bluuebunny/crossref_metadata_2025 huggingface dataset:
A Method for Extracorporeal Heparin Removal from Blood by Affinity Chromatography
Authors: Hou Kenneth C. , Roy Sujata , Zaniewski Richard , Shumway Edward
Published: November 2008

Abstract: A high level of heparin, infused into blood, often causes severe complications such as hemorrhage, especially when a drug is administered over a long period. The most common way of preventing a patient from bleeding after transfusion is by administering a heparin antagonist such as protamine. The complex molecules formed between heparin and protamine, if left in the bloodstream, may cause hypotension and other side effects. Protamine was immobilized as a bioligand on the affinity matrix formed by grafting an acrylic polymer on cellulose backbone. By flowing blood tangentially along the matrix surface immobilized with protamine, 70–90% heparin reduction was achieved from 1 L of blood containing 10 IU/ml of heparin studied in vitro. The acrylic gel surface avoids lysis of blood, the cellulose support sustains the flow of viscous blood at 50 ml/min, and the tangential flow design permits direct processing of blood without pressure buildup in the system. The example demonstrates the feasibility of applying such a device as a means of immunoadsorptive filter for the selective removal of disease‐causing factors from blood.
Thoughts and Progress
Authors: Solen Kenneth A. , Mohammad Syed F. , Pijl Aarnout J. , Swier Patrick , Monson Ryan D. , Olsen Don B.
Published: November 2008

Abstract: The constant‐pressure filtration (CPF) method has been developed to assess blood microemboli (BME) in terms of their ability to occlude microvascular flow. Previous reports suggest that the method is sensitive to the effects of platelet stimulation and to blood‐pumping conditions. BME production and heparin activity were studied in bovine and human blood pumped by a Pelle‐thane ventricle with Pellethane molded valves connected via smooth quick‐connects to a Pellethane horseshoe‐shaped reservoir. In each experiment, blood was collected into heparin by cardiac puncture from a stunned animal or by venepuncture from a human donor. The blood from each donor was filled into three ventricle‐reservoir systems (50 cc ventricle and 1,500 cc reservoir for the bovine blood, and 20 cc ventricle and 150 cc reservoir for the human blood). One of the systems received aspirin (ASA; 25 mg/dl) shortly after the onset of pumping, whereas the other two served as pumping and non‐pumping controls. The blood was pumped in a full‐fill/full‐eject mode for up to 10 h. BME concentration was measured by the CPF method in which the blood was filtered through 20‐μm pore filters at 20 mm Hg for 10 s, and the flowrate curves were evaluated from an occlusion model. Heparin activity was measured by the activated partial thromboplastin time (APTT) test. In the early period after the onset of pumping, the BME concentration increased, whereas the APTT decreased from an initial value of<250 s, with the relative rate of change for both the BME and the APTT being the following: pumping control < pumping ASA blood < quiescent control. When the APTT fell below a critical value (an average oi 36 s for the bovine blood and 126 s for the human blood), the BME increased very rapidly, presumably because oi microdot formation. The CPF method appears to be sufficiently sensitive to detect BME when anticoagulation is adequate and to detect microdot formation when anticoagulation is inadequate. The method also indicated that the effects of ASA on BME formation were similar to ASA effects on heparin neutralization. Finally, the results indicated species differences in the rate of heparin neutralization and in the heparin activity corresponding tc the onset of microdot formation.
Development of a New Antithrombogenic Continuous Ultrafiltration System
Authors: Arakawa Masaaki , Nagao Masanosuke , Gejyo Fumitake , Terada Ryozo , Kobayashi Takuichi , Kunitomo Tetsunosuke
Published: November 2008

Abstract: By interfacing a polyacrylonitrile (PAN)polyethyleneoxide (PEO) membrane with an ionically heparin–bound catheter, tubing, and module header, a totally antithrombogenic continuous ultrafiltration system (ACUS) was developed and its performance, persistent antithrombogenicity, and well–maintained ultrafiltration level were confirmed through animal experiments. Although the amount of heparin released and accumulated in vitro from those heparinized parts was very low and stable (on the order of 1 times 10‐2 U/cm2/min), partial thromboplastin time evaluated in vivo was not elongated during passage through the ACUS. Extracorporeal circulation time with the ACUS in unheparinized dog model was 458 ± 302 min (n = 24), whereas those of partially modified (antithrombogenic) system did not exceed 100 min. As compared with that in a conventional continuous arteriovenous hemofiltration system, an extracorporeal circulation with the ACUS in an unheparinized dog model revealed significantly less fluctuation of platelet count, and no adherent platelets were observed on the surface of the PAN–PEO membrane. An ACUS consisting of a PAN–PEO membrane and heparinized parts was thus demonstrated to have good platelet compatibility. An ACUS with a surface area of 0.25 m2 was applied to two patients with acute renal failure. Hemofiltration without systemic heparinization lasted for 44 h per hemofilter, and a stable level of ultrafiltration was maintained. This system seems to be applicable for the clinical management of volume overload, especially in patients with bleeding tendencies or postoperative bleeding.
Evaluation of a Filtration Lymphocytapheresis (LCP) Device for Use in the Treatment of Patients with Rheumatoid Arthritis
Authors: Kondoh Takefumi , Hidaka Yasuo , Katoh Hitoshi , Inoue Noboru , Saito Shiro
Published: November 2008

