bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of the Baylor‐Nikkiso Centrifugal Pump with a Purging System for Circulatory Support
Authors: Naito Kozo , Miyazoe Yuki , Aizawa Takeshi , Mizuguchi Kazumi , Tasai Kimitaka , Ohara Yasuhisa , Orime Yukihiko , Glueck Julie , Takatani Setsuo , Noon George P. , Nosé Yukihiko
Published: July 2010

Abstract: The Baylor‐Nikkiso centrifugal pump is a magnetically coupled system with a V‐ring seal separating the pump and the actuator chamber. To prevent thrombus formation behind the impeller and to extend the life of the pump to 2 weeks of continuous operation, we incorporated a purging chamber behind the V‐ring seal. An external pump connected to this purging chamber infused fluid at a constant rate to wash the shaft‐seal area. To evaluate the effectiveness of the purging system, we have carried out biventricular bypass experiments using calves. The purging system was successful in reducing the level of thrombus formation after 2 weeks of operation. The results of these studies confirmed that the Baylor‐Nikkiso centrifugal pump with this purging system is suitable for at least 2 weeks of continuous operation as a circulatory support system.
Clinical Experience Using the Bio‐Pump for Extracorporeal Circulation during Open‐Heart Surgery
Authors: Yada Isao , Yuasa Uhito , Suzuki Hitosi , Hatanaka Katsumoto , Kondo Chiaki , Wada Kiyoto , Kusagawa Hitoshi , Onoda Kouji , Shimono Takatsugu , Shimpo Hideto , Tanaka Kuniyoshi , Yuasa Hiroshi , Kusagawa Minoru
Published: July 2010

Abstract: The Bio‐pump is still being used in a wide range of clinical applications such as open‐heart surgery, left‐heart bypass, extracorporeal membrane oxygenation, and supplementary circulation. Clinical application of the Biopump for extracorporeal circulation in 21 patients under‐going open‐heart surgery was compared with application of the roller pump in terms of their effects on hemolysis, platelet function, and renal function. Although the amount of hemolysis was not significantly different between the Bio‐pump group and the roller‐pump group, platelet function was slightly better maintained in the Bio‐pump group as judged by the levels of platelet factor 4, β‐thromboglobulin, and 6‐keto‐prostaglandin F1α/thromboxane B2. There was no difference between the two pumps in terms of their effects on renal function. The above findings lead us to conclude that there is a slight advantage to use of the Bio‐pump in clinical settings.
Circulatory Support for Patients Experiencing Postcardiotomy Cardiogenic Shock: Analysis of Risk Factors for Death and Long‐Term Follow‐up
Authors: Murakami Taiji , Nakayama Hironobu , Irie Hiroyuki , Kino Koichi , Hisamochi Kunikazu , Koomoto Takushi , Takagaki Masami , Sugawara1 Eiji , Senoo Yoshimasa , Teramoto Shigeru
Published: July 2010

Abstract: Over the last 5 years, 12 patients received ventricular assist devices (VADs) while in postcardiotomy cardiogenic shock. There were 7 male and 5 female patients ranging in age from 22 to 73 years (average age, 54). Eight patients underwent surgery for valve replacements, 3 for coronary artery bypass graftings, and 1 for closure of a ventricular septal rupture. The duration of VAD support ranged from 6 h to 9 days (mean, 4.2 days). Ten patients were weaned from the VADs, and 6 survived. Univariate analysis indicated that renal failure, infection, and heart failure had a negative impact on those patients who survived. Multivariate analysis indicated that heart failure, renal failure, and preoperative left ventricular ejection fraction were the most important predictors of hospital death. The 6 survivors were followed for 4 to 42 months (mean, 25 months); 5 were in New York Heart Association (N YHA) Class I, and 1 was in Class II. The cardiac functions in 5 patients who lived over 1 year were assessed by echocardiography. Preoperative and postoperative UCG revealed that ejection fraction and mean velocity of circumferential fiber shortening increased significantly (p < 0.01). Also, the left ventricular diastolic and systolic dimensions decreased significantly (p < 0.05). However, the patients did not show further changes in these parameters during exercise. Eight patients who had double valve replacements were observed for comparison (control group). In the control group, exercise improved cardiac output and mean velocity of circumferential fiber shortening (p < 0.01). From these data, we concluded that VAD patients exhibited improvement in postoperative cardiac functions but had less tolerance in exercise tests than the control patients did.
Isolation and Culture of Human Hepatocytes from Resected Liver Tissue as a Bioreactor for a Hybrid Artificial Liver
Authors: Takahashi Manabu , Matsue Hirokazu , Matsushita Michiaki , Nakajima Yasuaki , Uchino Junichi
Published: July 2010

Abstract: To use cultured human hepatocytes as a hybrid artificial liver, effective methods for isolating and culturing the hepatocytes from resected surgical specimens were investigated. Two different procedures for isolating hepatocytes, perfusion and agitation with a collagenase solution (Method 1) and perfusion with a mixed solution of collagenase and dispase (Method 2), were examined. The yield of isolated hepatocytes obtained by Method 2 (13.31 times 106 cellslg of liver) was significantly higher than that by Method 1 (0.94 times 106). The warm ischemia time (0–90 min) of the liver fragments obtained did not disturb the viability and yield of the isolated hepatocytes. The gluconeogenesis and urea synthesis of the cultured human hepatocytes were well preserved for 10 days. These results show that for prolonged human hepatocyte culture (10 days), isolation from resected human liver tissues by a combination of the proteolytic enzymes collagenase and dispase was effective and warm ischemia was tolerated for up to 90 min, which indicates the possibility of using cultured human hepatocytes as a hybrid artificial liver.
Continuous On‐Line Optical Absorbance Recording of Blood Volume Changes during Hemodialysis
Authors: Mancini Elena , Santoro Antonio , Spongano Marco , Paolini Francesco , Rossi Marco , Zucchelli Pietro
Published: July 2010

