bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Polyethylene Glycol Conjugated Bovine Hemoglobin in Both Top‐Load and Exchange Transfusion Rat Models
Authors: Conover Charles D. , Linberg Rita , Gilbert Carl W. , Shum Kwok L. , Shorr Robert G.L.
Published: July 2010

Abstract:The purpose of this study was to determine the effect of the hemoglobin based oxygen carrier, polyethylene glycol conjugated bovine hemoglobin (PEG‐Hb) on the physiology of the rat. This study was divided into the following 3 parts: pharmacokinetics, cardiovascular, and histopathology. Pharmacokinetic studies evaluated the PEG‐Hb circulatory life and the resultant effect on urine composition. Telemetric intravascular blood pressure probes monitored the heart rate and mean arterial pressure. Renal arterial blood flow was determined by intra‐operative perivascular ultrasound. Tissue histology was evaluated for both time and model dependent responses. The mean circulatory half‐life of PEG‐Hb was 17.7 ± 0.3 h. Proteinuria and hemoglobinuria were greatly reduced with PEG conjugation. PEG‐Hb treated rats produced 8.5 times and 49 times less proteinuria and hemoglobinuria, respectively, than unmodified bovine Hb treated animals. The mean arterial pressure (MAP) in PEG‐Hb treated rats was insignificantly different from sham controls undergoing a 30% exchange transfusion while dextran caused an initial reduction and bovine Hb produced a prolonged elevation in the MAP. In these same anesthetized rats. PEG‐Hb slightly decreased the heart rate while dextran caused an increase and bovine Hb had no effect. In addition, PEG‐Hb was able to maintain the renal arterial blood flow while both Ringer's lactate and bovine Hb caused a reduction in the blood flow. Finally, PEG‐Hb treated rats showed a dose and time dependent formation of vacuoles within the renal proximal convoluted tubules and splenic macrophages in both top‐load and exchange transfusion models, but no other morphological changes. In conclusion, PEG‐Hb had a relatively long vascular persistence that did not cause any significant alterations in the urinalysis, cardiovascular function, or tissue histopathology in the rat.
Mechanical Stability of the Cementless Acetabular Component with Three Spikes
Authors: Hamada Yoshiki , Akamatsu Noriya , Yamamoto Yasuhiro , Horiuchi Tadahiro
Published: July 2010

Abstract: We studied the stability of our cementless acetabular component (socket) with 3 spikes in 65 joints of 65 patients who were followed for over 5 years. In 1 case, there was osteolysis around the femoral component (stem) but not around the socket. The movement of the socket and the radiolucent line was observed in 11 cases of os‐teoarthritis with acetabular hypoplasia (a mean of 43 degrees of the sharp angle) and 3 cases with rapidly destructive coxarthrosis. We could obtain favorable stability in 50 patients, including 38 with osteoarthritis (a mean of 41 degrees of the sharp angle), 8 with aseptic necrosis, 2 with rapidly destructive coxarthrosis, and 2 with rheumatoid arthritis. Our socket is very effective in preventing osteolysis and is expected to provide more stable mechanical stability by arranging an insertion angle (35 degrees of the optimal open angle and 10 degrees of the anteversion angle) and a full bone graft in osteoarthritic patients.
Effects of Ultrathin Silicone Coating of Porous Membrane on Gas Transfer and Hemolytic Performance
Authors: Niimi Yoshinari , Ueyama Keishi , Yamaji Ken , Yamane Shingo , Tayama Eiki , Sueoka Akinori , Kuwana Katsuyuki , Tahara Koichiro , Nosé Yukihiko
Published: July 2010

Abstract: To assess the effect of an ultrathin (0.2 μm) silicone‐coated microporous membrane oxygenator on gas transfer and hemolytic performance, a silicone‐coated capillary membrane oxygenator (Mera HP Excelung‐prime, HPO‐20H‐C, Senko Medical Instrument Mfg. Co., Ltd. Tokyo, Japan) was compared with a noncoated polypropylene microporous membrane oxygenator of the same model and manufacturer using an in vitro test circuit. The 2 oxygenators showed little difference in the oxygen (O2) transfer rate over a wide range of blood flow rates (1 L/min to 8 L/min). The carbon dioxide (CO2) transfer rate was almost the same in both devices at low blood flow rates. but the silicone‐coated oxygenator showed a decrease of more than 20% in the CO2 transfer rate at higher blood flow rates. This loss in performance could be partly attenuated by increasing the gas/blood flow ratio from 0.5 or 1.0 to 2.0. In the hemolysis study, the silicone‐coated membrane oxygenator showed a smaller increase in plasma free hemoglobin than the noncoated oxygenator. The pressure drop across both oxygenators was the same. These results suggest that the ultrathin silicone‐coated porous membrane oxygenator may be a useful tool for long‐term extracorporeal lung support while maintaining a sufficient gas transfer rate and causing less blood component damage.
A Biomechanical Double Sac (Pericardium‐Pebax) for Specially Shaped Artificial Ventricles: A Computerized Study to Evaluate Its Mechanical and Volumetric Properties
Authors: Chatel Didier , Delamare Laurent , Dang Patrick , Lebouvier Daniel , Trocherie Franqois
Published: July 2010

