bluuebunny/crossref_metadata_2025_split huggingface dataset:
Xenopus embryonic spinal neurons recorded in situ with patch‐clamp electrodes – conditional oscillators after all?
Authors: Aiken Simon P. , Kuenzi Frederick M. , Dale Nicholas 
Published: July 2003

AbstractThe central pattern generator for swimming Xenopus embryo is organized as two half‐centres linked by reciprocal inhibition. Microelectrode recordings suggest that Xenopus neurons are poorly excitable, necessitating a key role for postinhibitory rebound in the operation of the central pattern generator. However the Xenopus central pattern generator seems unusual in that the component neurons apparently have no intrinsic or conditional rhythmogenic properties. We have re‐examined the firing properties of Xenopus embryo spinal neurons by making patch‐clamp recordings in situ from intact spinal cord. Recordings made from 99 neurons were divided into three groups. Central pattern generator neurons overwhelmingly (44/51) fired trains of action potentials in response to current injection. Just over half of the sensory interneurons (13/22) also fired trains of action potentials. Neurons that received no synaptic inputs during swimming mostly fired just one or two action potentials (22/26). Thirty‐four neurons were identified morphologically. Commissural (8/12) and descending (6/6) interneurons, key components of the spinal central pattern generator, fired repetitive trains of action potentials during current injection. Neurons that were not part of the central pattern generator did not demonstrate this preponderance for repetitive firing. Analysis of the interspike intervals during current injection revealed that the majority of central pattern generators, descending and commissural interneurons, could readily fire at frequencies up to twice that of swimming. We suggest that Xenopus neurons can be considered as conditional oscillators: in the presence of unpatterned excitation they exhibit an ability to fire rhythmically. This property makes the Xenopus embryonic central pattern generator more similar to other model central pattern generators than has hitherto been appreciated.
A high‐titer, high‐thermal‐amplitude autoanti‐B associated with acrocyanosis but no obvious hemolytic anemia
Authors: Arndt Patricia A. , Do Jennifer B. , Garratty George , Kuriyan Mercy A. , Strair Roger K. , Baranwal Akhil 
Published: July 2003

BACKGROUND: ABO autoantibodies are rare. Most reported examples have been antibodies with 4°C titers not greater than 256 in patients without apparent hemolytic anemia. Most high‐titer, high‐thermal‐amplitude, complement‐activating cold agglutinins are associated with hemolytic anemia.STUDY DESIGN AND METHODS: A 52‐year‐old man presented with acrocyanosis and mild small‐vessel brain disease, but no evidence of obvious hemolytic anemia. Regular plasmapheresis treatment was helpful in relieving the clinical symptoms associated with acrocyanosis. Serologic methods were used to study the patient's RBCs and sera.RESULTS: The patient's RBCs were strongly reactive with anti‐C3 and anti‐IgM and weakly reactive with anti‐IgA. The patient's serum contained a high‐titer, high‐thermal‐amplitude, IgMκ autoanti‐B, capable of activating complement in vitro.CONCLUSION: A patient with a powerful ABO autoantibody is described. This patient had acrocyanosis but did not appear to have an obvious hemolytic anemia. This case is a good example of the lack of correlation between in vitro serologic tests and in vivo reactions in individual patients.
Circulating RBC volume, measured with biotinylated RBCs, is superior to the Hct to document the hematologic effects of delayed versus immediate umbilical cord clamping in preterm neonates
Authors: Strauss Ronald G. , Mock Donald M. , Johnson Karen , Mock Nell I. , Cress Gretchen , Knosp Laura , Lobas Lori , Schmidt Robert L. 
Published: July 2003