Abstract: A practical on–line lymphocytapheresis (LCP) system using a leukapheresis filter (Cellsorba, Asahi Medical Co.) was evaluated in six patients with refractory rheumatoid arthritis. This filter consists of nonwoven fine polyester fiber wound around a porous cylinder. The blood was passed through the polyester fiber at a flow rate of 50 ml/min for 60 min. LCP was carried out once a week in the first month and biweekly in the next 2 months. An average of 98% of the leukocytes that entered the filter (1.27 times 1010 cells) and 100% of the lymphocytes that entered the filter (3.66 times 109 cells) were removed in the first LCP. A total of 96.6% of the platelets and 2.7% of the erythrocytes that entered the filter were also removed. All of the patients showed clinical improvement in morning stiffness, Lansbury articular index, and func tional capacity, with no adverse reaction. The number of circulating erythrocytes and platelets and the concentration of various serum components showed no significant change during the treatments. This LCP system required no fresh frozen plasma, albumin, or other blood transfusion. The number of circulating lymphocytes decreased to 65–70% of the pretreatment circulating lymphocyte count at the last procedure, with a decrease in the ratio of Leu3a positive cells to Leu2a positive cells. The proliferative response to phytohemagglutinin and concanavalin A was improved. These data suggest that LCP to remove ˜3 times 109 lymphocytes once a week or biweekly has an immunomodulatory effect.
Development of an Artificial Placenta: Survival of Isolated Goat Fetuses for Three Weeks with Umbilical Arteriovenous Extracorporeal Membrane Oxygenation
Authors: Unno Nobuya , Kuwabara Yoshinori , Okai Takashi , Kido Koichiro , Nakayama Hirotoshi , Kikuchi Akihiko , Narumiya Yumiko , Kozuma Shiro , Taketani Yuji , Tamura Masanori
Published: November 2008

Abstract: The purpose of our study was to examine the feasibility of long‐term extrauterine incubation of an isolated premature fetus in artificial amniotic fluid with arteriovenous extracorporeal circulation. Two premature goat fetuses (age 120 and 128 days) were incubated in an isothermal artificial amniotic fluid incubator with arteriovenous extracorporeal membrane oxygenation via the umbilical vessels. We administered pancuronium bromide to suppress fetal movement and swallowing because movement and swallowing have been implicated in fetal deterioration during extrauterine fetal incubation. The fetuses maintained stable circulatory and respiratory parameters. The total incubation time was 494 and 543 h. The animals were then removed from the incubator and stimulated to initiate lung respiration. With ventilator support, both animals maintained stable blood‐gas exchange and survived for more than 1 week. These results clearly indicate that umbilical arteriovenous extracorporeal membrane can effectively support extended extrauterine incubation of an isolated premature fetus.
Interesting Features of an Activated Carbon Supported Urease System
Authors: (Demirel) Kibarer Günay
Published: November 2008

Abstract: Spherical activated carbon was employed as a new support material for the immobilization of urease. Activity and kinetic behavior of the enzyme were observed. Urease activity was decreased by 10% for the uncoated samples during the washing process whereas a 30% reduction in activity was observed for the coated samples due to the electrical discharge. Activity versus time plots generally appeared to be s‐shaped curves at different initial urea levels. At high substrate concentration the kinetics no longer obeyed the Michaelis‐Menten relationship due to the inhibition mechanism and diffusion for the support system.
Subclavian Vein Hemodialysis Catheters: Advantages and Disadvantages
Authors: De Moor B. , Vanholder R. , Ringoir S.
Published: November 2008

Abstract: The pros and cons of subclavian vein hemodialysis catheters are reviewed. The subclavian vein catheter offers rapid and adequate vascular access. Other advantages are preservation of patient mobility and the ease with which the dressing can be secured. In contrast, subclavian vein stenosis has recently been identified as an important long‐term complication of subclavian vein catheters that seriously compromises the creation and long‐term viability of later ipsilateral arteriovenous fistulas. For this reason, we recommend restricting use of the subclavian hemodialysis catheter for acute situations and preferential use of internal jugular catheters for more chronic approaches because they better preserve venous integrity.
Vascular Access in Continuous Arteriovenous Hemodiafiltration
Authors: Bosch Frank H. , van Ieusen Rob
Published: November 2008

Abstract: We describe experiences with the use of silicone catheters for continuous arteriovenous hemodiafiltration (CAVHD) in 43 patients in the Intensive Care Unit from July 1991 through March 1993. There were no serious complications with regard to the use of these wide‐bore catheters at introduction, during therapy, or at removal. All patients who needed renal replacement therapy could be treated with CAVHD. This low complication rate is probably due to a very strict CAVHD protocol and the fact that only a few people supervise this therapy.
Vascular Access Device for Treatment of Cancer Patients
Authors: Honda Hiroshi , Hayashi Taketoshi , Kimikawa Masaaki , Teraoka Satoshi , Agishi Tetsuzo
Published: November 2008

Abstract: Vascular access devices that are completely implanted have been used for treatment of cancer patients. Vascular access devices are useful for transarterial infusion of anticancer drugs, intravenous hyperalimentation, and drainage of bile juice in obstructive jaundice. These systems have several advantages in the care of patients: they are sealed, they have no external tubes, and they may be useful for blood or biliary sample and intravenous hyperalimentation or chemotherapy. There are only minimal discomforts related to the implantation procedure and no need for routine external catheter care. Most importantly, the quality of the patient's life is dramatically improved without external tubes. For these reasons, we believe that vascular access devices should be indicated for patients with malignant tumors as much as placement of these devices is technically feasible.
Complications and Side Effects Associated with Large‐Bore Catheters in the Subclavian and Internal Jugular Veins
Authors: Bambauer R. , Inniger R. , Pirrung K.J. , Schiel R. , Dahlem R.
Published: November 2008

