: Kooman Jeroen P. , Van Der Sande Frank , Leunissen Karel , Locatelli Francesco 
Published: September 2003

AbstractWater and sodium overload is the predominant factor in the pathogenesis of hypertension in dialysis patients. In many dialysis patients, dry weight is not reached because of an imbalance between the interdialytic accumulation of water and sodium and the brief and discontinuous nature of routine dialysis therapy. During dialysis, sodium is removed by convection and to a lesser degree by diffusion. However, with supraphysiologic dialysate sodium concentrations, diffusive influx from dialysate may occur, especially in patients with low predialytic plasma sodium concentrations. Measuring sodium removal during dialysis is difficult and hampered by the variability in conventional sodium measurements. Ionic mass removal by continuous measurement of conductivity in the dialysate ports appears to be a promising tool for the approximation of sodium removal during dialysis. While the beneficial effects of concomitant water and sodium removal on blood pressure control in dialysis patients are undisputed, it is less well known whether a change in hydrosodium balance solely by reducing dialysate sodium is beneficial. Considering the inherent dangers of such an approach (intradialytic hemodynamic instability), the beneficial effects of strict dietary sodium restriction appear to be of much larger clinical benefit. It has become possible to individualize dialysate sodium concentration by means of online measurements of plasma conductivity and adjustment of dialysate conductivity by feedback technologies. The clinical benefits of this approach deserve further study. Still, reducing dietary sodium intake remains the most important tool in improving blood control in dialysis patients.
Ethical Issues in Dialysis Alan Spital, Series Editor: Organ Allocation: A Case for not Transplanting the Violent Criminal
Authors: West John C. , Chao Stan , Kelley Stephen E. , Schwartz Jan A. , Bertsch David J. , Marsh James F. 
Published: September 2003

AbstractAs organ transplantation outcomes become ever more successful, vigilance as to appropriate recipient selection must be ensured, for without careful monitoring the already great disparity between organ supply and demand will continue to grow. There is a public perception that justice requires equal access to treatment for all, but this is not always the case. We suggest that, while violent felons do not account for a large number of transplant recipients, transplanting even one such individual should be deemed inadvisable—and could well be fraught with irreparable public repercussions.
Review Articles: Management Options for Hydrothorax Complicating Peritoneal Dialysis
Authors: Chow Kai Ming , Szeto Cheuk Chun , Li Philip Kam‐Tao 
Published: September 2003

AbstractHydrothorax as a result of pleuroperitoneal communication occurs in approximately 2% of continuous ambulatory peritoneal dialysis (CAPD) patients. Although our understanding of its mechanisms is incomplete, it is apparent that the key to successful therapy is obliteration of a transdiaphragmatic route of dialysate leakage (pleuroperitoneal communication), possibly coupled with reduction of intra‐abdominal pressure. This review corroborated the findings from 10 major population‐based case series in which 60 of the 104 cases (58%) were able to resume long‐term peritoneal dialysis (PD). Temporary interruption of PD alone was successful in half of them. As compared to this conservative approach, as well as chemical pleurodesis via intercostal chest drain, video‐assisted thoracoscopic intervention (including direct pleurodesis and diaphragmatic repair) has shown a promising role. Efficacy of thoracoscopic treatment has been confirmed by several case series from various centers and the demonstration of a success rate in excess of 90%. With accumulating experience using the thoracoscopic technique, it remains to be seen whether this mode of treatment will obviate the traditional closed pleurodesis.
Dialysis Rounds A Dialysis Case Presentation and Discussion Edited by Roger A. Rodby: Bloody Ascites in a Patient After Transfer from Peritoneal Dialysis to Hemodialysis
Authors: Pollock Carol A. 
Published: September 2003