BACKGROUND: One problem assessing the hematologic physiology of preterm infants after delivery and/or the efficacy and toxicity of therapeutic interventions affecting RBC measurements is the inability of blood Hct values to accurately reflect circulating RBC volume—owing to changes in plasma volume that influence Hct (i.e., a fall in plasma volume concentrates RBCs to increase Hct; a rise in plasma volume dilutes RBCs to decrease Hct).STUDY DESIGN AND METHODS: As part of a randomized, clinical trial testing the hypothesis that delayed clamping of the umbilical cord at delivery expands neonatal circulating RBC volume, blood Hct was compared to circulating RBC volume results measured directly with autologous, biotinylated RBCs or estimated mathematically with neonatal body weight and Hct values in neonates after immediate or delayed (60 sec) cord clamping.RESULTS: Circulating RBC volume measured directly with biotinylated RBCs significantly increased (p=0.04) in neonates after delayed (42.1 ± 7.8 mL/kg) versus immediate (36.8 ± 6.3 mL/kg) cord clamping—a difference not detected indirectly by measuring Hct or estimating circulating RBC volume mathematically.CONCLUSIONS: Because true hematologic effects of delayed versus immediate cord clamping may not be apparent or may be misinterpreted, when based on indirect measurements of Hct or calculations of circulating RBC volume, it is important to measure circulating RBC volume directly—as done with autologous, biotinylated RBCs—to document whether delayed cord clamping truly results in a transfer of significant quantities of RBCs from placenta to neonate. The clinical benefits and potential toxicities of increased RBC transfer to neonates require further studies.
Peripheral blood cell telomere length measurements indicate that hematopoietic stem cell turnover is not significantly increased in whole blood and apheresis PLT donors
Authors: Scheding Stefan , Ersöz Inci , Hartmann Ulrike , Bartolvic Kerol , Balabanov Stefan , Salama Abdulgabar , Kanz Lothar , Brümmendorf Tim H. 
Published: July 2003

BACKGROUND: The telomere length (TEL) of peripheral blood leukocytes (PBLs) can be used to estimate hematopoietic stem cell turnover. The current study investigated whether the repetitive stimulation of the hematopoietic system caused by regular whole blood (WB) and PLT donations would affect PBL TEL.STUDY DESIGN AND METHODS: PBLs were obtained from healthy donors (n=94) with a history of at least 3 years of WB donation (median, 7.7 years; range, 3.0‐43.0 years) plus additional apheresis PLT donations. The median (range) numbers of WB and PLT donations were 22.0 (6.0‐194.0) and 42.0 (7.0‐336.0), respectively. Additionally, samples were obtained from healthy nondonors (n=47). PBL TEL was measured with fluorescence in situ hybridization and flow cytometry (flow‐FISH). Flow‐FISH results were expressed in molecular equivalents of soluble fluorochrome units (MESF; 1000 MESF=1 kMESF) either as absolute (TEL) or as age‐adjusted TEL (ΔTEL).RESULTS: Donor granulocyte and lymphocyte TELs were 12.6 ± 0.3 (mean ± SEM) and 13.2 ± 0.3 kMESF, respectively. No differences were observed when compared with corresponding nondonor data (granulocytes, 12.5 ± 0.4 kMESF; lymphocytes, 13.6 ± 0.5 kMESF). Furthermore, ΔTEL values did not differ between the two groups and were not different from previously established reference values. In addition, neither donor data for age‐adjusted TEL for granulocytes nor ΔTEL for lymphocytes were correlated with either total years or total numbers of WB and/or PLT donations.CONCLUSION: Long‐term WB and PLT donation does not affect PBW TEL as measured by flow‐FISH, arguing against a significantly increased stem cell turnover.
Collection of WBC‐reduced single‐donor PLT concentrates with a new blood cell separator: results of a multicenter study
Authors: Moog Roger , Zeiler Thomas , Heuft Hans‐Gert , Stephan Berckard , Fischer Eike G. , Kretschmer Volker , Rödel‐Spieker Regina , Strasser Stephan , Zingsem Jürgen 
Published: July 2003