Abstract: Conventional techniques that measure blood volume changes during hemodialysis are invasive, hard to reproduce, and provide only intermittent evaluations. To overcome these drawbacks, we have developed an optoelectronic instrument that estimates intradialytic blood volume percentage changes by the optical absorbance of blood. This device is based on the absorption of light transmitted through blood, which is directly related to the hemoglobin concentration. A personal computer interfaced to the device provides a continuous on‐line graphic display of the hemoglobin levels and the percentage changes in blood volume. The noninvasive measurement of dialysis blood volume changes by an optical method may be helpful in detecting the appearance of severe hypovolemia that can be dangerous in critically ill patients.
Renal Complications of Infected Ventriculoatrial Shunts
Authors: Samtleben Walter , Bauriedel Gerhard , Bosch Thomas , Goetz Claudia , Klare Bernd , Gurland Hans J.
Published: July 2010

Abstract: Contamination of a ventriculoatrial shunt (VAS) with skin organisms that are usually nonpathogenic may be followed by an immunologically mediated renal injury. The bacteria characteristically involved are coagulase‐negative Staphylococci (e.g., Staphylococcus epidermidis), which strongly adhere to the plastic surface of the VAS. These bacteria are protected from the body's natural defense mechanisms and respond only poorly to antibiotics. As a result, their growth persists and produces a continuous antigenic stimulation. Circulating immune complexes (CIC) are an appropriate tool to screen for chronically infected VASs. We followed CIC in 138 VAS patients. An infected VAS was seen in 20 of the 24 patients with highly elevated CIC and in 1 of the 19 patients with moderately elevated CIC, but none of the 95 patients with normal CIC had evidence of shunt infection. Of the 21 patients with shunt infections, 8 had renal involvement (4 requiring dialysis, and 4 with proteinuria, hematuria, and/or elevated creatinine). Results from kidney biopsy specimens available from 4 patients confirmed glomerulonephritis. Of the 4 patients requiring dialysis at diagnosis, renal function recovered sufficiently to stop dialysis after successful VAS exchange in all but 1. In the other 4 patients, renal symptoms (proteinuria, creatinine) also improved after VAS revision. Chronic infection with S. epidermidis or other bacteria is a continuing problem in patients with VASs and can lead to an immune‐mediated renal injury. However, the prognosis for reversal of the renal injury is relatively good if the VAS infection is treated promptly.
Anticoagulation with Low Molecular Weight Heparin (Fragmin) during Continuous Hemodialysis in the Intensive Care Unit
Authors: Jeffrey R.F. , Khan A.A. , Douglas J.T. , Will E.J. , Davison A.M.
Published: July 2010

Abstract: A preparation of low molecular weight heparin (Fragmin) was administered to patients with multiorgan failure receiving continuous venovenous hemodialysis. Three patients received a high‐dose regimen (35 IU/kg bolus followed by 13 IU/kg infusion), and 7 received a low‐dose regimen (8 and 5 IU/kg, respectively) for 36 h. High‐dose Fragmin was associated with minimal clotting in the extracorporeal circuit. Plasma fibrinopeptide A levels declined, and mean anti‐Xa activity was in the range 0.47‐0.79 IU/ml. The urea equilibration coefficient (UEC) (100% at initiation) remained above 90% throughout. All 3 patients had mild bleeding episodes, which led to discontinuation of Fragmin in 1. During all low‐dose treatments, marked thrombus formation occurred in the extracorporeal circuit, and in 2, the circuit clotted within the study period. Fibrinopeptide A levels further increased in 4 patients, and mean anti‐Xa activity was in the range 0.27‐0.53 IU/ml. UEC declined appreciably in 3 treatments (including the 2 in which early circuit clotting occurred). One patient experienced a mild bleeding episode. The low‐dose Fragmin regimen produced safer anticoagulation in patients at risk from bleeding and is suitable for prolonged renal support although the tendency to thrombosis may necessitate more frequent circuit changes.
Extracorporeal Endotoxin Removal by Immobilized Polyethylenimine
Authors: Mitzner S. , Schneidewind J. , Falkenhagen D. , Loth F. , Klinkmann H.
Published: July 2010

Abstract: The neutralization of bacterial endotoxins (ET) is still an unsolved problem in therapeutic medicine. The efficacy of antiendotoxin antibodies or receptor antagonists and other substances interferring with the endotoxininduced pathomechanisms is dependent on an intact cellular degradation system of the host. However, the phagocytosis function of that system seems to be impaired regularly in patients with intense or long‐lasting endotoxemia or septic shock and in patients undergoing hemodialysis. Extracorporeal adsorption of ET might well be an effective support in the anti‐ET therapy by lowering the amount of circulating ET and thus relieving the defense system of the body. In this work a new ET‐adsorbent based on macroporous cellulosic beads with immobilized polyethylenimine (PEI) was tested for its ET‐removal capacity in vitro. A test solution with 100 ng/ml ET from Escherichia coli 055:B5 was recirculated in a system containing the adsorbent beads. Polymyxin B immobilized to the same carrier was used for comparison. PEI as well as polymyxin B showed complete removal of ET from plasma and water as was measured by the Limulus Amebocyte Lysate (LAL) test (Chromogenix). The biocompatibility of the PEI adsorber was superior to that of polymyxin B. The results indicate that the PEI adsorber is of high efficacy and possibly of interest for the treatment of endotoxemia.
Urea Kinetic Modeling: Comparing the Options
Authors: Hoenich Nicholas A. , Keir Michael J. , Hildreth Kathryn , Woffindin Celia , Goodall Robert , Vanholder Raymond , Ward Michael K.
Published: July 2010

