bluuebunny/crossref_metadata_2025 huggingface dataset:
A Randomized and Controlled Pilot Trial of β‐blockers for the Treatment of Recurrent Syncope in Patients with a Positive or Negative Response to Head‐Up Tilt Test
Authors: VENTURA RODOLFO , MAAS RENKE , ZEIDLER DANIEL , SCHODER VOLKER , NIENABER CRISTHOPH A. , SCHUCHERT ANDREAS , MEINERTZ THOMAS
Published: July 2003

VENTURA, R., et al.: A Randomized and Controlled Pilot Trial of b‐Blockers for the Treatment of Recurrent Syncope in Patients with a Positive or Negative Response to Head‐Up Tilt Test. The aim of this study was to assess the efficacy of lipophilic β‐blockers in preventing recurrent neurocardiogenic syncope and the value of head‐up tilt test (HUT) in predicting response to therapy. The efficacy of β‐blockers in recurrent syncope is controversial. The value of HUT in predicting efficacy of therapy has not been investigated. Fifty‐six patients (44 ± 18 years, 36 women) with recurrent syncope (> 1 event in the last 6 months) of suspected neurocardiogenic origin were included in the study. Independent of the response to HUT, patients were randomized to receive metoprolol or propanolol at the maximal tolerated dose (28 patients, group A, 86 ± 23 vs 98 ± 29 mg/d) or no pharmacological therapy (28 patients, group B). The primary endpoint was the first recurrence of syncope. During the 1‐year of follow‐up, 20 patients of group A and 8 of group B had no recurrence. In group A, of 20 patients without recurrences 12 had a positive and 8 a negative HUT result while of 8 patients with recurrences 5 had a positive and 3 a negative response to HUT. In the group B, of 20 patients with recurrences 10 had a positive and 10 a negative HUT result while of 8 patients without recurrences 4 had a positive and 4 a negative response to HUT. In a multivariate Cox‐regression analysis, medical therapy was the only independent factor for predicting recurrence of syncope (P = 0.004); HUT had no influence in this regard (P = 0.773). In conclusion, lipophilic β‐blockers appear efficacious in preventing recurrent syncope of suspected neurocardiogenic origin. The efficacy of therapy seems to be not predicted by HUT.
Nitroglycerin Induced Syncope Occurs in Subjects with Delayed Phase Shift of Baroreflex Action
Authors: MELENOVSKY VOJTECH , WICHTERLE DAN , MALIK JAN , SIMEK JAN , HRADEC JAROMIR , CESKA RICHARD , MALIK MAREK
Published: July 2003

MELENOVSKY, V., et al.: Nitroglycerin Induced Syncope Occurs in Subjects with Delayed Phase Shift of Baroreflex Action. Nitroglycerin (NTG) administration occasionally leads to syncope due to severe hypotension and bradycardia. This reaction resembles neurocardiogenic syncope but it may occur when the patient is in the supine position. To address the possible role of prevailing autonomic tone and baroreflex control in precipitation of NTG induced syncope, continuous noninvasive blood pressure and an ECG were taken shortly before NTG application in the supine position. Frequency‐domain measures of heart rate variability (HRV) and noninvasive indices of baroreflex were compared between subjects who did (n = 6) and did not (n = 41) develop syncope after NTG. Both groups differed only in the phase shift (PCR) between oscillations of blood pressure and heart rate during controlled respiration (0.1 Hz). PCR was significantly delayed in subjects who developed syncope than in controls (−99.3 ± 14.1 vs −65.5 ± 27.0 degrees, P = 0.002). Thus, subjects with prolonged PCR are prone to NTG induced syncope because of increased lagging and, consequently, less stable baroreflex control.
Pacemaker Stored Electrograms: Teaching Us What Is Really Going On in Our Patients
Authors: NOWAK BERND
Published: July 2003

NOWAK, B.: Pacemaker Stored Electrograms: Teaching Us What Is Really Going On in Our Patients. Stored electrograms (EGMs), well‐known diagnostic tools in implantable cardioverter defibrillators, have now been incorporated in pacemakers as well, thereby increasing their diagnostic capabilities. The clinician can detect and diagnose patient arrhythmias with EGMs and directly validate diagnostic data stored by the devices. The appropriateness of detection algorithms can also be judged. Initial experiences with pacemaker EGMs reveals their potential to detect and diagnose sensing or detection algorithm problems. These so‐called “false‐positive” EGMs help to optimize pacemaker programming. Date and time stamp can correlate an event to patient symptoms. Recent advances, like onset recordings and marker annotation, have further increased the effectiveness of stored EGMs. The use of patient‐triggered magnet‐stored EGMs facilitates diagnostic workups in symptomatic pacemaker patients and reveals nondevice related symptoms in a considerable number of cases. Stored EGMs in pacemakers will soon be a standard diagnostic tool that can illustrate what is really going on in our patients.
Radiofrequency Catheter Ablation of an Incessant Supraventricular Tachycardia in a Premature Neonate
Authors: BRUGADA JOSEP , CLOSAS RICARDO , ORDÓÑEZ AUGUSTO , MABROK MAGED , GRECU MIHAELA , MERCÉ JORDI , MORTERA CARLOS
Published: July 2003

