bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of Absence of Porcine Endogenous Retrovirus (PERV) Infection in Patients Treated with a Bioartificial Liver Support System
Authors: Pitkin Zorina , Mullon Claudy
Published: March 2003

Abstract: Porcine endogenous retrovirus (PERV) genomes are present in all pig cells. In this retrospective study, we assessed PERV infectivity in 28 patients treated with an extracorporeal bioartificial liver (HepatAssist system) that includes a membrane device containing porcine hepatocytes. All patients tested negative for PERV using polymerase chain reaction analysis of peripheral blood mononuclear cells (PBMC) collected up to 5 years after treatment. In vitro results showed that the membrane decreased the risk of PERV transmission by a factor of 105, and porcine hepatocytes did not produce infectious PERV in co‐cultures with human cell line 293. Our results do not support the presence of PERV infection in patients treated with this porcine hepatocyte‐based bioartificial liver.
Acute Clinical Deterioration in a Patient with End‐Stage Dilated Cardiomyopathy and Left Ventricular Thrombus Formation
Authors: Marx Manfred , Golej Johann , Wollenek Gregor , Boigner Harald
Published: March 2003

Abstract: The case of a 17‐year‐old male patient with severe end‐stage dilated cardiomyopathy and a large thrombus formation within the cavum of the left ventricle is reported. After an acute thrombectomia combined with a partial left ventriculectomy (Batista procedure), the patient was successfully treated with an appropriate left ventricular assist device (LVAD) system using a centrifugal nonocclusive pump (Biomedicus, Medtronic, Anaheim, CA, U.S.A.). Mechanical support was removed on Day 9, and the patient was discharged from the hospital on Day 19. The effectiveness of emergency mechanical support in patients with very unfavorable prognoses is discussed.
Comparative In Vitro Evaluation of Two Different Preparations of Small Diameter Polyurethane Vascular Grafts
Authors: Hsu Shan‐hui , Tseng Hsiang‐jung , Wu Meng‐shou
Published: March 2003

Abstract: Polyurethane (PU) frequently has been used to manufacture small diameter vascular grafts due to its good bicompatibility. In this study, sponge PU small diameter vascular grafts were fabricated from Pellethane 2103, as well as a self‐synthesized PU, by utilization of a salt casting technique and by varying the salt/polymer ratios. Two types were made; one of them had a thin solid layer on the outer surface. The inner surface was identical and was coated with gelatin crosslinked by epoxide. Tensile properties, compliance, platelet activation, and endothelial cell attachment were evaluated in vitro. It was found that for the grafts with an outer nonporous coating, compliance could not be estimated from modulus due to anisotropy. The most compliance‐matched grafts were made of self‐synthesized polyurethane with a salt/polymer ratio 4 to 8 or Pellethane with a ratio 6 to 8 without the outer nonporous coating. The former had better elongation. Self‐synthesized PU had lower platelet adhesion as well as more endothelial attachment than Pellethane. Porosity activated platelets strongly and reduced endothelial adhesion unless the surface was modified by the crosslinked gelatin layer. It was concluded that PU synthesized in our lab with a salt/polymer ratio of at least 4 and coated with epoxy crosslinked gelatin was a better substrate for preparation of small diameter vascular grafts.
A Clinical Use of the Kyocera Gyro C1E3 Centrifugal Pump
Authors: Hata Mitsumasa , Shiono Motomi , Orime Yukihiko , Yagi Shinya , Yamamoto Tomonori , Okumura Haruhiko , Kimura Shun‐ichi , Sezai Akira , Kashiwazaki Satoshi , Choh Shinsuke , Negishi Nanao , Sezai Yukiyasu , Matsui Takahiro , Suzuki Mitsunori , Nakata Kin‐ichi , Nosé Yukihiko
Published: March 2003

Abstract: The Kyocera Gyro C1E3 centrifugal blood pump was clinically applied for a cardiopulmonary bypass (CPB) of coronary artery bypass grafting (CABG). The patient was 72‐year‐old male with postinfarction unstable angina. The surgery was carried out on November 20, 1998. The air inside the pump was easily and quickly removed, and its controllability was excellent. The pump flow during operation was maintained 2.2 L/m2. Total CPB time was 173 min. Perioperative parameters of hemolysis and cytotoxicity were not remarkably changed. Macroscopically and microscopically, there were no thrombi inside the pump after usage. This is the first reported case of clinical use of the Kyocera Gyro C1E3 pump.
Enhanced Responsiveness of Circulatory Neutrophils After Cardiopulmonary Bypass: Increased Aggregability and Superoxide Producing Capacity
Authors: Kawahito Koji , Kobayashi Eiji , Ohmori Masami , Harada Kazuhiro , Kitoh Yasuhiko , Fujimura Akio , Fuse Katsuo
Published: March 2003

Abstract: Cardiac surgery with cardiopulmonary bypass (CPB) induces a whole body inflammatory response that sometimes leads to postoperative organ dysfunction, and neutrophil activation plays an important role in this reaction. Neutrophil priming has been described as a change in neutrophil status such that neutrophils show enhanced responsiveness to a second activating stimulus. We hypothesized that neutrophil priming occurs by cardiac surgery with CPB and is temporally related to the neutrophilia after surgery. To evaluate primed circulatory neutrophil status, we measured aggregation activity stimulated by N‐formyl‐methyl‐leucyl‐phenyl‐alanine (FMLP) and free radical producing activity by tumor necrosing factor (TNF) α in peripheral blood samples. Eleven adult patients undergoing elective cardiac surgery with CPB were studied. Blood samples were taken before surgery, at the end of bypass, 12 h after surgery, and 7 days after surgery. Aggregation activity and superoxide generation were significantly elevated 12 h after sugery when compared to presurgery values, indicating that cardiac surgery is associated with circulatory neutrophil priming. The number of neutrophils markedly increased at the end of cardiopulmonary bypass and reached a peak 12 h after surgery. The circulatory neutrophils of cardiac surgical patients become primed after surgery, coincident with the peak neutrophil count. These results suggest that circulatory neutrophils after cardiac surgery with CPB have enhanced responsiveness and are predisposed to systemic inflammation.
Validation of a Model for Flow‐Dependent Carbon Dioxide Exchange in Artificial Lungs
Authors: Hout Mariah S. , Hattler Brack G. , Federspiel William J.
Published: March 2003