Abstract: In this study 6 commercially produced kinetic modeling packages utilizing a variable volume, single pool urea model, as well as formulae to determine the delivery of therapy, have been compared by applying to each the same set of rigorously collected data for a group of 12 patients. Comparison of the kinetically derived parameters (urea generation rate [G], urea distribution volume [V], delivery of therapy [Kt/V], and normalized protein catabolic rate [nPCR]) showed that the values obtained for both G and V differed between packages owing to the numerical methods and the clearance used in the solution of the differential equations. Although a broad agreement between the values established for Kt/V and nPCR was noted, the 95% limits of agreement indicated that it would be prudent to exercise caution when comparing results established by different modeling packages.
Past, Present, and Future of Total Artificial Heart Development at Research Institute of Replacement Medicine, Hiroshima University School of Medicine
Authors: Matsuura Yuichiro , Fukunaga Shintaro , Sueda Taijiro
Published: July 2010

Abstract: The history and recent progress in total artificial heart (TAH) development were reviewed and divided into three stages. The first stage was between 1966 and 1972, when a trial developing an artificial heart (AH) driver was begun using poppet valves. Fluid amplifiers and air operated valves were then employed as a controller. The second stage was between 1973 and 1983. Several models of pneumatic AH were manufactured and implanted into animals, and it was confirmed that animals could survive with their circulation supported by these mechanical hearts. The third stage was from 1984 to the present, and now a trial to construct a totally implantable type of AH is under way. On the basis of the experience of developing TAHs, the following points are discussed as future problems to be solved: first, the production of small yet powerful actuators; second, the establishment of safe and reliable controls and an energy supply method; third, the development of a durable blood chamber containing valves; and fourth, the acquisition of large research funds for TAH from governments and other granting agencies. Key Words: Artificial heart–Future artificial heart developments.
New Immunosuppressive Proteins (KX‐2, ‐4, and ‐5) Induced by Liver Transplantation
Authors: Kamada Naoshi
Published: July 2010

Abstract: The presence in rat serum of three novel immunosuppressive proteins is associated with induction of tolerance after liver grafting. One of these, KX‐5 (40 kilodal‐ton molecular weight) is present 40–100 days after grafting of DA liver into PVG, a combination in which liver grafts are not rejected; two others, KX‐2 (87 kilodaltons) and KX‐4 (10 kilodaltons), are present in PVG sera in a retransplantation model. N‐terminal amino acid sequencing indicated that none of the proteins had been described previously. Induction of KX‐5 was inhibited by cyclosporin A. All three proteins inhibited mixed lymphocyte responses nonspecifically. Administration of a single dose of 300 ^g purified KX‐5 to PVG rats receiving heterotopic heart allografts led to prolonged graft acceptance. The results raise the possibility of clinical application of the immunosuppressive properties of liver grafts through administration of soluble proteins.
Flow Cytometric Characterization of Isolated Porcine Hepatocyte Suspensions for Liver Support
Authors: Pan Jing , Naik Sharda , Santangini Henry , Trenkler Donna , Jauregui Hugo
Published: July 2010

Abstract: The high yield hepatocyte isolation necessary for hybrid liver assist devices (LAD) unavoidably increases contamination by nonparenchymal cells and depresses hepatocyte viability and functions. We have developed a flow cytometric procedure that improves quality control of the isolations. Cells present in these preparations were labeled by immunofluorescent antibody staining against cytokeratin 8,18 as well as vimentin to identify hepatocytes, fibroblasts, and endothelial cells. Antibody staining against albumin and carbamoylphos‐phate synthetase allowed assessment of levels of albumin and carbamoylphosphate synthetase based on the hepatocyte relative fluorescence intensity. Hepatocyte P450 enzyme activity was measured by its ability to convert 5,6‐methoxycarbonylfluorescein, a nonfluorescent substrate, to an intracellular fluorescent product. Flow cytometric methods of cell type identification and cell function assessment are fast and accurate and can be applied to commercial cell production. They may also provide an avenue for the enrichment of otherwise heterogeneous hepatocyte suspensions with cells presenting the specific functions desired for an hybrid liver assist devices.
Efficiency of an External Support to Reduce Lipid Infiltration into Venous Grafts: In Vitro Evaluation
Authors: Deng Xiaoyan , Marois Yves , Guidoin Robert , Merhi Yahye , Stroman Patrick , King Martin W. , Douville Yvan
Published: July 2010

