bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Prognostic Significance of Transesophageal versus Transthoracic Stress Echocardiography
Authors: Kamalesh Masoor , Matorin Robert , Sawada Stephen
Published: July 2003

Patients with a negative transthoracic stress echocardiographic study (TTE‐SE) are at low risk for adverse cardiac events. Because of a higher sensitivity for detection of coronary artery disease, transesophageal dobutamine stress echocardiography (TEE‐DSE) might permit identification of an even lower risk population. We compared the relative prognostic values of TTE‐SE and TEE‐DSE in 236 patients with negative stress echocardiograms. Baseline and follow‐up information on 236 consecutive subjects who had a negative stress echocardiographic study during the period of October 1996 to December 1997 was obtained. Baseline cardiac risk factors and major cardiac events (nonfatal myocardial infarct or cardiac death) were identified. Follow‐up was obtained in 233 subjects for a mean duration of 25 months. At baseline, the TEE‐DSE group had more hypertensives (85% vs 67%, P = 0.02) and more baseline wall‐motion abnormalities (41% vs 26%, P = 0.03). At 34 months of follow‐up, there was no significant difference in the occurrence of major cardiac events between the two groups (8% vs 8.6%, P = NS). In the TEE‐DSE group, there were more than twice as many events in the second year of follow‐up as compared with the first year, indicating that a negative TEE‐DSE has lessened prognostic value 1 year after the test. Standard TTE‐SE provides prognostic data in patients at high risk for major cardiac ischemic events that is equivalent to that obtained by TEE‐DSE. While advances in ultrasound techniques may improve our ability to detect coronary artery disease, it remains to be seen whether this will have an impact on prognostication.
An Unusual Pulsed‐Wave Tissue Doppler Pattern in Mitral Valve Prolapse: Spikes on Systolic Velocities
Authors: Dağdeviren Bahadır , Bolca Osman , Eren Mehmet , Akdemir Osman , Arıkan Erdinç , Gürlertop Yekta , Tezel Tuna
Published: July 2003

Background: Mitral valve prolapse (MVP) can be associated with wall‐motion abnormalities. Pulsed‐wave Doppler tissue imaging (DTI) has been proposed as a method to obtain myocardial velocities with a high spatial and temporal resolution. Our aim was to investigate whether a specific DTI pattern exists in myocardial segments of patients with MVP. Methods and Results: We studied 49 consecutive patients with clinically suspected MVP. MVP was diagnosed in 35 patients. After recording the conventional echocardiographic variables, apical‐directed left ventricular (LV) segmental myocardial velocities were obtained by DTI. The DTI analysis of myocardial segments revealed a distinct spectral Doppler pattern of mid‐ and basal posterior and lateral walls consistent with spikes on systolic velocities. These spikes were noticed in 23 (65%) patients with MVP but in none of the 14 subjects without MVP (P = 0.002). The MVP patients with spikes had larger mitral annulus diameters and higher amounts of maximal leaflet displacement when compared with those without spikes (34.8 ± 5 mm vs 31.2 ± 4 mm, P = 0.03 and 4.1 ± 1 ms vs 3.1 ± 1 mm, P = 0.01, respectively). Conclusion: This newly described unique DTI pattern, which may be observed in the majority of patients with MVP, may contribute to the diagnosis of disease. However, future studies are required to evaluate the clinical significance and pathophysiology of the spikes on systolic velocities of posterior and lateral walls in patients with MVP.
Assessment of Myocardial Blood Flow and Volume Using Myocardial Contrast Echocardiography
Authors: Wei Kevin
Published: July 2003

The development of new microbubble agents and ultrasound imaging modalities now allows the assessment of myocardial perfusion with echocardiography. Microbubbles also can be administered intravenously as constant infusions, which allows their concentration in blood to reach steady state. If the relation between microbubble concentration and video intensity is within the linear range, then myocardial video intensity will reflect the concentration of microbubbles in that region, which at steady state is the myocardial blood volume. The ability to destroy microbubbles and measure their replenishment into the ultrasound beam provides an opportunity to evaluate microbubble (or red blood cell) velocity. The product of myocardial blood volume and red blood cell velocity represents myocardial blood flow.
Assessment of Myocardial Viability with Myocardial Contrast Echocardiography
Authors: Lindner Jonathan R.
Published: July 2003

The application of noninvasive imaging techniques to assess myocardial viability has become an important part of routine management of patients with acute myocardial infarction and chronic coronary artery disease. Information regarding the presence and extent of viability may help identify patients likely to benefit from revascularization or therapy directed at attenuating left ventricular remodeling. Myocardial contrast echocardiography (MCE) is capable of defining the presence and extent of viability by providing an accurate assessment of microvascular integrity needed to maintain myocellular viability. It is especially suited for the spatial assessment of perfusion, even when myocardial blood flow is reduced substantially in the presence of severe epicardial stenoses or in a bed dependent on collateral perfusion. The routine use of MCE to evaluate viability in patients with acute and chronic coronary artery disease is now feasible with the advent of new imaging technologies and microbubble agents capable of myocardial opacification from venous injections. The utility of this technique for determining treatment strategies has not been established but is forthcoming.
Contrast and Harmonic Imaging Improves Accuracy and Efficiency of Novice Readers for Dobutamine Stress Echocardiography
Authors: Vlassak Irmien , Rubin David N. , Odabashian Jill A. , Garcia Mario J. , King Lisa M. , Lin Steve S. , Drinko Jeanne K. , Morehead Annitta J. , Prior David L. , Asher Craig R. , Klein Allan L. , Thomas James D.
Published: July 2003

