bluuebunny/crossref_metadata_2025 huggingface dataset:
Serum Melatonin and 6‐Sulfatoxymelatonin in End‐Stage Renal Disease: Effect of Hemodialysis
Authors: Vaziri N.D. , Oveisi Fariba , Wierszbiezki Maryann , Shaw Viviana , Sporty Lawrence D.
Published: July 2010

Abstract: The pineal hormone melatonin plays a role in the regulation of hypothalamic‐pituitary axis, target gland function, sleep pattern, mood changes, cellular immunity, antibody response, and skin pigmentation, nearly all of which are also affected by renal insufficiency. We measured serum melatonin and its main urinary metabolite, 6‐sulfatoxymelatonin (6‐SM), by radioimmunoassay in 11 patients with end‐stage renal disease (ESRD) between the hours of 6 and 9 a.m. during hemodialysis and again on an off‐dialysis day. The results were compared with those obtained in a group of normal control subjects. Predialysis serum melatonin and 6‐SM levels obtained at 6 a.m. in the ESRD patients were comparable with those obtained in the normal control group. Serum melatonin concentration in the ESRD group fell approximately 25% during dialysis while 6‐SM remained virtually unchanged. The changes observed on the off‐dialysis day during the same time period were of nearly the same magnitude as those seen during dialysis (– 32% and 1.4%, respectively). No significant difference was found in the concentration of either analyte in the blood entering and leaving the dialyzer. These observations suggest a lack of discernible removal of either compound by hemodialysis. In contrast to the ESRD patients, who showed a slow fall in serum melatonin and no significant change in serum 6‐SM on both on‐ and off‐dialysis days, the normal control subjects showed an expected reduction in serum melatonin (– 43%) and a sharp fall in serum 6‐SM (– 53%) between 6 and 9 a.m. In conclusion, ESRD patients exhibited an attenuated variation in serum melatonin and its principal metabolite, 6‐SM, in the morning hours. In addition, neither melatonin nor 6‐SM showed significant dialyzability.
Complement Activation during Tryptophan Immunoadsorption Treatment
Authors: Alarabi Abdelmoniem Abdelmahmoud , Nilsson Bo , Nilsson Ulf , Wikström Björn , Danielson Bo G.
Published: July 2010

Abstract: Antibodies against human lymphocyte antigens (HLA) are frequently seen among patients undergoing repeated renal transplantations. Graft survival can be improved by eliminating these antibodies by plasmapheresis before transplantation. In this study, we have tried a new extracorporeal procedure to remove the anti‐HLA antibodies. An immunoadsorption column (IM‐TR) with a matrix of polyvinyl alcohol (PVA) gel conjugated with a hydrophobic amino acid tryptophan was utilized. Previous results have shown that repeated IM‐TR treatments are at least equally effective as plasmapheresis in reducing levels of specific immunoglobulins in treated patients. In this study, 7 HLA‐immunized patients were treated before renal transplantation. Each patient was subjected to a total of 12 treatment sessions divided into 3 sessions per week. After each treatment session, the reduction of the immunoglobulins was less than what has been reported for plasmapheresis. This suggests that mechanisms other than immunoglobulin depletion are involved in the reduction of the total immunoglobulin levels. The IM‐TR treatment resulted in a strong complement activation triggered by the alternative pathway. Since the adsorbed plasma was returned to the patient, exceedingly high levels of the activation fragment C3d (C3dg) were found in plasma during and after the treatment. We conclude that the extensive generation of C3dg may be one of the factors that plays a role in the reduction of the antibody levels since the C3dg fragment has been shown to down‐regulate the immune response.
Dialysis against a Recycled Albumin Solution Enables the Removal of Albumin‐Bound Toxins
Authors: Stange J. , Ramlow W. , Mitzner S. , Schmidt R. , Klinkmann H.
Published: July 2010

Abstract: The removal of protein‐bound substances of pathogenetic relevance from blood is of therapeutic interest for drug intoxications, renal and liver failure, and metabolic disorders. Current methods using adsorbents are effective but often not specific enough. This work presents an alternative method that enables the dialyzability of albumin‐bound toxins from plasma by the use of a high‐flux dialyzer (F 60 Fresenius) and an albumin solution circulating on the dialysate side to increase selectively the affinity for albumin‐bound toxins. This method resulted in effective removal of unconjugated bilirubin, drugs with a high protein‐binding ratio (sulfobromophtalein, theophylline), and a protein‐bound toxin (phenol). The additional removal of PBS could extend the applicability of dialysis, for example, to drug intoxications and liver failure or could improve the elimination of protein‐bound uremic toxins in chronic renal failure.
UCLA Liver Transplantation: Analysis of Immunological Factors Affecting Outcome
Authors: Dawson Sherfield , Imagawa David K. , Johnson Cheryl , Cecka Michael , Terasaki Paul I. , Shackleton Christopher R. , Busuttil Ronald W.
Published: July 2010

Abstract:From 1988 to 1993, UCLA completed 938 first and 1,146 total orthotopic liver transplants (OLT). Race analysis demonstrated a 1‐year patient survival of 89% in Blacks (n = 45) versus 80% in Whites (n = 492, p < 0.02), with no significant difference shown between His‐panics (n = 278) and Whites. The 1‐year patient survival in Asians was 50% (n = 58, p < 0.02 vs. Whites) even when hepatitis B was excluded (59%, n = 43). The 1‐year patient survival of hepatitis B surface antigen positive Asians (n = 15) was only 21% (p < 0.02 vs. all others). OLT patients whose panel reactive antibody (PRA) was < 10% (n = 339) demonstrated no graft or patient survival advantage versus recipients whose PRA was >10% (n = 71). A positive antidonor flow cytometry crossmatch (>30 mean channel shifts, n = 76) was associated with a decreased 1‐year graft survival (56% vs. 73%, p < 0.05) when compared to flow negative recipients (n = 185). Graft survival for 0 DR mismatches was 74% at 1 year compared with 57% for 1 DR mismatche (p < 0.02) and 59% for 2 DR mismatches (p < 0.02).
Bilateral Lobar Transplantation Utilizing Living Related Donors
Authors: Barr Mark L. , Schenkel Felicia A. , Cohen Robbin G. , Chan Kevin M. , Marboe Charles C. , Hagen Jeffrey A. , Barbers Richard G. , Starnes Vaughn A.
Published: July 2010

