bluuebunny/crossref_metadata_2025 huggingface dataset:
Patent ductus arteriosus in adult patients with aortic valvular disease: The importance of routine screening for a left‐to‐right shunt at cardiac catheterization
Authors: Mehl Sydney J. , Kronzon Itzhak , Glassman Ephraim
Published: February 2007

Two patients, catheterized primarily for the preoperative assessment of clinically apparent aortic stenosis and insufficiency, were found to have a patent ductus arteriosus as well at cardiac catheterization. The association of aortic valve disease and patent ductus arteriosus is reviewed, and the importance of making the diagnosis prior to aortic valve replacement is stressed, emphasizing the routine use of the hydrogen‐platinum electrode system.
External counterpulsation: Coronary hemodynamics and use in treatment of patients with stable angina pectoris
Authors: Solignac Alain , Ferguson Ronald J. , Bourassa Martial G.
Published: February 2007

External pressure counterpulsation (ECP) has been reported to improve the clinical status of patients with angina pectoris. To document the mechanisms for such an improvement left ventricular oxygen consumption and lactate metabolism, coronary sinus blood flow, and cardiac index were studied in 10 patients with angina pectoris 1) prior to and during ECP; and 2) during right atrial pacing before and after 4 consecutive 2‐hour sessions of ECP treatment. During ECP peak early and mean arterial diastolic pressures were significantly raised above control values by 32 and 13% respectively. However, coronary sinus blood flow, left ventricular oxygen consumption and left ventricular lactate extraction, mean systolic arterial pressure and cardiac index were not significantly altered by ECP. Right atrial pacing at 140 beats/min increased coronary sinus blood flow 70% over control values and induced angina and ischemic ST segment changes in 8 patients before and after 4 consecutive treatments of ECP. ECP treatment did not significantly modify the above metabolic and hemodynamic responses at rest or during atrial pacing. Although 5 patients reported improvement in angina symptoms the effect was transitory. No significant improvement over pre ECP‐treatment exercise angina threshold was observed immediately following or at 1 and 3 months post treatment. This method of noninvasive circulatory assistance appears to be of doubtful value in the management of patients with stable angina pectoris.
Effects of propranolol on coronary hemodynamic and metabolic responses to tachycardia stress in patients with and without coronary disease
Authors: Schang Steven J. , Pepine Carl J.
Published: February 2007

To clarify the influence of propranolol—and particularly its heart‐rate effects—on myocardial ischemia, coronary hemodynamics and metabolism were studied in 15 patients utilizing a protocol to control heart rate. Ten patients had significant coronary narrowing (CAD) and 5 were normal. Systemic pressure, coronary sinus blood flow (CSBF), left ventricular oxygen utilization (LVV̇O2), ST Segment depression, and myocardial lactate extraction were measured before and after propranolol (10 mg IV), at rest, and during pacing‐induced tachycardia stress. Propranolol‐related reduction in CSBF and LVV̇O2 at rest was reversed when heart rate was controlled in both patient groups. Propranolol failed to alter heart‐rate threshold, tension‐time index (TTI), CSBF, or LVV̇O2 at angina in the CAD patients. Likewise, ischemic‐type ST depression, decreases in lactate extraction, and coronary resistance were unchanged compared to values observed during tachycardia stress before propranolol. In normal coronary patients, propranolol also produced no significant change in LVV̇O2 or coronary resistance when its heart rate effects were controlled.

These data imply that a major coronary and metabolic influence of propranolol relates to changes occurring secondary to its influence on heart rate. Furthermore, this agent's anti‐ischemic effect is not prominent during tachycardia stress suggesting that this stress test may be clinically useful in patients taking propranolol.
Single left pulmonary vein with normal pulmonary venous drainage: Association with partial anomalous pulmonary venous return
Authors: Belott P. H. , Vieweg W. V. R. , Alpert J. S. , Lacovoni V. E. , Francis G. S. , Johnson Allen D. , Hagan A. D.
Published: February 2007

An unusual case of a single left pulmonary vein draining the left lung and joining the left atrium without venous obstruction is reported. This anomaly occurred in association with partial anomalous pulmonary venous return from the upper lobe of the right lung to the superior vena cava. A similar case has been previously reported from our laboratory. The diagnosis of a single left pulmonary vein can be made by routine chest roentgenography because of the charácteristic radiologic appearance of this anomaly. It is important to distinguish this benign entity from more ominous pulmonary radiodensities.
Long‐term survival in preductal atresia of the aortic arch
Authors: Gomes Antoinette S. , Levisman Jorge A. , Grollman J. H. , Eber Leslie M.
Published: February 2007

Atresia of the aortic arch is distinguished from complete interruption of the aorta by the presence of a fibrotic strand bridging the 2 discontinuous segments of aorta. Most patients with aortic arch atresia have associated intracardiac defects. There is a high neonatal mortality in this condition, with 95% of the patients dying in the first year of life. The case described herein is the first long‐term survivor with atresia of the aortic arch, a patent ductus arteriosus, and an atrial septal defect to reach adulthood.