Abstract: For original ovoid shaped artificial ventricles. a biomechanical double sac consisting of a biological sac (porcine pericardium) as the blood contact interface and a synthetic sac (Pebax 3533) as the mechanical support to assume systolic‐diastolic dynamic constraints was conceived. The volumetric and mechanical properties were assessed with a three‐dimensional modeling of Pebax sacs and computerized simulations of their systolic distortions for both right and left ventricular configurations. The stresses and strains of these sacs were represented as quantitative mappings for a maximum end‐systolic state and were below the respective threshold values above which the Pebax material is jeopardized for permanent structure impairment. After fatigue tests applied on Pebax strips under the alleged working conditions of Pebax sacs, the material structure was unchanged and maintained its intrinsic mechanical properties. The theoretical maximum stroke volumes were 74.4 cm3 and 62.4 cm for the left and right ventricular configurations, respectively. With these mechanical and volumetric features, the biomechanical double sac concept was considered valid and could be provided for a consequent specific total artificial heart.
Unsteady Fluid Dynamics of Several Mechanical Prosthetic Heart Valves Using a Two Component Laser Doppler Anemometer System
Authors: Akutsu Toshinosuke , Modi V.J.
Published: July 2010

Abstract: Five typical mechanical heart valves (Starr‐Edwards, Björk‐Shiley convexo‐concave (c‐c), Björk‐Shiley monostrut, Bicer‐Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component laser Doppler anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level.
Implantation of a Synthetic Cornea: Design, Development and Biological Response
Authors: Trinkaus‐Randall Vickery , Wu Xin Yi , Tablante Rita , Tsuk Andrew
Published: July 2010

Abstract: Our goal was to evaluate 3 different designs of synthetic corneas in vivo. All devices had a transparent hydrogel center molded to a porous peripheral skirt. Over 30 devices were implanted into rabbits and followed for up to 6 months. The devices were preseeded with rabbit stromal fibroblasts, which enhanced the rate of fibroplasia. The anterior surface of the hydrogel was modified using argon of plasma treatments. Clinical examinations were performed, and histological analyses were conducted on tissue throughout the time course. Our optimal model ranged from 4.5 to 6 mm and had an extended porous skirt increasing the surface area for fibroplasia and ultimate anchorage of the device. Fibroplasia occurred in this model, and collagen was detected by 28 days. The anterior chamber was normal with no detectable leakage of aqueous humor. Glycosaminoglycans were detected and followed the time course outlined previously when porous material itself was inserted into the stroma. We present the first demonstration that rabbit limbal epithelial cells can migrate onto the synthetic cornea in vivo.
On Matching Compliance Between Canine Carotid Arteries and Polyurethane Grafts
Authors: Hsu Shan‐hui , Karnbic Helen
Published: July 2010

Abstract: Compliance mismatch between a host artery and an implanted graft has been suggested as a contributing factor to a small diameter graft failure. In this study, static compliance and dynamic compliance were defined and measured in vitro and in vivo for canine carotid arteries and 2 types of polyurethane grafts. Based on these compliance values, the circumferential modulus (Eθ) and longitudinal modulus (Ez) were calculated. It was shown that grafts have constant moduli over a wide range of pressure while the moduli of carotid arteries increase significantly with increasing pressure (dynamic Eθ from 0.20 to 1.32 MPa). Polyurethane grafts are nearly isotropic, with the modulus almost identical in each direction, while carotid arteries are anisotropic (Eθ Ez= 2–3). The dynamic moduli are generally higher than static values and are especially pronounced for arteries. Due to these different inherent characteristics, the compliance of a synthetic graft may match that of the host artery only in the circumferential direction and within a small pressure range. A stated limitation is therefore given for complete compliance matching. The results provide a rationale for identifying the degree of compliance match. These efforts may lead to better designed vascular grafts.
Plasma Hemoglobin Measurement Techniques for the In Vitro Evaluation of Blood Damage Caused by Medical Devices
Authors: Malinauskas Richard A.
Published: July 2010

Abstract: A sensitive measure of the in vitro blood damage potential of a medical device is the rate at which hemoglobin is released into the plasma from red blood cells flowing through the device. Presently there is no one widely accepted method for measuring the plasma hemoglobin concentration. Nine currently used assays, classified as either direct optical or added chemical techniques, were evaluated for accuracy, reproducibility, sensitivity, interference effects, and ease of use by adding hemoglobin (1–200 mg/dl) to saline, lipid, and bilirubin solutions and to normal cow plasma. Most of the assays displayed good linearity, accuracy, and reproducibility down to 1 mg/dl when interferents were absent. However, representative of the effects caused by interferents, the endogenous hemoglobin concentration of a typical cow plasma sample measured by the 9 techniques ranged from ‐2 to 39 mg/dl. Although used by fewer organizations, some of the direct optical spectrophotometric methods (e.g., the Cripps and Harboe baseline correction methods) are safer, easier, and more precise and accurate than the chemical addition methods used to measure plasma hemoglobin concentration from in vitro blood damage testing of medical devices.
Hemolysis Test of a Centrifugal Pump in a Pulsatile Mode: The Effect of Pulse Rate and RPM Variance
Authors: Tayama Eiki , Niimi Yoshinari , Takami Yoshiyuki , Ohashi Yukio , Ohtsuka Goro , Glueck Julia A. , Mueller Juergen , Nosé Yukihiko
Published: July 2010