Abstract: As the recipient list for patients requiring lung transplantation continues to increase, cadaveric donor lung availability has remained static. Our experience with utilizing lobes from living related donors for bilateral pulmonary transplantation in 20 patients has yielded a 75% survival at 1 year follow‐up. Morbidity and mortality have been predominately due to infection. Rejection episodes have been mild and unilateral and have responded to augmented corticosteroids. Pulmonary function tests in the recipients tend to improve steadily during the first year postoperatively, and the patients have excellent functional capacity. There have been no significant complications in the donors. On the basis of our clinical experience, we have found that bilateral lobar transplantation utilizing living related donors has resulted in organ availability that can be lifesaving in critically ill patients and can provide a good alternative in certain noncritical, deteriorating patients.
Recovery of Adenosine Triphosphate Tissue Levels of Grafts Preserved by the Two‐Layer Method after Reperfusion
Authors: Kim Yongsik , Kuroda Yoshikazu , Tanioka Yasuki , Matsumoto Shin‐ichi , Fujita Hirofumi , Sakai Tetsuya , Hamano Mitsuaki , Suzuki Yasuyuki , Ku Yonson , Saitoh Yoichi
Published: July 2010

Abstract: Recovery of tissue adenosine triphosphate (ATP) levels after transplantation is very important for graft survival. We examined whether the pancreas grafts preserved by the two‐layer method have the ability to synthesize ATP after reperfusion, and this is one of the mechanisms of action for the two‐layer method in successful pancreas preservation. After preservation by the two‐layer method using Euro‐Collins' solution (EC) for 48 h (Group 1, n = 5) or simple cold storage in EC for 48 h (Group 2, n = 5), canine pancreas grafts were au‐totransplanted. In controls (Group 3, n = 5), canine pancreas grafts were autotransplanted without preservation. Graft viability was judged from graft survival after transplantation. Tissue adenine nucleotide concentrations were measured using high performance liquid chromatography after preservation, before reperfusion, and after 1 and 2 h of reperfusion. Graft survival rates were 5 of 5, 0 of 5, and 5 of 5, in Groups 1, 2, and 3, respectively. However ATP tissue levels in Group 1 were significantly higher compared with those in Group 2 after preservation and before reperfusion, respectively (10.95 ± 1.52 vs. 2.75 ± 0.33 and 2.90 ± 0.51 vs. 2.03 ± 0.68 n‐mol/g dry weight, p < 0.01 and p < 0.05, respectively). Total tissue adenine nucleotide levels in Group 1 before reperfusion were 7.41 ± 1.47 u.mol/g dry weight, and there was no significant difference compared with Group 2, 6.64 ± 2.23 jxmol/g dry weight. After reperfusion, there was no significant difference of ATP tissue levels between Groups 1 and 2 (4.07 ±1.18 vs. 4.48 ± 1.32, not significant [NS|) after 1 h of reperfusion. However, after 2 h of reperfusion, tissue ATP levels in Group 1 (6.71 ±1.19 (xmol/g dry weight) were significantly higher than were those in Group 2 (4.51 ± 0.51 ujnol/g dry weight, p < 0.01) and almost at the same levels as control (6.32 ± 1.62 u.mol/g dry weight). It was clear that recovery of ATP after reperfusion did not depend on the residual nucleotides pool but on the ability of the pancreas graft to synthesize ATP after reperfusion. We conclude that oxygenation of the pancreas graft during preservation by the two‐layer method allows for ATP synthesis, which is essential in maintaining cellular integrity and leads to maintaining the graft's ability to synthesize ATP promptly after reperfusion. This is one of the mechanisms of action of the two‐layer method in successful pancreas preservation.
Veno‐occlusive Disease of the Liver Following Bone Marrow Transplantation: A Clinical‐Pathological Study of Autopsy Cases
Authors: Watanabe Kazushige , Iwaki Hiroyuki , Satoh Masaaki , Ikeda Tatsuru , Ichimiya Shingo , Suzuki Nobuhiro , Kudoh Tooru , Oda Takanori , Matsuura Akihiro , Mori Michio , Kikuchi Kokichi
Published: July 2010

Abstract: A total of 28 patients with leukemia underwent intensive therapy with megadose chemotherapy and stem cell transplantation. Of 16 patients who had busulfan therapy, 2 developed the clinical syndrome of veno‐occlusive disease of the liver (VOD) characterized by progressive abnormalities in liver function, abdominal pain, and ascites. Postmortem findings showed VOD of the central and sublobular hepatic vein. Immunohistochemical analysis using anti‐actin and CD34 mAb was employed in an attempt to clarify the process of fibrosis. Actin positive cells had accumulated around the central vein. Ito cell activation might be responsible for secondary fibrosis following endothelial injury. We report autopsy findings and immunohistochemical results.
Dialysis in Rats with Acute Renal Failure: Evaluation of Three Different Dialyzer Membranes
Authors: Kränzlin B. , Gretz N. , Kirschfink M. , Mujais S.K.
Published: July 2010