Abstract: The exchange rate of CO2 in artificial lungs depends on the sweep gas flow rate. Control of the amount of CO2 removed by an artificial lung requires quantitative knowledge of the flow dependence. A simple model of the dependence of CO2 exchange on sweep gas flow rate in artificial lungs has been previously presented
(1). For a given partial pressure of CO2 in the blood phase, sweep gas flow rate, and CO2 exchange rate, the model indicates how close the CO2 exchange rate is to the maximum level attainable by the artificial lung. The focus of this study was to validate the model experimentally by testing 2 commercial artificial lungs in an in vitro test loop. The CO2 exchange rate for each artificial lung was measured over a range of sweep gas flow rates. Linear regression was used to fit the data to the model and estimate the maximum possible CO2 exchange rate and the average water‐side P
co2 (
Pco2w). The difference between the measured and regressed values of
Pco2w was used as an indicator of the ability of the model to quantitatively predict the dependence of CO2 exchange on gas flow rate. This difference was less than 5% for each experiment, indicating that the model can be used to guide control of CO2 exchange rates in artificial lungs.
Paper is a Compatible Bed for Rat Hepatocytes
Authors: Mizuguchi Toru , Mitaka Toshihiro , Sato Fumihiko , Mochizuki Yohichi , Hirata Koichi
Published: March 2003

Abstract:To develop an effective hybrid bioartificial liver (BAL) device, the material of the scaffold is very important to support hepatocytes that have both growth ability and hepatic differentiated functions. In this study we used paper (Kimwipe, Kimberly‐Clark Corp., Roswell, GA, U.S.A.) as a scaffold. Primary hepatocytes isolated from a normal adult rat liver could proliferate on the paper. The secretion of albumin into culture medium by the cells on the paper increased with time in culture and, compared to the cells on dishes, the amount of 48 h albumin secretion at Day 10 was two times larger. Perpendicular sections of hepatocytes on the paper revealed that the cells fell into cavities made by intersecting fibers, piled up, and formed three to four layers. The piled‐up cells changed their shape from flat to cuboidal and enlarged their cytoplasm, which was rich in organelles such as mitochondria and peroxisomes with a nucleoid. In addition, they formed bile canalicular structures between the cells. Their morphological appearance was similar to in vivo hepatocytes. Paper (Kimwipe) may be a good candidate as a scaffold to make a BAL device.
Artificial Articular Cartilage: Mechanoelectrical Transduction Under Dynamic Compressive Loading
Authors: Malmonge Sônia Maria , Arruda Antonio Celso
Published: March 2003

Abstract: The search for biomaterials to be used as an artificial articular cartilage in joint restoration is a challenging research area. Because the articular cartilage plays a fundamental role in joint function, the biomaterial has to be able to mimic the behavior of the natural healthy surface. Articular cartilage is a biphasic material composed by a solid extracellular matrix and a fluid phase, the synovial fluid. When the tissue is pressed, there is a mechanoelectrical transduction that is believed to modulate the cellular activity of chondrocytes, being fundamental for tissue repair. This work aimed at the development of hydrogels for use as an artificial articular cartilage. Hydrogels with negative groups fixed in the macromolecular network were obtained by copolymerizing 2‐hydroxyethyl methacrylate with acrylic acid. The obtained hydrogels showed a mechanoelectrical transduction under dynamic compressive loading with potential amplitude increasing with fixed charge density values.
Age Dependency of Neointima Formation on Vascular Prostheses in Dogs
Authors: Noishiki Yasuharu , Yamane Yoshihisa , Ichikawa Yukio , Yamazaki Ichiya , Yamamoto Kenji , Kosuge Takayuki , Manabe Takahiro , Mo Makoto
Published: March 2003

Abstract: Neointima formed quickly on vascular prostheses implanted in young dogs but not in aged dogs. Previously, we found that impeding neointima formation on vascular prostheses occurred more frequently in aged animals. From these observations, we hypothesized that neointima formation was age‐dependent in dogs. To test the hypothesis, 26 fabric Dacron vascular prostheses were analyzed. Half of them were retrieved from aged dogs (more than 13 years old) while the other half were from young ones (less than 1 year old). The grafts were harvested at 8 weeks and 3 months after implantation. The graft surfaces were photographed and analyzed by computer for the ratio of the areas with and without thrombus. Light and scanning electron microscopic observation revealed that most of the thrombus‐free areas were lined with endothelial cells. Then the endothelialized areas were calculated. Using data obtained from macroscopic, light microscopic, and scanning electron microscopic observations, the arithmetic means were calculated as the degree of neointima formation. In young animals, the degrees at 8 weeks and at 3 months were 89.1 ± 8.5% (mean ± SD) and 95.7 ± 3.3%, respectively. In old animals, they were 27.9 ± 5.9% and 31.5 ± 6.8%, respectively. From these results, we concluded that neointima formation was age‐dependent in dogs.
Is Erythrocyte Damage Prevented by Gardos Effect in Hemodialyzed Uremic Patients?
Authors: Agroyannis B. , Paraskevopoulos A. , Kopelias I. , Tzanatos H. , Kapetanaki A. , Tsomi A.
Published: March 2003