Background: Newer contrast agents as well as tissue harmonic imaging enhance left ventricular (LV) endocardial border delineation, and therefore, improve LV wall‐motion analysis. Interpretation of dobutamine stress echocardiography is observer‐dependent and requires experience. This study was performed to evaluate whether these new imaging modalities would improve endocardial visualization and enhance accuracy and efficiency of the inexperienced reader interpreting dobutamine stress echocardiography. Methods and Results: Twenty‐nine consecutive patients with known or suspected coronary artery disease underwent dobutamine stress echocardiography. Both fundamental (2.5 MHZ) and harmonic (1.7 and 3.5 MHZ) mode images were obtained in four standard views at rest and at peak stress during a standard dobutamine infusion stress protocol. Following the noncontrast images, Optison was administered intravenously in bolus (0.5–3.0 ml), and fundamental and harmonic images were obtained. The dobutamine echocardiography studies were reviewed by one experienced and one inexperienced echocardiographer. LV segments were graded for image quality and function. Time for interpretation also was recorded. Contrast with harmonic imaging improved the diagnostic concordance of the novice reader to the expert reader by 7.1%, 7.5%, and 12.6% (P < 0.001) as compared with harmonic imaging, fundamental imaging, and fundamental imaging with contrast, respectively. For the novice reader, reading time was reduced by 47%, 55%, and 58% (P < 0.005) as compared with the time needed for fundamental, fundamental contrast, and harmonic modes, respectively. With harmonic imaging, the image quality score was 4.6% higher (P < 0.001) than for fundamental imaging. Image quality scores were not significantly different for noncontrast and contrast images. Conclusion: Harmonic imaging with contrast significantly improves the accuracy and efficiency of the novice dobutamine stress echocardiography reader. The use of harmonic imaging reduces the frequency of nondiagnostic wall segments.
Bioeffects of Myocardial Contrast Microbubble Destruction by Echocardiography
Authors: Chen Shuyuan , Kroll Martin H. , Shohet Ralph V. , Frenkel Peter , Mayer Susan A. , Grayburn Paul A.
Published: July 2003

Background: Microbubble destruction during contrast echocardiography is known to cause capillary leaks and red blood cell extravasation in skeletal muscle. This study evaluated the biological effects of microbubble destruction on cardiac muscle. Methods: Contrast echocardiography was performed in 36 rats randomized to receive either Definity or Optison at a mechanical index (MI) of 1.6, 1.2, or 0.8. Myocardial bioeffects were assessed by measuring left ventricular (LV) size and fractional area shortening and histopathology. In addition, blood samples for troponin T were drawn at baseline, postinfusion (30 minutes), day 1, day 4, and day 7. LV size and function were measured at baseline and immediately prior to euthanasia on day 7, after which the heart was removed and sectioned for histopathology. Results: There was no statistical difference in LV size or function regardless of the contrast agent or MI, nor was there any histopathological evidence of myocardial damage. However, troponin T increased over time (F = 3.77, P = 0.012), peaking at 30 minutes and returning to normal by day 4. The difference between Definity and Optison was not statistically significant. However, troponin T values were higher at a higher MI (F = 5.01, P = 0.012). Of 12 rats imaged at a MI of 1.6, 9 (75%) had elevated troponin T as compared to 4 (33%) of 12 at a MI of 1.2. None of the 12 rats imaged at a MI of 0.8 had an elevated troponin T at any time point. Conclusions: Microbubble destruction at high acoustic power (MI 1.6) can cause mild troponin T elevations that are not associated with LV dysfunction or histopathological evidence of myocardial damage.
One‐Year Follow‐Up of a Patient with Reversible Tricuspid Valve Stenosis Due to Lymphomatic Mass into the Right Atrioventricular Wall
Authors: Chrissos Dimitrios , Kalmantis Themistocles , Belegrati Maria , Katsaros Andreas , Tapanlis Efstratios , Katsimichas Alexandros , Triantafillou Georgios , Kallikazaros Ioannis
Published: July 2003

We present the case of a 66‐year‐old man with a history of coronary artery disease and chronic lymphocytic leukemia (CLL) who was admitted to the hospital complaining of chest discomfort and shortness of breath on exertion. The echocardiogram revealed a severe pericardial effusion and a large echogenic mass that infiltrated the lateral wall of the right atrium and ventricle and created a moderate tricuspid valve stenosis. B cell intracardiac non‐Hodgkin lymphoma/CLL was diagnosed, and the patient was treated with six courses of CHOP chemotherapy. After the third course, the mass disappeared and the patient′s general condition substantially improved.
Transesophageal Color Doppler Three‐Dimensional Echocardiographic Assessment of Left Circumflex Coronary Artery Fistula
Authors: Nekkanti Rajasekhar , Mukhtar Osman , Nanda Navin C. , McGiffin David C.
Published: July 2003

We describe an adult patient with a left circumflex coronary artery fistula in whom color Doppler three‐dimensional transesophageal echocardiography demonstrated clearly the exact site of the communication with the coronary sinus near the left atrial appendage. This could not be delineated definitively by multiplane two‐dimensional transesophageal echocardiography.
The Role of Intraoperative Transesophageal Echocardiography in Heart Transplantation
Authors: Romano Paval , Mangion Judy R.
Published: July 2003