Abstract: Excessive distension of venous grafts due to arterial pressure enhances the convective water transport (filtration flow) through the vessel wall, and thus might affect the infiltration of macromolecules such as lipoproteins. In this paired experimental study, filtration velocities were measured at 100 mm Hg for canine jugular veins with or without external supports of expanded poly‐tetrafluoroethylene (ePTFE) arterial prostheses. In addition, to assess the effect of filtration velocity on lipid infiltration or uptake, canine jugular veins were wrapped over half of their lengths with ePTFE arterial prostheses and perfused with dog serum containing 3H‐cholesterol at a pressure of 100 mm Hg. At 100 mm Hg, the average filtration velocity of the wrapped jugular veins was 7.9 ± 1.3 ± 10‐6 cm/s whereas the average filtration velocity of the unwrapped veins was 27.3 ± 2.7 ± 10‐6 cm/s (p < 0.005). Moreover, the unwrapped veins had a significantly higher uptake rate of labeled cholesterol than the wrapped veins (10.9 ± 7.3 ± 10‐4 cm/h and 5.0 ± 1.6 ± 10‐4 cm/h, respectively, p < 0.005). In conclusion, under arterial pressure, veins experience excessive distention, which leads to significant increases in both filtration flow and cholesterol uptake. An external wrap or support of ePTFE material protects veins from excessive distension and thus may prevent atherosclerosis in venous grafts by reducing cholesterol uptake.
Development of a Potassium‐Specific Adsorbent for Direct Hemoperfusion
Authors: Terai Chikanori , Shimizu Shoichiro , Matsushima Shunsuke , Tanaka Ikuo , Okada Yoshiaki , Miyahara Tadashi , Nakaji Shuhei
Published: July 2010

Abstract: Direct hemoperfusion (DHP) over an exchange resin for sodium is capable of rapidVVly lowering an vated serum potassium level but has not been used clin‐ ically because of subsequent electrolyte abnormalities. After the completion of detailed in vitro studies, we de‐ veloped a sodium/calcium/magnesium exchange resin mixture specifically to remove potassium from the blood. The mixture, which consisted of exchange resins for so‐ dium (48%), calcium (48%), and magnesium (4%), gave the most satisfactory results in vitro. DHP through these resin‐mixture columns for 2 h reduced elevated plasma potassium levels (6.7 ± 1.1 to 3.5 ± 0.6 mEq/L, p < 0.001) in anephric dogs without including any significant change in the levels of sodium, calcium, magnesium, al‐ bumin, total protein, or cholesterol. The platelet losses and changes in the plasma free hemoglobin levels ob‐ served were similar to those found with activated char‐ coal hemoperfusion. These results suggest that this resin hemoperfusion may be useful in patients with acute hyperkalemia.
In Vitro Studies on a New Method for Islet Microencapsulation Using a Thermoreversible Gelation Polymer, N‐Isopropylacrylamide‐Based Copolymer
Authors: Shimizu Shinichi , Yamazaki Manabu , Kubota Sunao , Ozasa Takao , Moriya Hitonobu , Kobayashi Kenyu , Mikami Masato , Mori Yuichi , Yamaguchi Susumu
Published: July 2010

Abstract: Various materials for the semipermeable mem‐ brane for microencapsulation of islets, such as alginate complex and agarose, have been used. In this study, a thermoreversible gelation polymer, N‐isopropylacrylamide based copolymer was used to make microencapsulated islets and was examined in vitro. The polymer has little or no cytotoxicity for human dermal fibroblasts. The characteristics of viscoelasticity below the soluble gel transition temperature (SGTT) and of thermoreversibility, the water soluble polymer below the SGTT (22oC) becoming water insoluble upon heating, contributed to simplifying the encapsulation technique. We obtained viable islets at the center of the membrane with a thickness of approximately 20–50 pm, accounting for a 40% yield of encapsulated islets. Static glucose challenge test with mi‐ croencapsulated islets revealed the insulin response to the concentration of glucose. The insulin concentrations of the culture medium in the microencapsulated islet group were the same as those in a similar free islet group up to 42 days. These results indicate that the morpholog‐ ical and functional stability of the new method for mi‐ croencapsulation may be sufficient for it to be used for transplantation in diabetic animals.
A Remotely Controlled and Powered Artificial Heart Pump
Authors: Mussivand Tofy , Hendry Paul J. , Masters Roy G. , Holmes Kevin S. , Hum Albert , Keon Wilbert J.
Published: July 2010

Abstract: An intrathoracic pulsatile artificial heart pump has been developed. Transcutaneous energy transfer and biotelemetry systems provide continuous power and remote monitoring and control, with no percutaneous connections required. The electrohydraulic system can be used either as a ventricular assist device or with modifications as a total artificial heart. The device uses a unidirectional axial flow pump coupled with a pressure activated one‐way valve to allow hydraulic fluid to passively return to the volume displacement chamber during diastole. The transcutaneous energy transfer system provides power to the device and recharges the implantable battery pack. A wearable external controller and external battery pack provide the patient enhanced mobility and thus an improved quality of life. The biotelemetry system allows control and monitoring of the device after implantation, as well as an added capability to monitor and control the device remotely over public communication lines. Early prototypes have functioned failure free for up to 3 years in vitro. The device has sustained circulation in vivo for up to 4 days. Design optimization is continuing, and chronic in vivo evaluation is planned.
Current Status of Heart Assist and Replacement in Taiwan
Authors: Wang Shoei‐Shen , Chu Shu‐Hsun
Published: July 2010