Abstract: Centrifugal pumps are generally employed as nonpulsatile blood flow pumps; however, these pumps can produce pulsatile flow by periodically alternating the impeller rotation speed. This study investigates blood trauma due to the effect of pulse frequency and various ranges of pump speed. The hemolysis tests were conducted using the Gyro C1E3 pump. The study was divided into the following categories: Group 1 in a nonpulsatile mode; Group 2 operated at 40 bpm with 30% of speed variance; Group 3, 60 bpm with 30% of speed variance; Group 4, 40 bpm with 70% of speed variance; and Group 5, 60 bpm with 70% of speed variance. A flow rate of 3 L/min and a total pressure head of 200 mm Hg were employed in all groups to simulate a percutaneous cardiopulmonary support condition. There were no significant differences in the hemolysis levels among Groups 1, 2, and 3. However, Groups 4 and 5 exhibited a significantly higher hemolysis rate compared to the other groups. These results indicate that a high rate of speed variance increases hemolysis; however, a range of less than 30% does not affect hemolysis. The pulse rate has no significant effect on hemolysis. In conclusion, the higher speed variance increases the hemolysis level when a pulsatile mode is applied with a centrifugal pump at the given test conditions. However, a speed variance of less than 30% or a pulse rate of less than 60 bpm does not affect hemolysis.
Control System Modification of an Electromechanical Pulsatile Total Artifical Heart
Authors: Ohushi Yukio , Andrude Aron de , Müller Jürgen , Nosé Yukihiko
Published: July 2010

Abstract: A reliable control system is one of the most important characteristics of the electromechanical pulsatile total artificial heart (TAH). Obtaining an error‐free procedure is essential for a successful in vivo implantation. To avoid any malfunction of the electrical control system, a modification of the previously designed controller was made to ensure stable pumping without the Hall effect sensor missensing. The installation position of the Hall effect sensor was changed from the top of the housing to the central piece with small magnets being installed in the stabilizer rods. The usage of the Hall effect sensor was chosen as an electrical switch. An in vitro one month running test of the TAH demonstrated adequate hydro‐dynamic performance with a completely error‐free pumping characteristic. The total efficiency of the TAH was 12.6 ± 1.4% at an 8 L/min outflow and 10.7 ± 1.0% at a 6 L/min outflow condition.
LDL Hemoperfusion‐A New Procedure for LDL Apheresis: First Clinical Application of an LDL Adsorber Compatible with Human Whole Blood
Authors: Bosch T. , Schmidt B. , Kleophas W. , Gillen C. , Otto V. , Passlick‐Deetjen J. , Gurland H.J.
Published: July 2010

Abstract: To date, lipid apheresis procedures can remove low‐density lipoprotein (LDL) cholesterol (LDL‐C) only from plasma. Thus, initially plasma has to be separated from the blood cells, which increases the costs and complexity of the extracorporeal circuit. This paper describes the first clinical application of a new LDL adsorber that eliminates LDL directly from whole blood. The goal of this pilot study was to test the efficacy, safety, and feasibility of direct lipoprotein adsorption in patients. In a 2 center Phase II clinical trial, 12 hypercholesterolemic patients suffering from overt coronary or peripheral artery disease were treated once with LDL hemoperfusion. The new LDL adsorber (DALI, Fresenius, St. Wendel, Germany) contained 480 ml of polyacrylate coated polyacrylamide gel. The anticoagulation consisted of an initial heparin bolus followed by an acid citrate dextrose (ACD)‐A infusion during the treatment. The processing of nearly 1 patient blood volume resulted in a reduction of LDL‐C by 45 ± 8% and triglycerides by 23 ± 20%. HDL‐C, fibrinogen, and cell counts were not significantly influenced. In a subgroup of 5 patients who exhibited elevated lipoprotein (a) (Lp[a]) levels, Lp(a) reduction was 43 ± 15% (all results corrected for plasma volume shifts). The sessions were clinically uneventful; the system was technically safe and easily handled. In conclusion, short‐term LDL hemoperfusion by the DALI proved to be a safe, effective, and simple procedure for the treatment of patients suffering from symptomatic recalcitrant hypercholesterolemia. The present study represents a solid basis for the clinical long‐term evaluation of this new technique in the future.
Adsorption of Basic Fibroblast Growth Factor onto Dacron Vascular Prosthesis and Its Biological Efficacy
Authors: Takahashi Kazuhiro
Published: July 2010

Abstract: Adsorption of basic fibroblast growth factor (bFGF) onto a plain fabric Dacron vascular prosthesis (Micron, Intervascular Co., Ltd., Clearwater, FL, U.S.A.) and its release properties from the graft were examined using labeled bFGF, and its biological efficacy was evaluated in an animal study. In an in vitro study, 6 pieces of a Dacron graft were soaked in [125I]‐bFGF solution for 30 min. Then these pieces were soaked in 500 ml saline solution for 15 days, and the radioactivity of each piece was counted at various times. The initial amount of adsorbed bFGF was 2.48 ng/cm2. At 24 h, 41% of the adsorbed bFGF was released and 59% remained. On the third day 55% remained, on the seventh day 52%, and on the 15th day 50% remained on the Dacron surface. Using the atmospheric glow discharge (APG) plasma treatment to render hydrophilic properties, no significant difference between plasma‐treated grafts and non‐plasma‐treated grafts regarding the adsorption of bFGF was observed. In an in vivo study, 6 Dacron pieces adsorbed with bFGF were implanted in the subcutaneous layer of 2 dogs and removed 5 days after implantation. Six Dacron pieces without bFGF were also implanted as a control into the 2 dogs. Fibroblast migration with capillary ingrowth was observed in the specimens with bFGF compared to the controls. These results indicate that the simple adsorption of bFGF onto Dacron fabric is a useful method for the acceleration of host cell migration and capillary ingrowth into Dacron fabric vascular prostheses.
Nitric Oxide and the Lung: An Overview
Authors: Head C. Alvin
Published: July 2010