The number of centers that perform heart transplants has increased rapidly in recent years. Although transthoracic and transesophageal echocardiography (TTE and TEE) are utilized frequently to diagnose and manage cardiac complications commonly found in this population postoperatively, little has been written about the routine use of intraoperative TEE. Intraoperative echo is ideally suited to identify acute complications during cardiac transplantation. This can include immediate signs of rejection, valvular abnormalities, and mechanical complications related to the surgical procedure. Many of these patients might require ventricular assist devices (VAD) to provide circulatory support, and intraoperative TEE can be used to verify correct positioning of the VAD hardware. In addition, many of the chronic complications that patients with heart transplants are at risk for may be serious yet asymptomatic. Therefore, a high quality, complete intraoperative echocardiographic study might serve as an important baseline to compare postoperative changes.
Validation of Six Noninvasive Doppler Methods for the Assessment of Left Ventricular Filling Pressure
Authors: Kucher Nils , Schwerzmann Markus , Lipp Ernst , Eyer David , Meier Bernhard , Seiler Christian
Published: July 2003

Objectives: The aim of this study was to determine the accuracy of six noninvasive Doppler methods for assessing invasively derived left ventricular diastolic pressure (LVDP). Background: To date, no studies have evaluated which of the various available Doppler methods are most reliable in determining LVDP in a consecutive patient population with different cardiac diseases. Methods: LVDP was estimated by the following Doppler methods (M): (1) M1—the peak mitral regurgitant flow velocity (peak MR), (2) M2—the mitral regurgitant velocity at the time of aortic valve opening (MRAVO), (3) M3—the aortic regurgitant end‐diastolic flow velocity (ARED), (4) M4—the ratio of the transmitral to mitral annular early diastolic velocity (ETM/EDTI), (5) M5—a transmitral flow velocity regression equation (RegrTM), and (6) M6—the difference of pulmonary venous and transmitral A wave duration (APV− ATM duration). For M1–M3, sphygmomanometric blood pressure was used to calculate LVDP. Results: In 101 patients, the regression coefficient, standard error of estimate, and mean difference with confidence limits between Doppler and catheter‐derived measurements were as follows: M1 (n = 46): r = 0.81 (P < 0.0001), 4.3 mmHg and 3.7 ± 12.0 mmHg; M2 (n = 47): r = 0.79 (P < 0.0001), 5.4 mmHg and 1.1 ± 11.2 mmHg; M3 (n = 20): r = 0.64 (P = 0.002), 7.8 mmHg and 4.6 ± 17.6 mmHg; M4 (n = 50): r = 0.62 (P < 0.0001), 5.6 mmHg and 0 ± 11.2 mmHg; M5 (n = 79): r = 0.24 (P = 0.03), 7.1 mmHg and −0.1 ± 16.8 mmHg; and M6 (n = 79): r = 0.22 (P = 0.05), 7.3 mmHg and 0 ± 14.4 mmHg, respectively. Conclusions: The Doppler measurement of mitral regurgitant jets is most accurate method to estimate left ventricular filling pressure noninvasively.
Intraoperative Transesophageal Echocardiography in Congenital Heart Disease
Authors: Smallhorn Jeffrey F.
Published: July 2003

Intraoperative transesophageal echocardiography has become an integral component of the repair of congenital heart defects. It currently has a direct impact on reducing morbidity and mortality in the pediatric cardiac population. To establish a successful program, it is important to follow guidelines for training as well as having a systematic approach to the evaluation of this patient population. This article addresses the specific indications in a patient population as practiced at the Hospital For Sick Children, Toronto. While there may be subtle differences between programs, the objectives are to provide excellent service to the pediatric cardiac patient in the operating room.
The North American experience with the Ablate and Pace Trial (APT) for medically refractory atrial fibrillation
Authors: Wood M. A. , Kay G. N. , Ellenbogen K. A.
Published: July 2003

The Ablate and Pace Trial (APT) was a prospective registry study of clinical outcomes and survival following ablation and pacing therapy for medically refractory atrial fibril-lation. One hundred and fifty-six patients were enrolled at 16 centres in North America. The mean patient age was 66±11 years, with mean left ventricular ejection fraction of 48%±18%. Seventy-eight percent of the patients had structural heart disease.

During one year of follow up, multiple measures of quality-of-life showed significant and sustained improvement following ablation and pacing therapy. Also, left ventricular ejection increased significantly for patients with baseline left ventricular ejection fraction <45%. Metabolic exercise testing showed trends toward improved exercise tolerance; however, these did not achieve statistical significance. The one year overall survival was 85%, with 3% of patients experiencing sudden death.