Abstract: The purpose of this study was to determine the changes of calcium and potassium content in red blood cells (RBC) from uremic patients during a hemodialysis (HD) session. In 17 uremic patients on HD, the calcium and potassium content of RBC was determined in 3 blood samples collected at 0 min‐HD (pre‐HD), 45 min‐HD, and 240 min‐HD (end‐HD) during a 4 h HD session. The calcium and potassium content of RBC also was determined in 20 normal subjects (controls). The mean values (±SD) of RBC calcium content in patients at 0 min‐HD, 45 min‐HD, and 240 min‐HD were 1.95 ± 0.34, 2.82 ± 0.50, and 2.05 ± 0.4 μg/ml, respectively, and in controls 0.61 ± 0.14 μg/ml. These values show that the RBC calcium in patients was generally significantly higher (p < 0.0001) in comparison to that of controls. The RBC calcium at 45 min‐HD was significantly higher as compared to that at 0 min‐HD and at 240 min‐HD (p < 0.0001). The mean values (±SD) of RBCs' potassium in uremic patients at the previously mentioned measurements were 95.9 ± 3.34, 92.5 ± 4.32, and 93.85 ± 3.89 mEq/L, respectively, and in controls 98.46 ± 2.30 mEq/L. These values show that RBC potassium of patients was generally significantly lower in comparison to controls (0 min‐HD: p < 0.01, 45 min‐HD and 240 min‐HD: p < 0.001). Potassium decrease also was significantly lower at 240 min‐HD (p < 0.01) and even lower at 45 min‐HD (p < 0.001) compared to that at 0 min‐HD. In conclusion, uremic patients during an HD session present a high calcium and a low potassium content of erythrocytes. These changes may prevent swelling of the cells (Gardos effect).
Engineering Analysis of Diamond‐Like Carbon Coated Polymeric Materials for Biomedical Applications
Authors: Alanazi Ali , Nojiri Chisato , Kido Takayuki , Noguchi T. , Ohgoe Y. , Matsuda T. , Hirakuri Kenji , Funakubo Akio , Sakai Kiyotaka , Fukui Yasuhiro
Published: March 2003

Abstract: Diamond‐like carbon (DLC) films have received much attention recently owing to their properties, which are similar to diamond: hardness, thermal conductivity, corrosion resistance against chemicals, abrasion resistance, good biocompatibility, and uniform flat surface. Furthermore, DLC films can be deposited easily on many substrates for wide area coat at room temperature. DLC films were developed for applications as biomedical materials in blood contacting‐devices (e.g., rotary blood pump) and showed good biocompatibility for these applications. In this study, we investigated the surface roughness by Atomic Force Microscopy (AFM) and Hi‐vision camera, SEM for surface imaging. The DLC films were produced by radio frequency glow discharge plasma decomposed of hydrocarbon gas at room temperature and low pressure (53 Pa) on several kinds of polycarbonate substrates. For the evaluation of the relation between deposition rate and platelet adhesion that we investigated in a previous study, DLC films were deposited at the same methane pressure for several deposition times, and film thickness was investigated. In addition, the deposition rate of DLC films on polymeric substrates is similar to the deposition rate of those deposited on Si substrates. There were no significant differences in substrates' surface roughness that were coated by DLC films in different deposition rates (16–40 nm). The surface energy and the contact angle of the DLC films were investigated. The chemical bond of DLC films also was evaluated. The evaluation of surface properties by many methods and measurements and the relationship between the platelet adhesion and film thickness is discussed. Finally, the presented DLC films appear to be promising candidates for biomedical applications and merit investigation.
Fluid Dynamic Characteristics of the VentrAssist Rotary Blood Pump
Authors: Tansley G. , Vidakovic S. , Reizes J.
Published: March 2003

Abstract: The VentrAssist pump has no shaft or seal, and the device is unique in design because the rotor is suspended passively by hydrodynamic forces, and urging is accomplished by an integrated direct current motor rotor that also acts as the pump impeller. This device has led to many challenges in its fluidic design, namely large flow‐blockage from impeller blades, low stiffness of bearings with concomitant impeller displacement under pulsatile load conditions, and very small running clearances. Low specific speed and radial blade off‐flow were selected in order to minimize the hemolysis. Pulsatile and steady‐flow tests show the impeller is stable under normal operating conditions. Computational fluid dynamics (CFD) has been used to optimize flow paths and reduce net axial force imbalance to acceptably small values. The latest design of the pump achieved a system efficiency of 18% (in 30% hematocrit of red blood cells suspended in phosphate‐buffered saline), and efficiency was optimized over the range of operating conditions. Parameters critical to improving pump efficiency were investigated.
Antithrombogenicity Evaluation of a Centrifugal Blood Pump
Authors: Nakata K. , Yoshikawa M. , Takano T. , Maeda T. , Nonaka K. , Linneweber J. , Kawahito S. , Glueck J. , Fujisawa A. , Makinouchi K. , Yokokawa M. , Nosé Y.
Published: March 2003