Abstract: Exposure to complement‐activating cellulosic dialysis membranes has been claimed to adversely affect the course of acute renal failure (ARF). To test this hypothesis, male Sprague‐Dawley rats were allocated to 2 groups: in Group t, ARF was induced by bilateral renal artery clamping whereas in Group 2, animals underwent a sham procedure. In each group, rats were further allocated to undergo hemodialysis with either a Cu‐prophan, a Hemophan, or a polyacrylonitrile minidialyzer on Days 4 and 8 after surgery, or no dialysis. Renal function was measured by inulin clearance on the days after dialysis. Additionally, total complement activity (CH50) was estimated on Days 1, 2, 4, and 8, and complement factor C3 was detected immunohistochemically. The degree of renal failure and the rate of recovery of renal function were similar in all the ARF groups irrespective of whether they had undergone dialysis or not, or of the type of the dialysis membrane. Furthermore, there were no significant differences in the course of CH50 or in the amount and distribution of complement factor C3 in the kidney tissue between the rats of Groups 1 and 2. Our findings refute the hypothesis that in ischemic ARF exposure to complement‐activating cellulosic dialysis membranes impairs the recovery of renal function in rats.
Antimicrobial Activities of Iodinated Polystyrene Derivatives
Authors: Lin Kuo‐Juei , Tani Tohru , Endo Yoshihiro , Kodatna Masashi , Teramoto Kazuo
Published: July 2010

Abstract: The antimicrobial activities of insoluble haloge‐nated acetamidomethyl‐styrene polymers (prepared by covalent bonding of iodine to polystyrene) were assessed as were the factors determining antimicrobial efficacy. The most active materials were selected from chlorinated or iodinated polymers. Antimicrobial activities were assessed for Escherichia coli (ATCC 25922; American Type Culture Collection, Rockville, MD, U.S.A.), Saccharo‐myces cerevisiae, and Candida albicans by determining time‐course changes in microbial counts in vitro. A 2‐iodoacetamidomethylstyrene polymer (No.6‐I:‐CH2I) was found to have the greatest antimicrobial activity against both bacteria and fungi. No.6‐1 is the first antimicrobial material that did not make an inhibition hollow in the conventional diffusion test or for which conjugated iodine showed antibacterial activity. This material can be introduced into styrene units on the surface of devices by chemical modification. This material was most active at 37oC. For coated dishes, antimicrobial activity depended on the depth or swollen character of the reactive layer. No.6‐1 requires not only a minimum width of polymer layer, but also frequent contact with microbes to have an antimicrobial effect. No.6‐1 is valuable as a new material because it has strong antimicrobial activity by itself but does not release active iodine. This material is expected to have various applications in implantable clinical devices.
Total Artificial Heart Using Neural and Fuzzy Controller
Authors: Lee Minho , Ahn Jae Mok , Min Byoung Goo , Lee Soo‐Young , Park Cheol Hoon
Published: July 2010

Abstract: The aortic pressure (AoP) and pulmonary artery pressure (PAP) are important factors for the long‐term survival of the patient receiving an implant of a total artificial heart (TAH). A new afterload regulation method using neural controllers has been developed for a moving actuator type TAH. Without any transducer, the proposed neural controller, based on the predetermined peak level of the motor current, regulates AoP by adjusting the actuator velocity. At the same time, a fuzzy controller based on expert knowledge prevents the PAP from being abnormally high. The proposed controller not only regulates the pump output on the maintenance of the normal AoP and PAP, but it also successfully controls the suction in the right heart. In vitro tests show that the proposed neural and fuzzy controllers effectively regulate AoP and PAP as well as prevent atrial suction.
Mock Test Characteristic of Intraaortic Balloon Pump Using Linear Motor
Authors: Yamada Hajime , Wakiwaka Hiroyuki , Suzuki Kenji , Nakagawa Hiroshi , Fujii Naofumi , Matsuura Yuichiro , Fukunaga Shintaro
Published: July 2010

Abstract: This article describes the composition of the intraaortic balloon pump (IABP) system, which uses a linear pulse motor, that is, the linear type of IABP, and the results of the mock test that was performed. The expansion time is 100–110 ms, and the contraction time is 85–95 ms at the balloon of the linear type IABP. This level is similar to that of the IABP system used in the market. When the speed of the mover is 0.3 m/s, the necessary thrust of the linear pulse motor to drive the balloon of the IABP is 200 N. The conversion efficiency from the bellows to the balloon is 5.6%, and the efficiency of the entire linear type IABP system is 0.6%. The volume of the entire system is 45 L, and the mass is 40 kg excluding the chassis. Therefore, there is an expectation that the IABP system can be miniaturized to about half of the conventional model.
Organ Transplantation in Taiwan
Authors: Lee Chun‐Jean
Published: July 2010

Abstract: We performed the first successful kidney transplantation in Taiwan on May 27, 1968. Since then, kidney, heart, lung, pancreas, liver, and heart‐kidney transplantations have been increasingly successful in restoring lives of otherwise dying patients with organ failure. The first successful kidney, liver, and heart transplantations in Asia were achieved in Taiwan in 1968, 1984, and 1987, respectively. Individual organ transplantation, organ transplant recipient survival, graft survival, and problems and pitfalls encountered in the care of organ transplantation recipients are analyzed. Using polymerase chain reaction amplification with sequence‐specific primers, donor‐specific DNA was detected in the peripheral blood of the patient who survived the longest (26 years) in this series. Interestingly enough, recently, we had a patient undergoing cadaveric renal transplantation in whom chi‐merism was detected in her lymph nodes and skin only 3 years after transplantation. Organ procurement in Taiwan is the greatest problem, and we have been exerting our maximal effort to establish a transplantation coordination team to create a central network and to educate, procure, preserve, distribute, and increase the availability of organs and tissues for transplantation.
The Influence of the Product Liability Act, Governmental Regulation, and Medical Economics on Medical Devices and Their Clinical Applications
Authors: Hirose Teruo T.
Published: July 2010