In this patient an extensive collateral network existed in spite of the presence of a patent ductus arteriosus.
Determination of shunt flow in a case of multiple arteriosystemic connections
Authors: Brewster Hollister P. , Goldschlager Nora , Goldschlager Arnold
Published: February 2007

A 64‐year‐old woman presented with acute congestive heart failure and atrial fibrillation, with good response to medical management. Selective coronary and left ventricular cineangiography demonstrated multiple arteriosystemic connections arising from both left and right coronary arteries, but normal (although tortuous) coronary vessels and ventricular contraction pattern. Determination of the magnitude of the shunt flow and concommitant measurement of myocardial lactate extraction suggested that this type of coronary vascular abnormality was an angiographic curiosity without discernible clinical import; however, the etiology of the patient's heart disease remains an enigma.
A historical review of the concept of the left ventricle as a pump
Authors: Cole James S.
Published: February 2007

Although the concept of the left ventricle as pump has gradually evolved over the past 2000 years, the „modern era”︁ of our understanding began in the 1880's. Studies by Howell and Donaldson, using an isolated heart‐lung preparation, provided insight into the inter‐relationship between preload, afterload and contractility. These concepts were further advanced by Frank, Henderson and Starling, all using isolated heart preparations. The development of new techniques by Wiggers and Hill in the 1920's and 1930's opened up entirely new areas of investigation using intact animal preparations (Wiggers) and isolated muscle segments (Hill). Our debt to these investigators is enormous, and it is perhaps appropriate to reflect on their creative energies as we attempt to define more clearly the mechanical and biochemical functions of heart muscle.
A simple, inexpensive technique to permit the half‐axial projection in laboratories with single plane cineangiography
Authors: Krone Ronald J. , Townsend Richard D.
Published: February 2007

A simple inexpensive modification to permit x‐ray beam angulation of a cineradio‐graphic system consisting of a ceiling‐suspended image intensifier and an under‐the‐table x‐ray tube is described. This has permitted the incorporation of the half‐axial projection into the routine evaluation of the proximal left anterior descending artery (LAD) with a minimum of patient discomfort.
A heart model for understanding three‐dimensional cardiac anatomy
Authors: Wolf N. M. , Santamore W. , Kreulen T. H. , Bove A. A. , Spann J. F.
Published: February 2007

A simple procedure for making cardiac casts has been described. These casts aid in the understanding of the spacial relationships of the ventricles, valves and coronary arteries as they appear at the time of cardiac angiography.
Specification of angulated projections in coronary arteriography
Authors: Taylor K. W. , McLoughlin M. J. , Aldridge H. E.
Published: February 2007

In coronary arteriography cranial and caudal angulations are combined with oblique angulations to obtain additional views. These angulations are obtained with a variety of equipment rotating about different axes.

The planes and axes in and about which the patient and equipment rotate are defined and the equipment is grouped according to the axes about which it rotates. It is shown that a simple definition of the angulation of a projection may be obtained using concepts and terminology consistent with current radiological practice. One group of equipment then gives directly from the rotation of its component parts the angles specifying the projection. For other equipment, the angles specifying the projection are calculated and tabulated for angles of rotation of the equipment from 0 to 90°. Thus, equivalent projections for the different equipment may be found and compared.
High‐frequency pressure fluctuations: Their significance in the documentation of turbulent blood flow
Authors: Sabbah Hani N. , Blick Edward F. , Stein Paul D.
Published: February 2007

The purpose of this report is to indicate the presence of high‐frequency pressure fluctuations that are superimposed upon intra‐arterial pressure curves in man, and to establish their significance as an indication of the presence of turbulent blood flow. Intracardiac pressure was obtained in 23 patients, utilizing catheter‐tip micromanometers. Velocity fluctuations indicative of turbulence were measured in 10 of these patients above the aortic valve. High frequency pressure fluctuations occurred in patients with elevated cardiac output, aortic valvular disease, subaortic stenosis, and atrial septal defect. Patients in whom high frequency velocity fluctuations were measured by hot film anemometry almost always showed high frequency pressure fluctuations on the pressure tracings. This indicated a qualitative relationship between the occurrence of turbulent or disturbed blood flow and the presence of high‐frequency pressure fluctuations. A qualitative relationship between fluctuating pressures and fluctuating velocities was also derived on the basis of fluid dynamic theory. Recognition that high‐frequency pressure fluctuations result from turbulent blood flow may be of value in the localization of turbulent blood flow which, in some instances, may relate to pathological processes.
Closed foramen ovale: A potential entrance to left atrium
Authors: Sweeney Lauren J. , Rosenquist Glenn C.
Published: February 2007

The anatomy of the limbus and its relationship to the fossa ovalis were studied in 90 normal human hearts in an attempt to explain the clinical success of blunt trans‐septal catheterization. Previously reported rates of patent foramen ovale (25–35% of adult specimens) were confirmed, well below the reported rate of success for blunt transseptal catheterization (67–87%). A possible reason for this success is the fragile attachment of the fossa ovalis to its limbus in nearly all hearts without persistent patency.
Bacterial arteritis as a rare complication of coronary arteriography by the brachial arteriotomy approach
Authors: Swaye Paul S. , Worthington Francis X.
Published: February 2007

An unusual case of a systemic bacterial infection in a patient demonstrating localized clinical findings is presented.
Aneurysmal dilatation of the right ventricular outflow tract in infancy: Severe form of uhl's anomaly?
Authors: Graham Thomas P. , Smith Clyde W.
Published: February 2007