Abstract: The Gyro C1E3 pump was developed not only for cardiopulmonary bypass but also as a short‐term assist device. The main purpose of this study was to examine the correlation between the thrombus formation factor and the Gyro C1E3 pumps. Seven pumps were implanted into 3 calves and evaluated for different periods of duration as a paracorporeal left ventricular assist device (LVAD). One pump was subjected to percutaneous cardiopulmonary support condition (PCPS) (total pressure head 500 mm Hg with a pump flow rate of 3 L/min). The anticoagulation treatment consisted of a continuous administration of heparin to maintain an activated clotting time (ACT) of 200–250 during the LVAD study and 250–300 during the PCPS study. After the experiment, the pumps were disassembled and examined. In cases where there were any blood‐derived deposits inside the pumps, the dry weight of these thrombi that adhered to the bearing area of the pump was measured. A multiple correlation was attempted to speculate possible thrombus formation. The estimated dry weight of thrombi was calculated from pump flow rate, pumping day, motor speed, and activated clotting time. This equation was estimated dry weight of thrombi = 1.140 × pump flow rate −0.001 motor speed + 1.652 pumping time −0.041 × ACT + 2.198 R2 = 0.944. This study suggested that there was a possibility to calculate the amount of adhered thrombus formation from pump flow rate, motor speed, pumping day, and ACT.
Biocompatibility of Heparin‐Coated Extracorporeal Bypass Circuits: New Heparin Bonded Bioline System
Authors: Tayama Eiki , Hayashida Nobuhiko , Akasu Koji , Kosuga Tomokazu , Fukunaga Shyuji , Akashi Hidetoshi , Kawara Takemi , Aoyagi Shigeaki
Published: March 2003

Abstract: Biocompatibility of a new type of heparin‐coated cardiopulmonary bypass equipment, the Bioline, was evaluated in coronary artery bypass surgery cases. The heparin‐coated (H) group (n = 15; Quadrox Bioline oxygenator/reservior and Carmeda BioMedicus BP‐80 centrifugal pump) was compared with the nonheparin‐coated (N) group (n = 12; uncoated, otherwise similar oxygenator, centrifugal pump, tubing, and filter set). Both groups used full systemic heparinization. The peak values of neutrophil elastase, C3a, IL‐6, and IL‐8 at 2 h after cardiopulmonary bypass (CPB), and C3a levels at the end of CPB and at 2 h after CPB were significantly reduced in the H group compared with those of the N group. However, no statistically significant intergroup differences were observed in thrombin‐antithrombin complex, D‐dimer, β‐thromboglobulin, or platelet factor‐4. No significant differences were observed in hemostasis time, postoperative 12 h blood loss, required amount of blood transfusion, or intubation time. In conclusion, the Bioline demonstrated partially improved biocompatibility, in terms of leukocyte and complement activation, and proinflammatory cytokine production. However, it did not improve platelet activation, coagulation, or fibrinolysis cascade under full systemic heparinization. As a result, the clinical beneficial impact seemed to be the minimum.
Effect of Low‐Dose Citrate Anticoagulation on the Clinical Safety and Efficacy of Direct Adsorption of Lipoproteins (DALI Apheresis) in Hypercholesterolemic Patients: A Prospective Controlled Clinical Trial
Authors: Bosch T. , Heinemann O. , Duhr C. , Wendler T. , Keller C. , Fink E. , Kirschner T. , Klebert S. , Samtleben W.
Published: March 2003

Abstract: Direct adsorption of lipoproteins (DALI) is the first lipid apheresis system compatible with whole blood with the advantage of a very simple procedure. A mixture of heparin plus citrate (ACD‐A) is used for the anticoagulation regimen (AR). A clinical, prospective, controlled crossover study was performed to test the safety and efficacy of low‐dose citrate (LDC) anticoagulation in DALI. Five chronic DALI patients suffering from coronary heart disease and hypercholesterolemia underwent 3 DALI sessions each using the LDC anticoagulation regimen (60 IU heparin/kg body weight as initial bolus; 1:40 ACD‐A: blood as perfusion). This was compared to 3 sessions per patient with the standard AR (bolus of 20 IU heparin/kg, 1:20 ACD‐A as perfusion). Patient blood volumes (1.6; average of 7,040 ml) were treated with 750 ml adsorber gel per session at a blood flow rate of 60 ml/min. Mean LDL and Lp(a) reductions exceeded 60% with both AR. No clinical side effects were observed. Both AR controlled the coagulation well as evidenced by a sufficient prolongation of the partial prothrombin time (PTT) and activated clotting time as well as low thrombin–antithrombin (TAT) formation. Biocompatibility parameters exhibited favorable results (low activation of complement and cells, and only slight formation of C3a, C5a, β‐thromboglobulin, elastase, and TNF‐α). The asymptomatic bradykinin generation was comparable in both study arms. LDC optimized the ionized calcium levels and pH in the efferent blood postadsorber. LDC anticoagulation was safe and effective, and may further improve the tolerance of DALI apheresis in hypercholesterolemic patients.
Late Symptomatic Venous Stenosis in Three Hemodialysis Patients Without Previous Central Venous Catheters
Authors: Morosetti Massimo , Meloni Carlo , Gandini Roberto , Galderisi Cristina , Pampana Enrico , Nicoletti Maria , Gallucci Massimo Taccone , Simonetti Giovanni , Casciani Carlo Umberto
Published: March 2003