Abstract: The advancement of medical technology constantly demands the introduction of safer and more efficient medical instruments and devices. Recent litigation and rulings against the manufacturers of breast implants and the subsequent refusal of major plastic companies to supply materials to them are seriously threatening the production and development of other permanent implants such as ventricular assist devices and even disposable catheters. In addition, government overregulation also discourages and hinders production and clinical applications of new instruments. Current trends such as cost effectiveness measures and economic restraints imposed by government agencies and managed care systems are endangering investments from the medical and industrial communities to exploit more expensive and sophisticated instrument technologies. The resultant lack of grant money and pressure from animal rights advocates also suppress experimentation on primates and domestic laboratory animals.
The Optimal Tidal Volume Delivered by Ventilator after Pulmonary Resection: Its Effect on Cardiopulmonary Hemodynamics
Authors: Lee Jang‐Ming , Lee Yung‐Chie , Chen Ta‐Liang , You San‐Lin , Luh Shi‐Ping , Lee Chun‐Jean
Published: July 2010

Abstract: Pulmonary function and gas exchange deteriorate after pulmonary resection. The vital capacity, tidal volume, and functional capacity decrease after pulmonary resection because of loss of effective lung volume and, therefore, affect the setting of the ventilator. Nineteen patients undergoing pulmonary resection were included in this study on the optimal tidal volume delivered by a ventilator. Five patients received mediastinal surgery or wedge resection of the lung, 4 had pneumonectomy, and 10 had lobectomy. Immediately after the pulmonary surgery, they were maintained with ventilatory support. Subsequently, a different setting of tidal volume on the ventilator was given for each patient, i.e., 6 ml/kg, 8 ml/kg, 10 ml/kg, 12 ml/kg, and 14 ml/kg. For each setting of tidal volume, a hemodynamic study was performed including cardiac output and other parameters. With the examination of Wilk's Lambda test, there was no difference in association with different settings of tidal volume on blood pressure (F = 0.92, p = 0.51), pulmonary artery pressure (F = 0.95, p = 0.43), pulmonary vascular resistance (F = 0.24, p = 0.97), systemic vascular resistance (F = 0.42, p = 0.78), and cardiac output (F = 0.35, p = 0.93) in 3 different groups of patients. It is concluded that after pulmonary resection a patient's lungs can be inflated with a tidal volume to 14 ml/kg during ventilatory support without compromise of cardiovascular performance.
Extracorporeal Membrane Oxygenation Support for Postcardiotomy Cardiogenic Shock
Authors: Wang Shoei‐Shen , Chen Yih‐Sharng , Ko Wen‐Jer , Chu Shu‐Hsun
Published: July 2010

Abstract: Extracorporeal membrane oxygenation (ECMO) has had promising results in life‐threatening respiratory failure and postcardiotomy cardiogenic failure. From October 1994 to October 1995, 18 patients received 19 ECMOs at National Taiwan University Hospital for severe cardiogenic shock after cardiac surgery. They included patients receiving cardiac massage or repeated bolus injections of norepinephrine to maintain blood pressure (n = 10), patients who could not be weaned off cardiopulmonary bypass after several attempts despite in‐traaortic balloon pumping and maximal doses of catecholamine (n = 7), and patients with progressive intractable cardiogenic shock after cardiac surgery. Venoarterial ECMO was set up via femoral artery (17 or 19 Fr cannula) and vein (19 or 21 Fr) in all patients except 2 infants. No left heart drainage was performed in any of the patients. The heparin‐coated circuit (with Carmeda Bio‐active Surface) was used in the last 13 patients to reduce bleeding. Ten (52.6%) of the 19 cases could be smoothly weaned off ECMO, and 6 (33.3%) of the 18 patients were discharged from the hospital in good condition. Four (80%) of the 5 patients after valvular surgery and all 3 heart transplant patients could be weaned off ECMO successfully with the survival rate being 60% and 67%, respectively. Complications included leg ischemia (n = 3), bleeding (n = 4), renal failure (n = 3), and tube rupture (n = 1). The inability to wean off ECMO was caused by multiple organ failure (n = 5), sepsis (n = 2), tube rupture (n = 1), and dysfunction of the ECMO system (n = 1). The major cause of multiple organ failure was hesitation to set up ECMO. Our preliminary results confirmed the effect of ECMO in postoperative cardiogenic shock.
Simple Evaluation Method of Biocompatibility of Artificial Oxygenator Hollow Fiber
Authors: Nishida Hiroshi , Shibuya Mitsuhiro , Endo Masahiro , Koyanagi Hitoshi
Published: July 2010

Abstract: We made miniature modules filled with artificial oxygenator hollow fibers and conducted a simple experiment to study the effect of different membrane structures on the blood. Three types of modules were made: one filled with polyolefin, one filled with polypropylene, and a blank module. The 3 modules were connected through 3 fine tubings to one needle so that the same blood that passed through the 3 modules could be analyzed simultaneously. Nonheparinized blood was continuously withdrawn from 6 healthy volunteers using a small pump and passed through the circuit by a single pass (10 ml/min, for 10 min). Platelet count, thrombin‐anti‐thrombin complex, and complement‐3 were measured in the blood collected at 10 min from the outlet of each module. The results showed significantly better biocompatibility of polyolefin than polypropylene, which is attributable to the dense layer of the blood contact surface of polyolefin fibers. This method is useful in assessing biocompatibility of various hollow fibers in a simple and safe manner.
Marine Propellers: The Latest Topics
Authors: Kubo Hironao
Published: July 2010