BRUGADA, J., et al.: Radiofrequency Catheter Ablation of an Incessant Supraventricular Tachycardia in a Premature Neonate. A 32‐week, premature neonate with incessant supraventricular tachycardia and hemodynamic compromise who failed to respond to antenatal and postnatal antiarrhythmic therapy underwent successful radiofrequency catheter ablation (RCA) of a concealed left free‐wall accessory pathway when the infant was 4‐days‐old and weighed only 1,840 grams. At follow‐up performed 60 days after the procedure, the infant remained free of any drug, in sinus rhythm, and in normal hemodynamic condition.
Long‐Term Structural Failure of Coaxial Polyurethane Implantable Cardioverter Defibrillator Leads
Authors: HAUSER ROBERT G. , CANNOM DAVID , HAYES DAVID L. , PARSONNET VICTOR , HAYES JOHN , RATLIFF NORMAN , TYERS G. FRANK O. , EPSTEIN ANDREW E. , VLAY STEPHEN C. , FURMAN SEYMOUR , GROSS JAY
Published: July 2003

HAUSER, R.G., et al.: Long‐Term Structural Failure of Coaxial Polyurethane Implantable Cardioverter Defibrillator Leads. Transvene models 6936/6966, a coaxial polyurethane ICD lead, may be prone to structural failure. These models comprise 54% of ICD lead failures in the authors' Multicenter Registry database. Because ICD leads perform a vital function, the clinical features, causes, and probability of Transvene 6936/6966 lead failure were determined. The Registry and United States Food and Drug Administration databases were queried for the clinical features and structural causes of the Transvene 6936/6966 lead failure, and a five‐center substudy estimated the survival probability for 521 Transvene 6936/6966 implants. The mean time to failure was 4.8 ± 2.1 years, and the estimated survival at 60 and 84 months after implant were 92% and 84%, respectively. Oversensing was the most common sign of failure (76%), and 24 patients experienced inappropriate shocks. The manufacturer's reports indicated that high voltage coil fracture and 80A polyurethane defects were the predominant causes of lead failure. Transvene models 6936 and 6966 coaxial polyurethane ICD leads are prone to failure over time. Patients who have these leads should be evaluated frequently. Additional studies are needed to identify safe management strategies.
Performance of a Rate Responsive Accelerometer‐Based Pacemaker with Autocalibration During Standardized Exercise and Recovery
Authors: GARRIGUE STEPHANE , GENTILINI CLAUDIO , HOFGARTNER FRANZ , MOUTON ELISABETH , ROUSSEAU ANNE , CLEMENTY JACQUES ,   OPUS G STUDY GROUP
Published: July 2003

GARRIGUE, S., et al.: Performance of a Rate Responsive Accelerometer‐Based Pacemaker with Autocal‐ibration During Standardized Exercise and Recovery. The rate responsiveness of a single chamber, accelerometer‐based pacemaker with an autocalibration function (Opus G VVIR pacemaker, ELA Medical) was studied with a daily life protocol developed to automatically optimize the programming of accelerometer‐based sensors. This new sensor was compared with two other body activity sensors that were manually optimized patient by patient. Forty‐three pacemaker recipients (mean age 71 ± 11 years), paced > 95% of the time, underwent a daily life protocol consisting of rapid walking for 6 minutes (W), climbing upstairs for 1.5 minutes (U), and downstairs for 1.5 minutes (D), alternated by recovery phases. The results were compared with performances measured in a control population of healthy subjects and in two paced patient populations (one equipped with a Dash Intermedics VVIR pacemaker and the other equipped with a Sensolog III Pacesetter/St. Jude VVIR pacemaker). Sex distribution and mean age between paced patients and control subjects were statistically comparable. The mean heart rate achieved by all paced patients at each time sample was compared with the normograms, assigning acceleration (slope) and rate (rate) scores for exercise and recovery phases. Scores ranged from ‐10 (hypochronotropic) to +10 (hyperchronotropic). Zero represents exact concordance with the responses of healthy individuals, and values between ‐2.5 and +2.5 were considered statistically similar to normal. During W, although the overall performances of the Dash, Sensolog, and Opus G did not statistically differ from healthy controls, the scores obtained by the Opus G were significantly closer to controls than those of the two other pacemakers (P = 0.02). For U, the three sensors were hypochronotropic (P = 0.03), though the Opus G was associated with a heart rate response closer to that of healthy controls (P = 0.04). D provided similar mean heart rate scores for the Opus G and the Dash compared with healthy controls, in contrast with the hyperchronotropic behavior of the Sensolog (P = 0.02). Opus G revealed a physiological modulation of the heart rate for W and D tests with a slightly hypochronotropic behavior during U. The Opus G autocalibration function provided daily life performances closer to those of healthy controls than two other pacemakers equipped with a body activity sensor that were manually optimized.
Simultaneous Atrial and Ventricular Pacing to Facilitate Mapping of Concealed Left‐Sided Accessory Pathways
Authors: NAKAO KOJIRO , SETO SHINJI , ILIEV IVAN I. , MATSUO KIYOTAKA , KOMIYA NORIHIRO , ISOMOTO SHOJIRO , HAYANO MOTONOBU , YANO KATSUSUKE
Published: July 2003