BACKGROUND: A new cell separator (COM.TEC, Fresenius) was recently developed aimed at efficient collection of WBC‐reduced single‐donor PLT concentrates (SDPs).STUDY DESIGN AND METHODS: Five German centers collected 554 WBC‐reduced SDPs with help of the COM.TEC cell separator. Two multicenter cell counting studies were performed at the beginning and at the end of the study to document uniform counting results among the participating centers.RESULTS: A total of 441 (79.6%) PLT collections were included in the study according to the protocol. A total of 342 single‐dose and 99 double‐dose SDPs were collected. For single‐dose SDPs, an average blood volume of 2826 ± 409 mL was processed in a donation time of 55 ± 11 minutes. Mean PLT yield of these products was 3.11 × 1011± 0.40 × 1011 and the WBC contamination was 0.11 × 106± 0.20 × 106. For double‐dose SDPs (PLT count, 5.29 ± 0.93 × 1011), 3943 ± 639 mL was processed. The average difference between the target and the collected PLT concentration was −2.8 ± 12.0 percent for single‐dose SDPs and −1.8 ± 9.5 for double‐dose SDPs, respectively. The collection efficiency was 53.7 ± 5.8 percent for single‐dose SDPs and 58.2 ± 6.2 percent for double‐dose SDPs. If all results of each sample from the counting study were set to unity (to the mean over all centers), most PLT determinations were very similar to the mean, for example, near or 1 if set to unity.CONCLUSION: The COM.TEC machine makes it possible to obtain WBC‐reduced SDPs that comply with current standards.
Mutations that diminish expression of Kell surface protein and lead to the Kmod RBC phenotype
Authors: Lee Soohee , Russo David C.W. , Reid Marion E. , Redman Colvin M. 
Published: July 2003

BACKGROUND: Kmod is an inherited rare RBC phenotype characterized by weak but detectable expression of high‐incidence Kell antigens.STUDY DESIGN AND METHODS: The 19 exons and the intron‐exon regions of the KEL gene from four unrelated Kmod individuals were sequenced and compared to wild‐type KEL. To study the mechanisms by which the mutations result in depression of Kell antigens, mutant and wild‐type Kell proteins were expressed in 293T cells and the amounts of protein present on the cell surface were determined.RESULTS: The following point mutations were identified: Kmod−1, homozygous 1208G>A, S363N; Kmod−2, heterozygous, 1208G>A, S363N and 2150 A>G, Y677C; Kmod−3 (previously classified as KEL:−13), heterozygous 1106T>C, L329P and 1716G>A, W532Stop; Kmod−4, heterozygous, 2227G>A, G703R and a silent 1839C>T mutation. In transfected 293T cells, fewer G703R and L329P mutant Kell proteins were transported to the cell surface compared with wild‐type Kell protein, and there was no detectable Y677C mutant Kell protein. Previously, it was shown that that S363N Kell protein was not detected on the cell surface.CONCLUSION: Different point mutations, causing amino acid substitutions and presumably altering protein conformation, inhibit transport of the mutant Kell proteins to the cell surface. The different mutations leading to the Kmod phenotype explain why anti‐Ku made by persons with the Kmod phenotype are not mutually compatible.
Extended blood grouping of blood donors with automatable PCR‐ELISA genotyping
Authors: St‐Louis Maryse , Perreault Josée , Lemieux Réal 
Published: July 2003