In summary, this large, non-randomized, trial showed significant improvement in quality of life and left ventricular function following ablation and pacing therapy. Ablation and pacing therapy is a viable strategy for palliative management of patients with medically refractory, highly symptomatic atrial fibrillation.
Ablation of the atrioventricular junction
Authors: Marshall H. J. , Griffith M. J.
Published: July 2003

Atrioventricular junctional ablation is an attempt to interrupt conduction from the atrium to the ventricle using radiofrequency energy. The objective is to ablate the compact atrioventricular node as high as possible, leaving a stable ventricular escape rhythm. The compact node is identified in part by its relation to His recordings and partly through the known anatomy. In our series of 115 consecutive patients, atrioventricular block was achieved from the right side in 96% of patients and the remainder had the atrioventricular node ablated from the left side. Long-term success, i.e. complete heart block, was achieved in all patients. Complications in this and other series are rare, but there remains concern about sudden death in these patients.
Prospective, randomized study of atrioventricular ablation and mode-switching, dual chamber pacemaker implantation versus medical therapy in drug-resistant paroxysmal atrial fibrillation
Authors: Brignole M. , Gianfranchi L. , Menozzi C. , Alboni P. , Musso G. , Bongiorni M. G. , Gasparini M. , Raviele A. , Lolli G. , Paparella N. , Acquarone S.
Published: July 2003

We performed a prospective randomized 6-month evaluation of the clinical effects of atrioventricular junctional ablation together with placement of a DDDR mode-switching pacemaker vs pharmacological treatment in 43 patients with intolerable paroxysmal atrial fibrillation not controlled with antiarrhythmic drugs. Ablation and pacemaker treatment were highly effective and superior to drug therapy in controlling symptoms and improving quality of life. However, discontinuation of drug therapy exposed patients to further recurrences of paroxysmal atrial fibrillation and the risk of developing permanent atrial fibrillation.
Determinants of development of permanent atrial fibrillation and its treatment
Authors: Gianfranchi L. , Brignole M. , Menozzi C. , Lolli G. , Bottoni N.
Published: July 2003

We evaluated the rate of progression of permanent atrial fibrillation (AF) and identified clinical factors that predict this event in 63 consecutive patients who had undergone AV junctional ablation and DDDR pacemaker implantation for drug-refractory paroxysmal atrial fibrillation/flutter. Immediately after ablation, anti-arrhythmic drugs were discontinued in all cases. Permanent AF was con-sidered to have developed if AF was present on two consecutive 6-monthly examinations with no interim documented sinus rhythm. During a mean follow-up of 23±16 months, 22 (35%) of the 63 patients developed permanent AF. The actuarial estimate of progression of permanent AF was 22%, 40% and 56%, respectively, 1, 2 and 3 years after ablation. Age and underlying heart disease were independent predictors of progression of permanent AF. Only one (6%) of 16 patients with idiopathic AF had permanent AF (low risk group). Among the 47 patients with structural heart disease, permanent AF developed in 18 (62%) of the 29 who were aged >75 years or had >12 arrhythmic episodes per year and a symptom duration >4 years (high risk group), but only in three (17%) of the remaining 18 patients who did not (intermediate risk group). In conclusion, during a 3-year follow-up period, about half of the patients with a history of drug-refractory paroxysmal AF did not develop permanent AF after AV junctional ablation and dual-chamber pacemaker implantation, even in the absence of anti-arrhythmic drug therapy. Moreover, subgroups of patients whose risk of permanent AF progression differed were identified on the basis of simple baseline clinical variables. The results of this study form the necessary background for the correct management of patients after AV junction ablation and for the planning of future trials in this field.
Chronic atrial fibrillation in patients with paroxysmal atrial fibrillation, atrioventricular node ablation and pacemakers
Authors: McComb J. M. , Gribbin G. M.
Published: July 2003

Aims

This study examined the factors associated with the development of chronic (or permanent) atrial fibrillation (AF) in patients who had undergone atrioventricular (AV) node ablation with permanent pacing because of paroxysmal AF.

Methods

A retrospective review of case notes of all 65 consecutive patients identified as having had paroxysmal atrial arrhythmias, AV node ablation and permanent pacemaker implantation was performed. Atrial rhythm was established from all pacing records and from the surface ECG. Treatment with anti-arrhythmic drugs and with warfarin was recorded. A multivariate analysis was undertaken, using atrial rhythm on final ECG and chronic AF as outcome measures.

Results

During a mean follow-up of 30 months, 42% of patients with paroxysmal AF had developed chronic AF. Multivariate analysis showed that increasing age, history of electrical cardioversion and VVI pacing all contributed to the development of chronic AF. 25/62 patients were taking warfarin, and four had had strokes (2·5%/year).

Conclusions

The majority of patients with paroxysmal atrial arrhythmias treated with AV node ablation and pacing develop chronic AF eventually. Stroke remains a risk, particularly in those who develop chronic AF.
Assessment of accessory pathway and atrial refractoriness by transoesophageal and intracardiac atrial stimulation
Authors: Nanthakumar K. , Bergfeldt L. , Darpö B.
Published: July 2003

Aims

Measurement of the refractory properties of asymptomatic overt accessory pathways is performed to assess the risk for significant arrhythmias. We hypothesized that a transoesophageal atrial stimulation (TAS) protocol would accurately predict simultaneously measured invasive intra cardiac stimulation (ICS) of the anterograde effective refractory period of the accessory pathway (AP-ERP)

Methods and Results

Fourteen single pathway Wolff-Parkinson-White (WPW) syndrome patients underwent TAS during ICS and 24 h prior to it. The AP-ERP was measured using incremental atrial extra stimuli from TAS, the right atrium (RA) and the coronary sinus (CS) using drive trains of 500 and 600 ms. Stimulus latency was measured from intracardiac electrocardiograms. For methodological comparison, Altman–Bland analysis was used to create the limits of agreement (within-patient mean of differences±two standard deviations). There were no or small differences in the AP-ERP, as assessed by TAS, compared to RA and CS. Methodological disagreement between the three sites were common, however, and the limits of agreement ranged from ±30 to±76 ms. The concordance between TAS and RA, with regards to the AP-ERP value of 270 ms, was 63% when measured as S1S2 and was 67% when measured as A1A2. The stimulation site delay was significantly shorter for TAS compared to RA and CS sites. The two TAS procedures performed a day apart, revealed a coefficient of variation of 9% and a coefficient of reproducibility of 63 ms.