A previously unreported cardiovascular malformation is presented consisting of aneurysmal dilatation of the right ventricular outflow tract associated with a cardiomyopathy, a possible variant of Uhl's anomaly. The patient presented at 8 days of age with mild cyanosis and congestive failure. Cardiac catheterization revealed severe cardiomegaly associated with very poor pump function of both right and left ventricles. The present case is unique in showing 1) severe aneurysmal dilatation of the right ventricular outflow tract, 2) only partially absent right ventricular musculature documented before death by the pressure tracing and cineangiocardiograms, and 3) the first quantitation of both right and left ventricular size and function in this syndrome. A review of previous cases of Uhl's anomaly indicates that this case may represent a variant of that condition and that intrauterine myocarditis or myocardial infarct should be considered in regard to etiology.
Ventricular septal defect following blunt trauma: Spontaneous closure of residual defect after surgical repair
Authors: Krajcer Zvonimir , Cooley Denton A. , Leachman Robert D.
Published: February 2007

As a result of blunt chest trauma a patient developed a large ventricular septal defect (VSD). After surgical closure of the defect a grade 2/6 systolic murmur persisted. One year later findings were the same and left ventriculogram revealed a small residual VSD. Two years after the operation the systolic murmur had disappeared. We postulate that gradual endothelialization and possibly small thrombi (formed around and over the Dacron patch graft) caused the defect to close. This case serves to illustrate some of the complexities in the diagnosis and management of an acquired VSD. To our knowledge this is the first reported spontaneous closure of a VSD occurring after incomplete surgical repair.
Comparison of the performance of pigtail catheters with different number of sideholes
Authors: Schwartz Leonard , Vaughan‐Neil Edward
Published: February 2007

The standard 12 sidehole pigtail catheter is compared with pigtail catheters with 6, 8, and 10 sideholes in 40 patient studies. The catheter with fewer sideholes performed as well as the standard catheter with respect to the quality of left ventricular opacification, lack of catheter recoil during angiography, and absence of complications. An in vitro study confirmed that better flushing of the terminal segment beyond the sideholes is achieved with the 6 sidehole catheter compared to the 12 sidehole catheter. It is anticipated that this feature will decrease the risk of thromboembolism associated with the use of the pigtail catheter.
Percutaneous balloon pulmonary valvuloplasty: State of the art
Authors: Rao P. Syamasundar
Published: February 2007

Since the first description of balloon pulmonary valvuloplasty in 1982 by Kan, the procedure has been extensively utilized by several groups of workers for relief of pulmonary valve stenosis. It is generally recommended that the procedure be performed for peak‐to‐peak gradients in excess of 50 mmHg. The technique involves positioning one or more balloon catheters across the stenotic valve, usually over an extra‐stiff guide wire and inflating the balloons with diluted contrast material, thus producing valvotomy. The procedural details are described in this paper. The currently recommended balloon/annulus ratio is 1.2 to 1.25. Immediate reduction of gradient, increase in jet width and free motion of the pulmonary valve leaflets with less doming have been observed following balloon dilatation. Improvement of right ventricular function, tricuspid insufficiency and right‐to‐left shunt has also occurred. Complication can occur, but are rare and minimal. At mid‐term follow‐up, both catheterization measured peak‐to‐peak gradients and Doppler‐measured peak instantaneous gradients remain improved for the group as a whole. However, restenosis, defined as gradient ≥50 mmHg, has been observed in nearly 10% of children. Predictors of restenosis include balloon/annulus ratio <1.2 and immediate post‐valvuloplasty gradient ≥30 mmHg. Small pulmonary valve annulus, earlier study year and post‐surgical complex pulmonary stenosis have also been identified as factors predictive of restenosis. Redilatation with balloons that are larger than those used at the time of initial balloon valvuloplasty produces excellent results and redilatation is the procedure of choice in the management of restenosis after previous balloon pulmonary valvuloplasty. Long‐term follow‐up results are scanty, but the limited data reveal minimal additional restenosis, event‐free rates in mid‐80s and mid‐70s at 10 and 15 years respectively and significant increase in prevalence of pulmonary insufficiency. Balloon pulmonary valvuloplasty is equally successful in neonates as well as in adult subjects. In conclusion, balloon pulmonary valvuloplasty is the treatment of choice for relief of pulmonary valve stenosis. Use of balloons 1.2 to 1.25 times larger than pulmonary valve annulus may produce optimal results. Life‐long follow‐up to identify the significance of residual pulmonary insufficiency is indicated. © 2007 Wiley‐Liss, Inc.
Antegrade popliteal artery approach for the treatment of critical limb ischemia in patients with occluded superficial femoral arteries
Authors: Feiring Andrew J. , Wesolowski Amy A.
Published: February 2007

Treating patients with critical limb ischemia (CLI) secondary to superficial femoral artery (SFA) occlusions and jeopardized tibial‐peroneal run‐off is challenging, especially when the SFA cannot be recanalized. These patients are frequently poor candidates for surgical revascularization and thus amputation is the therapy most often recommended. In this article, we describe a new technique for treating these patients, which combines antegrade popliteal arterial access with tibial arterial revascularization using drug eluting stents (DES). Five patients scheduled for below‐knee amputations were successfully treated using this endovascular approach. For the duration of follow‐up (29 ± 8 months), all patients remained free of death, amputation, or target lesion revascularization. ABI's post intervention demonstrated a modest improvement (ABI = 0.32 ± 0.09 vs. 0.58 ± 0.09 pre vs. post, P ≤≤≤ 0.01). Technical details and rationale for this approach are discussed. Thus, in a well defined subset of patients with recent onset CLI and SFA occlusion, antegrade popliteal DES supported angioplasty offers additional options for patients who might otherwise face amputation. © 2007 Wiley‐Liss, Inc.
Origin of all three major coronary arteries from the right sinus of Valsalva: Clinical, angiographic, and magnetic resonance imaging findings and incidence in a select referral population
Authors: Patel Kashyap B. , Gupta Himanshu , Nath Hrudaya , Aqel Raed A. , Zoghbi Gilbert J. , Soto Benigno , Perry Gilbert J. , Lloyd Steven G.
Published: February 2007