BACKGROUND: In the past 10 years, PCR‐based methods have been described to allow the detection of gene polymorphisms responsible for many blood group antigens. These methods are routinely used to test samples of fetal origin and to resolve serologic discrepancies. Another interesting application of blood group genotyping could be the extended typing of blood donors for minor antigens to facilitate the procurement of compatible blood for alloimmunized patients.STUDY DESIGN AND METHODS: PCR‐based tests have been modified to allow multiplex amplification of specific fragments of blood group genes and the convenient detection of hybridized amplicons by ELISA in a microplate format.RESULTS: The results obtained show that fragments of the Rh (D, c, C, e, E), Kell (K, k), Duffy (Fya, Fyb), and Kidd (Jka, Jkb) genes could be amplified along with controls in multiplex PCR reactions. Labeling of amplicons with digoxigenin allowed their solid‐phase detection in microplate wells previously coated with individual blood group‐specific oligonucleotides. A comparative study performed with 100 individuals showed a 99.7 percent concordance between genotypes and phenotypes for the 11 antigens assayed, with only three discrepant Fyb genotypes.CONCLUSION: Extended genotyping could be performed once on regular donors and confirmed when needed by standard serologic RBC assays. The format of these tests will allow easy automation of the procedure including the interpretation and downloading of the results with existing ELISA software.
Donor exposure to the plasticizer di(2‐ethylhexyl)phthalate during plateletpheresis
Authors: Buchta Christoph , Bittner Claudia , Höcker Paul , Macher Maria , Schmid Rainer , Seger Christoph , Dettke Markus 
Published: July 2003

BACKGROUND: Di(2‐ethylhexyl)phthalate (DEHP) is a plasticizer that is contained in most PVC devices, including apheresis disposables. Because DEHP can be extracted from apheresis disposables as the blood passes through the apheresis device, DEHP exposure was determined in healthy donors undergoing plateletpheresis performed with commercially available apheresis systems.STUDY DESIGN AND METHODS: The study population consisted of 36 healthy PLT donors undergoing plateletpheresis with either continuous or discontinuous apheresis devices. Serum concentrations of DEHP were determined from peripheral blood obtained before and after plateletpheresis, with gas chromatography‐mass spectroscopy.RESULTS: Plateletpheresis performed with standard collection disposables resulted in a median increase of 232 percent of serum DEHP compared to levels before apheresis, corresponding to a total amount of DEHP exposed during a single apheresis of a median of 6.46 (range, 1.8‐20.3) μg per kg of body weight. Endogenous levels of triglycerides showed a positive correlation with the amount of DEHP released. Increase in serum DEHP was short‐term as serum DEHP rapidly returned to levels obtained before apheresis within 3 hours after completion of the apheresis course. Donor exposure to DEHP led to no variation in liver cell function within 48 hours after plateletpheresis.CONCLUSION: Commercial plateletpheresis disposables release considerable amounts of DEHP during the apheresis procedure, but the total dose of DEHP retained by the donor is within the normal range of DEHP exposure of the general population.
West Nile virus infection transmitted by blood transfusion
Authors: Harrington Theresa , Kuehnert Matthew J. , Kamel Hany , Lanciotti Robert S. , Hand Sheryl , Currier Mary , Chamberland Mary E. , Petersen Lyle R. , Marfin Anthony A. 
Published: July 2003

BACKGROUND: A patient with transfusion‐transmitted West Nile virus (WNV) infection confirmed by viral culture of a blood component is described. A 24‐year‐old female with severe postpartum hemorrhage developed fever, chills, headache, and generalized malaise after transfusion of 18 units of blood components; a serum sample and the cerebrospinal fluid tested positive for the presence of WNV IgM antibodies. An investigation was initiated to determine a possible association between transfusion and WNV infection.STUDY DESIGN AND METHODS: Blood donors were assessed for recent infection through questionnaires and WNV testing of serum samples. Whole‐blood retention segments and untransfused blood components were sent to the CDC to test for the presence of WNV through PCR (TaqMan, Applied Biosystems), IgM ELISA, plaque reduction neutralization testing, and viral culture.RESULTS: Three of 15 available donor retention segments were WNV PCR‐positive. WNV was recovered from one associated blood component. The implicated donor was symptomatic near the time of donation; serology confirmed WNV IgM seroconversion.CONCLUSION: Seroconversion of a symptomatic donor, the presence of viral genetic material in an associated whole‐blood retention segment, and recovery of WNV from an associated component provides compelling evidence for transfusion‐acquired infection. This report has important implications for blood safety.
Combination HCV core antigen and antibody assay on a fully automated chemiluminescence analyzer
Authors: Shah Dinesh O. , Chang Chi D. , Jiang Lily X. , Cheng Kevin Y. , Muerhoff A. Scott , Gutierrez Robin A. , Leary Thomas P. , Desai Suresh M. , Batac‐Herman Irenea V. , Salbilla Vince A. , Haller Alla S. , Stewart James L. , Dawson George J. 
Published: July 2003