Abstract: It is well known that catheters placed in the subclavian or internal jugular veins may develop stenosis in the vein in which the catheter lies. Because the arteriovenous fistula (AVF) relies on good venous outflow, patients with ipsilateral central venous stenosis are subject to the malfunctioning of AVF. Until now, no data were published on patients showing central vein stenosis (CVS) without a previous central venous catheter (CVC) or a pacemaker. In this article, we report on 3 hemodialysis patients manifesting CVS ipslateral to AVF. None of these patients previously had undergone CVC. The stenosis observed had characteristics and symptoms similar to those observed in stenoses consequent to CVC. We concluded that CVS also may occur in subclavian or axillary veins proximal to a working AVF in hemodialysis patients who have never had a CVC and in the absence of compressive phenomena.
Midterm Results of Stent‐Graft Repair for Thoracic Aortic Aneurysms: Computed Tomographic Evaluation
Authors: Yamazaki Ichiya , Imoto Kiyotaka , Suzuki Shin‐ichi , Ichikawa Yukio , Karube Norihisa , Manabe Takahiro , Noishiki Yasuharu , Kondo Jiro , Takanashi Yoshinori
Published: March 2003

Abstract: Midterm observation of endovascular surgery using a fabric‐covered stent graft for thoracic aortic aneurysms is discussed with postoperative follow‐up findings based on regularly performed thoracic computed tomography (CT). From 1996 to 1999, 20 patients with thoracic aortic aneurysm underwent stent‐graft placement in our hospital. One year follow‐up CT results after placement were obtained for 17 patients. The CT scans found that there were both thrombosis and size reduction of aneurysm in 8 patients (46%), thrombosis without size reduction in 2 (13%), a new ulcerlike projection (ULP) in 3 (19%), persistent minor endoleakage in 2 (13%), a new endoleak in 1 (6%), and a recurrent endoleak from intercostal arteries in 1 (6%). The new ULP formation seemed to be a peculiar problem stemming from an intimal injury caused by edges of the stent. Therefore, we recently adopted a new spiral stent instead of the previous stent to avoid the injury. The new endoleak suggested that aneurysmal thrombosis without size reduction could cause the aneurysm to develop recurrent endoleaks. From these findings, we concluded that midterm observation of stent‐graft repair for thoracic aortic aneurysms did not give satisfactory results. In order to improve the results of endovascular surgery using stent‐grafts, we need to develop safer stent grafts with a reliable design to prevent endoleaks and to avoid intimal injury of the aorta. We also hope to develop effective technologies that can accelerate organization of thrombus in the aortic aneurysm after stent‐graft placement.
Introduction of Tissue Engineering Concepts into the Field of Endovascular Grafts: An Attempt to Solve Endoleakage Problems of Endovascular Grafts Implanted in Aortic Aneurysms
Authors: Noishiki Yasuharu , Ichikawa Yukio , Kosuge Takayuki , Yamazaki Ichiya , Yamamoto Kenji , Manabe Takahiro , Lu Yao , Yamane Yoshihisa
Published: March 2003

Abstract: To solve endoleakage problems of endovascular prostheses inserted in aortic aneurysms, a concept originating from tissue engineering was proposed. We proposed that in order to accelerate the thrombus inside the aneurysm, three major factors for successful tissue engineering, i.e., appropriate cells, extracellular matrices, and growth factors, should be introduced into a space between the endovascular grafts and the aneurysm. As a simulation model in animals, two kinds of fabric vascular prostheses were used. One was a small graft used as an endovascular graft and another was a large graft as an envelope for the small graft, used as the aneurysm wall. Adipose tissue fragments with fresh blood coagula were injected between the two grafts. The control was a preparation without tissue fragments. Two months and a half after surgery, the test group showed complete connective tissue formation in the space between the two grafts, but in the control, brownish thrombus remained. From this experiment, we speculated that tissue fragment transplantation will accelerate connective tissue formation of the thrombus, and this complete organization of the thrombus might reduce endoleakage.
Red Eye Syndrome: Clinical and Experimental Experience in a New Aspect of Diffuse Eosinophilic Infiltration?
Authors: Averbukh Z. , Modai D. , Sandbank J. , Berman S. , Cohn M. , Galperin E. , Cohen N. , Dishi V. , Weissgarten J.
Published: March 2003

Abstract: Twenty‐two of 24 hemodialysis patients dialyzed simultaneously with a new batch of cellulose acetate dialyzers promptly developed a spectrum of symptoms and physical signs including red eyes, hearing loss, tinnitus, and bone pain, previously described as red eye syndrome. We subsequently injected 4 rabbits with an eluate from a dialyzer of the same or a control batch. Six hours following exposure, the animals developed, in addition to red eyes, diffuse eosinophilic infiltration of various organs as well as myopathic changes and moderate brain edema. On the basis of these data, we suggest that it cannot be concluded whether the underlying pathophysiological mechanisms were toxic, allergic or both and that the occurrence of relevant symptomatology in 2 or more simultaneously dialyzed patients is a strong argument against unnecessary diagnostic or therapeutic procedures. Finally, a second exposure in a given patient should be avoided.
Development of a Totally Implantable Pulsatile Centrifugal Pump as a Ventricular Assist Device
Authors: Chou Nai‐Kuan , Wang Shoei‐Shen , Lin Yuan‐Hsiang , Shyu Jeou‐Jong , Hsieh Kuo‐Huang , Jan Gwo‐Jen , Chu Shu‐Hsun
Published: March 2003