AbstractA 65‐year‐old woman with end‐stage renal disease (ESRD) presented with bloody ascites. She had been maintained on peritoneal dialysis (PD) for 7 years and had eight episodes of peritonitis. She was eventually transferred to hemodialysis (HD) because of ultrafiltration failure. This was associated with “high” peritoneal transport by peritoneal equilibration test (PET). A period of “peritoneal rest” did not improve PET results. Within a year of transfer to HD, ascites developed, which was hemorrhagic upon evaluation. A computed tomography (CT) scan suggested encapsulating sclerosing peritonitis, which was confirmed upon peritonoscopy. The patient was treated with prednisone and tamoxifen. Encapsulating peritoneal sclerosis (EPS) is a devastating complication of PD. Although it is rare and its development often unpredictable, this case demonstrates several clinical features commonly observed in the condition. These include more than 6 years on PD, a high transporter status, recurrent peritonitis, and the development of blood‐stained dialysis effluent (or ascites if PD has been discontinued, as was the case in this patient). The initial presentation is often incipient with vague abdominal pain. Symptoms are progressive, however, and EPS has a high mortality rate, with most patients dying within 1 year of diagnosis, usually from malnutrition and sepsis. Treatment options include systemic immunosuppression and regular peritoneal irrigation after transfer to HD. Response to treatment is more likely to occur in the early inflammatory stage of EPS, when symptoms are nonspecific and imaging is relatively normal. Hence a high degree of suspicion for the diagnosis should be present in patients “at risk” of this condition, as early diagnosis is essential if progressive encapsulation of the abdominal viscera is to be prevented.
Analysis of Implantable Cardioverter Defibrillator Therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial
Authors: KLEIN RICHARD C. , RAITT MERRITT H. , WILKOFF BRUCE L. , BECKMAN KAREN J. , COROMILAS JAMES , WYSE D. GEORGE , FRIEDMAN PETER L. , MARTINS JAMES B. , EPSTEIN ANDREW E. , HALLSTROM ALFRED P. , LEDINGHAM ROBERT B. , BELCO KAREN M. , GREENE H. LEON ,   The Avid Investigators
Published: September 2003

Introduction: The implantable cardioverter defibrillator (ICD) is commonly used to treat patients with documented sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia recurrence rates in these patients are high, but which patients will receive a therapy and the forms of arrhythmia recurrence (VT or VF) are poorly understood. Methods and Results: The therapy delivered by the ICD was examined in 449 patients randomized to ICD therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. Events triggering ICD shocks or antitachycardia pacing (ATP) were reviewed for arrhythmia diagnosis, clinical symptoms, activity at the onset of the arrhythmia, and appropriateness and results of therapy. Both shock and ATP therapies were frequent by 2 years, with 68% of patients receiving some therapy or having an arrhythmic death. An appropriate shock was delivered in 53% of patients, and ATP was delivered in 68% of patients who had ATP activated. The first arrhythmia treated in follow‐up was diagnosed as VT (63%), VF (13%), supraventricular tachycardia (18%), unknown arrhythmia (3%), or due to ICD malfunction or inappropriate sensing (3%). Acceleration of an arrhythmia by the ICD occurred in 8% of patients who received any therapy. No physical activity consistently preceded arrhythmias, nor did any single clinical factor predict the symptoms of the arrhythmia. Conclusion: Delivery of ICD therapy in AVID patients was common, primarily due to VT. Inappropriate ICD therapy occurred frequently. Use of ICD therapy as a surrogate endpoint for death in clinical trials should be avoided. (J Cardiovasc Electrophysiol, Vol. 14, pp. 940‐948, September 2003)
Effects of Isoproterenol and Amiodarone on the Double Potential Interval After Ablation of the Cavotricuspid Isthmus
Authors: TADA HIROSHI , ÖZAYDIN MEHMET , CHUGH AMAN , SCHARF CHRISTOPH , ORAL HAKAN , PELOSI FRANK , KNIGHT BRADLEY P. , STRICKBERGER S. ADAM , MORADY FRED 
Published: September 2003

Introduction: A corridor of double potentials along the ablation line has been recognized to be an indicator of complete cavotricuspid isthmus block. Isoproterenol is used to confirm cavotricuspid isthmus block, but the effects of isoproterenol on the double potential interval (DPI), either in the absence or presence of amiodarone, are unknown. Methods and Results: Thirty‐two patients with isthmus‐dependent atrial flutter underwent successful ablation of the cavotricuspid isthmus. The procedure was performed in the drug‐free state in 23 patients, and 2 to 7 days after discontinuation of chronic amiodarone therapy in 9 patients. Electrograms recorded along the ablation line before and during isoproterenol infusion were analyzed after isthmus block was achieved. Double potentials were recorded along the entire ablation line upon achievement of complete isthmus block in all patients. The DPI in 9 patients treated with amiodarone was longer than in the other patients (147 ± 32 msec vs 119 ± 19 msec, P < 0.001). The DPI increased as the pacing cycle length shortened in patients treated with amiodarone, but not in the other patients. At all pacing cycle lengths, isoproterenol shortened the DPI to a greater extent in the patients treated with amiodarone than in the other patients. Conclusion: Amiodarone results in rate‐dependent prolongation of the DPI during coronary sinus pacing after ablation of the cavotricuspid isthmus. Isoproterenol shortens the DPI despite the presence of complete isthmus block, and this effect is accentuated in the presence of amiodarone. (J Cardiovasc Electrophysiol, Vol. 14, pp. 935‐939, September 2003)
Evaluation of Myocardial Performance with Conventional Single‐Site Ventricular Pacing and Biventricular Pacing in a Canine Model of Atrioventricular Block
Authors: FRIAS PATRICIO A. , CORVERA JOEL S. , SCHMARKEY LAURA , STRIEPER MARGARET , CAMPBELL ROBERT M. , VINTEN‐JOHANSEN JAKOB 
Published: September 2003