Abstract: The impeller of the axial flow blood pump in an artificial heart is essentially based on the same principle as a marine propeller. Impellers designed for artificial hearts and marine propellers have a number of points in common. Decreased cavitation and relieved fluctuation load are only representative of them. As for a distinct concept of pressure distribution, the inverse method could be very useful. Skew may led to a more mild and natural character in the blood. Highly skewed blades and super elastic blades have the potential to decrease the burden on the entire circulatory system. This paper will address the main points and latest issues in propeller design concluding with a discussion of the implications of these issues for blood pump impellers.
Current Status of Extracorporeal Membrane Oxygenation for Severe Respiratory Failure
Authors: Ichiba Shingo , Bartlett Robert H.
Published: July 2010

Abstract: Extracorporeal membrane oxygenation (ECMO) for respiratory failure was reviewed. ECMO progressed from laboratory research to initial clinical trials in 1972. Following a decade of clinical research, ECMO is now standard treatment for neonatal respiratory failure refractory to conventional pulmonary support techniques worldwide. The application of neonatal ECMO has been extended with improved outcome to premature and low birth weight infants as well as older children and adults. As of July 1994, 9,258 neonates, 754 pediatric, and 130 adult patients with respiratory failure treated with ECMO were entered in the registry of the Extracorporeal Life Support Organization (ELSO). Overall survival rates were 81% in neonates, 49% in pediatric, and 38% in adult patients. Recently the adult and pediatric populations treated with ECMO have increased rapidly, and the outcome has improved significantly.
A New Magnetically Suspended Centrifugal Pump: In Vitro and Preliminary In Vivo Assessment
Authors: Park Chang‐Hee , Nishimura Kazunobu , Akamatsu Teruaki , Tsukiya Tomonori , Matsuda Katsuhiko , Ban Toshihiko
Published: July 2010

Abstract: To overcome problems derived from the shaft within the conventional centrifugal pump, we have been developing a new centrifugal pump, namely a magnetically suspended centrifugal pump (MSCP), which has no shaft and operates as a noncontacting and bearingless pump. The impeller is suspended magnetically between the magnetic bearing and the driving motor. Hemolysis tests were performed in comparison with the Biopump (BP80, BioMedicus). The index of hemolysis (IH) was significantly lower in the MSCP than in the Biopump. In addition, a smaller gap in the MSCP induced lower hemolysis. In preliminary studies using mongrel dogs, the layer of thrombus adherent to the impeller was observed in a few hours, which impaired the pumping efficiency. However, by using an impeller coated with silicone, no aggregations of platelets or fibrin on the impeller were observed in 24 h of continuous pumping. In conclusion, the MSCP had a gentler influence on blood cells than the Biopump, and the impeller coated with silicone may contribute to the long‐term pumping of the MSCP.
A Quantitative Visualization Study of Flow in a Scaled‐up Model of a Centrifugal Blood Pump
Authors: Ikeda Tadashige , Yamane Takashi , Orita Toyoki , Tateishi Tetsuya
Published: July 2010

Abstract: A quantitative flow visualization study of a scaled‐up model of a centrifugal blood pump was performed. Since the size of the scaled‐up model was three times as large as the original pump under development, and the kinematic viscosity of the saline solution used as the working fluid was approximately one‐third that of the blood, we obtained a similar flow at one twenty‐seventh the angular velocity of the original pump. The flow was visualized by seeding the saline solution with neutrally buoyant particles and by illuminating the model with a laser light sheet. Since the gap flow behind the impeller is important for thrombus formation, it was recorded by a high‐speed video camera, and the velocity field was evaluated automatically by particle tracking velocimetry. It was shown that in the gap behind the impeller there existed a region where the velocity profile was almost flat which can be called a core region. The results indicated the effectiveness of the present visualization technique for centrifugal blood pumps.
Comparison Studies of Major Organ Microcirculations Under Pulsatile‐ and Nonpulsatile‐Assisted Circulations
Authors: Sezai Akira , Shiono Motomi , Orime Yukihiko , Nakata Kin‐ichi , Hata Mitsumasa , Nemoto Mitsuhiro , Saitoh Toshimi , Sezai Yukiyasu
Published: July 2010

Abstract: In these comparison studies, we examined changes in major organ microcirculations during circulatory support using pulsatile and nonpulsatile pumps. Acute myocardial infarction was created by left anterior descending (LAD) branch ligation. After the animals in these studies fell into cardiogenic shock, they were supported by mechanical assist devices: a pulsatile ventricular assist device (VAD) in 4 pigs, a nonpulsatile VAD in 4 pigs, and an intraaortic balloon pumping (IABP) plus nonpulsatile VAD in 4 pigs. Each group was supported for 3 h with an identical mean aortic pressure being maintained. As for parameters, the stomach mucosa, liver regional blood flow, stomach mucosal pH, and arterial blood keton body ratio (AKBR) were measured. Both regional blood flow and AKBR increased in the pulsatile group as compared with the nonpulsatile group. There were no differences in the stomach mucosal pH among the 3 groups. These results suggest that pulsatile assist rather than the nonpulsatile assist plays a significant role in the recovery of deteriorated splanchnic organs due to cardiogenic shock.
A Percutaneously Accessible Pulsatile Left Ventricular Assist Device: Modified Assist Device Type 5
Authors: Imanishi Kaoru , Imachi Kou , Yoshito Hiroshi , Isoyama Takashi , Abe Yusuke , Chinzei Tsuneo , Mabuchi Kunihiko , Kanda Katsuki , Tsutsui Nobumasa , Suma Kozo , Fujimasa Iwao
Published: July 2010