NAKAO, K., et al.: Simultaneous Atrial and Ventricular Pacing to Facilitate Mapping of Concealed Left‐Sided Accessory Pathways. Several local electrogram characteristics have been proposed as criteria to predict successful ablation. However, poor specificity due to obscuration of the retrograde atrial electrogram by the ventricular electrogram is problematic. The aim of this study was to analyze local electrograms obtained by simultaneous pacing to identify quantitative criteria that may predict successful ablation sites for concealed left free‐wall accessory pathways. Twenty‐four local electrograms from 10 successful and 14 unsuccessful ablation sites in ten patients were analyzed. Retrograde atrial electrograms were confirmed by the simultaneous pacing method. The intervals between the retrograde atrial electrogram of the coronary sinus and the ablation site, the initiation of the ventricular electrogram and the retrograde atrial electrogram, and the stimulus and retrograde atrial electrogram were analyzed. All retrograde atrial electrograms could be confirmed clearly by the simultaneous pacing method. The interval between the retrograde atrial electrogram of the coronary sinus and that of the ablation site was shorter at successful sites than at unsuccessful sites (‐7.0 ± 9.2 ms vs 5.7 ± 2.7 ms; 95% confidence interval, ‐18 to ‐7; P < 0.0001). An interval of ≤ 0 ms resulted in 100% sensitivity and 92.7% specificity for success. The other two interval measurements at successful sites did not differ significantly from those at unsuccessful sites. The authors propose an interval of ≤ 0 ms between the retrograde atrial electrogram of the coronary sinus and that of the ablation site confirmed by the simultaneous pacing method as a quantitative criterion to identify the successful ablation site for concealed left free‐wall accessory pathways. Application of this criterion may reduce the number of unnecessary ablations.
Atrioventricular Cross‐talk in Biventricular Pacing: A Potential Cause of Ventricular Standstill
Authors: TAIEB JEROME , BENCHAA TEWFIK , FOLTZER ERIC , COSTE ANDRE , TARLET JEAN‐MICHEL , JOUVE BERNARD , RAHAL YOUSSEF , POCHON PASCALE , MOUDNI FATIMA , BARNAY CLAUDE
Published: July 2003

TAIEB, J., et al.: Atrioventricular Cross‐talk in Biventricular Pacing: A Potential Cause of Ventricular Standstill. The aim of the study was to evaluate, in recipients of biventricular pacing systems, the risk of asystole due to ventricular pacing inhibition by sensing the left atrial signals by the LV lead at conventional sensitivity. Long‐term ventricular sensitivity was programmed at ≥4 mV in 17 consecutive recipients of ventricular resynchronization systems implanted for chronic management of congestive heart failure. Ventricular pacing inhibition due to AV cross‐talk on spontaneous left atrial electrogram (AVCSA) was tested at a 2 mV ventricular sensitivity immediately after implantation of the stimulation system and 1 month later. Pacemaker dependence was also tested during temporary VVI pacing at a rate of 30 beats/min. AVCSA was observed in three patients. It was present on the day of implantation in one patient, and developed within the first month in two others. Asystole was observed in two of the three cases of AVCSA. Three pacemaker nondependent patients at the time of system implantation had become pacemaker dependent at 1 month. AVCSA was observed only with LV leads positioned in the great cardiac vein. In conclusion, asystole due to AVCSA was observed in 11% of recipients of ventricular resynchronization stimulation systems. Care should be taken in these patients to minimize the risk of atrial sensing by the LV lead, preferably avoiding its placement in the great cardiac vein. This phenomenon could be eliminated by the programmability of a right ventricular only sensing configuration.
Extracorporeal blood volume of donors during automated intermittent‐flow plasmapheresis and its relevance to the prevention of circulatory reactions
Authors: Karger Ralf , Slonka Janus , Junck Heike , Kretschmer Volker
Published: July 2003

BACKGROUND: Intermittent‐flow plasmapheresis often involves a large extracorporeal blood volume of the donor during the procedure with the concomitant risk of circulatory reactions. Guidelines governing donor recruitment often apply an arbitrary threshold of 15 percent of the donors’ blood volume not to be exceeded during hemapheresis procedures. No data demonstrating the suitability of this approach exist.

STUDY DESIGN AND METHODS: The blood volumes of 1204 plasmapheresis donors were calculated with different formulae that utilized either body weight or body surface area. Extracorporeal blood volumes of these donors were determined for a commonly used intermittent‐flow plasmapheresis machine known to result in a large extracorporeal blood volume. A validated model was employed that calculated the fluid volume shifts occurring during the procedure. The records of all plasmapheresis procedures of these donors were retrospectively reviewed for circulatory reactions.

RESULTS: The median extracorporeal volumes ranged from 14 to 17 percent of the blood volume at a donor Hct level of 0.40 to 0.48 L per L for men and from 17 to 20 percent at a Hct level of 0.36 to 0.44 L per L for women. In more than 60 percent of male and more than 90 percent of female donors, extracorporeal volumes exceeded 15 percent of the blood volume during plasmapheresis. In this subgroup, 65 percent of male and 75 percent of female donors never presented with any signs of circulatory reactions.

CONCLUSION: Application of an arbitrary threshold of 15 percent of the donors’ blood volume not to be exceeded during hemapheresis procedures is expected to lead to an unjustified deferral rate in plasmapheresis donors.
Frequency, viral loads, and serotype identification of enterovirus infections in Scottish blood donors
Authors: Welch Jon , Maclaran Kate , Jordan Tony , Simmonds Peter
Published: July 2003

BACKGROUND: Enteroviruses are non‐enveloped, frequently pathogenic RNA viruses infecting humans. Infection is potentially transmissible through blood or blood component transfusion from donor in the viremic phase before seroconversion for antibody. To investigate the threat to blood safety from enteroviruses, a large‐scale survey of frequency and levels of viremia in blood donors was conducted.

STUDY DESIGNS AND METHODS: Blood donations from Scotland over a period of 22 calendar months were screened for enterovirus RNA sequences by PCR. Positive samples were quantified, and serotypes were identified by nucleotide sequencing of VP1.

RESULTS: From a total of 3658 pools of 95 donations tested, 73 samples that were enterovirus‐positive were identified (corrected annual frequency 0.024% or 1 in 4000). The highest rates of viremia were in late summer months (e.g., 0.055%, 1 in 1800 in July) and lowest from January to May (0.009 and 0.012%). Viral loads ranged from 500 (the lower cutoff of the assay) to greater than 100,000 amplifiable enterovirus template copies per mL. Coxsackievirus A16, echoviruses 11 and 30, and enterovirus 71 were most often identified.