Conclusions

Despite adequate reproducibility, TAS fails to predict the AP-ERP by ICS. Differences in stimulus latency is responsible, in part, for the disagreement. In-vasive ICS cannot be replaced by TAS for risk stratifying WPW patients.
Report of a study group on ablate and pace therapy for paroxysmal atrial fibrillation
Authors: Brignole M. , Gammage M. , Jordaens L. , Sutton R.
Published: July 2003

Atrioventricular junctional (AVJ) catheter ablation followed by pacemaker implantation is now widely accepted for patients affected by paroxysmal atrial fibrillation (PAF) not controlled by antiarrhythmic drugs. However, few data exist on its indications, optimal methodology and complications. Therefore a study group examined current practice in Europe and North America, using a questionnaire, followed by a Study Group Meeting to discuss the results. Based upon this, class I, class II and class III indications were proposed. Class I indications (for which general agreement existed) include drug-refractory PAF, correlating with important symptoms, the bradycardia–tachycardia syndrome already treated with a pacemaker, and continued PAF. Large differences exist in the current methodology, but consensus was reached on the technical approaches of right and left-sided AVJ ablation, and on the timing of pacemaker implant in relation to ablation. No complete agreement was reached on technical features such as catheter choice and heparin use. The recommended pacing mode was DDDR with mode switching.
Heritability of a Quantitative and Qualitative Protease Inhibitor Polymorphism in Nicotiana attenuata
Authors: van Dam N. M. , Baldwin I. T.
Published: July 2003

Abstract: Many plant species contain chemical defenses that protect them against herbivores. Despite the benefit of these chemical defenses, not all individuals contain high levels of these compounds. In the native tobacco Nicotiana attenuata we found that plants from three natural populations differed considerably in their ability to produce trypsin protease inhibitors (PIs), which are defensive proteins that reduce herbivore damage to plants. Plants from a Utah (U) population produced high levels, whereas plants from Arizona (A) contained no detectable PI levels. Californian (C) plants had intermediate levels. The PI‐producing U and C plants thus differ quantitatively from each other, whereas they both differ qualitatively from PI‐deficient A plants. Here we analyze how PI production is inherited in N. attenuata with the ultimate goal of better understanding how the quantitative and qualitative differences between the three populations have evolved. Using a series of classical crossing designs, we determined that the ability to produce PIs is inherited as a dominant Mendelian trait. PI‐deficient plants contain two non‐functional recessive alleles, whereas heterozygous plants or homozygous dominant plants both are able to produce PIs. Similarly, the level of constitutive PIs may be determined by its genotype, either by an interaction between a functional and a non‐functional allele in heterozygotes, or by a factor on the PI allele itself in homozygous C plants. Based on these data and on previous studies with A and U plants we postulate that the PI‐deficient A plants may have originated from a mutant that lost its ability to produce PIs. The fitness loss due to reduced herbivore resistance may be offset by the fitness gain associated with increased competitive ability, a trade‐off which may maintain this mutation in the Arizona population.
Energy‐dependent Solute Uptake Into the Symplast of Leaves: ATP/KCl, ATP/Sucrose, ATP/D‐serine and H+/ATP Stoichiometries of Transmembrane Transport
Authors: Bukhov N. G. , Hedrich R. , Heber U.
Published: July 2003

Abstract: KCl, sucrose, D‐serine and some other solutes were fed through the petiole to leaflets of Solanum tuberosum and uptake into the symplast was monitored. Solute transport was accompanied by changes in membrane potential, apoplastic pH and respiration. After termination of solute feeding, membrane potential, apoplastic pH and respiration returned to initial steady state values. From transpiration, solute uptake was calculated and compared to ATP production during stimulated respiration, assuming an ATP/CO2 ratio of 5. On this basis, calculated ATP/KCl ratios of energized transport approached 0.5. Similar ATP/solute ratios were observed with sucrose, mannitol, methylglucose and D‐serine. With glucose, many ratios were somewhat above 0.5, possibly because of some metabolization of imported glucose. We conclude that solute uptake is energized by the proton motive force across the plasma membrane. Low ATP/substrate ratios suggest that the H+/ATP ratio of proton export by the plasma membrane ATPase is not 1 as presently assumed but 2 in potato leaves, and that the contribution of the alternative cyanide‐resistant oxidase to leaf respiration is small, if not negligible, in the dark.
Energized Uptake of Ascorbate and Dehydroascorbate From the Apoplast of Intact Leaves in Relation to Apoplastic Steady State Concentrations of Ascorbate
Authors: Heber U. , Bukhov N. G. , Wiese Ch. , Hedrich R.
Published: July 2003