Abstract: This brief discussion focuses on the effects of nitric oxide (NO) in the lung. A short introduction of some of the physical characteristics of the NO gas molecule and the endogenous production of NO by the vascular endothelium is addressed first. This is followed by a review of inhaled NO use as a hronchodilator of the airway and recent findings of the endogenous production of NO during positive end‐expiratory pressure and the possible role of NO produced in the paranasal Sinuses. Next, the use of inhaled NO for both pulmonary hypertension and improvement in oxygenation under a variety of clinical situations is discussed. Finally, some suggestions are given regarding the safe delivery of inhaled NO during clinical applications using a facemask, an anesthesia circuit, and a mechanical ventilator.
Effect of Nitric Oxide on Oxygenation and Hemodynamics in Infants after Cardiac Surgery
Authors: Sadao Kawasalu , Masahiro Shinozaki , Toshihiko Morinaga , Yasuaki Naito , Yusaku Takagaki
Published: July 2010

Abstract: We evaluated the effect of nitric oxide (NO) on infants after congenital cardiac surgery. Inhaled NO was administered to 7 infants after congenital cardiac surgery. Inhaled NO concentration ranged from 2.5 to 10 parts per million (ppm). The respiratory index (RI = A‐aDo,/Pao,) decreased from 7.4 ± 2.5 to 4.7 ±3.1 in the high RI group (RI ≥ 3, n = 4) 30 min after NO inhalation. After discontinuation of NO inhalation, RI increased to the preinhalation level. NO inhalation was restarted in 2 patients in the high RI group because of severe worsening of oxygenation. RI was not affected by starting or discontinuing of NO in the low RI group (R1 < 3, n = 3). Systemic blood pressure did not significantly change in the 2 groups. Pulmonary arterial pressure (PAP) was measured in 4 patients, and it decreased by 21, 10, and l0%, respectively, 30 min after NO inhalation in 3 patients, but did not change in the remaining patient. After discontinuation of NO inhalation, PAP increased in all patients, and in 2 cases, PAP was higher than baseline value. NO inhalation is effective in improving oxygenation in infants with a high RI after cardiac surgery. However, careful monitoring of the respiratory and hemodynamic states is required after discontinuing NO inhalation.
Hydraulic Assessment of the Floating Impeller Phenomena in a Centrifugal Pump
Authors: Nakazawa Tadashi , Takami Yoshiyuki , Makinouchi Kenzo , Benkowski Robert , Glueck Julie , Damm George , Nosé Yukihiko
Published: July 2010

Abstract: A compact eccentric inlet port centrifugal blood pump (C1E3) has been perfected for a long‐term centrifugal ventricular assist device as well as a cardiopulmonary bypass pump. The C1E3 pump incorporates a sealless design and a blood stagnation free structure. The pump's impeller is magnetically coupled to the driver magnet in a sealless manner. The latest hemolysis study reveals that hemolysis is affected by the magnetic coupling distance between the driver and impeller magnet. Furthermore, a floating phenomenon can be observed in a pivot bearing supported pump. Attention was focused on the relationship between the floating phenomenon's characteristics and the magnetic coupling design in the C1E3 pump. Studies were conducted to evaluate the hydromechanical performance in the floating phenomenon. In this study, the relationship between the magnetic coupling design and the floating phenomenon was verified with a smooth spinning condition. The optimized magnetic coupling distance for the floating mode was estimated to be 12 mm for left ventricular assist device and 9 mm for cardiopulmonary bypass pump. Obtaining an optimal spinning condition is required for regulating the magnetic coupling force. To develop a double pivot bearing pump, it is necessary to establish an optimal spinning and/or floating condition and to determine the proper magnetic coupling and magnetic force between the impeller and driver.
Glutamine and Other Amino Acid Losses During Continuous Venovenous Hemodiafiltration
Authors: Novák I. , ŝrámek V. , Pittrová H. , Ruŝavý Z. , Têŝinský P. , Lacigová S. , Eiselt M. , Kohoutková L. , Veselá E. , Opatrný K.
Published: July 2010