Abstract: The first clinical application of intraaortic balloon pumps (IABP) in Taiwan was in 1976 to treat post‐cardiotomy cardiogenic shock. It is now the most commonly used circulatory assist. From 1991 to 1995, 186 patients received IABP support with an overall mortality rate of 41.9%. The male patients had the best survival rate, 67%, after coronary artery bypass grafting. The first extracorporeal membrane oxygenation (ECMO) was in 1987 to treat intractable heart failure caused by severe acute rejection after heart transplantation. Because of poor outcome, patients only received ECMO sporadically during the past years. From November 1994 to November 1995, 30 patients received ECMO support with 50% of them eventually weaned from ECMO and 27% discharged. For short‐term support or emergency rescue, ECMO was a good choice. When long‐term support was required, the ventricular assist device (VAD) was a more suitable assist. One patient who received Thermedics VAD developed right heart failure and finally died of sepsis and multiple organ failure. VAD should be implanted before the secondary organ failure. The first successful clinical heart transplantation in Taiwan was performed on July 17, 1987. From 1991 to 1995, 102 patients underwent heart transplantation. The operative mortality was 3.9%, and the 1 and 5 year actuarial survival rates were 86 ± 3% and 77 ± 5%, respectively. To improve the success rate of clinical heart transplantation, organ donation should be encouraged.
Skeletal Muscle Ventricles: Frontiers in 1995
Authors: Isoda Susumu , Thomas Gregory A. , Nakajima Hidehiro , Lu Huiping , Hammond Robert L. , Nakajima Hisako O. , Walters Henry L. , Stephenson Larry W.
Published: July 2010

Abstract: Skeletal muscle ventricles (SMVs) constructed from electrically conditioned latissimus dorsi muscle (LDM) may become an alternative for assisting the failing heart. Left and right heart circulatory assist using SMVs has been performed successfully in both acute and chronic animal models. The configurations used to connect SMVs to the circulation have included a left atrium to aorta bypass, a left ventricle apex to aorta bypass, aortic counterpulsators, a cavopulmonary bypass, and a right ventricle to pulmonary artery bypass. One SMV used as an aortic counterpulsator functioned effectively in the circulation for more than 27 months. Recent application of the pericardium to the SMV as an inner layer and design changes in the connection of the SMV to the circulation have reduced the risk of thrombus formation and SMV rupture. Although several problems have yet to be solved, the goal of the SMV as a permanent circulatory assist device without the limitation of an external power source seems within reach.
Long‐term Animal Survival with an Implantable Axial Flow Pump as a Left Ventricular Assist Device
Authors: Konishi Hiroaki , Antaki James F. , Litwak Philip , Kameneva Marina , Yamazaki Kenji , Macha Mahender , Kerrigan John P. , Mandarino William A. , Butler Kenneth C. , Borovetz Harvey S. , Kormos Robert L.
Published: July 2010

Abstract: We are developing an axial flow blood pump with Nimbus Inc. (AxiPump). For in vivo evaluation the AxiPump has been used as a left ventricular assist device with a left ventricular and descending aorta cannulation and implantation in a small pocket on the left lateral abdominal wall just posterior to the costal margin. Electrical and flow probe leads exit the body transcutaneously. A purge line that delivers the purge fluid for lubrication of the seal between the rotor and stator bodies in the purge fluid bearing system is tunneled with the other leads. Following acute animal studies, 3 animals have been supported for over 1 month with this AxiPump system. All laboratory results were within normal limits except during a recovery period from surgical damage. Hemolysis was not a serious problem. In the first case, the purge system failed at 28 days, and in the second and third cases, the nonpurge bearing system worked well for 57 and 52 days, respectively. Bearings are still under development in this kind of pump. However, this success encourages us to improve the AxiPump as a long‐term assist device.
Influence of Ventricular Fibrillation on Sympathetic Nerve Activity Under Biventricular Bypass Circulation
Authors: Todag Koichi , Tatsumi Eisuke , Taenaka Yoshiyuki , Masuzawa Toru , Miyazaki Koji , Nakatani Takeshi , Baba Yuzo , Eya Kazuhiro , Wakisaka Yoshinari , Takano Hisateru
Published: July 2010

Abstract: Autonomic nerves play an important role in circulatory control. The characteristics of sympathetic nerve activity (SNA) during artificial circulation, however, are not well understood. In this study, we examined the influence of natural heart beating on the renal SNA (RSNA) using pulsatile 100% biventricular assistance and electrically induced ventricular fibrillation in anesthetized goats, whose heart rate and size are similar to the human heart's. Following induction of the ventricular fibrillation, the pulse‐synchronous discharges in the RSNA did not change their periodicity and quantity significantly. It was concluded that the beating of the heart had little influence on the RSNA and was presumably not essential for maintaining nervous control of circulation as long as the circulation was maintained by an artificial heart.
Double Balloon Catheter for Concomitant Augmentation of Abdominal Organ Perfusion During Intraaortic Balloon Counterpulsation
Authors: Katsumata Takahiro , Sato Wataru , Bonkohara Yukihiro , Nishida Hiroshi , Endo Masahiro , Koyanagi Hitoshi
Published: July 2010

Abstract: A newly devised double balloon catheter to augment abdominal organ perfusion concomitant with original cardiac assist during intraaortic balloon counterpulsation provided satisfactory hemodynamics and urinary output around cardiac surgical procedures in 2 patients with coronary artery disease. Some optional advantages in clinical application and problems arising in the catheter design which need to be investigated are discussed.
Optimal Oxygen Tension Conditions for Functioning Cultured Hepatocytes in Vitro
Authors: Nishikawa Makoto , Uchino Junichi , Matsushita Michiaki , Takahashi Manabu , Taguchi Koichi , Koike Masahiko , Kamachi Hirofumi , Kon Hirofumi
Published: July 2010