CONCLUSIONS: The detection of enterovirus‐positive blood units indicates the potential for enteroviral transmission by blood components. Although the infrastructure established for PCR‐based screening for HCV RNA would allow parallel screening for enteroviruses, any decision concerning donor testing would require further information on the outcome of transfusion‐acquired enterovirus infections.
West Nile virus in blood: stability, distribution, and susceptibility to PEN110 inactivation
Authors: Mather Thomas , Takeda Tsutomu , Tassello Jodie , Ohagen Asa , Serebryanik Diana , Kramer Ed , Brown Fred , Tesh Robert , Alford Bernadette , Chapman John , Lazo Aris
Published: July 2003

BACKGROUND: The outbreak of West Nile virus (WNV) is the most recent reminder that the blood supply continues to be vulnerable to emerging and reemerging pathogens. A potentially prospective approach to reducing the risk of transfusion‐transmitted infections of a known or newly emerging microbe is implementation of a broad‐spectrum pathogen reduction technology. The purpose of this study was to evaluate the susceptibility of WNV to PEN110 inactivation in RBCs and to characterize the WNV interaction with blood, including the stability of WNV in RBCs stored at 1 to 6°C, its distribution and infectivity, and its ability to infect WBCs.

STUDY DESIGN AND METHODS: Inactivation was performed with three WNV isolates spiked into WBC‐reduced RBCs. The stability of the virus was evaluated by spiking two viral loads into RBCs followed by storing at 1 to 6°C for up to 42 days. The distribution of the virus in plasma, RBCs, and PBMCs was evaluated with whole blood from infected hamsters. Finally, in vitro propagation of WNV was evaluated with the THP‐1 cell line and primary monocytes.

RESULTS: The kinetics of PEN110 inactivation of WNV isolates RI‐44, NJ‐176, and 99‐3494031 were fast and complete within 24 hours with reduction factors of 5 to 7 log plaque‐forming units per mL. WNV remained infectious for up to 42 days at 1 to 6°C. The WNV titers in whole blood, plasma, RBCs, and PBMC fractions were equally distributed and ranged from 2 to 3 log tissue culture infectious dose 50 percent per mL. Productive infection of stimulated monocytes and THP‐1 cells was also demonstrated.

CONCLUSIONS: These studies demonstrated that PEN110 efficiently inactivated WNV in RBCs and whole blood from infected hamsters to the limit of detection. WNV survived in RBCs stored at 1 to 6°C with a gradual loss of titer but infectivity could still be observed for up to 42 days. In addition, it was observed that WNV was equally distributed in all blood fractions including PBMCs and it was possible to establish productive infection of a human monocytic cell line and stimulated human monocytes.
Single hospital experience of TRALI
Authors: Wallis Jonathan P. , Lubenko Anatole , Wells Angus W. , Chapman Catherine E.
Published: July 2003

BACKGROUND: TRALI is a serious adverse effect of blood transfusion. There is evidence that the condition is underrecognized and underreported.

STUDY DESIGN AND METHODS: This study was an observational study carried out in a single hospital.

RESULTS: Eleven cases of TRALI were recognized over 12 years. In 10 cases the implicated donor unit was FFP and in 1 case uncertain. All implicated donors were parous women. In 4 cases the presumed causative antibodies were to an HLA class II antigen only. Specific anti‐neutrophil antibodies, possibly causative, were detected in 1 case only. Ten of the 11 cases required mechanical ventilatory support. Five persons died as a result of the TRALI. The observed incidence of TRALI caused by FFP is 1 in 7900 units transfused.

CONCLUSION: TRALI is the most common serious adverse effect of blood transfusion in our hospital. Antibodies to HLA class II antigens should be looked for routinely when investigating a possible case of TRALI.
Do blood donors read and understand screening educational materials?
Authors: Rugege‐Hakiza S.E. , Glynn S.A. , Hutching S.T. , Bethel J. , Nass C.C. , McEntire R.L. , Hirschler N.V. , Campbell J.G. , Ladavac A. , Schreiber G.B.
Published: July 2003

BACKGROUND: Blood donors with high‐risk behaviors may not self‐defer because they failed to read or understand the screening educational materials.

STUDY DESIGN AND METHODS: In 1993, a total of 34,726 allogeneic donors responded to an anonymous mail survey of 50,162 donors that inquired about demographics, donor status, amount of the donor educational materials read, new HIV knowledge gained, and donors’ opinions on the length and difficulty of materials.

RESULTS: Although 78 percent reported reading all materials, only 32 percent indicated reading carefully; 34 percent learned new information about HIV and 95 percent perceived the materials as easy to understand. First‐time donors were more likely to read carefully (OR, 7.9) and gain more HIV knowledge from the materials (OR, 1.9) than repeat donors. Minority, less educated, screening test‐reactive, and HIV test‐seeking donors reported reading the materials more carefully and learning more about HIV than their respective counterparts. Donors with less education, those with reactive screening tests, those seeking HIV test results, and those not reporting a risk behavior were more likely to find the materials difficult to understand.

CONCLUSION: Most donors reported skimming and not having difficulty understanding the educational materials. Some donors may be aware that they should not donate or are failing to assimilate the information in the materials. Methods to present information more clearly and concisely are clearly needed. However, some high‐risk donors may still continue donating no matter how improved the educational materials are.
Vasovagal reaction rates and body weight: findings in high‐ and low‐risk populations
Authors: Newman Bruce H.
Published: July 2003

BACKGROUND: The effect of weight on vasovagal reaction rates has not been evaluated in high‐ and low‐risk populations or in first‐time versus repeat blood donors. In addition, vasovagal reaction rates and weight have not been evaluated based on solicited information.