BACKGROUND:HCV exposure among blood donors is serologically determined by detection of antibodies to HCV (anti‐HCV); however, the recent development of an assay for the detection of HCV core antigen identifies infection before anti‐HCV development. Simultaneous detection of HCV core antigen and anti‐HCV would shorten the window period before seroconversion over conventional HCV antibody screening assays.STUDY DESIGN AND METHODS:A prototype chemiluminescent immunoassay was developed for simultaneous detection of HCV core antigen and anti‐HCV in human sera and plasma. The assay was performed on a single‐channel instrument representing an automated serologic analyzer (PRISM, Abbott Laboratories) system. Sensitivity and specificity were evaluated by testing 23 HCV seroconversion panels and plasma or sera from volunteer blood donors.RESULTS:The prototype HCV core antigen and antibody combination assay detected 80 of 89 (89.9% ) HCV RNA‐positive and antibody‐negative specimens from 23 panels, thereby reducing the seroconversion window period by an average of 34.3 days compared to PRISM HCV antibody detection. All PRISM HCV antibody‐positive specimens were detected by the combination assay for a relative sensitivity of 100 percent. The repeatedly reactive rate was 0.20 percent based on testing of 3017 screened anti‐HCV‐negative sera and plasma.CONCLUSIONS:The prototype combination assay was shown to detect HCV core antigen and anti‐HCV simultaneously and significantly closed the time gap between the initial detection of HCV RNA and the first appearance of detectable antibodies to HCV.
Fiber Orientation and Cell‐Cell Coupling Influence Ventricular Fibrillation Dynamics
Authors: Choi Bum‐Rak , Liu Tong , Lavasani Mitra , Salama Guy 
Published: July 2003

Introduction: The structure of ventricular fibrillation (VF) is influenced by regional differences in action potential durations and perhaps restitution kinetics and fiber anisotropy. The spatial organization of VF was investigated by measuring the cross‐correlation (CC) and mutual information (MI) of membrane potential (Vm) oscillations recorded from multiple sites. Methods and Results: Rabbit hearts (n = 6) were retrogradely perfused and stained with di‐4‐ANEPPS, and VF was elicited by burst pacing. Vm oscillations were recorded optically from multiple locations on the epicardium using a 16 × 16 photodiode array or a 72 × 78 CCD camera. The spatial organization of VF was investigated by calculating the maximum CC (CCmax) and MI (MImax) that can be obtained between any two sites. CCmax and MImax were extended to all pixels and served as indices of the similarities between Vm transients at a reference pixel and all other pixels on the map. We found that maps of CCmax and MImax did not contain discrete regions with high CC or MI. However, CCmax and MImax decreased monotonically with increasing distance between any arbitrarily chosen reference pixel and all other pixels. In VF, maps of CCmax and MImax revealed elliptical gradients of CC and MI that were closely aligned with fiber orientation, with major axis at 127°± 8° on the left ventricles. Conclusion: CC and MI analysis in fibrillation provides new evidence that anisotropy of fiber orientation and cell‐cell coupling have a direct influence on VF dynamics. (J Cardiovasc Electrophysiol, Vol. 14, pp. 851‐860, August 2003)
Defibrillation Efficacy and Pain Perception of Two Biphasic Waveforms for Internal Cardioversion of Atrial Fibrillation
Authors: Jung Jens , Siaplaouras Stephanos , Buob Axel , Schubert Bernd D. , Hahn Stephen J. , Heisel Armin 
Published: July 2003