Abstract: With a view toward furthering the development of artificial liver systems, we have been culturing hepatocytes in vitro. The object of this research was to investigate the ideal conditions of oxygen tension for the efficient functioning of hepatocytes. Viable hepatocytes isolated from rat livers were cultured under five different oxygen tensions: 5, 10, 20, 50 and 90% O2. DNA contents, gluconeogenesis, urea synthesis, adenosine triphosphate (ATP) levels, and lipid peroxidation of hepatocytes were evaluated. Under the 5% oxygen conditions, the function of hepatocytes was very inferior and was accompanied by a low ATP level. However, hepatocytes cultured under 90% oxygen tension functioned less effectively than the control (20% O2) with elevated lipid peroxidation. The data in this study suggest that the optimum oxygen condition for cultured hepatocytes is 10 ˜ 50%, and that especially under conditions of 20% oxygen tension, i.e., that of the ordinary atmosphere, hepatocytes can function most effectively.
Mathematical Investigation of Some Physiological Factors Involved in Hemodialysis Hypotension
Authors: Ursino Mauro , Innocenti Marina
Published: July 2010

Abstract: A previously developed mathematical model is used to investigate the role of some hemodynamic, regulatory, and osmotic factors in the development of symptomatic hypotension during hemodialysis. Sensitivity analysis of the model parameters suggests that a decrease in atrial pressure, with a consequent fall in cardiac output (Frank‐Starling mechanism), is the primary hernodynamic perturbation induced by ultrafiltration. Also, during the first hours of a hemodialysis session, the sympathetic mechanism working on systemic resistance is the main factor responsible for arterial pressure maintenance, and the physiological response is probably characterized by a prevalence of the cardiopulmonary over the arterial baroreflex control. During this period, a decrease in plasma osmolarity, caused mainly by urea removal, may contribute to the reduction of vascular refilling. During the last hours of the session, the arterial pressure level is also significantly affected by other factors that influence vascular refilling and mean circulatory filling pressure (systemic compliance; action of feedback mechanisms working on venous unstressed volume; plasma oncotic pressure; and, especially, capillary wall permeability and interstitial space elastance). Simulation of hemodialysis with different modalities emphasizes the importance of avoiding high ultra filtration rates and of maintaining the sodium concentration in the dialysate close to the sodium concentration of the extracellular fluid to limit the risk of symptomatic hypotension. Higher values of sodium in the dialysate are, however, associated with poor sodium removal from the extracellular pool with risks of interdialytic morbidity. In the future, the model may be used to optimize the ultra‐filtration rate and sodium profile in the dialysate according to individual patient prescriptions.
In Vivo Comparison of Two Enteric‐Pouch Power Transformers for Circulatory Support
Authors: Melvin David B. , Glos David L. , Nebrigic Dragan , Helmicki Arthur J. , Brown Rebeccah L. , Purcell Peter N. , Henderson H. Thurman
Published: July 2010

Abstract: A defunctionalized ileal pouch is thin‐walled (1–2 mm), well perfused (blood flow, 0.3–1.0 ml/g/min), and tactile‐insensitive. If fixed within the abdominal wall and provided with a miniature stoma for primary wire en try, the heat dissipating capacity and achievable geometries could facilitate small efficient intra‐ to extracorporeal power transformers with virtually complete magnetic flux containment. Two transformers (A, weighing 102 gm with dual ferrite cores, intraluminal primary and extraluminal secondary each with 10 turns on its own crescentic ferrite core, 90 kHz, coupling coefficient k = 0.90–0.96; and B, 68 gm, a single flexible torroidal magnetic metallic tape core with attached 11 turn primary and free 14 turn serosal secondary, 14.7 kHz, k = 0.99) met the electrical and anatomic requirements. Each was implanted (minilapa‐rotomy, coil‐pouch fixation within abdominal musculature) in 4 dogs for 14–21 days to test the operative feasibility, electrical function, warming, and flux containment. For canine testing, wires were tunneled to a chewing‐inaccessible site. Neither tissue necrosis, infection, pro‐vokable interference from contiguous metal, nor coil displacement were observed; secretions were retained in Group A pouches only. The mean power transmissions for the transformers were A: 24.90 ± 1.50 W and B: 24.92 ± 0.89 W, after operation for 7 days or more. The mean efficiencies were A: 75.6 ± 0.1% total DC/DC, 96.2% coils and B: 80.4 ± 0.1% total DC/DC, 96.2% coils. The peak skin surface magnetic fluxes for transformers A and B, both trivial at 1.7 and 1.2 G, respectively, were similar. Warming was 0.62 k 0.30“C in Group A and 0.73 ± 0.19±C in Group B. The probability values were p < 0.5 (NS) for DC/DC efficiency and p > 0.10 (NS), for A versus B in all other areas of comparison. Observations for both were encouraging. Transformer B, with less mass, lower frequency, higher efficiency, and intrinsic invulnerability to displacement, was selected for longer term evaluation.
Double Filtration Plasmapheresis for the Treatment of Rheumatoid Arthritis: A Study of 21 Cases
Authors: Liu Jing‐Duo , Zhang Chunjing , Li Wei‐Sheng , Lun Li‐De
Published: July 2010

Abstract: The treatment of rheumatoid arthritis remains difficult and often controversial. Plasma exchange has been advocated in some cases. In the present study 71 sessions of double filtration plasmapheresis (DFPP) were performed in 21 patients with rheumatoid arthritis in an average of 3.7 ± 1.1 sessions per patient within 1–2 weeks. Seven patients had received prednisone, and all the patients had received nonsteroid anti‐inflammatory drugs with poor results. Although after the DFPP therapy, only 2 patients were still receiving nonsteroid anti‐inflammatory drugs, the function capacities improved in all patients. Five out of 8 positive rheumatoid factors became negative for the group. These results suggest that DFPP could be a regular therapy for rheumatoid arthritis.
Hepatocytes Entrapped in Collagen Gel Following 14 Days of Storage at 4°C: Preservation of Hybrid Artificial Liver
Authors: Suzuki Masayuki , Takeshita Kazuyoshi , Yamamoto Takumi , Ishibashi Haruaki , Kodama Masashi
Published: July 2010