STUDY DESIGN AND METHODS: A total of 1073 Caucasian high school students from randomly selected whole‐blood drives in 2001 and 949 randomly selected Caucasian donors from the general donor population in 2001 and 2002 were subdivided into weight groups and evaluated for vasovagal reaction rates.

RESULTS: The high school population had a much higher vasovagal reaction rate than the general donor population (8.0 vs. 2.6%). The vasovagal reaction rate was inversely proportional to body weight in first‐time blood donors in both populations, but the trend was not as well defined in repeat blood donors. Solicitation of information from the general donor population increased the vasovagal reaction detection rate by 2.5 times (from 2.6% to 6.5%), and it is suggested that the vasovagal reaction rate might be as high as 27 percent in first‐time general donors who weighed between 110 and 139 pounds.

CONCLUSION: Body weight is a very important determinant of vasovagal reaction rates in first‐time donors, but previous successful blood donation appears to mitigate the effect of body weight on vasovagal reaction rates. Solicitation of information from blood donors increases the number of vasovagal reactions detected and enhances the data.
Estimated risk of transmission of the West Nile virus through blood transfusion in the US, 2002
Authors: Biggerstaff Brad J. , Petersen Lyle R.
Published: July 2003

BACKGROUND: The West Nile virus (WNV) epidemic in 2002 in the US saw over 3300 reported human cases of WNV disease, with over 2300 reported cases of WNV encephalitis and meningitis. The first documented cases of transfusion transmission of WNV through voluntary blood donation also occurred.

STUDY DESIGN AND METHODS: Case onset dates from the 2002 WNV epidemic in the US were used to estimate the risk of transfusion‐associated transmission with statistical resampling. An easily computed approximating formula for the mean risk was derived. Estimates were computed for six high‐incidence states and metropolitan areas.

RESULTS: Mean and maximum risk of transfusion‐associated WNV transmission (per 10,000 donations) during the epidemic period for the selected states ranged from 2.12 to 4.76 and from 4.34 to 10.46, respectively; for the selected metropolitan areas, they ranged from 1.46 to 12.33 and from 3.02 to 21.32, respectively.

CONCLUSIONS: Estimates of the mean risk of WNV transmission by transfusion ranged from 1.46 to 12.33 per 10,000 donations for six high‐incidence metropolitan areas during the 2002 epidemic. Because the risk was highly geographically and temporally variable, computation of geographically localized estimates is recommended. The derived approximating formula for the mean risk performed well for the estimates given.
West Nile virus and the safety of plasma derivatives: verification of high safety margins, and the validity of predictions based on model virus data
Authors: Kreil Thomas R. , Berting Andreas , Kistner Otfried , Kindermann Johanna
Published: July 2003

BACKGROUND: During the 2002 West Nile virus (WNV) epidemic in the US, virus transmission through solid organ transplantation and transfusion of blood components was observed. This raised concerns about the safety of plasma derivatives. To verify the safety margins of these products, which were initially shown with a panel of model viruses including some very similar to WNV, the effectiveness of the virus inactivation procedures incorporated into their manufacturing processes was reinvestigated.

STUDY DESIGN AND METHODS: An infectivity assay for 1999 New York isolate of WNV was established to investigate virus inactivation steps commonly used during the manufacture of plasma derivatives, such as pasteurization for human albumin, S/D treatment for IVIG and FVIII, vapor heating for FVIII inhibitor‐bypassing activity, and incubation at low pH for IVIG.

RESULTS: The results show that WNV behaves exactly as had been predicted based on available data for similar model viruses; that is, it is readily inactivated by all the commonly used virus inactivation procedures tested.

CONCLUSION: Our investigation verifies the safety margins of plasma derivatives against a potential transmission of WNV and that the model virus concept is valid for predicting the behavior of closely related viruses.
Combined Amiodarone and Silymarin Treatment, But Not Amiodarone Alone, Prevents Sustained Atrial Flutter in Dogs
Authors: Vereckei András , Besch Henry R. , Zipes Douglas P.
Published: July 2003

Introduction: Because amiodarone generates free radicals that may mediate amiodarone's toxicity, simultaneous therapy with an antioxidant might be beneficial if the antioxidant did not impair amiodarone's antiarrhythmic action. We tested whether simultaneous administration of a flavonoid antioxidant, silymarin, altered the electrophysiologic (EP) actions of amiodarone in 62 open chest dogs with electrically induced atrial flutter created by a Y‐shaped right atrial incision.

Methods and Results: Fifteen dogs received oral amiodarone (600 mg/day); 15 dogs received amiodarone (600 mg/day) and silymarin (70 mg bid); and 8 dogs received silymarin (70 mg bid) alone. All dosing was for 8 weeks; 24 control dogs received no drugs prior to induction of atrial flutter. Atrial flutter was induced by rapid right atrial pacing, and EP measurements were made before (presurgical) and after (postsurgical) creation of a Y‐shaped right atrial incision. There was no difference in the frequency of induction of atrial flutter lasting >30 minutes among amiodarone‐treated (8/15 [53%]), silymarin‐treated (4/6 [67%]), and control (15/21 [71%]) groups, whereas the frequency of induction in the amiodarone+silymarin dogs (2/15 [13%]) was significantly reduced (P = 0.008) compared with the other three groups. Both amiodarone and amiodarone+silymarin treatment prolonged the presurgical and postsurgical right atrial effective refractory period (P = 0.012) compared with control; however, there was no significant difference in either parameter between the amiodarone+silymarin–treated and amiodarone‐treated groups. The increase in atrial flutter mean cycle length (postsurgical minus presurgical) was significantly (P = 0.005) less in the amiodarone+silymarin–treated and control dogs compared with the amiodarone‐treated dogs (16 ± 11 msec for amiodarone+silymarin; 24 ± 8 msec for control; and 42 ± 14 msec for amiodarone treatment). Amiodarone+silymarin treatment resulted in a longer postsurgical right atrial refractory period (155 ± 13 msec) than atrial flutter mean cycle length (154 ± 19 msec), consistent with reduction and/or elimination of the excitable gap. Silymarin alone did not exert significant EP or antiarrhythmic action.