Abstract: The Taita No. 1 ventricular assist device (T‐VAD) is a totally implantable pulsatile impeller centrifugal pump driven by a magnetically suspended motor. The flow can achieve 2.01 ± 0.17 L/min against a pressure of 100 mm Hg under 0.266 ± 0.017 amp and 13.55 ± 0.41 voltage. The speed was around 3,500 rpm. It consumed less than 6 W of power, resulting in less heat production and mechanical bearing complications. The impeller vane was designed to have both radial and axial curves according to the stream surface and stream lines to reduce thrombosis and hemolysis. Eight calves weighing 80 to 100 kg (mean 87 ± 12 kg) were used for experiments. With the calves under general anesthesia, left posterolateral thoracotomy was performed to connect the inflow tube with the atrial appendage and to anastomose the outflow tube with the descending aorta. The calves usually awoke and stood up within hours after discontinuation of anesthetics. The mean survival of the calves was 75 ± 42 days (range 33–148 days). The terminations of experiments were mainly due to infection. During the course of pumping, no significant deterioration of liver or renal function was noted. The evaluation of serum samples from the implanted calves indicated that hemolysis was not associated with use of the T‐VAD. The average daily free hemoglobin level was 8.08 ± 3.05 mg/dl, which was less than the set limit of 20 mg/dl. The red blood cell and platelet count and hemoglobin of implanted animals were within the normal range. In our results, the T‐VAD provided competent pulsatile function without severe blood damage or organ dysfunction.
Design and Evaluation of a Single‐Pivot Supported Centrifugal Blood Pump
Authors: Yoshino M. , Uemura M. , Takahashi K. , Watanabe N. , Hoshi H. , Ohuchi K. , Nakamura M. , Fujita H. , Sakamoto T. , Takatani S.
Published: March 2003

Abstract: In order to develop a centrifugal blood pump that meets the requirements of a long‐term, implantable circulatory support device, in this study a single‐pivot bearing supported centrifugal blood pump was designed to evaluate its basic performance. The single‐pivot structure consisted of a ceramic ball male pivot mounted on the bottom surface of the impeller and a polyethylene female pivot incorporated in the bottom pump casing. The follower magnet mounted inside the impeller was magnetically coupled to the driver magnet mounted on the shaft of the direct current brushless motor. As the motor rotated, the impeller rotated supported entirely by a single‐pivot bearing system. The static pump performance obtained in the mock circulatory loop revealed an acceptable performance as a left ventricular assist device in terms of flow and head pressure. The pump flow of 5 L/min against the head pressure of 100 mm Hg was obtained at rotational speeds of 2,000 to 2,200 rpm. The maximum pump flow was 9 L/min with 2,200 rpm. The maximum electrical‐to‐hydraulic power conversion efficiency was around 14% at pump flows of 4 to 5 L/min. The stability of the impeller was demonstrated at the pump rpm higher than 1,400 with a single‐pivot bearing without an additional support at its top. The single‐pivot supported centrifugal pump can provide adequate flow and pressure as a ventricular assist device, but its mechanical stability and hemolytic as well as thrombotic performances must be tested prior to clinical use.
In vitro Construction of a Potential Skin Substitute through Direct Human Keratinocyte Plating onto Decellularized Glycerol‐Preserved Allodermis
Authors: Herson Marisa Roma , Mathor Monica Beatriz , Altran Silvana , Capelozzi Vera Luiza , Ferreira Marcus Castro
Published: March 2003

Abstract: This work demonstrates that glycerol‐preserved acellular allodermis can be used as support for the proliferation of human keratinocytes and that the characteristics of this bioengineered tissue suggest its possible use as a permanent skin substitute for therapeutic challenges such as extensive burns as well as its possible use as an in vitro model for pharmacological studies. The removal of all basal membrane components during preparation of the dermal support also provides an original in vitro situation that allows observation of the reorganization of the dermal‐epidermal junction. The tissue composite obtained is constituted of dermis covered by a well attached, multistratified epithelium with morphological characteristics that resemble human epidermis as evidenced by light and transmission electron microscopy, including the neoformation, albeit incomplete, of the dermal‐epidermal junction. Assessment of involucrin and cytokeratin 14 expression by immunohistochemical assays established differentiation patterns. Both immerse and air‐liquid interface culture systems were tested.
Intravenous Ascorbic Acid Administration for Erythropoietin‐Hyporesponsive Anemia in Iron Loaded Hemodialysis Patients
Authors: Sezer S. , Özdemir F.N. , Yakupoglu U. , Arat Z. , Turan M. , Haberal M.
Published: March 2003

Abstract: Intravenous ascorbic acid administration (IVAA) could override recombinant human erythropoietin (rHuEPO) resistance in hemodialysis patients with iron overload. We investigated the hematopoietic response to IVAA in iron‐overloaded hemodialysis patients. We included 36 patients whose ferritin levels were higher than 500 μg/L and who needed more than 100 U/kg/week of rHuEPO. The study included an initial phase (500 mg IVAA twice weekly was administered to all of the patients for 8 weeks) and a maintenance phase (patient groups were formed; Group 1 received IVAA 500 mg/week for 8 weeks and Group 2 received no therapy). We observed a significant increase in hematocrit and transferrin saturation and a decrease in the percentage of hypochromic red cells and ferritin levels at the end of the initial phase. The total weekly‐required rHuEpo dose and rHuEpo/hemoglobin also fell significantly after the initial phase. The response remained stable in patient groups during the maintenance phase. In 6 nonresponders, the hypochromic red cells were <10%. In conclusion, IVAA effectively overrides rHuEPO resistance in iron‐overloaded hemodialysis patients.
Chronic Evaluation of the Cleveland Clinic CorAide Left Ventricular Assist System in Calves
Authors: Fukamachi Kiyotaka , Ochiai Yoshie , Doi Kazuyoshi , Massiello Alex L. , Medvedev Alexander L. , Horvath David J. , Gerhart Renee L. , Chen Ji‐Feng , Krogulecki Alexandra Y. , Takagaki Masami , Howard Michael W. , Kopcak Michael W. , Golding Leonard A.R.
Published: March 2003