Abstract: Since the introduction of large‐bore catheters for acute hemodialysis 30 years ago, many problems with handling, material, and contamination of these catheters exist. Nevertheless, catheterization of the inferior and superior vena cava with a large‐bore catheter has proved to be suitable as a rapid connection process for hemodialysis, hemofiltration, hemoperfusion, plasmapheresis, plasmaperfusion, among others. In a retrospective study with 2,741 large‐bore catheters in 1,716 patients, the frequency of infections, thrombosis, bleeding, and other side effects was investigated. All complications and side effects are presented dependent on vascular access route. In total, the complication rate was 48.9% higher in subclavian puncture than in internal jugular puncture (24.8%). The highest complication rates for both vascular access routes were infections or septicemia; infections were observed in 19.5% of subclavian catheters versus 10% of internal jugular catheters.
Use of an Implantable Catheter System for Intraperitoneal Chemotherapy in Ovarian Cancer
Authors: Brandner P. , Neis K.J.
Published: November 2008

Abstract: To check the efficiency of intraperitoneal chemotherapy of ovarian carcinomas, 15 patients were treated with instillations of mitoxantrone or cisplatinum. An implantable catheter system was used to access the abdominal cavity. Local therapy proved to be without any effect when large tumor masses were treated. Patients with small tumor residues after surgery did not benefit either, partly because of extraperitoneal progress of the disease. Patients without evidence of disease proved to be stable. Side effects of the therapy were usually mild compared with those of systemic chemotherapy. Access to the peritoneal cavity with the implantable catheter proved to be safe and reliable.
Comparison of Rechargeable Lithium and Nickel/Cadmium Battery Cells for Implantable Circulatory Support Devices
Authors: MacLean Gregory K. , Aiken Peter A. , Adams William A. , Mussivand Tofy
Published: November 2008

Abstract: Size and weight constraints are critical areas in the design of implantable medical devices. For this reason, a study of different rechargeable lithium and nickel/ cadmium (Ni/Cd) battery cell types was undertaken to determine which cell type, when assembled into a multicell battery pack, would provide the smallest and lightest power source for implantation. The discharge rate and cycle life characteristics of 2 different rectangular prismatic Ni/Cd cells and 5 different rechargeable lithium cells were determined at 37°C by charge/discharge cycling, the cells using a constant discharge load of 0.87 A. Using the observed discharge rate and cycle life characteristics of the cells, along with the desired performance criteria of 30 min operating time at the end of a 1‐year implant period, the projected weight and volume of the various 12‐V battery packs were determined. These results showed that one of the rectangular prismatic Ni/Cd cells would yield the smallest (53 ml) and lightest (189 g) 12‐V battery pack that met the performance criteria specified. The results also indicate that, for applications requiring long implant times, cycle life can be more important in the selection of cells for a small, lightweight battery pack than specific energy or energy density.
Nonbiological Liver Support: Historic Overview
Authors: Malchesky Paul S.
Published: November 2008

Abstract: An effective hepatic assist system could serve as a bridge to transplantation or to treat acute or chronic hepatic failure. Early nonbiological approaches focused on the removal of low molecular weight toxins by dialysis or hemoperfusion, such as over charcoals or resins. This approach led to clinical trials that showed varying degrees of success. Introduction of more porous membranes and blood separation technologies stimulated the development of plasma exchange, on‐line plasma fractionation technologies with sorbents and membranes, and other schemes of sorbent‐blood interactions based on the principles of dialysis and hemofiltration with sorbent perfusion. Although detoxification of blood has improved the prognosis for acute liver failure, key issues of when to initiate treatment and by which method need to be resolved. In chronic liver disease, blood detoxification can be applied in patients intractable to conventional therapies and for some awaiting transplantation to relieve disease symptoms such as pruritus, jaundice, elevated bile acids, hyperbilirubinemia, endotoxemia, and hypercholesterolemia. Although biological support is considered the ideal, nonbiological techniques can be useful because hepatocytes possess a regenerative capacity and temporary support is helpful. Available nonbiological liver support technologies can substitute for select liver functions in acute and chronic disease.
Effect of Nonbiological Hepatic Assist on the Mitochondrial Function of the Liver: Basic Consideration
Authors: Asanuma Yoshihiro , Koyama Kenji
Published: November 2008

Abstract: The significance of nonbiological hepatic assist (i.e., blood purification) in obstructive jaundice was considered using mitochondria (Mt) fractionated from hepatocytes. An obstructive jaundiced model was created using rats with ligated bile ducts. One, 2, and 3 weeks later, the respiratory function of the hepatic Mt were comparatively evaluated between Mt directly fractionated from liver tissue and Mt fractionated from hepatocytes obtained by Seglen's method for elimination of respiratory inhibitory factors around Mt. Of Mt from liver tissue, ATP synthesis decreased to 75% of the control at 1 and 2 weeks, and to 58% 3 weeks after ligation. In contrast, ATP synthesis was 97, 88, and 87% of the control at 1, 2, and 3 weeks in Mt from hepatocytes. Blood purification could remove respiratory inhibitory factors within or externally in liver cells and restore the mitochondrial function of the liver in obstructive jaundice.
A Comparison of Molecular Clearance Rates During Continuous Hemofiltration and Hemodialysis with a Novel Volumetric Continuous Renal Replacement System
Authors: Jeffrey Robin F. , Khan Afzal A. , Prabhu Prakash , Todd Neil , Goutcher Edward , Will Eric J. , Davison Alexander M.
Published: November 2008