Conclusion: Amiodarone exerted no preventative antiarrhythmic action in this atrial flutter model, probably because it could not reduce the excitable gap of atrial flutter. However, an antioxidant, silymarin, without a direct antiarrhythmic action, when administered together with amiodarone, potentiated amiodarone's antiarrhythmic actions and prevented sustained atrial flutter by reduction and/or elimination of the excitable gap. (J Cardiovasc Electrophysiol, Vol. 14, pp. 861‐867, August 2003)
Defibrillation Causes Immediate Cardiac Dilation in Humans
Authors: Sylvester Erin , Hoffmeister Brent , Johnson Eric , Hess Paul , Malkin Robert
Published: July 2003

Introduction: Prior studies in isolated heart tissue have shown both excitation and deexcitation to be the primary mechanism of defibrillation. This article presents the first evidence in man of deexcitation immediately following defibrillation by tracking the heart's mechanical response.

Methods and Results: The geometric changes of the ventricular chambers were measured before and after defibrillation in seven human subjects receiving an implantable cardioverter defibrillator (ICD). The ICD was used to produce approximately three episodes of ventricular fibrillation and defibrillation in each subject. Twenty‐two two‐dimensional echocardiographic images of the right ventricle (RV) and 11 images of the left ventricle (LV) were recorded and analyzed at 30 frames per second. Just over 2 seconds of each episode were digitized, beginning half a second before the defibrillation shock. Individual frames were analyzed to yield cross‐sectional, ventricular chamber area as a function of time. Immediately following defibrillation, ventricular chambers dilated with significant fractional area increase (RV: 1.58 ± 0.25, LV: 1.10 ± 0.06), with peak dilation at 194 ± 114 msec.

Conclusion: Defibrillation causes a rapid increase in ventricular chamber area due to relaxation of the myocardium, suggesting that defibrillation synchronizes the cardiac cells to the deexcited state in man. (J Cardiovasc Electrophysiol, Vol. 14, pp. 832‐836, August 2003)
Antiarrhythmic Effects of JTV‐519, a Novel Cardioprotective Drug, on Atrial Fibrillation/Flutter in a Canine Sterile Pericarditis Model
Authors: Kumagai Koichiro , Nakashima Hideko , Gondo Naoki , Saku Keijiro
Published: July 2003

Introduction: A new cardioprotective drug, JTV‐519, blocks Na+ current and inwardly rectifying K+ current and inhibits Ca2+ current. However, its role in atrial electrophysiology is unknown. We investigated the antiarrhythmic effects of JTV‐519 on atrial fibrillation/flutter in the canine sterile pericarditis model.

Methods and Results: In nine dogs with sterile pericarditis, 38 episodes of sustained (>30 sec) atrial fibrillation (8 dogs) and 24 episodes of sustained atrial flutter (7 dogs) were induced by rapid atrial pacing. When atrial fibrillation or atrial flutter was sustained >15 minutes, it was cardioverted and reinduced. The inducibility of atrial fibrillation/flutter, the atrial effective refractory period, and the intra‐atrial conduction time were compared before and after the continuous infusion of JTV‐519 (0.03 mg/kg/min). JTV‐519 significantly decreased the mean number of sustained atrial fibrillation episodes (from 4.2 ± 2.9 to 0 ± 0, P < 0.01). In contrast, atrial flutter was still inducible in 4 dogs after JTV‐519 (from 2.7 ± 2.5 to 1.6 ± 2.1, P = NS). JTV‐519 significantly prolonged effective refractory period (from 123 ± 18 to 143 ± 14 msec, from 127 ± 18 to 151 ± 12 msec, and from 132 ± 13 to 159 ± 9 msec at basic cycle lengths of 200, 300, and 400 msec, respectively, P < 0.01), but it did not affect the intra‐atrial conduction time (from 47 ± 11 msec to 48 ± 11 msec, P = NS).

Conclusion: JTV‐519 had significant protective effects on atrial fibrillation in the canine sterile pericarditis model, mainly by increasing effective refractory period, suggesting that it may have potential as a novel antiarrhythmic agent for atrial fibrillation. (J Cardiovasc Electrophysiol, Vol. 14, pp. 880‐884, August 2003)
Safety and Efficacy of Cryoablation of Accessory Pathways Adjacent to the Normal Conduction System
Authors: Gaita Fiorenzo , Riccardi Riccardo , Hocini Meleze , Haissaguerre Michel , Giustetto Carla , Jais Pierre , Grossi Stefano , Caruzzo Enrico , Bianchi Francesca , Richiardi Elena
Published: July 2003

Introduction: Catheter ablation has become a routine treatment for patients with Wolff‐Parkinson‐White syndrome because of its low risk and high efficacy; however, radiofrequency ablation in the septum close to the AV node or His bundle still carries a definite risk for AV block. Cryoenergy catheter ablation has recently become available. This technique has specific features, such as the ability to create reversible loss of function to predict the effects of ablation (ice mapping) and the adherence of the catheter tip to the endocardium with freezing, which avoids the risk for dislodgment. Both of these characteristics may minimize the risk of complications. The aim of this study was to analyze the effectiveness and safety of catheter cryoablation in 20 patients with para‐Hisian or midseptal accessory pathways (AP).