Abstract: Serum amino grams and daily losses of glutamine (Gin) and other amino acids (AAs) into diafiltrate were measured during the first 5 days of continuous venovenous hemodiafiltration (CVVHDF) in 6 ICU patients with acute renal failure (ARF). Four patients had ARF as a part of multiple organ failure (MOF) of septic origin, and 2 patients had isolated ARF because of primary renal disease. During the study, all the patients received defined total parenteral nutrition (TPN). The mean daily AA losses into dialysate were relatively low (0.61 ± 0.1 gN) and reached 4.5% of the daily AA substitution. Gln represented 32.7 ± 5.9% of the total AA losses (0.19 ± 0.04 gN). Serum levels of Gin (p = 0.002) and of most other AAs were significantly lower in the patients than in the control subjects (AA analysis in 16 healthy volunteers). Phenylalanine (Phe) was the only AA that was increased significantly (p < 0.01) in the patients. The mean patient serum concentrations of Phe and tyrosine were significantly higher (p < 0.03) than the correspondent concentrations in dialysate, but the lysine concentration was higher in dialysate (p < 0.03). The serum and dialysate concentrations of other AAs did not differ. Gin in serum decreased significantly (p < 0.03) on the second day of CVVHDF but returned to the baseline levels subsequently. Serum concentrations of Phe increased on the second day of CVVHDF (p < 0.05). Serum concentrations of other AAs remained stable during the whole study. We conclude that Gin losses into dialysate during CVVHDF are relatively low, but CVVHDF itself may induce changes in Gin metabolism and distribution that are reflected by a decrease of serum Gin levels at the institution of this treatment. Therefore, the need for Gin supplementation in ICU patients is even greater in the first days of CVVHDF.
Physiological Effect of Polyethylene Glycol Conjugation on Stroma‐Free Bovine Hemoglobin in the Conscious Dog After Partial Exchange Transfusion
Authors: Conover Charles D. , Lejeune Laura , Shum Kwok , Gilbert Carl , Shorr Robert G. L.
Published: July 2010

Abstract:This study was designed to determine the effect of polyethylene glycol (PEG) conjugation on stroma‐free bovine hemoglobin. This was accomplished by examining the effects of unmodified stroma‐free bovine hemoglobin (bovine Hb), PEG modified bovine hemoglobin (PEG‐Hb) and dextran 70 on heart rate (HR), mean arterial pressure (MAP), gross renal morphology, blood chemistry, and hemoglobinuria development in conscious beagle dogs following a 30% exchange transfusion. Dogs were implanted with telemetric blood pressure probes and after 2 weeks underwent an isovolumic 30% blood volume exchange transfusion. Dogs treated with bovine Hb displayed a significant increase in MAP for 2 h following the exchange transfusion with no effect on HR. These animals exhibited significant levels of hemoglobinuria (>20% of infused dose) within 24 h. Histopathologically, all bovine Hb infused dogs displayed renal tubular vacuolization, with 2 dogs showing regions of tubular casts and tubular cell regeneration. PEG‐Hb was shown to have a circulatory half‐life of 58.3 ± 2.4 h and caused no significant changes in MAP or HR throughout the study period. Dogs excreted less than 0.1% of infused PEG‐Hb within 24 h and displayed only renal tubular epithelial cell vacuolization. Dextran 70 caused a slight but insignificant decrease in MAP, elevated the HR, and exhibited only slight renal vacuole formation. Blood chemistry remained essentially stable following exchange transfusion with all the test articles. The conjugation of PEG to hemoglobin greatly increased the parent protein's vascular retention while attenuating some of its less favorable attributes.
Is the Dog a Useful Model for Accelerated Calcification Study of Cardiovascular Bioprostheses?
Authors: Chanda Jyotirmay , Kuribayashi Ryosei , Abe Tadaaki , Sekine Satoshi , Shibata Yoshiki , Yamagishi Itsuro
Published: July 2010

Abstract: Chitosan posttreatment has been shown to be effective in prevention of calcification of the glutaral‐dehyde treated bovine pericardium when implanted sub‐dermally in rats for 12 weeks. The efficacy of chitosan posttreatment in complete calcium mitigation of the glutaraldehyde treated porcine aortic valves implanted in the right side of the heart in dogs was well‐documented in our previous study. In this study, an attempt has been made to evaluate the merit of the chitosan posttreatment in prevention of calcification of the glutaraldehyde (GA) treated porcine aortic valved conduits in the systemic circulation in dogs for a period of 5 months. Eleven mongrel dogs underwent left thoracotomy. Porcine aortic valved conduits treated with 0.625% GA (n = 5) and GA‐chitosan (n = 6) were implanted in the descending thoracic aortas of the dogs for 5 months. Gross histological observations showed no calcification in either the 0.625% GA treated or in the GA‐chitosan treated valved conduits at 5 months. This was confirmed by results of quantitative analyses for calcium in each explant. There was no significant difference in calcium content between the GA only (Ca, 0.43 ± 0.26 mg/g) and GA‐chitosan treated (Ca, 0.51 ± 0.19 mg/g; p = 0.5959) valved conduits. This study suggests that the dog is not a suitable model for evaluating the efficacy of a calcium mitigating agent in bioprostheses implanted in systemic circulation.
Physiological Control of a Rotary Blood Pump With Selectable Therapeutic Options: Control of Pulsatility Gradient
Authors: Arndt Andreas , Nüsser Peter , Graichen Kurt , Müller Johannes , Lampe Bernhard
Published: July 2010