Abstract: We developed a continuous, volumetrically controlled veno‐venous renal replacement system that can be operated in filtration or dialysis modes. We compared the clearances of substances with a range of molecular weights (MW) in each mode. Ten patients with acute renal failure underwent serial postdilutional hemofiltration and hemodialysis, for 30 min each, in sequence and in randomized order. All were receiving vancomycin for concurrent sepsis. The system incorporated a Filtral 10 AN69 artificial kidney; blood flow rate was 200 ml/ min, and dialysate/filtrate flow rate was 25 ml/min. Sieving (SC) and diffusion (DC) co‐efficients, for hemofiltration and hemodialysis, respectively, were identical for urea (MW 60; 1.01 ± 0.05 vs 1.01 ± 0.07) and creatinine (MW 113; 1.00 ± 0.09 vs 1.01 ± 0.06), and clearance equated with dialysate/filtrate flow. There was a modest difference in uric acid clearance (MW 168; SC 1.01 ± 0.04 vs DC 0.97 ± 0.04; p < 0.05). Vancomycin (MW 1,800) removal was 19% greater during filtration compared with dialysis (SC 0.87 ± 0.10 vs DC 0.74 ± 0.06; p < 0.01). For small solutes, the two modalities were equivalent. Vancomycin clearance was appreciably greater with hemofiltration, which is consistent with a greater potential for convection‐based therapy in the removal of uremic and other middle molecules.
Reduced Susceptibility of Polytetrafluoroethylene Vascular Prostheses to Colonization by Staphylococcus aureus Following In Situ Endothelialization
Authors: Zdanowski Z. , Hallberg E. , Schalén C. , Ribbe E.
Published: November 2008

Abstract: The impact of endothelialization of polytetrafluoroethylene (PTFE) grafts on susceptibility to experimental colonization by Staphylococcus aureus was studied in a rat model. One hundred and eight grafts (2 mm inner diameter, 5 mm length) were implanted into the infrarenal aorta (54 rats) or the infrarenal caval vein (54 rats). The progress of endothelialization following graft implantation was evaluated by SEM at 1, 3, 7, and 14 days on 6 grafts from each group. We found that the endothelialization was more rapid in caval vein than in aorta: The caval vein grafts were completely endothelialized 2 weeks following implantation compared with endothelialization of approximately 0.5 mm of aorta grafts, measured from each anastomosis. During this time, the resistance to standardized intravenous challenge with 108 colony‐forming units of S. aureus increased gradually in both groups, and all caval vein grafts tested at 2 weeks were sterile. However, all aorta grafts challenged at 2 weeks were colonized, although to a somewhat lower degree than at earlier challenge. Resistance of PTFE grafts to colonization with S. aureus thus correlated to the degree of endothelialization.
The Need for Standardizing the Index of Hemolysis
Authors: Naito Kozo , Mizuguchi Kazumi , Nosé Yukihiko
Published: November 2008

Abstract: Hemolysis is one of the most important performance parameters of blood pumps. However, comparative in vitro evaluation of the reported hemolysis effect is difficult owing to the lack of uniformity in the test methods used. Currently, three types of formulas are generally accepted and widely used for the index of hemolysis: the traditionally used index of hemolysis (defined as grams of plasma free hemoglobin released per 100 L of blood pumped); the normalized index of hemolysis (normalized by hematocrit); and the modified index of hemolysis (taking into account not only hematocrit but also hemoglobin). In addition, the tested blood conditions are often not indicated in the reports. To address this confusing situation, all three indices of hemolysis were routinely derived in our laboratory. To avoid further confusion, the tested blood conditions and test loop were defined in each study in our laboratory. If we limit the acceptable range of hemoglobin in human blood, the normalized index of hemolysis is sufficient. Furthermore, using milligrams as the unit of expression would be easier and reasonable for comparing the less hemolytic blood pumps, such as the centrifugal pumps that are currently available clinically. We would like to propose this value of a normalized index of hemolysis in milligrams as the most useful formula for the index of hemolysis in the assessment of various types of rotary blood pumps.
Successful Thermal Management of a Totally Implantable Ventricular Assist System
Authors: Tasai Kimitaka , Takatani Setsuo , Orime Yukihiko , Damm George , Ohara Yasuhisa , Naito Kozo , Makinouchi Kenzo , Mizuguchi Kazumi , Matsuda Yukihiro , Shimono Takatsuga , Glueck Julie , Noon George P. , Nosé Yukihiko
Published: November 2008

Abstract: Thermal management of the implantable ventricular assist system (VAS) is important not only from the pathophysiological point of view but also from the standpoint of system endurance. The heat distribution within the Baylor VAS was measured using different motor housing materials and environmental conditions. The temperature of the circulating water in the mock loop was set at 37° and 42°C. A polycarbonate motor housing was not a suitable material because of the high temperature development in the actuation system. An anodized aluminum housing demonstrated excellent heat conductivity. The surface temperature of this motor housing was 41.6°C when immersed in circulating water at 42°C. Heat conduction from the motor to the circulating blood revealed an effective thermal path. In the worst case, the heat flux of the motor to the circulating blood revealed an effective thermal path. In the worst case, the heat flux of the motor housing was calculated to be less than 0.062 W/cm2—an acceptable level for the surrounding tissues.
The Status of Pacemaker Implantations in Japan
Authors: Kojima Ryusuke
Published: November 2008