Introduction: The aim of this study was to evaluate epicardial biventricular pacing as a means of maintaining synchronous ventricular activation in an acute canine model of AV block with normal ventricular anatomy and function. Chronic single‐site ventricular pacing results in dyssynchronous ventricular activation and may contribute to ventricular dysfunction. Biventricular pacing has been used successfully in adult patients with congestive heart failure. Methods and Results: This was an acute study of open chest mongrel dogs (n = 13). ECG, left ventricular (LV), aortic, and pulmonary arterial pressures were measured. LV impedance catheters were used to assess cardiodynamics using instantaneous LV pressure‐volume relations (PVR). Following radiofrequency ablation of the AV node, a temporary pacemaker was programmed 10 beats/min above the intrinsic atrial rate, with an AV interval similar to the baseline intrinsic PR interval. The pacing protocol consisted of 5‐minute intervals with the following lead configurations: right atrium‐right ventricular apex (RA‐RVA), RA‐LV apex (LVA), and RA‐biventricular using combinations of four ventricular sites (RVA, RV outflow tract [RVOT], LVA, LV base [LVB]). RA‐RVA was used as the experimental control. LV systolic mechanics, as measured by the slope of the end‐systolic (Ees) PVR (ESPVR, mmHg/cc), was statistically greater (P < 0.05) with all modes of biventricular pacing (RA‐RVA/LVA 20.0 ± 2.9, RA‐RVA/LVB 18.4 ± 2.9, RA‐RVOT/LVA 15.1 ± 1.8, RA‐RVOT/LVB 17.6 ± 2.9) compared to single‐site ventricular pacing (RA‐RVA 12.8 ± 1.6). Concurrent with this improvement in myocardial performance was a shortening of the QRS duration (RA‐RVA 97.7 ± 2.9 vs RA‐RVA/LVA 75.7 ± 4.9, RA‐RVA/LVB 70.3 ± 4.9, RA‐RVOT/LVA 65.3 ± 4.4, and RA‐RVOT/LVB 76.7 ± 5.9, P < 0.05). Conclusion: In this acute canine model of AV block, QRS duration shortened and LV performance improved with epicardial biventricular pacing compared to standard single‐site ventricular pacing. (J Cardiovasc Electrophysiol, Vol. 14, pp. 996‐1000, September 2003)
Prevention of Immediate Reinitiation of Atrial Tachyarrhythmias by High‐Rate Overdrive Pacing:
Authors: ISRAEL CARSTEN W. , GRÖNEFELD GERIAN , EHRLICH JOACHIM R. , LI YI‐GANG , HOHNLOSER STEFAN H. 
Published: September 2003

Introduction: Immediate reinitiation of atrial tachyarrhythmia (IRAT) is an important cause of failure to maintain sinus rhythm. IRAT prevention by overdrive pacing has not been evaluated in a prospective randomized trial. Methods and Results: Patients with a DDDRP pacemaker offering temporary atrial overdrive pacing after AT termination (Post Mode Switching Overdrive Pacing [PMOP]) were enrolled into the prospective PIRAT (Prevention of IRAT) trial if paroxysmal AT episodes occurred after implantation. PMOP was randomly activated (120 beats/min for 2 min) or inactive. After 3 months, device memory was interrogated, symptoms and quality of life assessed, and patients crossed over to the alternative treatment arm for another 3 months. Primary study endpoint was the number of AT episodes; secondary endpoints were the cumulative time in AT (AT burden), percentage of AT episodes with IRAT, symptoms, and quality of life with PMOP active versus inactive. In 37 patients (21 men; 69 ± 9 years), there was no difference in the median number of AT episodes (0.37 vs 0.34 per day), AT burden (both 1%), percentage of episodes with IRAT (30%vs 28%), symptoms, and quality of life during PMOP off versus on. With PMOP active, 29% of 439 ATs restarted during and 18% before PMOP intervention. The PMOP‐induced rate increase appeared to be associated with IRAT in 9% of AT episodes. Conclusion: Automatic overdrive pacing after AT termination did not prevent IRAT, mainly due to insufficient overdrive suppression even at 120 beats/min and the delay between AT termination and PMOP intervention. (J Cardiovasc Electrophysiol, Vol. 14, pp. 954‐959, September 2003)
Left Heart Pacing Lead Implantation Using Subxiphoid Videopericardioscopy
Authors: ZENATI MARCO A. , BONANOMI GIANLUCA , CHIN ALBERT K. , SCHWARTZMAN DAVID 
Published: September 2003