Abstract: Preservation of hepatocytes is a key technical factor toward the successful clinical application of hybrid artificial livers. It was possible to culture hepatocytes that had been preserved with collagen gel for 8 and 14 days in 4°C University of Wisconsin solution. Phase‐difference and scanning electron microscopy showed that most of the stored hepatocytes maintained a round‐shaped morphology. In the 14 day preservation group, on Days 2 and 8, respectively, ureogenesis was 98.3% and 69.6%, gluconeo‐genesis was 65.2% and 80.7%, lidocaine clearance was 81.7% and 72.5%, urea synthesis after ammonia load was 47.6% and 57.5% of those in the comparable control group. This implies that preserved hepatocytes maintained adequate functional capability even after 14 days of preservation. We suggest that our preservation method will be valuable for the future application and development of a practical hybrid artificial liver.
Design of Hollow Fiber Modules for Uniform Shear Elution Affinity Cell Separation
Authors: Nordon Robert E. , Schindhelm Klaus
Published: July 2010

Abstract: Large‐scale monoclonal antibody based systems for the selection of cell subsets will play a prominent role in the development of hematotherapy and graft engineering. Hollow fiber systems for affinity cell separation rely on the generation of uniform fluid shear stress at the lumenal attachment interface. Potential mechanisms for nonuniformity of lumenal wall shear stress are fiber wall permeation fluxes driven by the pressure gradient along individual fibers and the influence of inlet header dynamic pressure on the radial distribution of axial flow within the fiber module. Dimensional analysis and numerical solution of the flow field within the lumen of a hollow fiber module illustrate the main physical criteria for design of hollow fiber modules. There will be a nearly uniform distribution of flow within the fiber bundle provided that the dynamic inlet pressure is small in comparison with the pressure drop along fibers. Fiber wall permeation fluxes will have a negligible effect on axial flow rate for nonporous membranes such as Cuprophan.
The Implantable Fuzzy Controlled Helmholtz‐Left Ventricular Assist Device: First In Vitro Testing
Authors: Kaufmann Ralf , Nix Christoph , Klein Martin , Reul Helmut , Rau Günter
Published: July 2010

Abstract: To perform first experimental tests for validation of a new left ventricular assist device (LVAD) with a high efficiency energy converter, a new pump design and a novel type of perfusion control, a functional labtype, were manufactured. With a stroke volume of 65 ml, a total pump housing volume of 450 ml (including valves and connectors), and a weight of 430 g, it is one of the smallest and lightest implantable pulsatile electromechanical LVADs. Pulsatile operation is generated by a special reduction and displacement gear, which transforms a uniform rotational movement of a sensorless, electronically commutated DC motor into a translatory pusher plate movement. A prolonged duration for filling (60% of the cycle time) supports full‐empty pumping and consequently high overall pump efficiency. Active adaptation of output flow to organ perfusion demand is achieved by changing the rotational speed of the motor by means of a sensorless fuzzy controller, which detects preload and afterload induced effects at the motor current input. First in vitro test results obtained within a circulatory mock loop that simulates physiological preloads and afterloads are presented. They comprise preload sensitivity and the function of the novel perfusion controller as well as preload and afterload related flow data. The results prove the feasability of the energy conversion with the novel gear and control concept for an implantable electromechanical pulsatile LVAD.
Mechanical White Blood Cell Damage in Rotary Blood Pumps
Authors: Takami Yoshiyuki , Yamane Shingo , Makinouchi Kenzo , Glueck Julie , Nosé Yukihiko
Published: July 2010

Abstract: Mechanical trauma of white blood cells (WBC) due to the operation of a rotary blood pump was examined, using a simple method of trypan blue dye exclusion test for a cell viability measurement. The degree of WBC trauma was investigated using a roller pump (RP) and 3 commercially available centrifugal pumps (Bio‐Medicus [BP], Capiox [CP], Nikkiso [NK]), and compared with the red blood cell (RBC) trauma. Each pump was operated 3 times at a flow rate of 5 L/min against the total pressure head of 350 mm Hg for 6 h in a mock circuit with 400 ml of fresh bovine blood. Blood was sampled at 2 h intervals measuring plasma free hemoglobin concentration and the percentage of damaged WBC in the trypan blue dye exclusion test. Each pump demonstrated a linear increase in the degree of WBC trauma, and there were differences among the tested pumps (RP > BP > CP > NK). These findings were similar to those of the free hemoglobin measurements. To compare the degree of RBC and WBC trauma, the probability (γ,ω) of RBC and WBC to be damaged was calculated, respectively.

γ = δ DRBC
δAN, ω=δDWBCδAN

where DRBC and DWBC are the ratios of the damaged RBC and WBC, respectively, and N is the passing number defined as Qt/V (Q, flow rate; t, time; V, circulating volume). The data of this study demonstrated that the ω value was approximately 20 times or more greater than the γ equally in all the tested pumps. This suggests that a WBC is more vulnerable to mechanical damage by a rotary blood pump than a RBC.
A Novel Method to Evaluate Thromboresistance of Drip Chambers with Filter Used in Extracorporeal Blood Circuits for Hemodialysis
Authors: Yamazaki Manabu , Kobayashi Ken‐yu , Mori Yuichi , Satoh Tadaaki , Kubota Sunao
Published: July 2010