Objective: We sought to determine the incidence and imaging features by coronary angiography and cardiac magnetic resonance imaging (MRI) of anomalies in which the right, circumflex, and left anterior descending coronary arteries arise separately from the right sinus of Valsalva. Background: The anomalous origin of all major coronary arteries from separate ostia in the right sinus of Valsalva has been reported as exceedingly rare, with mainly isolated cases reported. A knowledge of the origin and proximal courses of aberrant arteries is critical for patient management. Methods: 42 consecutive patients without other congenital heart disease referred to our institution for MRI evaluation of anomalous coronary artery over a six year period were evaluated. Analysis of angiograms and MRI was done to determine the anatomic origin and proximal pathway of coronary arteries (determined by conventional angiography and MRI) and degree of any stenosis (by angiography). Results: Seven of the 42 patients (17%) in this referral population had the described anatomy. Both conventional angiography and MRI depicted the origin and proximal courses of these arteries. In all patients, the circumflex passed behind the aorta. In three, the left anterior descending passed through the ventricular septum; in four, it passed anterior to the pulmonary trunk. Conclusions: This series is the largest ever reported on this complex anatomical variant and the first to give a systematic analysis of the anatomy by angiography and MRI. This constellation of multiple anomalous coronary arterial origins and proximal courses may not be as rare as previously reported. Published 2007 Wiley‐Liss, Inc.
Formation of Polymer and Nanoparticle Doped Polymer Minirods by Use of the Microsegmented Flow Principle
Authors: Groß G. A. , Hamann C. , Günther P. M. , Köhler J. M.
Published: February 2007

The microsegmented flow principle was applied for the preparation of polymer minirods. A microfluidic assembly was used to form monomer segments separated by an immiscible perfluorinated aliphatic solvent. These segments were transformed into polymer rods by thermal polymerization. Uniform‐sized polystyrene rods with various diameters and lengths were prepared in this way. The microfluidic geometry and polymerization conditions were tuned to obtain polymer rods of various lengths and diameters. Metal nanoparticle doped polystyrene polymer rods were obtained by thermal polymerization of appropriate nanoparticle/monomer mixtures. After polymerization, the polystyrene rods were colored by an azo coupling reaction.
Flow Boiling of n‐Hexane in Small Channels: Heat Transfer Measurements and Flow Pattern Observations
Authors: Cortina Díaz M. , Schmidt J.
Published: February 2007

An experimental investigation was conducted to study flow boiling heat transfer to n‐hexane. Two different test sections were employed: a single 0.3 · 12.7 mm2rectangular microchannel and a 0.5 mm concentric annulus of 6 mm inner diameter. Both test sections were electrically heated. The examined parameter ranges were: mass fluxes between 50 and 400 kg/(m2 s) and heat fluxes up to 106 kW/m2, at an outlet pressure of 0.1 MPa. Infrared thermography was employed to measure the outer wall temperatures of the rectangular channel and to determine the heat transfer coefficients. This measurement method was especially appropriate for the analysis of the transient behavior of boiling in microchannels, which has been often reported in the literature. In addition, flow visualization was carried out under comparable experimental conditions, using an inner heated circular annulus with a narrow gap.
Formation of Au/Ag Nanoparticles in a Two Step Micro Flow‐Through Process
Authors: Köhler J. M. , Held M. , Hübner U. , Wagner J.
Published: February 2007

The optical properties of metal nanoparticles depend strongly on their composition and size. The plasmon absorption band can be shifted between the blue range and the red range of the optical spectrum, if silver and gold are mixed and aggregation of particles is also induced. The formation of different nanoparticles and nanoparticle aggregates was studied in a two‐step flow‐through process using a glass/Si/glass static micromixer. The educt solution was pumped through the mixer chips by programmable syringe pumps. The process was monitored online by a compact spectrometer connected to the outlet tube by glass fibers. The product solution was collected and investigated by a UV/VIS spectrophotometer. Selected samples were investigated by Scanning Electron Microscopy (SEM) to evaluate the particle morphology. The typical Ag nanoparticle absorption was found, when an excess of Ag ions was introduced into the system. The intensity of the peak decreased when the flow rate of AgNO3 solution was reduced in a reaction system, which included HAuCl4 solution and polyvinyl alcohol, as well as the reducing agent (ascorbic acid). The experiments show that the educt concentration ratios as well as the total flow rates influence the shape and composition of the nanoparticles. Therefore, microreactors with fast mixing and well reproducible mixing conditions are interesting options for the synthesis of nanomaterials.
Designstudie eines kontinuierlichen Ultraschall‐Fällungsreaktors
Authors: Machunsky S. , Peuker U. A.
Published: February 2007