Methods and Results: Eleven patients with para‐Hisian and 9 patients with midseptal AP underwent catheter cryoablation. Ice mapping at −30°C was performed to ascertain the disappearance of AP conduction and the absence of impairment of AV nodal conduction. If the expected result was obtained, cryoablation was performed by lowering the temperature to −75°C for 4 minutes in order to create a permanent lesion. Cryoablation was successful in all patients using a mean of 1.2 ± 0.4 applications. Recurrences occurred in 4 patients (20%) who underwent a second successful cryoablation session. No complications were observed.

Conclusion: Cryoablation appears to be a safe and effective technique for ablation of APs close to the AV node or His bundle because of the ability to predict the acute effects of ablation with ice mapping before creation of an irreversible lesion. (J Cardiovasc Electrophysiol, Vol. 14, pp. 825‐829, August 2003)
Heterogeneous Regional Endocardial Repolarization is Associated with Increased Risk for Ischemia‐Dependent Ventricular Fibrillation after Myocardial Infarction
Authors: Swann Michael H. , Nakagawa Hiroshi , Vanoli Emilio , Lazzara Ralph , Schwartz Peter J. , Adamson Philip B.
Published: July 2003

Introduction: The aim of this study was to investigate whether the characteristics of endocardial ventricular repolarization are associated with differential risk for sudden death. Prolonged surface QT interval is associated with increased arrhythmic risk after myocardial infarction (MI), but the underlying mechanism of QT prolongation and its relation to lethal arrhythmias are unclear.

Methods and Results: Ventricular fibrillation (VF) risk was assessed in 12 dogs 1 month after anterior MI during an exercise test coupled with brief circumflex coronary occlusion. Susceptible dogs (n = 5) developed VF during the brief ischemic episode, whereas resistant dogs did not (n = 7). Surface QT interval was measured at rest. Endocardial electroanatomic catheter maps of left ventricular repolarization were obtained in four unique regions identified by echocardiography and compared between groups. Compared to resistant dogs, susceptible dogs were characterized by prolonged surface QT intervals (240 ± 10 msec vs 222 ± 7 msec, P = 0.04). In addition, they had lower baroreflex sensitivity (9.7 ± 1.5 msec/mmHg vs 28 ± 9.8 msec/mmHg, P < 0.01) and a tachycardic response to acute ischemia suggesting higher propensity for stronger sympathetic reflexes. Surface QT interval prolongation in susceptible dogs was due to a marked heterogeneity of endocardial left ventricular repolarization (239 ± 42 msec, basal anterior wall vs 197 ± 35, lateral wall; P < 0.001). Resistant animals had no regional differences in endocardial repolarization.

Conclusion: Sympathetic activation following MI not only produces adverse structural remodeling but also contributes to adverse electrophysiologic remodeling resulting in heterogeneous ventricular repolarization and in a myocardial substrate conducive to lethal reentrant arrhythmias. (J Cardiovasc Electrophysiol, Vol. 14, pp. 873‐879, August 2003)
Clinical usefulness of head-up tilt test in patients with syncope and intraventricular conduction defect
Authors: Sagristà-Sauleda J. , Romero B. , Permanyer-Miralda G. , Moya A. , Rius-Gelabert T. , Mont Girbau L. , Soler-Soler J.
Published: July 2003

Head-up tilt test was performed in 99 patients with syncope of unknown origin and intraventricular conduction defect. Twenty-five per cent had a positive response to tilt with reproduction of spontaneous clinical symptoms. Holter recording revealed paroxysmal atrioventricular (AV) block in three patients. Carotid sinus massage was positive in four patients. An electrophysiological study was performed in 76 patients with abnormal findings in 17 (22%). Thus, vasovagal syncope was the discharge diagnosis in 25 patients (25%). Therefore, tilt test should be considered in patients with intraventricular conduction defect presenting with syncope of unknown origin, especially if clinical findings suggest the possibility of a vasovagal mechanism, or if the results of the electrophysiological study are inconclusive.
Molecular and Physiological Characterisation of an Insertion Mutant in the ARR21 Putative Response Regulator Gene from Arabidopsis thaliana
Authors: Horák J. , Brzobohatý B. , Lexa M.
Published: July 2003

Abstract: In our search for insertion mutants of Arabidopsis response regulator (ARR) genes, we identified a candidate for an ARR21 dSpm transposon insertion line in the SLAT collection by searching the SINS sequence database. Molecular characterisation of this line revealed that the transposon is integrated as a single copy 1727 bases downstream of the ATG signal, within the third intron of the ARR21 gene. The transposon insertion segregated in a Mendelian fashion from heterozygous plants that were allowed to self‐pollinate. RT‐PCR‐based expression analysis showed that ARR21 transcript predominantly accumulates in siliques. In contrast, the full‐length ARR21 transcript was not detectable in the ARR21 transposon insertion line, indicating that it harbours an insertion of dSpm transposon in the ARR21 gene. The ARR21 insertion mutant (arr21‐1) was subjected to several physiological tests for a possible insertion‐linked phenotype. However, our results revealed that the insertion in the ARR21 gene did not cause any alterations in viability and fertility, flowering time, sensitivity to ethylene, cytokinin or red light. We discuss these results in the light of recent findings about the function of the other members of the response regulator gene family of Arabidopsis.
Morphogenesis of Male Sporangiophores of Zamia amblyphyllidia D. W. Stev.
Authors: Mundry M. , Stützel T.
Published: July 2003