Introduction: We evaluated the influence of the peak voltage of waveforms used for internal cardioversion of atrial fibrillation on defibrillation efficacy and pain perception. A low peak voltage biphasic waveform generated by a 500‐μF capacitor with 40% tilt was compared to a standard biphasic waveform generated by a 60‐μF capacitor with 80% tilt. Methods and Results: In 19 patients with paroxysmal atrial fibrillation (79% male, age 55 ± 11 years, 21% with heart disease), the atrial defibrillation threshold (ADFT) was determined during deep sedation with midazolam for both waveforms in a randomized fashion using a step‐up protocol. Internal cardioversion with a single lead (shock vector: coronary sinus to right atrium) was successful in 18 (95%) of 19 patients. ADFT energy and peak voltage were significantly lower for the low‐voltage waveform (2.1 ± 2.4 J vs 3.5 ± 3.9 J, P < 0.01; 100 ± 53 V vs 290 ± 149 V, P < 0.01). Sedation then was reversed with flumazenil after ADFT testing. Two shocks at the ADFT (or a 3‐J shock if ADFT >3 J) were administered to the patient using each waveform in random order. Pain perception was assessed using both a visual scale and a numerical score. ADFTs were above the pain threshold in 17 (94%) of 18 patients, even though the ADFT with the 500‐μF waveform was <100 V in 63% of the patients. Pain perception was comparable for both waveforms (numerical score: 6.5 ± 2.4 vs 6.3 ± 2.6; visual scale: 5.4 ± 2.6 vs 5.2 ± 3.1; P = NS, 500‐μF vs 60‐μF). The second shock was perceived as more painful in 88% of the patients, independent of the waveform used. Conclusion: Despite a 66% lower peak voltage and a 40% lower energy, the 40% tilt, 500‐μF capacitor biphasic waveform did not change the pain perceived by the patient during delivery of internal cardioversion shocks. Pain perception for internal cardioversion probably is not influenced by peak voltage alone and increases with the number of applied shocks. (J Cardiovasc Electrophysiol, Vol. 14, pp. 837‐840, August 2003)
Prognostic Significance of Heart Rate Turbulence Following Ventricular Premature Beats in Patients with Idiopathic Dilated Cardiomyopathy
Authors: Grimm Wolfram , Sharkova Julia , Christ Michael , Müller Hans‐Helge , Schmidt Georg , Maisch Bernhard 
Published: July 2003

Introduction: The aim of this study was to investigate the prognostic significance of heart rate turbulence (HRT) characterized by HRT onset and slope after ventricular premature beats in patients with idiopathic dilated cardiomyopathy (IDC). Methods and Results: Blinded HRT analysis was performed in 242 patients with IDC who were enrolled in the Marburg Cardiomyopathy database between 1992 and 2000. During 41 ± 23 months of follow‐up, 54 patients (22%) died or underwent heart transplant. On Cox univariate regression analysis, abnormal HRT onset, HRT slope, HRT onset combined with HRT slope, left ventricular (LV) ejection fraction, LV size, and New York Heart Association (NYHA) functional class III showed a significant association with total mortality or the need for heart transplant. On multivariate analysis, abnormal HRT onset identified patients without transplant‐free survival, as did LV size and NYHA class III heart failure. Major arrhythmic events were observed in 42 patients (17%) during follow‐up. On univariate analysis, abnormal HRT onset, HRT onset combined with HRT slope, male sex, NYHA class III, LV ejection fraction, and LV size were associated with a higher incidence of major arrhythmic events. On multivariate analysis, only LV ejection fraction remained as a significant arrhythmia risk predictor, with a relative risk of 2.2 per 10% decrease in ejection fraction (95% confidence interval 1.5–3.2). Conclusion: In this selected patient population with IDC, HRT onset is a significant predictor of transplant‐free survival, as are LV size and NYHA class. For arrhythmia risk stratification, however, only LV ejection fraction remained a significant risk predictor on multivariate analysis. (J Cardiovasc Electrophysiol, Vol. 14, pp. 819‐824, August 2003)