Durchflussreaktoren werden für Fällungsreaktionen als Alternative zu den bisher verwendeten Rührkesselreaktoren gesehen. Der Einsatz von Ultraschall ermöglicht hier einen definierten, intensiven, lokal begrenzten Energieeintrag in den Verfahrensraum. Diese Reaktoren sind aber bisher wenig untersucht worden und damit am Markt nicht in optimierter Form erhältlich. Die hergestellten Partikel werden mittels Partikelgrößenanalyse charakterisiert. Der Effekt der Betriebsparameter Ultraschallleistung, Verweilzeit und Hilfswasserstrom auf die Partikelgröße wird herausgearbeitet. Weiterhin werden experimentelle Ergebnisse diskutiert, die sich auf das geometrische Design des Reaktionsraums konzentrieren. Dabei sind die Position des Ultraschallhorns, die Führung der Feed‐Ströme und die Strategie für die Bereitstellung des Stabilisierungsmittels von Interesse.
Zur Relevanz der Probenteilung für die Partikelgrößenanalyse
Authors: Teipel U. , Winter H.
Published: February 2007

Für die Charakterisierung von Partikeln und dispersen Systemen ist es erforderlich, vor der Durchführung der Größenanalyse aus der vorhandenen Grundgesamtheit eine repräsentative Probe mittels systematischer Probenteilung zu erzeugen. In dieser Arbeit wird gezeigt, dass bei identischer Probennahmetechnik die Probenzuführung und die Beanspruchung des Kollektivs zur Erzeugung einer repräsentativen Probe aus der Grundgesamtheit einen entscheidenden Einfluss auf die Struktur der Probe nach der Teilung aufweist.
Polymorphisms of the neuronal and inducible nitric oxide synthase genes and the risk of cutaneous melanoma
Authors: Li Chunying , Hu Zhibin , Liu Zhensheng , Wang Li‐E , Gershenwald Jeffrey E. , Lee Jeffrey E. , Prieto Victor G. , Duvic Madeleine , Grimm Elizabeth A. , Wei Qingyi
Published: February 2007

BACKGROUND.

Nitric oxide (NO) is a multifunctional molecule that is produced by both neuronal NO synthase (nNOS) and inducible NO synthase (iNOS), and the expression of nNOS and iNOS is up‐regulated in various cancer cells, including cutaneous melanoma (CM). The authors hypothesized that selected functional single‐nucleotide polymorphisms (SNPs) in the nNOS and iNOS genes are associated with the risk of CM.

METHODS.

In a hospital‐based case‐control study of 602 non‐Hispanic white patients with CM and 603 matched, cancer‐free controls, the authors genotyped the nNOS −84 guanine‐to‐adenine (G→A), nNOS 276 cytosine‐to‐thymine (C→T), iNOS Ex16+14C→T, and iNOS 974G→T SNPs and assessed their associations with the risk of CM in multivariate logistic regression models.

RESULTS.

A significantly increased risk of CM was associated with the nNOS −84G→A (adjusted odds ratio [OR], 1.49; 95% confidence interval [95% CI], 1.05–2.13) and −84AG+AA (OR, 1.48; 95% CI, 1.06–2.06) genotypes compared with the nNOS −84GG genotype, but not with other nNOS or iNOS SNPs. In a combined analysis, an increased risk of CM was associated with the nNOS −84AA+AG/276CT+TT genotype (OR, 1.70; 95% CI, 1.05–2.76) and the nNOS −84AA+AG/276CC genotype (OR, 1.70; 95% CI, 1.08–2.68) compared with the nNOS −84GG/276CT+TT genotypes. No altered risk of CM was associated with iNOS genotypes. In addition, there was statistical evidence of interaction of nNOS SNPs with having moles (P = .002) and sunburns (P = .017).

CONCLUSIONS.

Genetic variants of nNOS, but not iNOS, may be biomarkers for susceptibility to CM, and the risk of CM associated with sunburns and moles may be modulated by nNOS variant genotypes. Cancer 2007. © 2007 American Cancer Society.
Protein–Protein Interactions in Complex Cosolvent Solutions
Authors: Javid Nadeem , Vogtt Karsten , Krywka Chris , Tolan Metin , Winter Roland
Published: February 2007

The effects of various kosmotropic and chaotropic cosolvents and salts on the intermolecular interaction potential of positively charged lysozyme is evaluated at varying protein concentrations by using synchrotron small‐angle X‐ray scattering in combination with liquid‐state theoretical approaches. The experimentally derived static structure factors S(Q) obtained without and with added cosolvents and salts are analysed with a statistical mechanical model based on the Derjaguin–Landau–Verwey–Overbeek (DLVO) potential, which accounts for repulsive and attractive interactions between the protein molecules. Different cosolvents and salts influence the interactions between protein molecules differently as a result of changes in the hydration level or solvation, in charge screening, specific adsorption of the additives at the protein surface, or increased hydrophobic interactions. Intermolecular interaction effects are significant above protein concentrations of 1 wt %, and with increasing protein concentration, the repulsive nature of the intermolecular pair potential V(r) increases markedly. Kosmotropic cosolvents like glycerol and sucrose exhibit strong concentration‐dependent effects on the interaction potential, leading to an increase of repulsive forces between the protein molecules at low to medium high osmolyte concentrations. Addition of trifluoroethanol exhibits a multiphasic effect on V(r) when changing its concentration. Salts like sodium chloride and potassium sulfate exhibit strong concentration‐dependent changes of the interaction potential due to charge screening of the positively charged protein molecules. Guanidinium chloride (GdmCl) at low concentrations exhibits a similar charge‐screening effect, resulting in increased attractive interactions between the protein molecules. At higher GdmCl concentrations, V(r) becomes more repulsive in nature due to the presence of high concentrations of Gdm+ ions binding to the protein molecules. Our findings also imply that in calculations of thermodynamic properties of proteins in solution and cosolvent mixtures, activity coefficients may not generally be neglected in the concentration range above 1 wt % protein.
The dyslexic student and mathematics in higher education
Authors: Perkin Glynis , Croft Tony
Published: February 2007