Abstract: To provide percutaneous access, a new circulatory assist system was developed. We call this newly developed system the modified assist device (MAD). The system is composed of a sac‐type blood pump and cannula. Inflow and outflow valves are mounted in the apex and at the side wall 10 cm from the apex of the cannula, respectively. During systole, the blood is sucked from the left ventricle through the inflow valve of the cannula connected to the blood pump, and during diastole, the blood is ejected to the root of the aorta through the outflow valve. In vitro and in vivo evaluations of the pump performance were performed. The maximum flow rate of 1.9 L/min was obtained in the mock circulatory system. In our animal experiment, effective systolic unloading and diastolic augmentation were observed by activation of this system during regular sinus rhythm. In conclusion, the MAD‐5 is thought to be percutaneously accessible and increases systemic and coronary flow.
In Vitro and In Vivo Testing of an Implantable Motor‐Driven Left Ventricular Assist Device
Authors: Murakami Taiji , Kikugawa Daiki , Fukuhiro Yoshiaki , Kanazawa Shigeo , Fujiwara Takashi , Katsumura Tatsuki , Kukunaga Shintaro , Matsuura Yuichiro
Published: July 2010

Abstract: A totally implantable motor‐driven left ventricular assist device (LVAD) has been developed and tested. The performance of this LVAD was tested in a mock circulatory system. This pump provided 8 L/min of output against a mean afterload of 120 mm Hg with a filling pressure of 20 mm Hg when the pump was operated in the fill/empty mode. The right and left pumps were tested in a mock loop. The right pump afterload was kept in the range from 23–32 mm Hg. With increase in the left pump afterload, the pump power output varied from 1.64 to 2.37 W. The instantaneous motor power input varied from 22.6 to 30.6 W with the total system efficiency ranging from 6.7 to 9.4%. To date, 4 in vivo studies have been conducted for up to 12 h. Two animals survived 12 and 10 h, respectively. Termination was due to bleeding in 1 animal, vent tube obstruction in 1, and respiratory failure in 2. All animals died of technical failure. Another experiment is to be undertaken, and a newly designed cannula is now being manufactured.
Linear Skeletal Muscle Ventricle: A Pilot Study
Authors: Kaneko Yukihiro , Furuse Akira
Published: July 2010

Abstract: We have developed a new skeletal muscle ventricle (LSMV) powered by linear contraction of the latissimus dorsi muscle (LD). This consists of two bellows of different diameters joined by a connector containing a valve. The smaller bellows is connected to the left atrium with a valve, and the larger bellows is connected to the aorta. The caudal tendon of the LD is attached to the connector. LD contraction pulls the connector to compress the larger bellows and to elongate the smaller bellows. This motion closes the valve in the connector, ejects blood in the larger bellows, and draws blood into the smaller bellows. LD relaxation allows aortic blood to regurge into the larger bellows. Therefore, the LD is stretched. In acute canine experiments, the stroke work and power output of the LSMV measured 0.214 J and 0.135 W with a filling pressure of 4.3 mm Hg.
Function of Culturing Monolayer Hepatocytes by Collagen Gel Coating and Coculture with Nonparenchymal Cells
Authors: Koike Masahiko , Matsushita Michiaki , Taguchi Koichi , Uchino Junichi
Published: July 2010

Abstract: Since 1987, we have been developing a bioartificial liver (BAL) using multiplated cultured hepatocyte monolayers. With the goal of promoting hepatic functions of cultured hepatocyte monolayers, we combined the use of a collagen gel layer over the monolayers of hepatocytes and/or cocultured hepatocytes with nonparenchymal cells (NPCs). The study was divided into four groups according to culture configurations: Group 1: hepatocyte monolayer culture (control); Group 2: coculture of hepatocytes and NPCs; Group 3: hepatocyte monolayer with a overlaid collagen gel layer; and Group 4: coculture with a overlaid collagen gel layer. The culture continued for 14 days. Morphological changes and hepatic functions were evaluated by urea and albumin syntheses. The morphological status of the hepatocytes remained for 2 weeks in Groups 3 and 4. Deterioration and detachment of hepatocytes and/or NPCs started in Group 1 and 2 on the third day in culture. Significantly high urea synthesis was noted in Group 4 (p < 0.001 compared with Group 1 and 2: p = 0.0014 compared with Group 3). Although there was no significant difference in albumin synthesis among the four groups, those hepatocytes covered by the collagen gel (Groups 3 and 4) tended to secrete albumin throughout the observation period. These results indicted that the environment, although artificial (but close to the in vivo state), supplied with collagen gel and the coculture, enhanced the activities of the cultured hepatocyte monolayers. We suggest that use of cocultured hepatocytes under a collagen gel is a promising candidate for a bioreactor of multiplated BAL.
Modeling Arterial Hypotension During Hemodialysis
Authors: Ursino Mauro , Innocenti Marina
Published: July 2010

Abstract: A mathematical model of the hemodynamic response to hemodialysis is presented. This model includes the dynamics of sodium, urea, and potassium in the intracellular and extracellular pools; fluid balance equations for the intracellular, interstitial, and plasma volumes; systemic and pulmonary hemodynamics; and the action of several short‐term arterial pressure control mechanisms. The control mechanisms are triggered by information coming from both arterial and cardiopulmonary press receptors, and they work on systemic arterial resistance, heart rate, and systemic venous unstressed volume. Moreover, the model hypothesizes that decreasing left atrial pressure below a given threshold causes a paradoxical withdrawal of the sympathetic drive and a consequent vasodepressor syncope. The model is used to simulate the pattern of the main hemodynamic quantities (systemic arterial pressure, heart rate, total systemic resistance, and cardiac output) during hemodialysis in several groups of patients (both hypotension resistant and hypotension prone) whose data were drawn from the clinical literature. The simulation results point out that the model is able to reproduce a variety of different conditions, including no hypotension, moderate hypotension, and severe hypotension with ultimate vasodepressor syncope, by adjusting a few param eters with clear physiological meanings. Hypotension is principally imputed to a loss of the sympathetic mechanisms working on systemic resistance and to an impairment of vascular refilling at the capillary wall. The results suggest that hypotension during hemodialysis is a complex phenomenon that depends on the superimposition of several concomitant factors working together that can lead to a variety of distinct individual patterns.
Influence of Blood Flow on Adsorption of β2‐Microglobulin onto AN69 Membrane
Authors: Kandus Aljoša , Malovrh Marko , Bren Andrej F.
Published: July 2010