Abstract: It has been over 40 years since the initial clinical application of a cardiac pacemaker. Currently, approximately 300 per million patients in the United States and Europe are kept alive owing to the benefit of implantable pacemakers. Recently, the Japanese Cardiac Pacing Society and the Japanese Society of Artificial Organs performed pacemaker registry studies for 1989 and 1990. In this paper, results of this survey are described. Currently, implantable cardiac pacemakers are utilized only on the level of 120 per million patients in Japan. Surprisingly, all implantations were performed using foreign manufactured pacemakers. Despite the high level of electronic technologies available in Japan, no Japanese‐made implantable cardiac pacemakers are utilized in Japan. One could speculate that a major reason for the low level of clinical application of cardiac pacemakers is that these devices are quite expensive because of the import duties imposed on them. It is necessary and strongly recommended that implantable cardiac pacemakers be manufactured in Japan in order for them to be utilized as fully as they are in the United States and Europe.
Adsorption of Human Recombinant Erythropoietin on Dialysis Membranes In Vitro
Authors: Mori Hidetaro , Hiraoka Keisuke , Yorifuji Ryoichi , Iwasaki Tohru , Gomikawa Syuzo , Inagaki Ohshi , Inoue Seishi , Takamitsu Yoshihiro , Fujita Yoshikazu
Published: November 2008

Abstract: The adsorptive characteristics of 5 dialysis membranes for recombinant human erythropoietin (EPO) were studied in vitro in a closed circuit system. For 120 min, EPO added with bovine serum was significantly adsorbed by polymethylmetacrylate (PMMA) and polyacry–lonitrile (PAN) membranes but not by Cuprophan, ethylene vinyl alcohol (EVAL), or polysulfone (PS) membranes. In addition the EPO adsorptive rate, as well as that of β2–microglobulin (β2–MG), was greater with a PMMA membrane than with a PAN membrane. EPO was not detected in the ultrafiltrate at 15 min with 5 membranes. These results indicate that EPO was eliminated by membrane adsorption only with some dialysis membranes.
In Vitro and In Vivo Evaluation of Protamine–Heparin Membrane for Microencapsulation of Rat Langerhans Islets
Authors: Tatarkiewicz Krystyna , Sitarek Elzbieta , Fiedor Piotr , Sabat Marek , Orlowski Tadeusz
Published: November 2008

Abstract: Rat pancreatic islets were microencapsulated with multilayer protamine–heparin (PH) membrane. Basal and stimulatory insulin secretion of microencapsulated islets was similar to the controlled free islets in vitro. During the long–term culture (up to 2 weeks) mean insulin release of encapsulated islets did not significantly differ from the mean of free ones (the ratio of mentioned means was 54–167%). Empty PH microcapsules transplanted into Wistar rats intraperitoneally and under the kidney capsule were generally harmless up to 4 months. In only a few cases traces of fibrotic tissue around capsules entrapped in the omentum were found. No damage of microcapsules structure was observed. The worst results were obtained in the instance of retroperitoneal transplantation. We conclude, therefore, that PH membrane was proved to be highly biocompatible, nontoxic for islets, and did not impair viability and glucose–dependent insulin secretion of Langerhans islets in in vitro culture.
Preliminary Study on the Effect of Substrate Size on Cellular Immunomodulations
Authors: Miyazaki Hiroshi , Murabayashi Shun , Yuhta Toshio , Onoé Kazunori
Published: November 2008

Abstract: It is well known that the adsorption behavior of lymphocytes on fiber materials is related to the fiber size. In our previous study, murine lymphocytes cultured on various sizes of fibers showed different interleukin 2 (IL–2) activity, and ultrafine fibers of 1. 5 |j. m showed the highest value. Based upon those results and to further evaluate the effects of fibers of different sizes on the modulation of lymphocyte functions, Concanavalin A (Con A) was immobilized on the surface of fibers having different diameters, and murine lymphocytes were cultured on these fibers. Fiber size effects on the lymphocytes were evaluated in terms of IL–2 production and adhesion morphology. The Con A immobilized fibers could stimulate lymphocytes to levels as high as 70–80% of the maximal value induced by the Con A solution. Statistical differences in IL–2 production were not observed among the fiber sizes although as fibers decreased in size, the contact area of the lymphocytes with fibers became smaller. The results suggest that smaller diameter fibers with less contact to adherent lymphocytes can affect lymphocyte function to similar extents on larger diameter fibers and that ultrafine fibers might be useful substrates for immobilizing immunomodulators.
Extraction of Serum Proteins Adsorbed on the Surface of Dialysis Membranes
Authors: Ozasa Hisashi
Published: November 2008

Abstract: Extraction of adsorbed proteins from dialysis membranes that had been used during actual hemodialysis procedures was performed. The condition of extraction with SDS plus 2–mercaptoethanol at 95°C is more efficient than with only PBS or with SDS solution without 2–mercaptoethanol at 37°C.
Use of Hemoperfusion in Experimental Intoxication with Nerve Agents
Authors: Monhart Vaclav , Fusek Josef , Brndiar Miroslav , Tlustakova Marie
Published: November 2008

Abstract: The aim of this study was to evaluate the efficiency of hemoperfusion (HP) through coated resin adsorbent Synachrom E–5 in animal intoxications with or–ganophosphate inhibitors of cholinesterases type of nerve agents. Five anesthetized dogs were intoxicated with 2 to 6 LD50 of VX substance and another 4 with 2 to 3 LD50 sarine. Both nerve agents were given i. m. after starting 5 h HP. The clinical and laboratory tests were monitored during each HP. HP therapy prevented the development of serious signs of intoxication provided that the administered quantity of both sarine and the VX substance was only 2 doses of LD50. Specific antidote therapy was necessary to prevent cardiorespiratory failure in animals intoxicated with a higher dose of poison. The results obtained show that HP through Synachrom E–5 in intoxication with nerve agents sarine and the VX type is only partially successful.
The Effect of Stimulating Voltage on Time Characteristics of Contraction in Cardiomyoplasty
Authors: Taguchi Shinichi , Yozu Ryohei , Iseki Harukazu , Takahashi Ryuichi , Kawada Shiaki
Published: November 2008