Abstract: The Cleveland Clinic CorAide left ventricular assist system is based on a third‐generation, implantable, centrifugal pump in which a rotating assembly is suspended fully. To evaluate chronic in vivo system performance and biocompatibility, the CorAide blood pump was implanted in 18 calves for either 1 month or 3 months. Hemodynamics were stable in all calves with a mean pump flow of 5.9 ± 1.2 L/min and a mean systemic arterial pressure of 98 ± 5 mm Hg. There were no incidences of bleeding, organ dysfunction, or mechanical failure in any of the 18 calves. Hemolysis occurred in only 1 calf due to outflow graft stenosis. Thrombus inside the pump, seen in 4 of the first 6 cases, was totally eliminated by a final redesign in the remaining cases, including the last 6 implants conducted without anticoagulation therapy. The CorAide blood pump demonstrated good biocompatibility and reliable, effective system performance.
Long‐Term Follow‐Up of Cardiac Valve Replacement Using Bioprosthesis in Patients 70 Years Old and Older
Authors: Ueyama Keishi , Kamiya Hiroyuki , Kanamori Taro , Ohashi Hirokazu , Yasushi Tsutsumi , Kawai Takahiro , Ohnaka Masateru
Published: March 2003

Abstract: Good long‐term results with the bioprosthetic valves for patients 70 years old and older have been reported. However, because the average lifespan is increasing, we aimed to clarify whether patients older than 70 may still be candidates for valve re‐replacement. Seventy‐one patients 70 years old and older, who received a total of 81 bioprosthetic valve replacements during 73 procedures between 1988 and 2000, were reviewed. There were 8 hospital and 7 late deaths. Ten‐year actual survival after valve replacement was 73.5%, and 82.8% when hospital deaths were excluded. During the follow‐up period, 2 patients received mitral valve re‐replacement. Ten years of freedom from reoperation were found in 66.7% for all valves and in 50.0% for mitral valves. The average lifespan in Japan is currently 77.64 years for men and 84.62 years for women; therefore, valve degeneration in patients who receive bioprosthesis replacement in their early 70s should be anticipated.
Recruiting the Community for Supporting End‐Stage Renal Disease Management in the Developing World
Authors: Rizvi A. , Aziz R. , Ahmed E. , Naqvi R. , Akhtar F. , Naqvi A.
Published: March 2003

Abstract: Although the incidence of new end‐stage renal disease (ESRD) patients in Pakistan is estimated at 100 patients per million (ppm), the prevalence of those alive on renal replacement therapy (RRT) is around 40 ppm, reflecting the severe shortage of facilities. A national program was launched in 1998 to provide free RRT, but the funds were extremely limited, leading to the flourishing of suboptimal treatment in private dialysis and transplant centers. The Sindh Institute of Urology and Transplantation (SIUT), started as a small unit in 1975, took the lead in recruiting nongovernmental funds for RRT. Through the devotion of several groups, it was possible to raise funds from individuals, pharmaceutical firms, and other organizations, which permitted the development of SIUT into an independent, large, and fully equipped institution that provides free RRT including dialysis and transplantation to many thousands of patients. This prompted the government to increase its contributions to encourage SIUT to pursue its unique path.
Predicting Membrane Oxygenator Pressure Drop Using Computational Fluid Dynamics
Authors: Gage Kenneth L. , Gartner Mark J. , Burgreen Greg W. , Wagner William R.
Published: March 2003

Abstract: Three‐dimensional computational fluid dynamic (CFD) simulations of membrane oxygenators should allow prediction of spatially dependent variables and subsequent shape optimization. Fiber bed complexity and current computational limitations require the use of approximate models to predict fiber drag effects in complete device simulations. A membrane oxygenator was modified to allow pressure measurement along the fiber bundle in all cardinal axes. Experimental pressure drop information with water perfusion was used to calculate the permeability of the fiber bundle. A three‐dimensional CFD model of a commercial membrane oxygenator was developed to predict pressure drops throughout the device. Darcy's Law was used to account for the viscous drag of the fibers and was incorporated as a momentum loss term in the conservation equations. Close agreement was shown between experimental and simulated pressure drops at lower flow rates, but the simulated pressure drops were lower than experimental results at higher flows. Alternate models of fiber drag effects and flow field visualization are suggested as means to potentially improve the accuracy of the flow simulation. Computational techniques coupled with experimental verification offer insight into model validity and show promise for the development of accurate three‐dimensional simulations of membrane oxygenators.
Computational Fluid Dynamics Insights in the Design of Mechanical Heart Valves
Authors: Kelly Stuart G.D.
Published: March 2003

Abstract: Computational fluid dynamics (CFD) analysis can provide detailed, three‐dimensional predictions of blood flow through mechanical heart valves, which can help to optimize valve hemodynamics and reduce the potential for blood clotting. A number of CFD studies, considering both forward and retrograde flow through valves, have been published. In this paper, a geometrically accurate CFD model capable of predicting the three‐dimensional, time‐dependent flow through an open ATS bileaflet valve is presented. A detailed picture of the blood flow is obtained, including small‐scale flow features in the pivot regions. Results from the model can also be used to investigate the opening position of the ATS valve leaflets. Future work will be aimed toward improved models that provide valuable design information while minimizing the development time and computational resources required. Such practical CFD models clearly have the potential to reduce the costs, time scales, and risks associated with development of new heart valve designs.
Flow Rate and Pressure Head Estimation in a Centrifugal Blood Pump
Authors: Funakubo Akio , Ahmed Shahriar , Sakuma Ichiro , Fukui Yasuhiro
Published: March 2003