Abstract: Morphology, development and anatomy of the male cones of Zamia amblyphyllidia are studied here to amass additional information to develop a more convincing concept of the evolution of seed plants. The male sporangiophores of the cycads are usually regarded as simple sporangiophores with synangia on the abaxial side. Our developmental study of the male sporangiophores of Zamia amblyphyllidia, by scanning and light microscopy, suggests that the sporangiophores are pinnate, with synangia on reduced leaflets. This indicates that a significant difference between female and male sporangiophores in cycads, as previously stated, does not exist. Comparisons of male sporangiophores of cycads with those of conifers show that they are not homologous. Rather, the synangia of the cycads may better be homologised with the radial synangia groups in some pteridosperm taxa. Although several authors assume that the cycad precursor displayed entire, fertile and sterile leaves, our interpretations of the male sporangiophores indicate that cycads originated from a pinnate pteridospermous ancestor with radial synangia groups. These hypotheses may point to the Medullosaceae, although this remains to be substantiated.
RAPD Evidence for Apomixis and Clonal Populations in Eriotheca (Bombacaceae)
Authors: Martins R. L. , Oliveira P. E.
Published: July 2003

Abstract: Two woody species of Eriotheca (Bombacaceae) of the Central Brazilian Cerrados were submitted to RAPD analyses. Both species are bee pollinated and have a similar flower structure, but E. pubescens presents adventitious embryony and apomixis, while E. gracilipes is self‐incompatible. The RAPD screening reflects these differences in breeding systems, with very low genetic variation in the apomictic species, while the sexual species presented much higher variability with no similar genotypes among the sampled trees. The results suggest that adventitious embryony in E. pubescens effectively results in clonal populations or population mosaics of clonal individuals. Since recent studies have indicated poly‐embryony and possibly apomixis in a number of Cerrado woody species otherwise considered obligatorily allogamous, the RAPD results presented here indicate the technique will be a useful tool to detect clonal populations of apomictic origin among Cerrado woody species with mixed mating systems and will help to assess the importance of apomixis as a breeding system for the Cerrado flora.
“Real” and Feed Pollen of Lagerstroemia indica: Ecophysiological Differences
Authors: Nepi M. , Guarnieri M. , Pacini E.
Published: July 2003

Abstract: Lagerstroemia indica is heterantheric, its flowers bearing two kinds of stamens: six peripheral stamens with long, curved filaments and large anthers producing blue‐green pollen, capable of emitting pollen tubes and fertilizing ovules; or a central tuft of 35 ‐ 40 smaller anthers producing yellow feed pollen that does not germinate and is collected by insects, mainly bees. The two types of pollen differ in volume, number of pores, pore intine protrusion, wall structure, pollenkitt quality, hydration state, viability at anthesis, longevity and mono‐ and disaccharide composition. Although total sugar concentrations (glucose, fructose and sucrose) are the same in both types, relative concentrations are different, “real” pollen being sucrose‐rich (S / [G + F] = 1.2) and feed pollen glucose‐fructose‐rich (S / [G + F] = 0.3). A lower degree of dehydration, pore intine protrusion and higher monosaccharide content could make feed pollen more digestible for pollinators. On the other hand, the cytological features of “real” pollen (high dehydration, higher sucrose content) points to longer viability and reproductive function.
The Hummingbird Plant Community of a Tropical Montane Rain Forest in Southern Ecuador
Authors: Dziedzioch C. , Stevens A.‐D. , Gottsberger G.
Published: July 2003

Abstract: The diversity of a hummingbird plant community in the eastern Andes of southern Ecuador was studied on the equivalent of a hectare (two 500 ′ 10 m transects) at 1920 ‐ 2100 m a.s.l. over the course of a year. A total of 3186 flowering individuals, representing 12 plant families, 29 genera and 72 species, were found to be visited by hummingbirds. Bromeliaceae had the most species visited, followed by Orchidaceae and Ericaceae. The majority of visited plant species were represented by a very few individuals, and only a few species of the Bromeliaceae and Orchidaceae appeared in large numbers of visited individuals. With regard to life forms visited by hummingbirds, epiphytes predominated (59 %), followed by trees and shrubs (29 %), vines (8 %) and herbs (4 %). Visited flowers usually had short‐ to medium‐long floral tubes which were either functionally or morphologically tubiform or campanulate. Fifty percent of the species had red‐coloured flowers, and a considerable number of the blossoms (43 %) displayed contrasting colours. The 72 plant species received visits from 26 species of Trochilidae (hummingbirds) and two species of Coerebidae (honeycreepers). A mere eight species of hummingbirds were seen frequently at the study area; the remaining species were only occasionally sighted. The eight frequently sighted species of hummingbirds made use of a total of 74 % of all hummingbird‐visited plant species growing in the study area.
Sociospatial Dimensions of Technology Adoption: Recent M-Commerce and E-Commerce Developments
Authors: Aoyama Yuko
Published: July 2003

Despite globalization and alleged technological convergence, there remains great variation in the form, manner, and speed of technological adoption and adaptation across societies. In this paper I examine conceptual problems of the information society by considering the differential impacts of technology on production and consumption, and analyzing how sociospatial factors, such as urban form, consumer preference, and cultural attributes shape the patterns of technological adoption in the information age. Examples are drawn from the United States and Japan, to showcase distinctive trajectories of technological adoption by their respective consumers. In particular, practices in Japan's retail sector in participating E-commerce, and the present popularity of wireless web via cellular telephone access are examined to understand better the process of technological progress and consumption.