Abstract: In cardiomyoplasty (CMP), the strength of a skeletal muscle increases as the stimulating voltage in creases. On the other hand, timing of stimulation in CMP is a problem not yet solved. This experiment assessed the relationship between stimulating voltage and time characteristics in the contraction of skeletal muscles. In acute experiments using rabbits, the time required to reach maximal muscle contraction did not change significantly with voltage. In conclusion, stimulation voltage does not affect time characteristics. Thus, the best timing of stimulation in CMP can be assessed independently of voltage.
Development of an Intravenous Membrane Oxygenator: Enhanced Intravenous Gas Exchange Through Convective Mixing of Blood around Hollow Fiber Membranes
Authors: HATTLER BRACK G. , REEDER GARY D. , SAWZIK PATRICIA J. , LUND LAURA W. , WALTERS FRANK R. , SHAH ASHISH S. , RAWLEIGH JUDY , GOODE JOSEPH S. , KLAIN MIROSLAV , BOROVETZ HARVEY S.
Published: November 2008

Abstract: In vitro testing of a new prototype intravenous membrane oxygenator (IMO) is reported. The new IMO design consists of matted hollow fiber membranes arranged around a centrally positioned tripartite balloon. Short gas flow paths and consistent, reproducible fiber geometry after insertion of the device result in an augmented oxygen flux of up to 800% with balloon activation compared with the static mode (balloon off). Operation of the new IMO device with the balloon on versus the balloon off results in a 400% increase in carbon dioxide flux. Gas flow rates of up to 9. 5 L/min through the 14–cm–long hollow fibers have been achieved with vacuum pressures of 250 mm Hg. Gas exchange efficiency for intravenous membrane oxygenators can be increased by emphasizing the following design features: short gas flow paths, consistent and reproducible fiber geometry, and most importantly, an active means of enhancing convective mixing of blood around the hollow fiber membranes
Permissive Hypercapnia and Intravascular Oxygenator in the Treatment of Patients with ARDS
Authors: BRUNET F. , MIRA J. P. , CERF C. , BELGHITH M. , SOUBRANE O. , TERMIGNON J. L. , RENAUD B. , FIEROBE L. , HAMY I. , MONCHI M. , DESLANDE E. , BRUSSET A. , DHAINAUT J. F.
Published: November 2008

Abstract: This open clinical study was aimed at testing the hypothesis that an intravascular oxygenator (IVOX) may help to perform permissive hypoventilation in 10 patients with severe ARDS. After initial evaluation, we tried to reduce ventilator settings before and after IVOX implantation. Before IVOX, poor clinical tolerance and worsening oxygenation did not allow for a significant decrease in ventilator settings. With IVOX, peak inspiratory pressure (PIP) was reduced from 47 to 39 cm H2O (p = 0. 005) and minute ventilation from 13 ± 3. 5 to 11 ± 3 L/min. CO2 removal by IVOX allowed a significant decrease in Paco2 from 66 ± 15 to 59 ± 13 mm Hg. Improvement of oxygenation with IVOX was not signify cant. Furthermore, interruption of oxygen flow through IVOX did not change oxygenation variables. Tolerance of the IVOX device was good, but insertion of the device was followed by a significant decrease in both cardiac index and pulmonary wedge pressure. In conclusion, IVOX improves tolerance of hypoventilation by limiting hypercapnia in ARDS patients. These preliminary results must be confirmed by a randomized controlled study
In Vivo Gas Transfer Performance of the Intravascular Oxygenator in Acute Respiratory Failure
Authors: CONRAD STEVEN A. , ZWISCHENBERGER JOSEPH B. , EGGERSTEDT JANE M. , BIDANI AKHIL
Published: November 2008

Abstract: The intravascular oxygenator (IVOX) has undergone both animal and clinical trials. Data from the animal studies have demonstrated that the device is capable of transferring up to approximately 100 ml/min of oxygen and carbon dioxide. Initial data from the human trials suggest that gas transfer, although approaching these levels, varied widely in patients with respiratory failure. We studied the factors affecting gas exchange in 26 patients with severe acute respiratory failure who underwent intravenacaval support of gas exchange with IVOX. The patients underwent monitoring of IVOX gas transfer rates, hemodynamics, blood gases, and ventilation parameters at scheduled intervals following device insertion. All devices functioned following implantation. The mean value for O2 transfer was 64 ± 21 SD ml/min (range 15–114 ml/min) and for CO2 transfer was ± 17 ml min–1 (range 14–112 ml/min). CO2 transfer correlated positively with device surface area, cardiac output, and mixed venous PCO2 and negatively with duration of implantation. O2 transfer did not correlate with any patient factors probably due to error inherent in the measurement of this variable. Independent measurements of IVOX gas transfer by respiratory gas exchange in a subset of patients with normal values of mixed venous PCO2 were in good agreement with the routine measurements and indicated that the device provided up to 26% of gas exchange requirements in this subset. We conclude that IVOX transfers clinically useful amounts of oxygen and carbon dioxide in vivo. Factors that influence gas transfer include device surface area, PVCO2, cardiac output, and duration of implantion. Optimization of these factors (such as with permissive hypercapnea) could result in enhanced performance in vivo
Afterword: Bottom–Line Status Report: CAN Current Trends in Membrane Gas Transfer Technology Lead to an Implantable Intrathoracic Artificial Lung?
Authors: MORTENSEN JD
Published: November 2008