Abstract: We have developed a novel method to simultaneously evaluate thromboresistance of two different types of drip chambers with a filter used in extracorporeal blood circuits for hemodialysis using canine arteriovenous shunt models. Bilateral bypasses between the femoral artery and vein on both sides of the animal were formed with 2 test circuits consisting of polyvinyl chloride tubing and two types of drip chambers with filters. Blood flow was derived into the drip chambers with a filter and returned to the femoral vein without using peristaltic pumps and systemic anticoagulants. By monitoring the quantitative changes of the blood flow rate through each drip chamber with a filter and measuring the time elapsed before the blood flow through its was completely obstructed by clots, thromboresistance of the drip chambers was evaluated under the same blood conditions. The drip chamber with a filter that had a small effective filter area, a big pore size, and slitlike pores showed better thromboresistance. This novel method proved useful in evaluating the thromboresistance of differently designed drip chambers with a filter.
Working Pressure for Full Balloon Inflation During Intraaortic Balloon Pumping
Authors: Sakamoto Tohru , Akamastu Hideki , Aral Hirokuni , Shoji Yasushi , Komatsu Shigeo , Sasaki Shin , Kazama Shigeru , Fujiyoshi FKohji , Hashiguchi Yasuhiro , Suzuki Akira , Suzuki Akio
Published: July 2010

Abstract: With changes in heart rate and mean aortic pres sure, an intraaortic balloon (IAB) works with incomplete inflation. The effects of initial peak positive pressure and plateau holding positive pressure on IAB volume were investigated and minimum pressures necessary to inflate an IAB to a desired volume were established with a stan dard IAB catheter (Datascope type, 9.5 Fr, 40 ml). Initial peak pressure greater than 200 mm Hg was adequate to attain the desired volume of the IAB. Plateau positive pressure should be altered in accordance with hemody‐namic changes.
Influence of Dialysis Membranes on Interleukin‐1β and Interleukin‐1 Receptor Antagonist Production by Peripheral Blood Mononuclear Cells
Authors: Higuchi Terumi , Kuno Tsutomu , Takahashi Susumu , Kanmatsuse Katsuo
Published: July 2010

Abstract: We investigated the production of interleukin (1L)‐1β and IL‐1 receptor antagonist (Ra) by peripheral blood mononuclear cell (PBMC) in vitro during hemodialysis of 7 dialysis patients using 4 differential dialysis membranes (regenerated cellulose [RC], polyamide [PA], polysulfone [PSI and AN‐69). Blood sampling was performed before dialysis (0 min), 15 min after starting dialysis, and after dialysis (240 min) during the last session of each treatment. The cellular content of fresh cells and the production of IL‐1β and IL‐1Ra with and without lipopolysaccharide (LPS) stimulation of the cells were evaluated and measured by enzyme‐linked immunosorbent assay (ELISA). The level of IL‐1β with LPS stimulation using RC, PA, and PS membranes was significantly reduced at 15 min and was not changed at 240 min as compared with the level at 0 min. On the other hand, the level of IL‐1β with LPS stimulation using an AN‐69 membrane at 15 and 240 min was not significantly different from that at 0 min. Neither initial cellular content nor spontaneous production of IL‐1β were detected at 0, 15, or 240 min in any of the membranes. The spontaneous production of IL‐1Ra at 15 and 240 min was not significantly different from that at 0 min in any of the membranes. The cellular content of IL‐1Ra using the RC membrane was significantly lower at 15 min and did not differ at 240 min from the level at 0 min. The cellular content of IL‐1Ra using PA, PS, and AN‐69 membranes was not significantly different at 15 and 240 min from that at 0 min. However, the IL‐1Ra level with LPS stimulation using RC and PA membranes was significantly reduced from that at 0 min, but the level using PS and AN‐69 membranes was not different from that at 0 min. Because IL‐1β and IL‐1Ra levels 15 min after starting dialysis using bioincompatible dialysis membranes were reduced from the levels at 0 min, the findings suggest that measurement of cytokines during dialysis treatment at an early stage is a useful marker for evaluating the biocompatibility of a dialysis membrane.
Myristoyl Gelatin as a Sealant for Dacron Vascular Prostheses
Authors: Sasajima Tadahiro , Inaba Masashi , Azuma Nobuyoshi , Goh Kazutomo , Koshiko Susumu , Kubo Yoshihiko , Miyamoto Keiichi , Tokita Masayuki , Komai Takashi
Published: July 2010

Abstract: Myristoyl gelatin (MG) retains its gel structure at temperatures above body temperature without any crosslinking. As a coating material, MG adheres well to polyester fibers. and the outermost layers of the sealant that are in contact with blood or surrounding tissue become hydrophilic. We produced MG‐impregnated knitted Dacron vascular prostheses (MG graft [MGG]) and investigated the usefulness of MG as a sealant by replacing the thoracic aorta of dogs. MGGs (5 cm long with an inner diameter of 10 mm) were implanted in 5 mongrel dogs (10–20 kg), and the grafts were retrieved at intervals of 4 h and 2. 4. 8, and 15 weeks after grafting. There was no thrombus formation on the flow surface of the MGGs, indicating adequate antithrombogenic properties. No re‐sorption of MG occurred until after 2 weeks, and neither immune reaction nor excessive foreign body reaction was noted. Fragmentation of the sealant induced by cell infiltration began to occur at 4 weeks, yet the sealing effect persisted. The organization of MGG was almost complete at 8 weeks. Because of its pliability and effective adhesion to polyester fibers, its antithrombogenicity, and the persistent sealing effect due to delayed biodegradation and resorption, we conclude that MG is an extremely useful sealant for polyester vascular prostheses.