Abstract: Transport of ascorbate (AA) and dehydroascorbate (DHA) through the petiole into detached leaves of Lepidium sativum and other plant species via the transpiration stream, and energized uptake into leaf tissue, were measured indirectly by recording changes in membrane potential and apoplastic pH simultaneously with substrate‐stimulated respiration and transpiratory water loss. When 25 mM AA or DHA was fed to the leaves, steady state respiration at 25 °C was transiently increased by more than 50 % with AA and 70 % with DHA. Stimulation of respiration was accompanied by a transient breakdown of membrane potential followed by alkalinization of the leaf apoplast suggesting energized uptake at the expense of the transmembrane proton motive force. The average CO2/AA ratio calculated from stimulated respiration during ascorbate uptake was 0.76 ± 0.26 (n = 17). The corresponding ratio for DHA was 1.38 ± 0.28 (n = 11). Far lower CO2/substrate ratios were observed when NaCl or KCl were fed to leaves. The differences indicate either partial metabolism of AA and DHA in addition to energized transport, or less likely, higher energy requirement for transport of AA and DHA than for the inorganic salts. Maximum rates of energized AA transport into leaf tissue (deduced from maxima of extra respiration and calculated on the basis of CO2/AA = 0.76) were close to 650 nmol m‐2 leaf area s‐1, i.e. far higher than most previously reported rates of transport. When the apoplastic concentration of AA was decreased below steady state levels during infiltration/centrifugation experiments, AA was released from leaf cells into the apoplast. This suggests that AA oxidation to DHA in the apoplast (as occurs during extracellular ozone detoxification) triggers energized transport of the DHA into the symplast and simultaneously AA release from the symplast into the apoplast, perhaps together with protons in a reversal of the energized uptake process.
Evaluation and Comparison of the GUS, LUC and GFP Reporter System for Gene Expression Studies in Plants
Authors: de Ruijter N. C. A. , Verhees J. , van Leeuwen W. , van der Krol A. R.
Published: July 2003

Abstract: The detailed analysis of the expression pattern of a plant gene can give important clues about its function in plant development, cell differentiation and defence reactions. Gene expression studies have been greatly facilitated by the employment of proteins like β‐glucuronidase (GUS), green fluorescent protein (GFP), and firefly luciferase (LUC) as reporters of gene activity. The application of reporter genes in plants, specifically in the field of gene expression studies, has expanded over the years from a mere tool to quantify (trans) gene expression in tissue samples, to real‐time imaging of in planta promoter dynamics. To correctly interpret the activity that is given by each reporter, it is important to have a good understanding of the intrinsic properties of the different reporter proteins. Here we discuss those properties of GUS, LUC and GFP that are of interest in gene expression studies.
The Comparative Analysis of Osmotins and Osmotin‐Like PR‐5 Proteins
Authors: Anžlovar S. , Dermastia M.
Published: July 2003

Abstract:One of the ways that plants respond to biotic and/or abiotic stress factors is the accumulation of pathogenesis‐related proteins of class 5 (PR‐5), which are evolutionary conserved in the plant kingdom. Within the PR‐5 family, a distinct subgroup of osmotin and closely related proteins has been characterized. In contrast to the extracellular forms of PR‐5 proteins, osmotins presumably accumulate in the vacuole of the cell. They contain a C‐terminal propeptide that is considered to be a determinant for vacuolar targeting. The comparison of the three‐dimensional structure of tobacco PR‐5 d with the sequences of some osmotins showed that the proteins consist of three conserved domains, with the acidic cleft between domains I and II. Besides the constitutive species and tissue‐specific presence, the osmotins are also induced by several abiotic and biotic stresses. Among them, fungal infections can elicit osmotin gene expression, and most known proteins from the family have antifungal activity inin vitroassays. In agreement with the osmotin structure and data on the activity of similar proteins, a two‐step mechanism, which involves reaction of osmotins with the fungal wall and the permeabilization of fungal membranes, is discussed.
Ecology, Biogeography and Pollen Morphology of Bienertia cycloptera Bunge ex Boiss. (Chenopodiaceae), an Enigmatic C4 Plant without Kranz Anatomy
Authors: Akhani H. , Ghobadnejhad M. , Hashemi S. M.
Published: July 2003

Abstract: Bienertia cycloptera is a most interesting terrestrial plant which applies C4 photosynthesis without Kranz cells, but with dimorphic chloroplasts in one cell. In order to study this special quality and provide more information about the natural habitat of the species and probable evolutionary trends, we have examined the plant communities associated with B. cycloptera, the climatic conditions in which this species occurs, soil characteristics and pollen morphology in comparison with several other possible relatives. B. cycloptera is distributed around Central Iranian deserts and subdeserts with northern and southern radiation in the Persian Gulf countries and Central Asia, from 24° to 49° N latitude and from 43° to 67° E longitude. It grows in areas with mean daily temperatures between 20 and 30 °C during the hot months of the year, and annual precipitation of 400 to 76 mm (but mostly of 200 to 100 mm). B. cycloptera grows on high salty and temporarily moist clay soils with a salinity ranging from 21.7 to 89.6 ds/m, both in Na+ and SO42‐ rich salty soils. In most plots, the percentage of C4 species is over 50 % and in some cases 100 %. Climacoptera turcomanica is the most frequently associated species with B. cycloptera in most habitats. In order to look for further comparative data to find the affinity and evolutionary trends in Suaedeae and Salicornioideae, the pollen morphology of B. cycloptera, Borszczowia aralocaspica, Halopeplis pygmaea, Salicornia persica and six species of Suaeda, each representing one section, are compared by light and SEM microscopy. The pollen grains of B. cycloptera have the lowest pore number, with a mean of 42 pores per grain. The pore numbers of B. cycloptera are very close to Halopeplis pygmaea, a member of the tribe Halopeplideae of subfamily Salicornioideae. Among the studied Suaedeae, the pollen of B. cycloptera shows similarities with Suaeda physophora with regard to pore number and pore diameter. The affinity of B. cycloptera is a matter of discrepancy. Three different possible origins and relationships in Suaeda sect. Immersa, sect. Physophora, sect. Schanginia and tribe Halopeplidae are discussed. We conclude that the evolution, diversification and adaptation of Central and SW Asian halophytes is the result of intricate environmental and geological history of the area and needs intensive multidisciplinary research.
An Hsp90 Inhibitor, Geldanamycin, as a Brassinosteroid Antagonist: Evidence from Salt‐Exposed Roots of Vigna radiata
Authors: Amzallag G. N. , Goloubinoff P.
Published: July 2003