Abstract: Adsorption onto the dialyzer membrane is a contributing factor to the elimination of β2‐microglobulin (β2M) from the sera of uremic patients. The purpose of this prospective study was to ascertain the influence of the blood flow rate on adsorption of β2M onto the polyacrylonitrile (AN69) hollow‐fiber dialyzer membrane in 8 pa tients during regular hemodialysis (HD). Blood first passed through a low‐flux polysulfone dialyzer and then through an AN69 dialyzer, which was not in contact with the dialysis fluid. During the investigation period (first hour of the HD session), the blood flow rate was 100 ml/min (first part of the study), 200 mumin (second part of the study), and 300 ml/min (third part of the study). Ultrafiltration was not performed during the investigation period. At the start of the HD sessions, the serum concentration of β2M in the afferent blood line did not differ significantly among the 3 parts of the study. Serum β2M was measured in samples taken from the afferent and efferent blood lines of the AN69 dialyzer at 5,10, 15, 30, 45, and 60 min. The serum β2M concentration decreased significantly in blood that had passed through the AN69 dialyzer. This decrease, indicating membrane adsorption, was maximal during the first part and minimal during the third part of study. The decrease in the contact time between the blood and the AN69 could be the underlying cause. The calculated quantities of β2M adsorbed onto the AN69 membrane (44.2 ± 10.2, 43.2 ± 12.1, and 42.6 ± 17.3 mg) did not differ significantly among the 3 parts of the study. These results suggest that an increase in blood flow rate from 100 to 300 ml/min did not significantly affect the quantity of β2M adsorbed onto the AN69 membrane.
The Impact of Polyethylene Glycol Conjugation on Bovine Hemoglobin's Circulatory Half‐Life and Renal Effects in a Rabbit Top‐Loaded Transfusion Model
Authors: Conover Charles D. , Gilbert Carl W. , Shurn Kwok L. , Shorr Robert G.L.
Published: July 2010

Abstract: This study compares the effects of polyethylene glycol (PEG) modified bovine hemoglobin on vascular half‐life and renal function in rabbits to those of unmodi fied bovine hemoglobin. Renal function was assessed by the measurement of the glomerular filtration rate, urinalysis, blood chemistries, hemoglobin (Hb) excretion rates, and tissue histology. The influence of infusion rates on hemoglobin excretion rates and organ morphology was also examined. The mean half‐life of unmodified bovine hemoglobin was 3.0 ± 0.1 (mean ± SEM) h, which was extended 14‐fold to 43.2 ± 1.7 h following PEG conjugation. The glomerular filtration rate, urinalysis, and blood chemistries were not greatly affected by either the un modified bovine hemoglobin or the PEG modified bovine hemoglobin. However, unmodified bovine hemoglobin did demonstrate significant hemoglobinuria (Hb excretion levels in excess of 1.0% of the infused dose [p < 0.051) at all infusion rates given while PEG modified bovine hemoglobin did not. In addition, histological examination by light microscopy indicated that the most severe morphological changes occurred in animals that received unmodified bo vine hemoglobin. This data suggests that PEG modification of bovine hemoglobin significantly reduced some of the adverse effects of bovine hemoglobin on renal physiology and morphology.
The Importance of Pulsatile and Nonpulsatile Flow in the Design of Blood Pumps
Authors: Allen Gary S. , Murray Kevin D. , Olsen Don B.
Published: July 2010

Abstract: The traditional approach of total artificial heart (TAH) and ventricular assist device (VAD) development has been the mimicking of the native heart. Nonpulsatile flow using cardiopulmonary bypass has provided evidence of short‐term physiologic tolerances. The design of non pulsatile TAHs and VADs has eliminated the need for valves, flexing diaphragms, and large ventricular volumes. However, these devices require high efficiency power sources and reliable bearing seals or electromagnetic bear ings while simultaneously attempting to avoid thrombo‐emboli. The physiologic response to nonpulsatile flow is complex and variable. When compared to a pulsatile de vice, a nonpulsatile TAH or VAD needs to produce in creased flow and higher mean intravascular pressures to maintain normal organ function. Despite its maintaining normal organ function, nonpulsatile flow does cause alterations in biochemical functions and organ specific blood flow. The combination of bioengineering superiority and the maintenance of physiologic homeostasis has directed future TAH and VAD research towards nonpulsatile systems.
Blood Supply to the Latissimus Dorsi Muscle and Muscle Performance During Co‐ or Counterpulsatile Stimulation for Circulatory Assist
Authors: Takagi Hisato , Hirose Hajime , Sasaki Eisaku , Mikamo Hajime , Imaizumi Matsuhisa , Hirota Toshio , Bando Michiya , Furuzawa Yasunobu , Murakawa Shinji , Mori Yoshio
Published: July 2010