Introduction: Recent clinical data support the utility of left heart pacing. The transvenous approach for left heart pacing lead implantation is imperfect. A direct epicardial approach may have advantages, but heretofore its utility has been limited because of the requirement for thoracotomy. We sought to examine the feasibility of a method for epicardial lead implantation that did not require thoracotomy. Methods and Results: In five large swine, percutaneous access to the epicardium was achieved with subxiphoid videopericardioscopy, using a device that marries endoscopy with a port through which pacing leads could be introduced. In each animal, standard, active fixation pacing leads were implanted onto the left atrium and ventricle. The atrial lead was implanted at the base of the appendage. The ventricular lead was implanted on the anterior, lateral, and inferior walls. Continuous direct visualization of the epicardium provided guidance for lead localization and fixation, including avoidance of complications such as trauma to epicardial coronary vessels. Capture thresholds were uniformly low. Postmortem examination demonstrated anatomically accurate, uncomplicated lead fixation. Conclusion: Using subxiphoid videopericardioscopy, uncomplicated, anatomically accurate left heart epicardial pacing lead implantation can be achieved without thoracotomy. (J Cardiovasc Electrophysiol, Vol. 14, pp. 949‐953, September 2003)
Longevity and Life‐cycle Savings*
Authors: Bloom David E. , Canning David , Graham Bryan 
Published: September 2003

AbstractWe add health and longevity to a standard model of life‐cycle saving and show that, under plausible assumptions, increases in life expectancy lead to higher savings rates at every age, even when retirement is endogenous. In a stationary population these higher savings rates are offset by increased old age dependency, but during the disequilibrium phase, when longevity is rising, the effect on aggregate savings rates can be substantial. We find empirical support for this effect using a cross‐country panel of national savings rates.
Saving, Wealth and the Transition from Transfers to Individual Responsibility: The Cases of Taiwan and the United States*
Authors: Lee Ronald , Mason Andrew , Miller Timothy 
Published: September 2003

AbstractUnder the life‐cycle saving model, population aging leads to an increased demand for life‐cycle wealth. Changes in transfer systems create or destroy one component of life‐cycle wealth—transfer wealth. The decline in the familial transfer system in Taiwan and reform of the US Social Security system are two examples of ways that transfer wealth is reduced. The combined effects of aging and changes in transfer systems are analyzed using simulation analysis. Rapid aging and radical decline in transfer systems lead to a large but transitory surge in aggregate saving. Capital per worker increases rapidly and remains at a high level.
The Baby Boom and the Stock Market Boom*
Authors: Lim Kyung‐Mook , Weil David N. 
Published: September 2003

AbstractThis paper addresses two issues. The first is whether demographic change was plausibly responsible for the run‐up in stock prices over the last decade, and whether an attempt by the baby boom cohort to cash out of its investments in the period 2010–2030 might lead to an “asset meltdown”. The second issue is whether the rise in dependency that will accompany the retirement of the baby‐boom cohort calls for an increase in national saving. We analyze these issues using a forward‐looking macro‐demographic model, and show that they are related via the existence of installation costs for capital. If such costs are sufficiently large, then demographics do have the power to affect stock prices, but “saving for America's old age” is less optimal. However, conventional estimates of capital installation costs are not large enough to explain large stock price movements in response to actual demographic change.
Mortality and Early Growth in England, France and Sweden
Authors: Lagerlöf Nils‐Petter 
Published: September 2003

AbstractWe set up a stochastic open‐economy growth model with endogenous fertility and mortality. A three‐country version of the model is calibrated to pre‐industrial mortality data from England, France and Sweden. By fitting parameters to match observed rates of correlation in mortality rates, the model can also account for differences in both the volatility of mortality rates and the timing of the Industrial Revolution.