Abstract: For at least 170 years, attempts have been made to alleviate inadequate gas exchange of patients with respiratory failure. Major milestones in the struggle to assist failing natural lungs to achieve adequate blood gas exchange include utilization of oxygen inhalation therapy, mechanical ventilatory assistance, and development of both extracorporeal and intracorporeal mechanical blood gas exchangers. Current state–of–the–art technology related to mechanical membrane blood gas exchangers has produced highly efficient gas transfer membranes and designs capable of replacing all the gas transfer functions of the natural lungs by a mechanical oxygenator–CO2 remover that can fit into a unilateral thoracic cavity. The possibility thus exists of moving extracorporeal mechanical blood oxygenators into the body as an implantable intracorporeal artificial lung. Problems impeding the development of an implantable, intrathoracic artificial lung have been identified, and at least partially successful attempts to solve them have been reported. The conclusion drawn is that the appropriate answer to the question posed in the title of this communication is affirmative. Reasons for this conclusion include the persistent widespread major need for better relief from respiratory failure, the advanced state–of–the–art of mechanical blood gas exchanger technology, and the incompletely tapped ingenuity of the human mind.
Flow Pattern Analysis of the Baylor Total Artificial Heart
Authors: MEIER DIRK , ‐WERNICKE JENS‐TH. , ORIME YUKIHIKO , TAKATANI SETSUO , TASAI KIMITAKA , DAMM GEORGE , NAITO KOZO , MIZUGUCHI KAZUMI , MAKINOUCHI KENZO , GLUECK JULIE , SHIMONO TAKATSUGU , MATSUDA YUKIHIRO , OHARA YASUHISA , KOJIMA RYUSUKE , NOON GEORGE P. , DEBAKEY MICHAEL E. , NOSÉ YUKIHIKO
Published: November 2008

Abstract: To obtain an optimal design of the left blood chamber of the total artificial heart (TAH), flow visualization studies were performed. Information on velocities in critical areas of the left chamber was gathered using sectional pulsed laser light. The flow patterns on the entire pumping duration were photographed frame by frame. The inflow port, the opposite of the inflow and outflow of the pump (bottom area), and the diaphragm/ housing junction were the focal areas. The pump conditions, such as chamber pressure, preload and afterload pressure, pumping rate and roller screw, and displacement were recorded. Major stagnations and a low washout effect were observed in the bottom region. The closing of the inflow valve was irregular. In order to solve this problem, the inflow valve angle was changed 20 degrees. A comparison study showed a better valve closing characteristic, and no stagnation areas were observed with this new valve angle. Various velocity profiles confirmed the results. The valve closing characteristic is described in relationship to back flow.
Impact of Ultrafiltration on Back‐Diffusion in Hemodialyzer
Authors: WANIEWSKI JACEK , LUCJANEK PIOTR , Weryriski Andrzej
Published: November 2008

Abstract: Ultrafiltration of water from blood to dialysate decreases the rate of back–diffusion of solutes from dialysate to blood. Therefore, back–clearance (bK) of hemodialyzers may be expressed as bK=bKo–bTrQu, where bKo is the diffusive back–clearance, bTr is the “back–”transmittance coefficient, and Qu is the net ultrafiltration rate. A formula for bK was derived from the one–dimensional theory of hemodialyzer, and bTr was described as a function of bKo and the Staverman reflection coefficient. The transport parameters, bKo and bTr, for creatinine and vitamin B12 were measured in two types of hemodialyzers with negligible back–filtration, using water solutions, and compared with the transport parameters, Ko and Tr, for the case of both diffusion and ultrafiltration from blood to dialysate. bKo was in general equal to Ko. bTr was not different from Tr for creatinine whereas bTr was lower than Tr for vitamin B12. Experimental values of bTr for vitamin B12 were in general agreement with theoretical predictions. However, experimental values of bTr for creatinine were lower than predicted values. We conclude that the impact of ultrafiltration on back–clearance for slowly diffusing solutes is weaker than on their clearance.
A New Electrohydraulic Energy Converter for a Left Ventricular Assist Device
Authors: AFFELD K. , BAILLEU A. , BUß A. , DILUWEIT J. , FRIEDRICHSEN U. , GADISCHKE J. , HANITSCH R. , HETZER R. , HUBER A. , KÄHLER J. , KOEHLER M. , KÄUFER H. , MRASEK R. , RAMÖLLER A. , SCHICHL K. , SCHIESSLER U. , SIEKMANN H. , STROWICH S. , SVEJDA D. , TEUT J. , THELEN W. , THEOBALD J. N. , WEBER K. U. , WITTJEN C. , WALTER J. , ZIEMANN A. , ZIMMER R.
Published: November 2008

Abstract: An energy converting system that can function for years without maintenance is required for the drive of a left ventricular assist device (LVAD). To meet the requirements of safety, the energy converter should have a simple design with few moving elements. The design applied herein has only one moving part and thus has greater inherent safety than competing systems. The only moving part is the rotor unit, comprised of the impeller of a centrifugal pump, the rotor of an electric motor, and the rotor of an electric axial actuator. A reversal of flow of the transmitter fluid can be achieved with an axial shift of this rotor unit. This fluid acts on the outer surface of a blood chamber and enables it to draw in blood and to expel it. Valves direct the flow of blood. The energy converter performs a flow of 12 L/min at a motor speed of 6, 000 rpm against a pressure head of 115 mm Hg according to an output of the pulsatile blood pump of 5 L/min.
Improvement of Hemocompatibility on a Cellulose Dialysis Membrane with a Novel Biomedical Polymer Having a Phospholipid Polar Group
Authors: Ishihara Kazuhiko , Fukumoto Kikuko , Miyazaki Hideki , Nakabayashi Nobuo
Published: November 2008