Difficulties that are encountered by dyslexic undergraduates with their learning and understanding of mathematics are explored. Specific consideration is given to issues arising through mathematical content, its delivery, the procedures and processes of ‘doing’ mathematics, and its assessment. Particular difficulties, which have emerged through exploratory and explanatory multiple‐case studies, and witnessed through the provision of one‐to‐one support to a dyslexic and dyspraxic engineering undergraduate, are detailed. Recommendations for the provision of mathematical support to dyslexic students and proposals for future research are given. Copyright © 2007 John Wiley & Sons, Ltd.
Escape of TA3 tumors from allogeneic immune rejection: theory and experiments
Authors: Nowotny A. , Grohsman J. , Abdelnoor A. , Rote N. , Yang Cynara , Waltersdorff R.
Published: February 2007

A factor promoting tumor growth in allogeneic mice was found in the ascites fluid of TA3‐Ha tumor‐bearing mice. Preliminary attempts to isolate this factor resulted in a preparation (P3), devoid of free immunoglobulins or serum proteins, which had enhanced action in promoting tumor growth in vivo. Electron microscopy showed that the P3 preparation is of membranous origin. Biochemical assays for membrane marker enzymes were positive. 5′ ‐Nucleotidase and alkaline α‐glycerophosphatase activity was found. Chemical and gas‐liquid chromatographic analysis of long‐chain carboxylic acids present in the tumor cell membrane and in the P3 revealed the presence of fatty acids in almost identical ratios in both preparations, again indicating the membranous character of P3.

The P3 preparation as well as the ascites fluid have immunogenic properties. They could induce immune tolerance if injected neonatally and the P3 preparation could immunize against the TA3‐Ha tumor if injected intramuscularly or subcutaneously into adult mice. It had no effect if injected intravenously.

In vitro studies of the mode of action of the tumor growth facilitating component indicate that it acts through reaction with immunocytes. A cytotoxic effect of ascites fluid on normal thymocytes in the presence of added complement could be demonstrated. Exposure of immune spleen cells to ascites fluid abrogated their ability to adoptively transfer resistance.

A working hypothesis has been proposed according to which TA3‐Ha tumor cells produce highly reactive membranous decay products which intercept incoming immunocytes or immunoglobulins before they can reach their targets on living tumor cells. Whether this self protection of TA3 ascites tumors can be applied to other tumors remains to be investigated.
The binding of anti‐immunoglobulin antibodies to rat thymocytes and thoracic duct lymphocytes
Authors: Jensenius J. C. , Williams A. F.
Published: February 2007

Anti‐rat immunoglobulin antibodies were purified by acid elution from immunoadsorbents, and their binding to rat thoracic duct lymphocytes and thymocytes studied. Satisfactory binding was only achieved when pepsindegraded reagents were used and anomalous results were obtained if aggregated antibody was present.

From the thoracic duct lymphocytes of the PVG/c strain rat, 40–50 % of cells bound 20000–150000 molecules of anti‐rat Fab antibody, or 8000–60000 molecules of anti‐IgM reagent. Only 2.5 % of the cells bound more than 8000 molecules of anti‐IgG2a+2b antibody and few thymus cells bound any antibody at this level.

Thoracic duct lymphocytes without large amounts of surface immunoglobulin also bound anti‐Fab specifically. The binding was in the range of 200–3000 molecules per cell.
Cytotoxicity of human lymphocytes induced by pokeweed mitogen or in mixed lymphocyte culture. Specificity and nature of effector cells
Authors: Stejskal Vera , Härfast B. , Holm G. , Perlmann P.
Published: February 2007

Purified human peripheral blood lymphocytes were activated in vitro with pokeweed mitogen (PWM) or with mitomycin‐treated allogeneic lymphocytes (MLC). After incubation for several days, stimulation to DNA synthesis and cytotoxicity for phytohemagglutinin (PHA)‐activated lymphoblasts or for Chang cells was tested. Lymphocytes activated with PWM for 3–6 days were cytotoxic for both autologous and allogeneic PHA‐induced lymphoblasts. In addition, they destroyed human tissue culture cells (Chang cells) effectively. In contrast, lymphocytes activated in MLC were cytotoxic for lymphoblasts bearing stimulator cell antigens, but not for autologous PHA‐lymphoblasts. Cytotoxicity for Chang cells was variable. Lymphocytes which proliferate and become cytotoxic after activation in MLC are of T cell origin, since their ability is not reduced by prior removal of non‐T cells on columns charged with human IgG‐anti‐IgG complexes. On the other hand, this procedure reduced both DNA synthesis and cytotoxicity of PWM‐activated lymphocytes. This suggests that cells equipped with surface immunoglobulin and/or Fc recptors were required for activation of these cultures, or alternatively, were among the cells which responded to PWM by DNA synthesis and cytotoxicity.
Ultrastructural distribution and redistribution of alloantigens and concanavalin A receptors on the surface of mouse lymphocytes
Authors: de Petris S. , Raff M. C.
Published: February 2007