Abstract: Treatment of non‐stressed mung bean cuttings with 24‐epibrassinolide (BR) inhibited elongation of adventitious roots, but it stimulated root elongation in plants exposed to 70 mM NaCl. These findings confirm that brassinosteroids are involved in control of division and elongation of root cells. We found that both positive and negative effects are counteracted by the presence of geldanamycin in the root medium. Because of the high specificity of geldanamycin for the chaperone Hsp90, this suggests that, as in animal cells, Hsp90 is involved in expression or transduction of the brassinosteroid signals in plants. Moreover, a detailed analysis of root ranking showed an additional geldanamycin‐insensitive mode of action of BR, especially observed under salt stress conditions. These two modes differently affected elongation of the adventitious roots, depended on the phases of differentiation and on the presence of an environmental constraint.
Plant Sphingolipids Today ‐ Are They Still Enigmatic?
Authors: Spassieva S. , Hille J.
Published: July 2003

Abstract: Sphingolipids are a diverse group of lipids found in all eukaryotes and some bacteria, consisting of a hydrophobic ceramide and a hydrophilic head group. We have summarised the contemporary understanding of the structure of plant sphingolipids with an emphasis on glucosylceramides and inositolphosphorylceramides. Plant glucosylceramides are important structural components of plasma and vacuole membranes. Inositolphosphorylceramides have been identified as moieties of the glycosylphosphorylinositol (GPI) anchors of plant proteins targeted to the plasma membrane. In the last few years, progress has been made in the cloning of plant genes coding for enzymes involved in sphingolipid metabolism. As found in yeast and mammals, the plant sphingolipid pathway is a potential generator of powerful cell signals. The role of plant sphingolipid metabolites in programmed cell death and calcium influx is discussed.
Factors Influencing Seed: Ovule Ratios and Reproductive Success in Four Cleistogamous Species: A Comparison between Two Flower Types
Authors: Berg H.
Published: July 2003

Abstract: Ovule and seed numbers, and the ratio between the two, were determined in chasmogamous (CH) and cleistogamous (CL) flowers/fruits in four perennial herbs: Viola hirta, V. mirabilis, V. riviniana, and Oxalis acetosella. The results were applied to data from earlier studies on fruit set and progeny performance in these species, to find implications for factors influencing seed: ovule (S: O) ratio, to relate S: O ratio to other fitness components, and to compare final numbers of seedlings per initiated ovule between the two reproductive modes. Mechanisms considered to have a potential impact on S: O ratios were pollen limitation, resource limitation, and “genetic load”. In V. mirabilis and O. acetosella, mean S: O ratio was significantly higher in the CL phase than in the CH phase; in V. hirta and V. riviniana, there was no difference. Pollen limitation seemed improbable as a factor important for seed set in all species, and no indication was found of resource limitation. There was a negative correlation between S: O ratio and seed germination rate in O. acetosella, indicating that seed abortion, particularly in CH fruits, may be a way to purge inferior zygotes. The high CH S: O ratios in all species suggest that substantial selfing also occurs in this phase. The final number of seedlings per ovule did not differ significantly between modes in any of the species, partly due to poorer germination in CL seeds. This indicates that, despite the often lower pre‐emergent reproductive success (fruit and seed set) in the CH phase, total reproductive success will not differ between the two modes because post‐emergent selection is stronger on CL progeny. The strongest limitation on pre‐emergent reproductive success in both phases is apparently related to flower/fruit abortion.
Sex Allocation in a Long‐Lived Monocarpic Plant
Authors: García M. B.
Published: July 2003

Abstract: Hermaphroditic plants with perfect flowers often show within‐inflorescence flower differentiation, lower female success (and therefore female investment) as the inflorescence develops, and size‐dependent sex allocation to male and female functions. Here, I present the results of a descriptive and experimental study in the long‐lived monocarpic Saxifraga longifolia, a sequentially blooming plant showing a large variation in the size of the inflorescence. Natural patterns of relative investment in male and female reproductive components were explored, and flowers were removed from different positions, in order to test two models on sex allocation which predict that female investment increases with resource availability. Results of this study agree with this prediction at the flower level (within inflorescences), but not at the plant level. Pre‐ and post‐mating female allocation declined from early to late‐position flowers, while the pollen: ovule increased. Removal of flowers indicated that architectural effects do not prevent full compensation for overall seed production, although the participation of terminal flowers in female reproduction was low in most cases. There seem to be some ontogenic differences in specialization among early‐ and late‐produced flowers, so that the progressive maleness over time is reinforced after fertilization by a sink‐source effect, possibly combined with selective abortion. Overall seed production was significantly correlated with plant size; nevertheless, female success was not maximum for the largest plants, but for intermediate sized plants.
Genetic Variation Within and Among Metal‐Tolerant and Non‐Tolerant Populations of Armeria maritima (Mill.) Willd. s.l. (Plumbaginaceae) in Central and Northeast Germany
Authors: Baumbach H. , Hellwig F. H.
Published: July 2003