A control strategy for rotary blood pumps meeting different user‐selectable control objectives is proposed: maximum support with the highest feasible flow rate versus medium support with maximum ventricular washout and controlled opening of the aortic valve (AoV). A pulsatility index (PI) is calculated from the pressure difference, which is deduced from the axial thrust measured by the magnetic bearing of the pump. The gradient of PI with respect to pump speed (GPI) is estimated via online system identification. The outer loop of a cascaded controller regulates GPI to a reference value satisfying the selected control objective. The inner loop controls the PI to a reference value set by the outer loop. Adverse pumping states such as suction and regurgitation can be detected on the basis of the GPI estimates and corrected by the controller. A lumped‐parameter computer model of the assisted circulation was used to simulate variations of ventricular contractility, pulmonary venous pressure, and aortic pressure. The performance of the outer control loop was demonstrated by transitions between the two control modes. Fast reaction of the inner loop was tested by stepwise reduction of venous return. For maximum support, a low PI was maintained without inducing ventricular collapse. For maximum washout, the pump worked at a high PI in the transition region between the opening and the permanently closed AoV. The cascaded control of GPI and PI is able to meet different control objectives and is worth testing in vitro and in vivo.
Magnetic Drive System for a New Centrifugal Rotary Blood Pump
Authors: Hilton Andrew , Tansley Geoff
Published: July 2010

The purpose of this investigation was to design a novel magnetic drive and bearing system for a new centrifugal rotary blood pump (CRBP). The drive system consists of two components: (i) permanent magnets within the impeller of the CRBP; and (ii) the driving electromagnets. Orientation of the magnets varies from axial through to 60° included out‐lean (conical configuration). Permanent magnets replace the electromagnet drive to allow easier characterization. The performance characteristics tested were the axial force of attraction between the stator and rotor at angles of rotational alignment, ∅, and the corresponding torque at those angles. The drive components were tested for various magnetic cone angles, θ. The test was repeated for three backing conditions: (i) non‐backed; (ii) steel‐cupped; and (iii) steel plate back‐iron, performed on an Instron tensile testing machine. Experimental results were expanded upon through finite element and boundary element analysis (BEM). The force/torque characteristics were maximal for a 12‐magnet configuration at 0° cone angle with steel‐back iron (axial force = 60 N, torque = 0.375 Nm). BEM showed how introducing a cone angle increases the radial restoring force threefold while not compromising axial bearing force. Magnets in the drive system may be orientated not only to provide adequate coupling to drive the CRBP, but to provide significant axial and radial bearing forces capable of withstanding over 100 m/s2 shock excitation on the impeller. Although the 12 magnet 0° (θ) configuration yielded the greatest force/torque characteristic, this was seen as potentially unattractive as this magnetic cone angle yielded poor radial restoring force characteristics.
The BiVACOR Rotary Biventricular Assist Device: Concept and In Vitro Investigation
Authors: Timms Daniel , Fraser John , Hayne Mark , Dunning John , McNeil Keith , Pearcy Mark
Published: July 2010

The BiVACOR is a novel rotary Biventricular Assist Device (BiVAD) undergoing development to treat global end‐stage heart failure. The design includes left and right vanes positioned on a shared rotating hub to form a double‐sided magnetically and hydrodynamically suspended centrifugal impeller.

The performance of the device was assessed in a pulsatile mock circulation loop replicating end‐stage biventricular heart failure, and was shown to restore flow from pathological (2 L/min) to normal levels (5 L/min). A novel technique to balance the left/right outflow of the BiVAD was also investigated, for which a maximum relative left to right outflow differential of 1.8 L/min was achieved at normal physiologic afterloads.

The in vitro results encourage device progression to in vivo animal studies. Successful development of this BiVAD will provide a suitably miniature device for patients who require biventricular assistance.
Heat Shock Protein70: A New Marker for Subsequent Atrial Fibrillation Development?
Authors: Oc Mehmet , Ucar Halil Ibrahim , Pinar Asli , Akbulut Birkan , Oc Bahar , Akyon Yakut , Kanbak Meral , Dogan Riza
Published: July 2010

Atrial fibrillation (AF) is a common arrhythmia, after cardiac surgery, and it is associated with a twofold increase in cardiovascular mortality and morbidity. Reperfusion injury and inflammation associated with cardiac surgery are thought to be involved in its pathogenesis. Heat shock proteins (HSPs) are a family of chaperone proteins which assist in preservation of cellular integrity by maintaining proteins in their correctly folded state. The aim of this study was to investigate pre‐postoperative heat shock protein70 (HSP70) and high‐sensitivity C‐reactive protein in serum from patients in preoperative sinus rhythm. We prospectively screened 45 consecutive patients admitted to the hospital for elective coronary artery bypass surgery (CABG). Electrocardiogram characteristics and cardiovascular risk profile were documented. Pre‐ and postoperative blood samples were collected. HSP70 value was 8.9 ± 4.8 ng/mL in Group A (study group) preoperatively and decreased to 7.7 ± 7.0 ng/mL postoperatively. In contrast, preoperative value of HSP70 was 4.2 ± 2.2 ng/mL and decreased to 2.7 ± 2.6 ng/mL postoperatively in Group B (control group). Statistical analysis showed significant difference regarding preoperative HSP70 levels in Group A compared to Group B. To our knowledge, with this study, the association of pre‐ and postoperative circulating HSP70 with postoperative AF was demonstrated for the first time.
Numerical Simulations of Blood Flow in Artificial and Natural Hearts With Fluid–Structure Interaction
Authors: Doyle Matthew G. , Vergniaud Jean‐Baptiste , Tavoularis Stavros , Bourgault Yves
Published: July 2010