Abstract: For the application of the latissimus dorsi muscle (LDM) to circulatory assist, the muscle is stimulated with co‐ or counterpulsation during the cardiac cycle. The purpose of this study was to evaluate the blood supply to the LDM and its muscular performance during each respective stimulation. The origin of the LDM was connected to a tension gauge, a potentiometer, and 1 kg of weight in series. The LDM was stimulated at a ratio of 1:1 of heart to muscle contraction for 10 min. Copulsatile stimulation made thoracodorsal arterial flow (TDF) pre dominant during cardiac diastole. In counterpulsatile stimulation, TDF occurred predominantly during cardiac systole. Between the 2 patterns of stimulation, no significant differences were observed in the mean TDF rate during 1 cardiac cycle. The maximal force, maximal contrac tion length, and power of the LDM also did not differ significantly. These results suggest that despite the difference of the TDF profile, LDM performance may be com parable between co‐ and counterpulsatile stimulation for the application of the LDM to circulatory assist.
Mapping of Pump Efficiency on the Pressure‐Flow Curve of a Centrifugal Blood Pump
Authors: Takami Yoshiyuki , Nakazawa Tadashi , Makinouchi Kenzo , Glueck Julie , Benkowski Robert , Nosé Yukihiko
Published: July 2010

Abstract: Because pump efficiency is closely related to heat generation and blood trauma in a centrifugal blood pump, it is quite important to study pump efficiencies in a variety of conditions. In the present study, pump efficiencies were mapped on the pressure head‐flow rate curves of 4 different pumps; Bio Medicus Bio Pump (BP‐80), Nikkiso (NK), Gyro C1E3, and Gyro PI601 (diameter of the impeller, NK: 50 mm, ClE3: 65 mm, and PI601: 50 mm). The mapping of pump efficiency revealed the following findings. First, the cone type (BP‐80) has less pump efficiency than the impeller type (NK and ClE3); second, the miniaturization of the C1E3 to the PI601 has resulted in an increase in pump efficiency; and third, the diameter of the impeller may contribute to the pump efficiency of an impeller type pump. The mapping of the pump efficiency, as demonstrated in this study, is useful for the analysis of hydraulic pump performance in a wide range of clinically applied conditions.
Moving Actuator Type Total Artificial Heart with Reverse Position of the Aortic and Pulmonary Conduits
Authors: Kim Won Gon , Chang Jun Keun , Kim Hee Chan , Min Byoung Goo , Won Yong Soon , Rho Joon Ryang
Published: July 2010

Abstract: Adequate intrathoracic anatomical compatibility is one of the most important considerations in designing a fully implantable total artificial heart (TAH). We have recently developed an innovative concept of reverse positioning of the aortic and pulmonary conduits to facilitate anatomical compatibility of the moving actuator type TAH. The pulmonary conduit of this TAH is designed to be located posterior to the aortic conduit, which results in a substantial reduction in the anteroposterior diameter of this heart, as well as the virtual elimination of the compression of the low pressure pulmonary conduit. In ovine orthotopic implantation experiments with this model of the TAH, we consecutively achieved 3 day survival in 1 sheep and 2 day survival in another. To the best of our knowledge, these were the first significant short‐term survival cases in the orthotopic implantation of electric TAHs in sheep.
Hemodialysis Urea Rebound and Membrane Biocompatibility: Accuracy of Kt/V Estimations
Authors: Navarro Juan F. , del Castillo Nieves , Fernández José L. , Macía Manuel L. , Méndez María L. , Chahin J. , García‐Nieto Víctor , Gallego Eduardo , Mora‐Fernández Carmen , García Javier
Published: July 2010

Abstract: To date, the magnitude, causes, and factors that govern urea rebound are not clearly defined. This study was undertaken to determine the possible influence of the biocompatibility of dialyzer membrane on urea rebound and to assess the participation of rebound in the calculation of Kt/V‐urea by different methods. Blood urea samples were obtained before, and at 2, 30, and 60 min posthemodialysis in 8 patients undergoing dialysis with 2 different membranes, Cuprophan and polyacrylonitrile (24 sessions with each membrane). Urea rebound was documented in all patients. The degree of rebound was large,20%, and it was achieved within 30 min after the end of dialysis. Urea rebound was observed with both Cuprophan and polyacrylonitrile membranes, without significant differences. Kt/V‐urea significantly decreased (p < 0.001) by all methods when urea rebound was incorporated. We conclude that urea rebound is clinically very important and is not influenced by the biocompatibility of the dialyzer membrane. This phenomenon must be taken into account in the calculation of Kt/V; otherwise, it might be overestimated.
Effects of Self Washout Structure on the Antithrombogenicity and the Hemolytic Properties of a Centrifugal Pump
Authors: Wakisaka Yoshinari , Taenaka Yoshiyuki , Araki Kenzi , Chikanari Ken‐ichi , Nakatani Takeshi , Baba Yuzo , Anai Hirohumi , Eya Kazuhiro , Toda Koichi , Takano Hisateru
Published: July 2010

Abstract: Antithrombogenicity in an initial type (Nl) of a centrifugal pump (CP) developed in our institute is provided by the central balancing hole of an impeller. A new CP (N2) was modified to obtain better antithrombogenicity, in which the balancing hole was widened to improve self washout flow velocity (Vsf), and an edge of the thrust bearing was rounded off to minimize flow separation. Effects of the modifications were assessed in vitro and in vivo studies. The Vsf of the Nl and the N2 evaluated by a Doppler velocimeter were 12.8 and 22.1 cm/s, respectively. Flow around the thrust bearing, which was visualized by a light cutting method, confirmed less flow stagnation in the N2. The hemolytic indices of the Nl and the N2 were 0.023 and 0.008 mg/dl, respectively. In vivo antithrombogenicity and the hemolytic properties of the N2 and the Nl were investigated without anticoagulation therapy in 3 goats. In each goat the N2 was driven for 1 week and exchanged for the Nl, which was driven for the same period. Red thrombi at the thrust bearing were found in 2 Nls, and 2 small thrombi were on the impeller of another Nl, whereas a thrombus of less than 1 mm3 at the TB was noted in 1 N2. Plasma free hemoglobin was not increased in either CP. These results indicate that the N2 has better antithrombogenicity and hemolytic properties than the Nl.