The distribution of theta, TL and H‐2 alloantigens and concanavalin A (Con A) receptor sites on mouse lymphocytes was studied using immunoferritin electron microscopy. The alloantigens were demonstrated using alloantibodies followed by either a mono‐ or divalent anti‐mouse Ig‐ferritin conjugate, while Con A receptors were labeled directly with Con A‐ferritin and in some cases, cross‐linked by an additional layer of anti‐ferritin antibody. The results indicate that these membrane macromolecules are mobile in the plane of the membrane and that their distribution can be altered by cross‐linking them with multivalent antibodies or ligands. It is concluded that all lymphocyte membrane macromolecules are probably potentially mobile and diffusely dispersed in the unperturbed membrane, and that any patchy distribution seen is artifactually induced by the multivalent ligands used to demonstrate them.
T cell synergy in mixed lymphocyte culture‐induced cytolysis
Authors: Häyry P. , Andersson L. C.
Published: February 2007

When 0.9 × 106 mouse thymus cells plus 0.1 × 106 peripheral lymph node cells are primed together by allogeneic cells in one‐way mixed lymphocyte culture (MLC), both the MLC blast response and subsequent target cell lysis in cell‐mediated cytolysis are 5–10 times higher than the sum of separate responses. When 0.5 × 106 thymus cells plus 0.5 × 106 peripheral lymph node cells are similarly primed, the MLC response is still superadditive. However, this is no longer so when 0.1 × 106 thymus cells plus 0.9 × 106 peripheral lymph node cells are used as responders. The results confirm the earlier observation on similar T cell synergism in the graft‐vs‐host response. Furthermore, the in vitro method, that can be split into proliferative and effector phases, enables the investigation of the cooperative mechanism in detail.
IgM in bone marrow‐derived lymphocytes. Changes in synthesis, turnover and secretion, and in numbers of molecules on the surface of B cells after mitogenic stimulation
Authors: Melchers F. , Andersson J.
Published: February 2007

Stimulation of small, resting B cells by the mitogen lipopolysaccharide from E. coli induces changes in synthesis, turnover, carbohydrate composition, surface deposition and active secretion of IgM. With increasing time stimulation, the rate of synthesis of the glycoprotein IgM increases over the rates of syntheses of other proteins and carbohydrate‐containing macromolecules. IgM synthesis, being actinomycin D‐sensitive in small, resting lymphocytes, becomes more and more actinomycin D‐resistant. IgM molecules with a median disappearance time around 4 h are synthesized in increasing amounts. These rapidly turning over IgM molecules are no longer shed from the cells as 7–8 S subunits, but are actively secreted as 19 S pentamers. In the secreted 19 S form, they contain the branch sugars galactose and fucose attached to the Hμ‐chains.

Within 20 min after addition of the mitogen to unstimulated B cells, surface‐bound Ig determinants disappear and can no longer be approached from the outside of intact cells by anti‐Ig antibodies. “De novo” synthesis refurnishes the original amount of surface‐bound IgM molecules within 12 h. Beyond 12 h after exposure to the mitogen, more and more IgM molecules appear on the surface. At 40 to 60 h after stimulation, between 35 and 100 times more surface‐bound IgM molecules are on the stimulated B cells. The majority of these surface‐bound IgM molecules turn over rapidly with a median disappearance time around 5 h. The surface membrane appears to be an intermediate station in the migration of IgM molecules out of the cell during active secretion.

IgM synthesis before and after mitogenic stimulation is discussed as a part of the overall biogenesis of membranes in B cells.
Response of human thymus‐derived (T) and non‐thymus‐derived (B) lymphocytes to mitogenic stimulation in vitro
Authors: Geha R. S. , Merler E.
Published: February 2007

Highly pure populations of human T and B lymphocytes were prepared from tonsils using a two‐step fractionation procedure. Cells were first fractionated on discontinuous gradients of bovine serum albumin, then separated on the basis of their reactivity with the sheep red cell intermediates, E and EACl423. More than 95 % of the cells in the final suspensions were either T or B lymphocytes. Phytohemagglutinin and concanavalin A were mitogenic exclusively for T cells. Pokeweed was mitogenic for both T and B cells. T cell proliferation occurred in response to two antigens to which the cell donors were immune: tetanus toxoid (TT) and polyribosephosphate (PRP) capsular antigen of Hemophilus influenzae, type b. B lymphocytes did not transform in response to either PRP, soluble TT, or insoluble TT, but transformed vigorously in the presence of supernatants obtained from TT‐activated T cells.
Radiosensitivity of T and B lymphocytes. II. Effect of irradiation on response of T cells to alloantigens
Authors: Sprent J. , Anderson R. E. , Miller J. F. A. P.
Published: February 2007

The radiosensitivity of T cells was investigated by studying the effect of irradiation in vitro in suppressing the capacity of parental strain thoracic duct lymphocytes (a) to induce splenomegaly in newborn F1 mice, and (b) to proliferate in adult irradiated F1 mice as measured by incorporation of tritiated thymidine ([3H]dThd) 4 days after transfer. By these parameters, small T lymphocytes were found to be highly radiosensitive. It was calculated that, of cells with the reactivity to the alloantigens studied, 0.3 % were capable of a proliferative response after exposure to 500 r. Radiosensitivity was considered to be a reflection of lymphocyte death in interphase.