Abstract: Considering a miniaturization of percutaneous cardiopulmonary support (PCPS) system, we have developed a pump system that can estimate flow rate and pressure head in the circuit. A commercially available centrifugal blood pump (C1E3, Kyocera Co., Ltd., Kyoto, Japan) with an exclusive motor driver was used in the experiment. In this system, the motor revolutions per minute and torque were used to derive an estimation equation. Taking into consideration fluid viscosity, the accuracy of the estimation was increased. Bovine blood was used to evaluate the system in vitro. The average maximum difference between the estimated flow rate and the measured flow rate was 0.56 L/min (for 98% accuracy). The average difference between the estimated pressure head and the measured pressure head was 30.7 mm Hg (for 94.2% accuracy). Because of the stability of the estimations, we believe this system has the possibility of use for real‐time monitoring and miniaturization of PCPS system.
Chaos Attractors of Ventricular Elastance to Evaluate Cardiac Performance
Authors: Yambe Tomoyuki , Yoshizawa Makoto , Taira Ryuzo , Tanaka Akira , Tabayashi Kouichi , Sasada Hiroshi , Nitta Shin‐ichi
Published: March 2003

Abstract:Quantitative evaluation of cardiac function is very important in the clinical application of a ventricular assist device. This article reports a new evaluating method of E max, which is the most reliable parameter to evaluate cardiac function. Fluctuation in the E max time series data was evaluated by the nonlinear mathematical analyzing method including chaos and fractal theory. Experimental goats were anesthetized with halothane inhalation, and left ventricular volume and pressure were measured with other hemodynamic parameters to evaluate E max during various drug administrations. E max was evaluated by two methods. One was the conventional pressure volume loop evaluation and the other was the parameter optimization method without left ventricular volume data. As a result, E max evaluated by the parameter optimization method correlated well with the E max with conventional PV curve. Furthermore, interesting results were obtained. There were rhythmical fluctuations in the E max time series data. By the methodology of Takens, E max time series data was embedded into the phase space and a strange attractor was observed. These results may be important when considering E max evaluation during left ventricular assistance.
Culicidae Vectors and Anthropic Changes in a Southern Brazil Natural Ecosystem
Authors: Forattini Oswaldo Paulo , Massad Eduardo
Published: March 2003

ABSTRACT

The influences of human‐caused changes in a natural ecosystem of Southern Brazil on mosquitoes of the family Culicidae, which may be vectors of diseases, were investigated. Particular attention was given to the effects of deforestation and human settlements with artificial irrigation. The work assumes a preserved environment as representative of the natural ecosystem before human intervention. Another collection site, 50 kilometers from the primitive forest, that presented the same fauna and flora of the former some 50 years ago was chosen as the modified environment. The results clearly showed that some species, such as the Kerteszia subgenus, do not survive these changes, whereas others have found such conditions favorable and have proliferated.
Assessing Ecosystem Health in Governed Landscapes: A Framework for Developing Core Indicators
Authors: Bertollo Pietro
Published: March 2003

ABSTRACT

This article describes the development of a framework for selecting a core set of indicators suitable for an integrated ecosystem health assessment of a governed landscape. Integrated assessments are those that consider a combination of biophysical, socioeconomic, and human health considerations. Highly governed landscapes are cultural landscapes that are strictly controlled by humans to the extent that they would revert to an entirely different form were it not for continued human intervention. One example of such a landscape, which serves as the setting for this investigation, is the former wetlands of the northeastern Italian coastal zone, which have been subject to widespread land reclamation and coastal development over the past century. The science of ecosystem health has been chosen as the frame of reference because “health” is not judged by the degree of “naturalness” but instead on the ability of the ecosystem to maintain and renew itself. The framework consists of first reviewing literature and methods related to ecological and environmental monitoring, state‐of‐the‐environment reporting, landscape ecology, and sustainability. This is followed by the definition of indicator guidelines that are designed to assist in the evaluation and selection of potential indicators. A core set of indicators are then presented based on a conceptual framework devised for this purpose. Indicators are classed as abiotic, biotic, and cultural, and selected according to the ecological districts comprising the study area. The ultimate goal is their application to an ecological monitoring and assessment program within a governed landscape such as the northeastern Italian coastal zone. Given such a commitment, the normal process of core indicator refinement can then proceed, based on such actions as further consultations with interested stakeholders and evaluation of methodological and practical constraints to their actual application.
Quantitative Multiresolution Characterization of Landscape Patterns for Assessing the Status of Ecosystem Health in Watershed Management Areas
Authors: Johnson Glen D. , Patil Ganapati P.
Published: March 2003

ABSTRACT

Landscape ecology is a field that has grown from realizing that maintenance of ecological resources requires management at several spatial and temporal scales, including landscape‐level ecosystems as whole units of study and management. The subsequent need for characterizing landscape structure has led to a variety of measurements for assessing different aspects of spatial patterns; however, most of these measurements are known to depend on both the spatial extent of a specified landscape and the measurement grain. Therefore, measurements that incorporate a range of scales would be most informative. In response, this article introduces a new method for obtaining a multiresolution characterization of land cover fragmentation patterns within a fixed geographic extent. Our particular interest is in watershed‐delineated extents. The method applies the concept of conditional entropy as one moves from larger “parent” land cover pixels to smaller “child” pixels that are heirarchically nested within the parent pixels. When applied over a range of resolutions, one obtains a “conditional entropy profile.” The conceptual and methodological development of conditional entropy profiles is presented, followed by current and future directions for evaluating and applying this methodology.