This article describes two ongoing numerical studies of fluid–structure interaction in the cardiovascular system: an idealized pulsatile ventricular assist device (VAD), consisting of two fluid chambers separated by a flexible diaphragm; and blood flow and heart wall motion during passive filling of a canine heart. Simulations have been performed for the VAD and compared with the results of a previous study and to our own preliminary experimental results. Detailed measurements of the flow field in the VAD model and additional simulations are in progress. Preliminary simulations using both an idealized model of the natural heart as well as a realistic model have identified the limitations of the current numerical methods in dealing with large three‐dimensional deformations. Ongoing research aims at extending the range of simulations to include large deformations and to incorporate an anisotropic material model for the heart wall to account for the muscle fibers.
Contingent Conclusions: Year of Initiation Influences Ecological Field Experiments, but Temporal Replication is Rare
Authors: Vaughn Kurt J. , Young Truman P.
Published: July 2010

Interannual variation in experimental field conditions produce variability in the results of experiments monitored over multiple years, termed here “year effects.” When experimental treatments are replicated in separate years, interannual variation may influence treatment effects and produce significant treatment by initiation‐year interactions. Understanding the frequency and strength of these effects requires initiating identical experiments across years. We conducted a review of literature covering more than 500 experimental articles published in 7 journals between 1966 and 2008. Only 5% of the 276 general ecological field studies initiated experiments in multiple years. This rarity was even more evident in the journal Restoration Ecology, in which none of the 173 surveyed experimental studies initiated experiments in multiple years. In contrast, 48% of the 58 field experiments published in an agronomy journal were replicated across years. We found only 17 studies that tested treatment by initiation‐year interactions. Despite their rarity, 76% of these studies found significant interactions between treatment and initiation year. We conclude that the results of many ecological field experiments are likely to be contingent on the year in which they are implemented. We discuss the importance of treatment by initiation‐year interactions in ecology and restoration, factors that have hindered the inclusion of temporal replication in the past, and some suggestions for the appropriate design and analysis of temporally replicated experiments. We argue for more deliberate investigation of temporal contingency in ecological experimentation, especially in the field of restoration ecology, which may be particularly sensitive to treatment by initiation‐year interactions.
Factors Affecting Revegetation of Oil Field Access Roads in Semiarid Grassland
Authors: Simmers Sara M. , Galatowitsch Susan M.
Published: July 2010

We assessed vegetation recovery on access roads removed after well abandonment in an active oil‐producing region of northern Great Plains grasslands. We compared extant vegetation on 58 roads, restored 3–22 years previously, to records of species seeded on each and to adjacent, undisturbed prairie, to evaluate main differences between the restored and adjacent community and to explore patterns in the restored plant community over time. The restored plant community was dominated by low richness of seeded non‐native and native grasses and forbs, whereas adjacent prairie had numerous, abundant native graminoids and shrubs and higher richness of native forbs. Cover of seeded species on roads was double that of colonizing species. Disparity in cover of dominant native grasses between the adjacent community and relatively narrow restored roadway suggests that conditions for germination and survival in roadbeds are poor. This is at least partly due to persistence of seeded species. Differences in restored plant composition over time were best explained by changes in species seeded, from non‐natives to natives, and secondarily by successional shifts from ruderal to perennial non‐seeded species. Of the 30 species seeded at least once on these roads, only 10 were commonly used. The long‐term influence of seeding choices in grassland road restorations implies that improvements in these practices will be critical to reversing ecological impacts of roads.
Pharmacology of the β‐Carboline FG‐7142, a Partial Inverse Agonist at the Benzodiazepine Allosteric Site of the GABAA Receptor: Neurochemical, Neurophysiological, and Behavioral Effects
Authors: Evans Andrew K. , Lowry Christopher A.
Published: July 2010

Given the well‐established role of benzodiazepines in treating anxiety disorders, β‐carbolines, spanning a spectrum from full agonists to full inverse agonists at the benzodiazepine allosteric site for the GABAA receptor, can provide valuable insight into the neural mechanisms underlying anxiety‐related physiology and behavior. FG‐7142 is a partial inverse agonist at the benzodiazepine allosteric site with its highest affinity for the α1 subunit‐containing GABAA receptor, although it is not selective. FG‐7142 also has its highest efficacy for modulation of GABA‐induced chloride flux mediated at the α1 subunit‐containing GABAA receptor. FG‐7142 activates a recognized anxiety‐related neural network and interacts with serotonergic, dopaminergic, cholinergic, and noradrenergic modulatory systems within that network. FG‐7142 has been shown to induce anxiety‐related behavioral and physiological responses in a variety of experimental paradigms across numerous mammalian and non‐mammalian species, including humans. FG‐7142 has proconflict actions across anxiety‐related behavioral paradigms, modulates attentional processes, and increases cardioacceleratory sympathetic reactivity and neuroendocrine reactivity. Both acute and chronic FG‐7142 treatment are proconvulsive, upregulate cortical adrenoreceptors, decrease subsequent actions of GABA and β‐carboline agonists, and increase the effectiveness of subsequent GABAA receptor antagonists and β‐carboline inverse agonists. FG‐7142, as a partial inverse agonist, can help to elucidate individual components of full agonism of benzodiazepine binding sites and may serve to identify the specific GABAA receptor subtypes involved in specific behavioral and physiological responses.
The quality of fresh‐frozen plasma produced from whole blood stored at 4°C overnight
Authors: Cardigan Rebecca , Lawrie Andrew S. , Mackie Ian J. , Williamson Lorna M.
Published: July 2010

BACKGROUND: The aim of this study was to assess whether the quality of FFP produced from whole blood stored at 4°C overnight is adequate for its intended purpose.