Abstract: Six metal‐tolerant populations and sub‐populations of Armeria maritima ssp. halleri, ssp. hornburgensis, and ssp. bottendorfensis and two non‐tolerant populations of ssp. elongata in Central and Northeast Germany have been analysed using RAPD markers. The populations show very strong genetic differentiation (ΦST = 0.46), corresponding gene flow between them is low (Nem = 0.29). A moderate positive correlation between the matrices of genetic and geographical distances was found between the seven populations and sub‐populations of central Germany (r = 0.68, p < 0.001). Calculated parameters of genetic variability are molecular variance, percentage of heterozygosity and percentage of polymorphic loci. A significant correlation between population size and parameters of genetic variability was not recognisable. Genetic structure was investigated by an analysis of molecular variance (AMOVA). The studied populations show strong genetic differentiation. Genetic variation within populations (“normal” as well as metalliferous) is higher (53.9 %) than among them (46.1 %). Six hypotheses of possible genetic relatedness between the studied populations have been tested by AMOVA. A data set structure above the populational level is hardly recognisable. It was impossible to combine the populations to edaphic (tolerant and “non‐tolerant”) or taxonomic groups. A. maritima ssp. halleri of the north Harz mountains and ssp. hornburgensis are clearly separated from a geographical group containing all other populations (across taxonomic and edaphic boundaries). These results are a further indication for a polyphyletic origin of metal‐tolerant populations of A. maritima s.l. by multiple colonizations of metalliferous sites from neighbouring populations on non‐metalliferous soil.
Size‐Dependent Variation of Carbon and Nitrogen Isotope Abundances in Epiphytic Bromeliads
Authors: Hietz P. , Wanek W.
Published: July 2003

Abstract: While atmospheric species of bromeliads have narrow leaves, densely covered with water‐absorbing trichomes throughout their life cycles, many tank bromeliads with broad leaves, forming phytotelmata, go through an atmospheric juvenile phase. The effect of the different habits and the phase change in tank‐forming bromeliads on water and nutrient relations was investigated by analysing the relationship between plant size, C/N ratios and the natural abundance of 13C and 15N in five epiphytic bromeliad species or morphospecies of a humid montane forest in Xalapa, Mexico. The atmospheric species Tillandsia juncea and T. butzii exhibited full crassulacean acid metabolism, with δ13C values (mean ‐ 15.3 ‰ and ‐ 14.7 ‰, respectively) independent of size. In Tillandsia species with C3 photosynthesis, δ13C decreased with increasing plant size, indicating stronger drought stress in juveniles. The increase of the C/N ratio with size suggests that, at least in heteroblastic bromeliads, the availability of water is more limiting during early growth, and that limitations of nitrogen supply become more important later on, when water stored in the tank helps to bridge dry periods, reducing water shortage. δ15N values of the two atmospheric species were very negative (‐ 12.6 ‰ and ‐ 12.2 ‰, respectively) and did not change with plant size. Tank‐forming bromeliads had less negative δ15N values (c ‐ 6 ‰), and, in species with atmospheric juveniles and tank‐forming adults, δ15N values increased significantly with plant size. These differences do not appear to be an effect of the isotopic composition of N sources, but rather reflect N availability and limitation and stress‐induced changes in 15N discrimination.
Flower and Fruit Visitors of Marcgravia longifolia in Amazonian Peru
Authors: Tirado Herrera E. R. , Franke T. , Knogge C. , Skrabal J. , Heymann E. W.
Published: July 2003

Abstract: We recorded nectarivorous and frugivorous visitors of Marcgravia longifolia (Marcgraviaceae) at the Estación Biológica Quebrada Blanco in the northeastern Peruvian Amazonia. M. longifolia belongs to the subgenus Plagiothalamium, with downward facing flowers. A glossophagine bat, probably Anoura caudifer, was identified as a potential pollinator. Three primate species ‐ Saguinus fuscicollis, Saguinus mystax and Callicebus cupreus ‐ were recorded as potential seed dispersers. This is the first documentation of primate seed dispersal of a species from the family Marcgraviaceae.
Two-dimensional phononic crystal with tunable narrow pass band: Application to a waveguide with selective frequency
Authors: Khelif A. , Deymier P. A. , Djafari-Rouhani B. , Vasseur J. O. , Dobrzynski L.
Published: July 2003

We study theoretically the propagation of elastic waves in two-dimensional composite media composed of a square array of hollow steel cylinders embedded in water using the finite-difference time-domain method. These composite media constitute a class of acoustic band gap materials with narrow pass bands in their transmission stop bands. The frequency at which the pass band occurs is tunable by controlling the inner radius of the tubular steel inclusions. The effect of the tube inner radius on the transmission spectrum is semiquantitatively separable from the effect of the composite periodicity. A linear defect formed of a row of hollow cylinders in an array of filled cylinders produces an elastic waveguide that transmits at the narrow pass band frequency. We show that two of these tunable waveguides with different inner radii can be employed to filter and separate two specific frequencies from a broad band input signal.