Abstract: To improve surface hemocompatibility on cellulose hollow fibers for hemodialysis, newly designed hemocompatible polymers with a phospholipid polar group, 2–methacryloyloxyethyl phosphory[choline (MPC) polymers, were introduced on the surface through two different methods: direct grafting of MPC on the surface, or coating of a water–soluble cellulose grafted with MPC. The MPC was polymerized using cerium ion as an initiator in the cellulose hollow fibers, and the poly(MPC) chains were grafted directly on the surface. Another modification of the cellulose hollow fibers was attempted by coating them with a water–soluble graft copolymer composed of a poly(MPC) side chain and a cellulose backbone. The coating process from an aqueous solution of the graft copolymer was very convenient, and the graft copolymer on the surface was not detached even after water circulated into the hollow fibers. These cellulose hollow fibers modified with MPC polymers displayed excellent hemocompatibility such as prevention of blood cell adhesion and aggregation after contact with blood without an anticoagulant. The permeability of the hollow fibers did not decrease as a result of these modifications. From these results, it is clearly suggested that introduction of the MPC units was effective for improving the hemocompatibility of the hollow fibers for hemodialysis.
Novel Method to Determine Instantaneous Blood Volume in Pulsatile Blood Pump Using Electrical Impedance
Authors: Sasaki Eisaku , Nakatani Takeshi , Taenaka Yoshiyuki , Takano Hisateru , Hirose Hajime
Published: November 2008

Abstract: A novel real–time volumetric method was developed for a pulsatile pump. This method, the impedance method, used electrical impedance change in the blood chamber according to volume change while pumping. This method was evaluated with two kinds of air–driven diaphragm pumps. During in vitro tests, the impedance method indicated real–time volume change, and there was excellent correlation between computed stroke volume with the impedance method and measured stroke volume with the electromagnetic flowmeter. In chronic animal tests with goats and in a clinical case, the impedance method measured pump output accurately, and it detected diaphragm motion in real–time. In addition, excellent durability was seen. Full–fill to full–empty drive was realized accurately with this method. Application of the impedance method was easy, and it did not deteriorate native antithrombogencity of the pump. The impedance method is practical and useful to estimate the pumping condition of a pulsatile blood pump, especially a diaphragm pump. This method would be useful in clinical application.
Carotid Arterial Impedance During Oscillated Blood Flow
Authors: Kobayashi Shin–ichi , Nitta Shin–ichi , Yambe Tomoyuki , Naganuma Shigeru , Tanaka Motonao , Kasai Takeshi , Hashimoto Hiroyuki
Published: November 2008

Abstract: Blood perfusion of systemic circulation is influenced by the physical characteristics of artery. Several investigations proposed that the physical parameters of vessels are determined by neurological factors, hormonal factors, and physical properties of arteries among others. In this study, arterial impedance was estimated because it may express the condition of vessels. To examine the change of arterial impedance according to the blood flow pattern, the typical sine wave blood flow (oscillated flow) was used during total cardiopulmonary bypass (CPB) because it is considered the most simple pulsatile flow. CPB using oscillated blood flow was performed in acute experiments on adult goats. Total systemic flow was controlled to remain at approximately 80 ml/min. Carotid arterial flow, aortic pressure, central venous pressure, and systemic flow were measured. Total peripheral resistance, carotid arterial resistance, systemic impedance, and carotid arterial impedance were calculated to evaluate blood flow distribution during CPB. This study suggested that the parameters of carotid arterial blood flow changed according to the change of flow frequency during oscillated blood flow. This change may occur because arterial impedance was influenced by flow frequency; therefore, the blood flow of the carotid artery was significantly changed according to the change of the frequency component of blood flow.
Concept Designs of Nonrotating–type Centrifugal Blood Pump and Basic Study on Output Characteristics of the Oscillating Disk–type Centrifugal Pump
Authors: Kabei Nobuyuki , Tuichiya Kiichi , Sakurai Yasuhisa
Published: November 2008

Abstract: When designing a turbo–type blood pump as an artificial heart, the gap between a rotating shaft and a pump housing should be perfectly sealed to prevent any leakage or contamination through a seal. In addition, blood coagulation in a blood chamber must be avoided. To overcome these problems, we proposed five different nonrotating–type turbo pumps: a caudal–fin–type axialflow pump, a caudal–fin–type centrifugal pump, a nutating–column–type centrifugal pump, a nutating–collapsibletube–type centrifugal pump, and an oscillating–disk–type centrifugal pump. We selected and developed the oscillating–disk–type centrifugal pump that consists of a disk, a driving rod, a seal, an oscillation mechanism, and a pump housing. The disk is mounted on the end of the rod, which is connected to a high–speed DC motor through an oscillation mechanism. The rod and the disk do not rotate, but they oscillate in the pump housing. This movement of the disk generates forward fluid flow around the axis (i. e., the rotational fluid flow). Centrifugal force due to fluid rotation supports the pressure difference between the outlet and the inlet. The diameter of the disk is 39 mm, the maximum inner diameter of the pump housing is 40 mm, and the volume of the blood chamber for 25 degrees' oscillation is 16. 9 ml. The performance of the pump was tested in a mock circulatory system. Using the disk, in which two holes were bored and a blood chamber designed for 25 degrees' oscillation, output flow rate of 6 and 14 L/min were obtained under motor rotational speeds of 2, 700 and 3, 000 rpm, respectively, at 100 mm Hg mean aortic pressure.