The radiosensitivity of H‐2‐activated T cells (T. TDL) differed from that of small T cells. Thus, [3H]dThd incorporation by T. TDL measured 1 day after transfer to irradiated F1 hosts was not abolished, although lowered, by exposure to doses as high as 5000 r; [3H]dThd incorporation measured at 2 days, however, was greatly reduced by much smaller doses of irradiation. In view of evidence obtained elsewhere that the response of T. TDL to alloantigens involves DNA synthesis but not cell division, the present studies were interpreted in terms of irradiation causing death of T. TDL in interphase before entry into DNA synthesis. It was concluded that T. TDL were far more resistant to irradiation‐induced interphase death than were small T cells.

The small numbers of lymphocytes obtained from thoracic duct lymph of mice exposed to whole body irradiation 4 days before consisted almost entirely of T cells; these cells, although viable, were found incapable of mounting a proliferate response when exposed to alloantigens on transfer.
Action of dextran sulfate as a direct and general B cell mitogen
Authors: Dörries R. , Schimpl Anneliese , Wecker E.
Published: February 2007

Dextran sulfate (DS‐500) significantly stimulates the in vitro immune response against thymus‐dependent antigens in the absence of T cells. The stimulation of antibody production takes place both in the presence and absence of antigens. Dextran sulfate leads to increased cell division as measured by [3H]thymidine incorporation; the amount of TCA precipitable radioactivity is greater in the absence of T cells than in their presence. It is suggested that the stimulatory effect of DS‐500 is due to its function as a general and direct B cell mitogen.
Lightly haptenated proteins induce IgM‐deficient antibody responses
Authors: Sarvas H. , Mäkelä O.
Published: February 2007

Pairs of hapten‐protein conjugates were used for immunization of different groups of mice. One member of a pair always carried more than 7 moles of hapten per mole of protein (polyvalent conjugate), while the ratio was less than 1.5 for the other member of a pair (mainly monovalent conjugate). The total anti‐hapten response in the two groups of mice was equalized by dose adjustments. Even after this equalization, mice produced 2.3 to 4.3 times higher IgM titers in response to the polyvalent conjugates than to the mainly monovalent ones. A mixture of polyvalent conjugate and noncoupled carrier induced a lower response than the conjugate alone, but both were equally rich in IgM antibody.
Complement‐dependent cytolysis of human B lymphocytes with anti‐light chain antisera
Authors: Meyling F. H. J. Gmelig , Kooy‐Blok Lidy , Ballieux R. E.
Published: February 2007

Using anti‐light chain antiserum and rabbit complement, 12 % of human peripheral blood lymphocytes and 42 % of tonsillar lymphocytes were specifically lysed. From control experiments it could be assumed that these cells are B lymphocytes. Under comparable conditions, cytolysis of tonsillar lymphocytes on a preparative scale was achieved. After removal of the lysed cells by Ficoll‐Isopaque centrifugation, the T/B cell compositions of the remaining living cell population and the untreated cell suspension were compared using the immunofluorescence technique for demonstration of surface immunoglobulin‐bearing cells and the rosette tests for sheep erythrocyte‐binding and complement‐receptor leukocytes. A maximal B cell depletion of 97 % and a T cell enrichment up to 139 % could be obtained. The applicability of the described method for studies on lymphocyte functions is discussed.
Analysis of affinity of monoclonal antibody responses by inhibition of plaque‐forming cells
Authors: North J. R. , Askonas Brigitte A.
Published: February 2007

It has been suggested that dominant monoclonal responses in mice after transfer of small numbers of spleen cells are the result of strong selection for cell clones producing antibody of high affinity. We have attempted to measure the affinity of anti‐DNP (2,4dinitrophenyl) and anti‐NIP (4hydroxy5iodo3nitrophenacetyl) antibodies produced in monoclonal responses by inhibition of plaque‐forming cells (PFC) with free hapten. PFC from individual monoclonal spleen foci and from spleens after adoptive transfer of 5 × 105 to 2 × 106 primed spleen cells were generally inhibited at lower free antigen concentrations than the PFC found in a heterogeneous secondary response.

It was possible to compare several individual cell clones, forming monoclonal antibody to DNP, with respect to the free antigen concentration needed for 50 % plaque inhibition. These comparisons did not correlate well with the relative affinities of serum antibody estimated by the Stupp‐Farr technique.

Published work analyzing PFC from plasma cell tumor MOPC 315 forming antibody to DNP might have predicted that the curve of PFC inhibition by free hapten for a monoclonal PFC population would be steep. Usually this was not the case, and 20–80 % PFC inhibition occurred over 100‐fold concentration range of free hapten.

Some of the anti‐DNP clones formed large plaques and when these PFC were inhibited by free antigen, the plaque diameter decreased progressively as the hapten concentration increased. Large plaques consequently require more free antigen for inhibition than small plaques. The poor agreement between apparent affinity measured by plaque inhibition and that measured in serum antibody for monoclonal antibody responses may well be a result of the observed differences in plaque size between individual clones.

We therefore have strong reservations about the use of plaque inhibition by free antigen to estimate antibody affinity at the cellular level.
Interaction of human anaphylatoxin C3a with rat mast cells demonstrated by immunofluorescence
Authors: Laan Bianca Ter , Molenaar J. L. , Feltkamp‐Vroom Thea M. , Pondman K. W.
Published: February 2007

Specific interaction of human C3a with rat peritoneal mast cells was demonstrated by means of the indirect immunofluorescence technique using anti‐C3a. Anti‐C3b, an antiserum exclusively directed against the native structure of C3, anti‐C3c and anti‐C3d as well as antisera against other complement components and against IgE did not show fluorescence.