STUDY DESIGN AND METHODS: Fresh‐frozen plasma (FFP) separated from whole blood (n = 60) leukodepleted (LD) after storage at 4°C overnight (18‐24 hr from donation, Day 1 FFP) was compared with that LD within 8 hours of donation (Day 0 FFP, the current standard method).

RESULTS: In more than 95 percent of Day 1 FFP units, levels of factor (F) II, FV, FVII, FVIII, F IX, FX, FXI, and FXII were greater than 0.50 U per mL except for von Willebrand factor (VWF) antigen and FVIII, where 92 and 87 percent of units, respectively, contained greater than 0.50 IU per mL. Compared with historical data on FFP stored for 8 hours, fibrinogen, FV, FVIII, and FXI were reduced by 12, 15, 23, and 7 percent, respectively, but other factors were not significantly reduced. Levels of VWF‐cleaving protease activity were not different between FFP prepared from paired units of blood (n = 3) held for 8 or 24 hours, but were below the reference range in an additional 2 of 6 units held for 24 hours. The activities of protein S, protein C, antithrombin III, and α2‐antiplasmin were reduced by less than 10 percent in Day 1 FFP (n = 20), but with final levels above the lower limit of the normal range in greater than 95 percent of units. Activated FXII antigen was not significantly raised in plasma stored for 18 to 24 hours, but levels of prothrombin fragment 1 + 2 were slightly increased (0.88 ng/mL, 18‐24 hr; 0.65 ng/mL, < 8 hr).

CONCLUSION: These data suggest that there is good retention of relevant coagulation factor activity in plasma produced from whole blood stored at 4°C for 18 to 24 hours and that this would be an acceptable product for most patients requiring FFP.
Strategic Defiance and Compliance in the U.S. Courts of Appeals
Authors: Westerland Chad , Segal Jeffrey A. , Epstein Lee , Cameron Charles M. , Comparato Scott
Published: July 2010

Why do lower courts treat Supreme Court precedents favorably or unfavorably? To address this question, we formulate a theoretical framework based on current principal‐agent models of the judiciary. We use the framework to structure an empirical analysis of a random sample of 500 Supreme Court cases, yielding over 10,000 subsequent treatments in the U.S. Courts of Appeals. When the contemporary Supreme Court is ideologically estranged from the enacting Supreme Court, lower courts treat precedent much more harshly. Controlling for the ideological distance between the enacting and contemporary Supreme Courts, the preferences of the contemporary lower court itself are unrelated to its behavior. Hence, hierarchical control appears strong and effective. At the same time, however, a lower court's previous treatments of precedent strongly influence its later treatments. The results have important implications for understanding legal change and suggest new directions for judicial principal‐agency theory.
The Strategy of Territorial Conflict
Authors: Carter David B.
Published: July 2010

Many empirical studies have found that disputes over territory are central to the outbreak and intensity of the majority of interstate military conflict. However, the existing literature lacks an explicit theoretical link between the role territory plays in disputes and the outbreak of violence as well as an exploration of how the control of territory is related to conventional military capabilities. This article demonstrates that the targets of territorial claims can consolidate their control over disputed territory to improve their ability to fight effectively on it. The empirical analysis suggests that when territory is strategically located, target states are more likely to consolidate their position, while challenger states are less likely to escalate militarily. Furthermore, when the presence of territorial characteristics such as strategic location makes consolidation an effective strategy, target states are increasingly likely to consolidate as they face stronger opponents.
Shock as a Determinant of Poor Patient‐Centered Outcomes in Implantable Cardioverter Defibrillator Patients: Is There More to It Than Meets the Eye?
Authors: PEDERSEN SUSANNE S. , VAN DEN BROEK KRISTA C. , VAN DEN BERG MARTHA , THEUNS DOMINIC A. M. J.
Published: July 2010

The medical benefits of the implantable cardioverter defibrillator (ICD) are well established, but ICD shocks are known to influence patient‐centered outcomes. In this viewpoint, we examine the strength of the evidence as found in primary and secondary prevention trials that used quality of life as an outcome, and compare the influence of ICD shock with other factors (e.g., heart failure and psychological factors) as determinants of outcomes, with a view to providing recommendations for clinical practice and future research. Based on the large‐scale primary and secondary prevention trials (i.e., CABG‐PATCH, CIDS, AVID, AMIOVIRT, SCD‐HeFT, MADIT‐II, and DEFINITE), evidence for an association between ICD shocks and quality of life is mixed, with some indication that the influence of shocks may depend largely on the interval between shocks and assessment of quality of life. In order to improve the clinical management of ICD patients, we need to adopt a more rigorous and standardized methodology in future studies in order to be able to draw firm conclusions about the impact of ICD shocks on individual patients. We also need to acknowledge that the impact of shocks on psychological functioning and quality of life may not be as straightforward as previously assumed. Given that programming of the ICD is changing, leading to fewer shocks and improved quality of life, it may be timely to also examine the influence of other determinants (e.g., heart failure progression and the patient's psychological profile) of patient‐centered outcomes both in research and in clinical practice. (PACE 2010; 33:1430–1436)